Bio


Dr. Tsui completed his medical training at Dalhousie University, Halifax, in 1995 after obtaining his Masters of Science in Pharmacy in 1991. These degrees followed a Diploma in Engineering and Bachelors of Science in both Mathematics and Pharmacy. Dr. Tsui completed his anesthesia residency training at the University of Alberta Hospital in Edmonton in 2000, and he received further experience in pediatric anesthesia at British Columbia Children's Hospital in Vancouver. After 16 years of practice at the University of Alberta Hospital and Stollery Children’s Hospital, Dr. Tsui was recruited to Stanford University.

Currently, Dr. Tsui is a Medical Center Line (MCL) Professor in the Department of Anesthesiology, Perioperative and Pain Medicine at Stanford University. In his position as an adult and pediatric anesthesiologist at the Stanford University Medical Center and the Lucile Packard Children’s Hospital, he specializes in regional anesthesia techniques.

Dr. Tsui is an avid and internationally recognized researcher in many areas of regional anesthesia. During his residency, Dr. Tsui developed an interest in improving the accuracy of epidural catheter placement and was issued a U.S. patent in relation to his research. Dr. Tsui has expanded his research into the use of ultrasound in regional anesthesia, with particular relevance to peripheral nerve block performance. Dr. Tsui is also responsible for development of the E-Catheter catheter-over-needle kit for use during peripheral nerve blocks. The primary objective of his research is to transform regional anesthesia from an “art” into a reliable and reproducible “science” by further exploring the basic scientific and clinical aspects of electrophysiological signal monitoring and integrating this with the latest advances in ultrasound.

Dr. Tsui has received the Alberta Heritage Foundation for Medical Research (AHFMR) Clinical Scholar award and has previously received research awards and grants from the Canadian Institutes of Health Research (CIHR), Canadian Anesthesiologists’ Society, AHFMR, and University of Alberta. In 2015, a prestigious award, the CAS Research Recognition Award, was presented by the Canadian Anesthesiologists’ Society to Dr. Tsui "in recognition of significant research contributions to regional anesthesia, acute pain management and pediatric anesthesia in Canada and around the world".

Academic Appointments


Administrative Appointments


  • Director of Pediatric Regional Anesthesia (SUPRA), LPCH, Stanford University (2018 - Present)
  • Director of Research, Regional Anesthesia Division, Department of Anesthesiology, Stanford University (2018 - Present)
  • Vice Chair (Research), Department of Anesthesiology and Pain Medicine, University of Alberta (2009 - 2013)
  • Regional Rotational Coordinator, Department of Anesthesiology and Pain Medicine, University of Alberta (2006 - 2010)
  • Member of Residency Training Committee, Department of Anesthesiology and Pain Medicine, University of Alberta (2005 - 2010)
  • Director of Clinical Research, Department of Anesthesiology and Pain Medicine, University of Alberta (2003 - 2016)

Honors & Awards


  • CAS Research Recognition Award, Canadian Anesthesiologists' Society (2015)
  • Dr. R A Gordon Research Award, Canadian Anesthesiologists' Society (2014-2015)
  • University Hospital Foundation Medical Research Award, University Hospital Foundation (2014-2015)
  • Alberta Heritage Clinical Scholar Award, Alberta Heritage Foundation for Medical Research (2014)
  • Clinical Scholar Award, Alberta Heritage Foundation for Medical Research (2009-2016)
  • Canadian Institutes of Health Research Operating Grant, Canadian Institutes of Health Research (2008-2011)
  • CAS Career Scientist Award in Anesthesia, Canadian Anesthesiologists' Society (2008-2009)
  • Smiths Medical Canada Ltd. Canadian Research Award in Pain Research and Regional Anesthesia, Canadian Anesthesiologists’ Society (2008-2009)
  • John Bradley Young Educator Award, Canadian Anesthesiologists’ Society (2008)
  • Alberta Heritage Clinical Investigator Renewal Award, Alberta Heritage Foundation for Medical Research (2005-2008)
  • David S Sheridan Canadian Research Award, Canadian Anesthesiologists’ Society (2004-2005)
  • Sponsored Drug Trial, Purdue Pharma L.P. (2004)
  • Best Research Abstract, The American Society of Regional Anesthesia (Annual Meeting) (2003)
  • Clinical Investigator and Establishment Grant, Alberta Heritage Foundation for Medical Research (2002-2005)
  • Sponsored Drug Trial, Abbott Laboratories Ltd. (2002-2003)
  • Research Excellence Envelope, University of Alberta Faculty of Medicine and Dentistry (2001-2002)
  • Annual Residents’ Research Day (First Prize), Department of Anesthesiology and Pain Medicine, University of Alberta Hospital (2000)
  • Resident Publication Prize (Clinical Category), Faculty of Medicine, University of Alberta (2000)
  • Resident Publication Prize (Clinical Category), Faculty of Medicine, University of Alberta (1999)

Boards, Advisory Committees, Professional Organizations


  • Member, Association of University Anesthesiologists (2017 - Present)
  • Member (Regional Anesthesia), Guidelines and Regulatory Advocacy Committee, American Society of Regional Anesthesia and Pain Medicine (2017 - Present)
  • Associate Editor, Regional Anesthesia and Pain Medicine (2006 - Present)
  • Editorial Board Member, Canadian Journal of Anesthesia (2006 - Present)
  • Chair, ASRA Ultrasound Committee, American Society of Regional Anesthesia and Pain Medicine (2013 - 2016)
  • Member, Education Committee, American Society of Regional Anesthesia and Pain Medicine (2009 - 2016)
  • Member, Research Committee, Association of Canadian University Departments of Anesthesia (ACUDA) (2006 - 2016)
  • Research Member, Association of Canadian University Departments of Anesthesia (2000 - 2016)
  • Member, Research Committee, American Society of Regional Anesthesia and Pain Medicine (2010 - 2013)
  • Member, Annual Meeting Program Committee, American Society of Regional Anesthesia and Pain Medicine (2006 - 2007)
  • Head, Regional Anesthesia and Acute Pain Section, Canadian Anesthesiologists’ Society (2005 - 2007)
  • Treasurer/Secretary, Regional Section, Canadian Anesthesiologists’ Society (2002 - 2005)

Professional Education


  • Postgraduate Diploma, University of Melbourne, Postgraduate Diploma in Perioperative and Critical Care Echocardiography - Anesthesia (2010)
  • Board Certification, College of Physicians and Surgeons of British Columbia, Anesthesia (2001)
  • Board Certification, Royal College of Physicians and Surgeons of Canada, Anesthesia (2000)
  • Board Certification, Fellow of the Royal College of Physicians of Canada (FRCPC), Anesthesia (2000)
  • Board Certification, College of Physicians and Surgeons of Alberta, Anesthesia (2000)
  • Residency, University of Alberta Hospital, Anesthesia (2000)
  • Certificate, University of Alberta, Medical Acupuncture (1998)
  • MD, Dalhousie University, Medicine (1995)
  • MSc, Dalhousie University, Pharmacy (1991)
  • BSc, Dalhousie University, Pharmacy (1987)
  • BSc, Dalhousie University, Mathematics (1984)
  • Diploma in Engineering, Dalhousie University, Engineering (1983)

Patents


  • Chi-Ho Ban Tsui. "United States Patent 20080242975 Device and method for locating a cannula that is inserted into a body", Jun 9, 2010
  • Chi-Ho Ban Tsui. "United States Patent 20090210029 Device and method to position a cannula for nerve block", Aug 20, 2009
  • Chi-Ho Ban Tsui. "United States Patent 20080058757 Catheter Set for Epidural or Peripheral Nerve Blockade", Mar 6, 2008
  • Chi-Ho Ban Tsui. "United States Patent 6190370 Devices, systems and methods for determining proper placement of epidural catheter location", Feb 20, 2001

Clinical Trials


  • Interscalene Brachial Plexus Block Washout to Reverse Inadvertent Phrenic Nerve Blockade Not Recruiting

    One of the most frequently performed peripheral nerve blocks (the injection of local anesthetic near nerves to block sensation/ movement to a specific part of the body) is the interscalene brachial plexus block for upper extremity surgeries. This type of block can unmask underlying respiratory issues such as shortness of breath due to a well-known and typically insignificant side effect of temporary diaphragmatic paralysis. We may be able to use saline solution to wash out the local anesthetic and potentially reverse this respiratory side effect. Specifically, the goal of our study is to determine if the injection of saline through the nerve block catheter reverses blockade of the phrenic nerve supplying the diaphragm, without affecting the ability of the nerve block to provide pain control after surgery.

    Stanford is currently not accepting patients for this trial. For more information, please contact Lynn K Ngai, MD, (650) 575 - 0386.

    View full details

All Publications


  • Programmed Intermittent Bolus Regimen for Erector Spinae Plane Blocks in Children: A Retrospective Review of a Single-Institution Experience. Anesthesia and analgesia Munshey, F., Caruso, T. J., Wang, E. Y., Tsui, B. C. 2018

    Abstract

    With few published reports on erector spinae plane block use in children, limited guidance on perioperative local anesthetic dosing exists. We present a series of 22 patients who received erector spinae plane catheters with programmed intermittent bolus for various surgeries. Median loading dose of 0.4 mL/kg (interquartile range [IQR], 0.1 mL/kg) ropivacaine 0.5%, intraoperative bolus of 0.3 mL/kg/h (IQR, 0.1 mL/kg) ropivacaine 0.2%, and a postoperative programmed intermittent bolus regimen of maximum 0.6 mg/kg/h resulted in highest pain scores on postoperative day 1 with a median score of 1.7 of 10 (IQR, 1.8) and highest morphine equivalents consumed on postoperative day 2 with a median score of 0.16 mg/kg up to 120 hours after surgery.

    View details for DOI 10.1213/ANE.0000000000003817

    View details for PubMedID 30252704

  • The successful application of high flow nasal oxygen during microdirect laryngoscopy and bronchoscopy in patients under 7 kg. Journal of clinical anesthesia Caruso, T. J., Gupta, A., Sidell, D. R., Darling, C., Rodriguez, S., Fonseca, A., Tsui, B. 2018; 52: 27–28

    View details for DOI 10.1016/j.jclinane.2018.08.027

    View details for PubMedID 30153541

  • A Novel and Simple Setup for Positioning the Lower Extremity Using Commonly Accessible Equipment. Regional anesthesia and pain medicine Lin, C., Munshey, F., Tsui, B. C. 2018; 43 (5): 561–62

    View details for DOI 10.1097/AAP.0000000000000805

    View details for PubMedID 29927852

  • A systematic approach to scoring bleeding risk in regional anesthesia procedures. Journal of clinical anesthesia Tsui, B. C. 2018; 49: 69–70

    View details for DOI 10.1016/j.jclinane.2018.06.011

    View details for PubMedID 29909204

  • Early experience with PECS 1 block for Port-a-Cath insertion or removal in children at a single institution. Journal of clinical anesthesia Munshey, F., Ramamurthi, R. J., Tsui, B. 2018; 49: 63–64

    View details for DOI 10.1016/j.jclinane.2018.06.010

    View details for PubMedID 29894919

  • Intermittent Bolus Injection Via Peripheral Nerve Catheters May Exceed Occlusion Pressure Limit of an Ambulatory Infusion Pump: An In Vitro Study. Regional anesthesia and pain medicine Tsui, J. H., Ma, W., Tsui, B. C. ; 42 (4): 538–39

    View details for DOI 10.1097/AAP.0000000000000625

    View details for PubMedID 28632675

  • Letter to the Editor: Early Consequences of Pectus Excavatum Surgery on Self-Esteem and General Quality of Life. World journal of surgery Darling, C., Chao, S., Ramamurthi, R., Tsui, B. 2018

    View details for DOI 10.1007/s00268-018-4704-9

    View details for PubMedID 29882100

  • Washing off local anaesthetic induced phrenic dysfunction following interscalene block. Journal of clinical anesthesia Tsui, B. C., Price, D. 2018; 49: 38–39

    View details for DOI 10.1016/j.jclinane.2018.05.001

    View details for PubMedID 29883966

  • Continuing education: from FRCPC to ACGME fellowship CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Munshey, F., Tsui, B. H. 2018; 65 (5): 592–93

    View details for DOI 10.1007/s12630-017-1033-7

    View details for Web of Science ID 000429430700015

    View details for PubMedID 29204874

  • Survey of medical students' knowledge and perceptions of anesthesiology at one Canadian university: pre-clerkship and during clinical clerkship, a cohort study CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Henschke, S. J., Robertson, E. M., Murtha, L., Tsui, B. H. 2018; 65 (3): 325–26

    View details for DOI 10.1007/s12630-017-1012-z

    View details for Web of Science ID 000425021800016

    View details for PubMedID 29150785

  • Ultrasound-guided lateral-medial transmuscular quadratus lumborum block for analgesia following anterior iliac crest bone graft harvesting: a clinical and anatomical study CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Sondekoppam, R. V., Ip, V., Johnston, D. F., Uppal, V., Johnson, M., Ganapathy, S., Tsui, B. H. 2018; 65 (2): 178–87

    Abstract

    The anterior iliac crest (AIC) is one of the most common sites for harvesting autologous bone, but the associated postoperative pain can result in significant morbidity. Recently, the transmuscular quadratus lumborum block (TQL) has been described to anesthetize the thoraco-lumbar nerves. This study utilizes a combination of cadaveric models and clinical case studies to evaluate the dermatomal coverage and analgesic utility of TQL for AIC bone graft donor site analgesia.Ten ultrasound-guided TQL injections were performed in five cadaver specimens using a lateral-to-medial transmuscular approach. Twenty mL of 0.5% methylcellulose was injected on each side after ultrasound confirmation of the needle tip ventral to the quadratus lumborum muscle (QLM). Cranio-caudal and medial-lateral extent of the dye spread in relation to musculoskeletal anatomy and direct staining of the thoraco-lumbar nerves were recorded. Following the anatomical findings, continuous catheter TQL blocks were performed in four patients undergoing ankle surgery with autologous AIC bone graft. The dermatomal anesthesia and postoperative analgesic consumption were recorded.In the anatomical component of the study, 9/10 specimens showed a lateral spread anterior to the transversalis fascia and medially between the QLM and psoas major muscle. Direct staining of the branches of the T12, L1, and L2 nerves was noted ventral to the QLM, while variable staining of the T9-T11 nerves was seen laterally in the transversus abdominis plane and the transversalis fascia. The vertical spread of injectate anterior to the QLM was T12 to the iliac crest (n = 5/10) and L1 to the iliac crest (n = 4/10). In the four patients who received TQL, the T9-L2 dermatomal anesthesia correlated with the injectate spread seen in the cadavers and provided effective analgesia at the bone graft donor site.Ultrasound-guided TQL injections consistently cover the thoraco-lumbar innervation relevant to the AIC graft donor site. The injectate spread seen in anatomical dissections correlated with the dermatomal anesthesia clinically. The TQL has the potential to provide reliable analgesia for patients undergoing AIC bone graft harvesting.

    View details for DOI 10.1007/s12630-017-1021-y

    View details for Web of Science ID 000422637700006

    View details for PubMedID 29164530

  • Continuous erector spinae plane block for an open pyeloplasty in an infant. Journal of clinical anesthesia Munshey, F., Rodriguez, S., Diaz, E., Tsui, B. 2018; 47: 47–49

    View details for DOI 10.1016/j.jclinane.2018.03.015

    View details for PubMedID 29573732

  • Bilateral automatized intermittent bolus erector spinae plane analgesic blocks for sternotomy in a cardiac patient who underwent cardiopulmonary bypass: A new era of Cardiac Regional Anesthesia. Journal of clinical anesthesia Tsui, B. C., Navaratnam, M., Boltz, G., Maeda, K., Caruso, T. J. 2018; 48: 9–10

    View details for DOI 10.1016/j.jclinane.2018.04.005

    View details for PubMedID 29684728

  • Cervical erector spinae plane block catheter using a thoracic approach: an alternative to brachial plexus blockade for forequarter amputation. Canadian journal of anaesthesia = Journal canadien d'anesthesie Tsui, B. C., Mohler, D., Caruso, T. J., Horn, J. L. 2018

    View details for DOI 10.1007/s12630-018-1170-7

    View details for PubMedID 29868941

  • Successful directional thoracic erector spinae plane block after failed lumbar plexus block in hip joint and proximal femur surgery. Journal of clinical anesthesia Darling, C. E., Pun, S. Y., Caruso, T. J., Tsui, B. C. 2018; 49: 1–2

    View details for DOI 10.1016/j.jclinane.2018.05.002

    View details for PubMedID 29775780

  • The effect of an increased pulse width on the pattern of motor response (unilateral versus bilateral) during the Tsui test in labouring parturients: a randomized crossover trial CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Zakus, P., Bittencourt, R., Downey, K., Tsui, B. H., Carvalho, J. A. 2017; 64 (12): 1211–17

    Abstract

    The typical response to the Tsui test performed via an epidural catheter placed in the lumbar area is the unilateral motor response of the lower limbs. Studies show that longer pulse widths can stimulate peripheral nerves at a lower threshold current from a farther distance. Therefore, we designed a study to test the hypothesis that epidural catheter stimulation with a 1.0-msec pulse width would increase the incidence of bilateral motor response in parturients when compared with stimulation with a 0.1-msec pulse width.Parturients requesting epidural analgesia were recruited into this randomized crossover study. The Tsui test was performed at both pulse widths before and five minutes after an epidural test dose of 2% lidocaine 3 mL. The primary outcome was the motor response pattern (either unilateral or bilateral) to the epidural catheter stimulation at baseline.Twenty women were recruited for the study, which was stopped early due to futility. The rates of unilateral motor response in the 0.1-msec (18/20) and the 1-msec (18/20) group were both 90% (rate difference, 0%; 95% confidence interval [CI], -0.3 to 0.3; P = 1.0). The mean (SD) current required to elicit a motor response at baseline was 4.2 (2.6) mA in the 0.1-msec group and 1.7 (1.1) mA in the 1-msec group (mean difference, 2.5; 95% CI, 1.2 to 2.3; P < 0.001).The motor response pattern following the stimulation of a lumbar epidural catheter with pulse widths of 0.1 msec or 1 msec is similar and typically unilateral. The threshold current is lower with the 1-msec pulse width stimulus.www.clinicaltrials.gov, NCT02762149. Registered 2 May 2016.

    View details for DOI 10.1007/s12630-017-0977-y

    View details for Web of Science ID 000414996400007

    View details for PubMedID 28936608

  • Coming of Age for "Green" Anesthesia The Leading Role of Regional Anesthesia REGIONAL ANESTHESIA AND PAIN MEDICINE Ozelsel, T., Sondekoppam, R. V., Ip, V. Y., Tsui, B. H. 2017; 42 (6): 799–800

    View details for Web of Science ID 000423262000025

    View details for PubMedID 29053513

  • Practical dosing of propofol in morbidly obese patients CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Murtha, L., Lemmens, H. J. 2017; 64 (5): 449-455

    View details for DOI 10.1007/s12630-017-0853-9

    View details for Web of Science ID 000399006300001

    View details for PubMedID 28247242

  • Proper use and interpretation of diaphragmatic ultrasonography CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Sondekoppam, R. V., Naik, L., Tsui, J., Tsui, B. C. 2017; 64 (5): 548-549

    View details for DOI 10.1007/s12630-017-0843-y

    View details for Web of Science ID 000399006300017

    View details for PubMedID 28213699

  • In Response. Anesthesia and analgesia Patel, R., Arzola, C., Petrounevitch, V., Balki, M., Downey, K., Tsui, B. C., Carvalho, J. C. 2017; 124 (3): 1010-1011

    View details for DOI 10.1213/ANE.0000000000001828

    View details for PubMedID 28207451

  • Factors Associated With Risk of Neurologic Complications After Peripheral Nerve Blocks: A Systematic Review ANESTHESIA AND ANALGESIA Sondekoppam, R. V., Tsui, B. C. 2017; 124 (2): 645-660

    Abstract

    The onset of neurologic complications after regional anesthesia is a complex process and may result from an interaction of host, agent, and environmental risk factors. The purpose of this systematic review was examine the qualitative evidence relating to various risk factors implicated in neurologic dysfunction after peripheral nerve block (PNB). The MEDLINE, OVID, and EMBASE databases were primary sources for literature. Cochrane, LILACS, DARE, IndMed, ERIC, NHS, and HTA via Centre for Reviews and Dissemination (CRD; York University) databases were searched for additional unique results. Randomized controlled studies, case-control studies, cohort studies, retrospective reviews, and case reports/case series reporting neurologic outcomes after PNB were included. Relevant, good-quality systematic reviews were also eligible. Human and animal studies evaluating factors important for neurologic outcomes were assessed separately. Information on study design, outcomes, and quality was extracted and reviewed independently by the 2 review authors. An overall rating of the quality of evidence was assigned using GRADE (Grading of Recommendations Assessment, Development and Evaluation) criteria. Relevant full-text articles were separated based on type (prospective, retrospective, and nonhuman studies). Strengths of association were defined as high, moderate, inconclusive, or inadequate based on study quality and direction of association. The evidence from 77 human studies was reviewed to assess various host, agent, and environmental factors that have been implicated as possible risks. Most of the available evidence regarding the injurious effects of the 3 cardinal agents of mechanical insult, pressure, and neurotoxicity was extracted from animal studies (42 studies). Among the risk factors investigated in humans, block type had a strong association with neurologic outcome. Intraneural injection, which seems to occur commonly with PNBs, showed an inconsistent direction of association. Measures meant to increase precision and ostensibly reduce the occurrence of complications such as currently available guidance techniques showed little effect on the incidence of neurologic complications. Recovery from neurologic injury appears to be worse in patients with pre-existing risk factors. Categorization and definition of neurologic complication varied among studies, making synthesis of evidence difficult. Also, a significant portion of the evidence surrounding neurologic injury associated with PNB comes from animal or laboratory studies, the results of which are difficult to translate to clinical scenarios. Of the human studies, few had an a priori design to test associations between a specific risk factor exposure and resultant neurologic sequelae. A few risk factor associations were identified in human studies, but overall quality of evidence was low. Much of the evidence for risk factors comes from animal models and case reports. The final neurologic outcome seems to represent the complex interaction of the host, agent, and the environment.

    View details for DOI 10.1213/ANE.0000000000001804

    View details for Web of Science ID 000392366200037

    View details for PubMedID 28067709

  • Catheter Taping Methods-Single-Layer Versus Reinforced Double-Layer Technique A Volunteer-Simulated Study REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, J. H., Murtha, L. W., Tsui, B. C. 2017; 42 (1): 128-130

    View details for Web of Science ID 000391861700033

    View details for PubMedID 27997500

  • Peripheral Nerve Blockade Clinical Anesthesia Tsui, B. C., Rosenquist, R. Lippincott Williams & Wilkins. 2017; 8th
  • Local and Regional Anesthesia in the Elderly Complications of Regional Anesthesia: Principles of Safe Practice in Local and Regional Anesthesia Gragasin, F. S., Tsui, B. C. Springer. 2017; 3rd: 287–302
  • Nerve Injury Resulting from Intraneural Injection When Performing Peripheral Nerve Block Complications of Regional Anesthesia: Principles of Safe Practice in Local and Regional Anesthesia Sondekoppam, R., Tsui, B. C. Springer. 2017; 3rd: 67–102
  • Bedside Entertainment and Relaxation Theater: size and novelty does matter when using video distraction for perioperative pediatric anxiety. Paediatric anaesthesia Rodriguez, S., Caruso, T., Tsui, B. 2017; 27 (6): 668–69

    View details for DOI 10.1111/pan.13133

    View details for PubMedID 28474813

  • "PQRST": the shamrock method for lumbar plexus blocks. Journal of clinical monitoring and computing Tsui, B. C. 2016: -?

    View details for PubMedID 27885539

  • Monitoring waste anesthetic gas in the pediatric postanesthesia care unit CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Kim, S., Ozelsel, T., Tsui, B. C. 2016; 63 (11): 1301-1302

    View details for DOI 10.1007/s12630-016-0713-z

    View details for Web of Science ID 000387504800015

    View details for PubMedID 27473719

  • Response Patterns to the Electric Stimulation of Epidural Catheters in Pregnant Women: A Randomized Controlled Trial of Uniport Versus Multiport Catheters ANESTHESIA AND ANALGESIA Patel, R., Arzola, C., Petrounevitch, V., Balki, M., Downey, K., Tsui, B. C., Carvalho, J. C. 2016; 123 (4): 950-954

    Abstract

    The transcatheter electric stimulation test (Tsui test) can be performed at the bedside to confirm the correct placement of a wire-reinforced epidural catheter within the epidural space. The most commonly observed motor response with a uniport epidural catheter placed in the lumbar area is the unilateral contraction of the lower limbs. Wire-reinforced multiport catheters have recently been introduced into clinical practice; however, the characteristics of the Tsui test with such catheters are unknown. We designed a randomized controlled trial to test the hypothesis that the incidence of a bilateral response to the Tsui test would be higher with a multiport catheter, with all other characteristics of the test remaining unchanged.We recruited laboring women requesting epidural analgesia. The epidural catheter placement was performed in a standard fashion, assisted by ultrasound, aiming at the L3-L4 interspace. Patients were randomly allocated for the placement of either a 19-G uniport or a 19-G multiport wire-reinforced catheter. The Tsui test (frequency 2 Hz; pulse width 0.2 millisecond) was performed immediately after securing the catheter (baseline) and at 5 minutes after a test dose with 3 mL lidocaine 2%. The current output was increased from zero until motor activity was detected up to a maximum of 20 mA. Subsequently, an initial loading dose of 10 mL bupivacaine 0.125% and 50 μg fentanyl was administered. The sensory block level to ice was assessed bilaterally at 20 minutes after injection of the loading dose. The primary outcome was the motor response pattern to the electric stimulation of the epidural catheter, either unilateral or bilateral; secondary outcomes included minimal current intensity needed to elicit a motor response at baseline and 5 minutes after the test dose, sensory block level and incidence of symmetrical sensory block at 20 minutes after injection of the loading dose, pain scores before the test dose and at 20 minutes after the loading dose, and need for catheter replacement within 2 hours of completion of the loading dose.Sixty-three women were assessed for eligibility and 46 were randomly allocated equally to each group. Three patients were excluded, resulting in 21 subjects in the multiport group and 22 subjects in the uniport group. Patient characteristics in both groups were similar. The incidence of unilateral motor response to the Tsui test was 95.2% (20/21) and 95.5% (21/22) in the multiport and uniport groups, respectively (rate difference 0.22%; 95% confidence interval, for the difference -29.2 to 29.2%; P = 0.99). The minimal current intensity (mean ± SD) required to produce a motor response at baseline was 5.4 ± 3.5 mA and 5.4 ± 4.1 mA in the multiport and uniport groups, respectively (P = 0.98). The sensory block levels to ice on the left and right, as well as pain scores at 20 minutes, were similar in both groups. No epidural catheters were resited.The Tsui test produced a high percentage of unilateral motor response in women with both uniport and multiport wire-embedded catheters. A larger study is necessary to confirm that there is no clinically significant difference in the motor response patterns between the 2 catheter types.

    View details for DOI 10.1213/ANE.0000000000001236

    View details for Web of Science ID 000383923900021

    View details for PubMedID 27111644

  • An ultrasound-guided ABCDE approach with a sniff test to evaluate diaphragmatic function without acoustic windows CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Naik, L. Y., Sondekoppam, R. V., Tsui, J. J., Tsui, B. C. 2016; 63 (10): 1199-1200

    View details for DOI 10.1007/s12630-016-0685-z

    View details for Web of Science ID 000383592000011

    View details for PubMedID 27324892

  • Postoperative environmental anesthetic vapour concentrations following removal of the airway device in the operating room versus the postanesthesia care unit CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Cheung, S. K., Ozelsel, T., Rashiq, S., Tsui, B. C. 2016; 63 (9): 1016-1021

    Abstract

    This study was designed to compare waste anesthetic gas (WAG) concentrations within patients' breathing zones after removal of the patient's airway device in the postanesthesia care unit (PACU) vs in the operating room (OR).Following Research Ethics Board approval and patient consent, we recruited patients undergoing surgery who received volatile anesthesia via an endotracheal tube or supraglottic airway. Patients had their airway device removed in the OR or in the PACU depending on the attending anesthesiologist's preference. Upon the patient's arrival in the PACU, concentrations of exhaled sevoflurane and desflurane were measured at their breathing zone (i.e., 15 cm from the patient's mouth and nose) using a single-beam infrared spectrophotometer.Seventy patients were recruited during the five-month study period. The median [interquartile range] WAG levels in the patients' breathing zones were higher when their airway devices were removed in the PACU vs in the OR. The WAG levels for sevoflurane were 0.7 [0.4-1.1] parts per million (ppm) vs 0.5 [0.4-0.7] ppm, respectively; median difference, 0.3; 95% confidence interval (CI), 0.1 to 0.6; P = 0.04. The WAG levels for desflurane were 2.4 [1.2-3.4] ppm vs 4.1 [2.5-5.2] ppm, respectively; median difference, 1.5; 95% CI, 0.3 to 2.7; P = 0.04.After a volatile-based anesthetic, our results suggest that removal of the airway device in the PACU vs in the OR increases the amount of waste anesthetic gas in a patient's breathing zone and thus potentially in the PACU nurse's working zone.

    View details for DOI 10.1007/s12630-016-0678-y

    View details for Web of Science ID 000381287400003

    View details for PubMedID 27273061

  • ABC Diaphragmatic Evaluation for neonates PEDIATRIC ANESTHESIA Tsui, B. C., Tsui, J. 2016; 26 (7): 768-769

    View details for DOI 10.1111/pan.12914

    View details for Web of Science ID 000378629000014

    View details for PubMedID 27277652

  • Narrowing the blockade field: development of an optimal postoperative analgesia regimen for total knee arthroplasty CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C. 2016; 63 (5): 524-528

    View details for DOI 10.1007/s12630-016-0614-1

    View details for Web of Science ID 000373588800003

    View details for PubMedID 26885823

  • A novel systematic ABC approach to Diaphragmatic Evaluation (ABCDE) CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, J. J., Tsui, B. C. 2016; 63 (5): 636-637

    View details for DOI 10.1007/s12630-015-0566-x

    View details for Web of Science ID 000373588800020

    View details for PubMedID 26684458

  • The Second American Society of Regional Anesthesia and Pain Medicine Evidence-Based Medicine Assessment of Ultrasound-Guided Regional Anesthesia: Executive Summary. Regional anesthesia and pain medicine Neal, J. M., Brull, R., Horn, J., Liu, S. S., McCartney, C. J., Perlas, A., Salinas, F. V., Tsui, B. C. 2016; 41 (2): 181-194

    Abstract

    In 2009 and again in 2012, the American Society of Regional Anesthesia and Pain Medicine assembled an expert panel to assess the evidence basis for ultrasound guidance as a nerve localization tool for regional anesthesia.The 2012 panel reviewed evidence from the first advisory but focused primarily on new information that had emerged since 2009. A new section was added regarding the accuracy and reliability of ultrasound for determining needle-to-nerve proximity. Jadad scores are used to rank study quality. Grades of recommendations consistent with their level of evidence are provided.The panel offers recommendations based on synthesis and analysis of literature related to (1) the technical capabilities of ultrasound equipment and its operators, (2) comparison of ultrasound to other methods of nerve localization with regard to block characteristics, (3) comparison of block techniques where ultrasound is the sole nerve localization modality, and (4) major complications. Assessment of evidence strength and recommendations are made for upper- and lower-extremity, truncal, neuraxial, and pediatric blocks.Scientific evidence from the past 5 years has clarified and strengthened our understanding of ultrasound-guided regional anesthesia as a nerve localization tool. High-level evidence supports ultrasound guidance contributing to superior characteristics with selected blocks, although absolute differences with the comparator technique are often relatively small (especially for upper-extremity blocks). The clinical meaningfulness of these differences is likely of variable importance to individual practitioners. The use of ultrasound significantly reduces the risk of local anesthetic systemic toxicity as well as the incidence and intensity of hemidiaphragmatic paresis, but has no significant effect on the incidence of postoperative neurologic symptoms. WHAT'S NEW IN THIS UPDATE?: This evidence-based assessment of ultrasound-guided regional anesthesia reviews findings from our 2010 publication and focuses on new meta-analyses, randomized controlled trials, and large case series published since 2009. New to this exercise is an in-depth analysis of the accuracy and reliability of ultrasound guidance for identifying needle-to-nerve relationships. This version no longer addresses ultrasound for interventional pain medicine procedures, because the growth of that field demands separate consideration. Since our 2010 publication, new information has either supported or strengthened our original conclusions. There is no evidence that ultrasound is inferior to alternative nerve localization methods.

    View details for DOI 10.1097/AAP.0000000000000331

    View details for PubMedID 26695878

  • Evidence for the Use of Ultrasound Imaging in Pediatric Regional Anesthesia A Systematic Review REGIONAL ANESTHESIA AND PAIN MEDICINE Lam, D. K., Corry, G. N., Tsui, B. C. 2016; 41 (2): 229-241

    Abstract

    An earlier review to evaluate the quality and outcomes of studies assessing ultrasound imaging in regional anesthesia for the pediatric population considered articles published from 1994 to 2009 and showed some evidence in support of block-related outcomes (block onset, success, duration) and process-related outcomes (performance time, local anesthetic dose, and spread). At that time, strong evidence in the form of randomized controlled trials and well-designed prospective observational studies was limited, leading to a call for additional research. The current systematic review (2009-2014) compares and updates the evidence for ultrasound-guided pediatric regional anesthesia published since our last review. Using the MEDLINE and EMBASE databases, we included in this review studies examining ultrasound imaging for nerve localization in the pediatric population between 2009 and March 2014 (meta-analyses, systematic reviews, randomized controlled trials, controlled studies without randomization, observational studies, comparative studies, and case series involving at least 10 patients). In the current review, we identified 24 and 13 articles evaluating peripheral nerve blocks and neuraxial anesthesia, respectively.Studies in the current review provide stronger evidence and have addressed a number of outcomes that were previously inconsistent or lacked strength in evidence. In the current systematic review, we identified more studies in a shorter period compared with the previous review, and these studies contain higher levels of evidence compared with what we previously found. Randomized controlled trials and well-designed prospective observational studies have replaced case series. Stronger evidence from the literature suggests that ultrasound-guided peripheral blocks decrease block performance time when compared with nerve stimulation (but take longer than the landmark technique), increase block success, and increase block quality (as measured by analgesic consumption, block duration, and pain scores). Ultrasound guidance in neuraxial blocks improves needling time, predicts epidural depth, allows visualization of the catheter and local anesthetic spread, and improves block quality. Furthermore, we identified 2 large-scale prospective studies describing the incidence of adverse events and complications in pediatric regional anesthesia. The increase in evidence presented in this review reflects the efficacy and prevalent use of ultrasound imaging in pediatric regional anesthesia.

    View details for DOI 10.1097/AAP.0000000000000208

    View details for Web of Science ID 000378153300018

    View details for PubMedID 25675289

  • A closed-circuit anesthesia ventilator facilitates significant reduction in sevoflurane consumption in clinical practice CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Oezelsel, T., Kim, S. H., Rashiq, S., Tsui, B. C. 2015; 62 (12): 1348-1349

    View details for DOI 10.1007/s12630-015-0478-9

    View details for Web of Science ID 000365022300018

    View details for PubMedID 26362798

  • Use of a nerve stimulator to assist cricothyroid membrane puncture during difficult airway topicalization CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Green, J. S., Tsui, B. C. 2015; 62 (10): 1126-1127

    View details for DOI 10.1007/s12630-015-0411-2

    View details for Web of Science ID 000360829400017

    View details for PubMedID 26037955

  • Analysis of the number of publications by Canadian anesthesiology departments from 2000-2013 CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Lam, D. K., Tsui, B. C. 2015; 62 (9): 1021-1022

    View details for DOI 10.1007/s12630-015-0385-0

    View details for Web of Science ID 000359742900013

    View details for PubMedID 25894908

  • Generation of tidal volume via gentle chest pressure in children over one year old RESUSCITATION Tsui, B. C., Horne, S., Tsui, J., Corry, G. N. 2015; 92: 148-153

    Abstract

    In the event of cardiac arrest, cardiopulmonary resuscitation (CPR) is a well-established technique to maintain oxygenation of tissues and organs until medical equipment and staff are available. During CPR, chest compressions help circulate blood and have been shown in animal models to be a means of short-term oxygenation. In this study, we tested whether gentle chest pressure can generate meaningful tidal volume in paediatric subjects.This prospective cohort pilot study recruited children under the age of 17 years and undergoing any surgery requiring general anaesthetic and endotracheal intubation. After induction of general anaesthesia, tidal volumes were obtained before and after intubation by applying a downward force on the chest which was not greater than the patient's weight. Mean tidal volumes were compared for unprotected versus protected airway and for type of surgery.Mean tidal volume generated with an unprotected and protected airway was 2.7 (1.7) and 2.9 (2.3) mL/kg, respectively. Mean tidal volume generated with mechanical ventilation was 13.6 (4.9) mL/kg. No statistical significance was found when comparing tidal volumes generated with an unprotected or protected airway (p = 0.20), type of surgery (tonsillectomy and/or adenoidectomy versus other surgery) (unprotected, p = 0.09; protected, p = 0.37), and when age difference between groups was taken into account (p = 0.34).Using gentle chest pressure, we were able to generate over 20% of the tidal volume achieved with mechanical ventilation. Our results suggest that gentle chest pressure may be a means to support temporary airflow in children.

    View details for DOI 10.1016/j.resuscitation.2015.02.021

    View details for Web of Science ID 000360352500037

    View details for PubMedID 25749553

  • Use of Intralipid(A (R)) in managing refractory hypotension following epidural blockade CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Cheung, S. S., Ziwenga, O., Gragasin, F. S. 2015; 62 (5): 548-549

    View details for DOI 10.1007/s12630-014-0279-6

    View details for Web of Science ID 000352615100018

    View details for PubMedID 25420471

  • Benefits of the Costoclavicular Space for Ultrasound-Guided Infraclavicular Brachial Plexus Block Description of a Costoclavicular Approach REGIONAL ANESTHESIA AND PAIN MEDICINE Karmakar, M. K., Sala-Blanch, X., Songthamwat, B., Tsui, B. C. 2015; 40 (3): 287-288

    View details for Web of Science ID 000369616600015

    View details for PubMedID 25899958

  • Survey of pre-clerkship medical students' knowledge and perceptions of anesthesiology at one Canadian university CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Robertson, E. M., Henschke, S. J., Friesen, J., Tsui, B. C. 2015; 62 (5): 550-552

    View details for DOI 10.1007/s12630-014-0297-4

    View details for Web of Science ID 000352615100019

    View details for PubMedID 25510237

  • Lidocaine infusion for continuous interscalene nerve block: Is there evidence for local and systemic benefits? CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Ip, V. H., Tsui, B. C. 2015; 62 (3): 321-322

    View details for DOI 10.1007/s12630-014-0278-7

    View details for Web of Science ID 000349912900013

    View details for PubMedID 25410751

  • Low-dose intrathecal local anesthetic does not increase the threshold current for the epidural stimulation test: a prospective observational trial of neuraxial analgesia in labouring women CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Carvalho, J. C., Khemka, R., Loke, J., Tsui, B. C. 2015; 62 (3): 265-270

    Abstract

    The purpose of this study was to investigate the ability of the electrical epidural stimulation test (EST) to determine the position of the epidural catheter during combined spinal-epidural (CSE) anesthesia for labour analgesia.This was a prospective observational trial of attempted EST during neuraxial analgesia in labouring women. Ten women received a double-segment CSE technique and one woman underwent continuous spinal analgesia following inadvertent dural puncture and deliberate placement of the catheter tip in the intrathecal space. In all CSE cases, the spinal injection was performed below the level of the epidural insertion. The motor threshold current (MTC) was determined by EST through the existing epidural/intrathecal catheter immediately following and at five, ten, and 15 mins after intrathecal injection of bupivacaine 1.75 mg and fentanyl 15 μg. Changes in the MTC were expressed as a percent change compared with baseline.The MTC required to elicit muscle contractions in women with epidurally placed catheters was unaffected by the intrathecal injection of the analgesic mixture (P = 0.731). The MTC increased following an intrathecal injection of the same mixture in a woman who had the catheter placed intrathecally.The intrathecal injection of a low dose of bupivacaine-fentanyl does not affect the MTC if the catheter is placed in the epidural space; however, it does affect the threshold if the catheter is placed intrathecally. We also confirm that the EST can help to determine the position of the epidural catheter prior to injection of the test dose. This trial was registered at ClinicalTrials.gov (NCT00464841).

    View details for DOI 10.1007/s12630-014-0291-x

    View details for Web of Science ID 000349912900005

    View details for PubMedID 25501494

  • A reply. Anaesthesia Tsui, B. C. 2014; 69 (11): 1289-1290

    View details for DOI 10.1111/anae.12864

    View details for PubMedID 25302970

  • Alcohol Swabs as "Cold Test" in a Measure of Temperature Sensation in the Skin REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Ma, L., Cheung, S. S., Ozelsel, T. 2014; 39 (6): 561-562

    View details for Web of Science ID 000344933500026

    View details for PubMedID 25340491

  • Reversal of high spinal anesthesia with cerebrospinal lavage after inadvertent intrathecal injection of local anesthetic in an obstetric patient CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Ting, H. Y., Tsui, B. C. 2014; 61 (11): 1004-1007

    Abstract

    High or total spinal anesthesia commonly results from accidental placement of an epidural catheter in the intrathecal space with subsequent injection of excessive volumes of local anesthetic. Cerebrospinal lavage has been shown to be effective at reversing the effects of high/total spinal anesthesia but is rarely considered in obstetric cases. Here, we describe the use of cerebrospinal lavage to prevent potential complications from high/total spinal anesthesia after unintentional placement of an intrathecal catheter in a labouring obstetric patient.A 34-yr-old female presented to the labour and delivery unit in active labour. Epidural anesthesia was initiated, and after the first bolus dose, the patient experienced lower extremity motor block and shortness of breath. A high spinal was confirmed, and cerebrospinal lavage was performed. In total, 40 mL of cerebrospinal fluid (CSF) were exchanged for an equal volume of normal saline. The patient's breathing difficulties and motor block resolved quickly, and a new epidural catheter was placed after removal of the spinal catheter. Pain control was effective, and the patient delivered a healthy baby.We show that exchange of CSF for normal saline can be used successfully to manage a high spinal in an obstetric patient. Our results suggest that CSF lavage could potentially be an important and helpful adjunct to the conventional supportive management of obstetric patients in the event of inadvertent high or total spinal anesthesia.

    View details for DOI 10.1007/s12630-014-0219-5

    View details for Web of Science ID 000343718400005

    View details for PubMedID 25125249

  • Ultrasound-guided rectus sheath catheter placement ANAESTHESIA Tsui, B. C., Green, J. S., Ip, V. H. 2014; 69 (10): 1174-1175

    View details for DOI 10.1111/anae.12849

    View details for Web of Science ID 000342064800016

    View details for PubMedID 25204242

  • Regional anesthesia for pectoralis major tendon repair CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Ting, H. Y., Bergman, J. W., Tsui, B. C. 2014; 61 (10): 965-966

    View details for DOI 10.1007/s12630-014-0204-z

    View details for Web of Science ID 000342218200013

    View details for PubMedID 25030004

  • Common sense medicine and cerebrospinal lavage ANAESTHESIA Tsui, B. C. 2014; 69 (8): 936-937

    View details for DOI 10.1111/anae.12796

    View details for Web of Science ID 000339546600030

    View details for PubMedID 25039957

  • Serotonin, Morphine, and Neuropathic Pain Not a Simple Story ANESTHESIOLOGY Byrne, K., Tsui, B. 2014; 121 (2): 217-218

    View details for DOI 10.1097/ALN.0000000000000325

    View details for Web of Science ID 000340028500004

    View details for PubMedID 24887969

  • Intermittent bolus via infraclavicular nerve catheter using a catheter-over-needle technique in a pediatric patient CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Spencer, A. O., Tsui, B. C. 2014; 61 (7): 684-685

    View details for DOI 10.1007/s12630-014-0172-3

    View details for Web of Science ID 000337084200016

    View details for PubMedID 24798255

  • Regional Anesthesia: Business Class Pain Management? REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C. 2014; 39 (3): 265-266

    View details for Web of Science ID 000338774700032

    View details for PubMedID 24747325

  • Catheter-over-needle method reduces risk of perineural catheter dislocation BRITISH JOURNAL OF ANAESTHESIA Tsui, B. C., Ip, V. H. 2014; 112 (4): 759-760

    View details for DOI 10.1093/bja/aeu066

    View details for Web of Science ID 000333251000028

    View details for PubMedID 24645151

  • Sublingual ultrasound as an assessment method for predicting difficult intubation: a pilot study ANAESTHESIA Hui, C. M., Tsui, B. C. 2014; 69 (4): 314-319

    Abstract

    Current methods to assess the airway before tracheal intubation are variable in their ability to predict a difficult airway accurately. We hypothesised that sublingual ultrasound could provide additional information to predict a difficult airway with greater success than current methods. We recruited 110 patients to perform sublingual ultrasound on themselves following brief instruction. Ability to view the hyoid bone on sublingual ultrasound, mouth opening distance, thyromental distance, neck mobility, size of mandible and modified Mallampati classification were recorded and assessed for ability to predict a difficult intubation based on the grade of laryngoscope. Visibility of the hyoid using ultrasound was associated with a laryngoscopic grade of 1-2 (p < 0.0001), and (p < 0.0001) had a positive likelihood ratio of 21.6 and a negative likelihood ratio of 0.28. Each of the other methods had considerably lower positive likelihood ratios and lower sensitivity. Our results suggest that sublingual ultrasound is a potential tool for predicting a difficult airway in addition to conventional methods.

    View details for DOI 10.1111/anae.12598

    View details for Web of Science ID 000332923100005

    View details for PubMedID 24641637

  • The effects of general anaesthesia on nerve-motor response characteristics (rheobase and chronaxie) to peripheral nerve stimulation ANAESTHESIA Tsui, B. C. 2014; 69 (4): 374-379

    Abstract

    Using a simple surface nerve stimulation system, I examined the effects of general anaesthesia on rheobase (the minimum current required to stimulate nerve activity) and chronaxie (the minimum time for a stimulus twice the rheobase to elicit nerve activity). Nerve stimulation was used to elicit a motor response from the ulnar nerve at varying pulse widths before and after induction of general anaesthesia. Mean (SD) rheobase before and after general anaesthesia was 0.91 (0.37) mA (95% CI 0.77-1.04 mA) and 1.11 (0.53) mA (95% CI 0.92-1.30 mA), respectively. Mean (SD) chronaxie measured before and after general anaesthesia was 0.32 (0.17) ms (95% CI 0.26-0.38 ms) and 0.29 (0.13) ms (95% CI 0.24-0.33 ms), respectively. Under anaesthesia, rheobase values increased by an average of 20% (p = 0.05), but chronaxie values did not change significantly (p = 0.39). These results suggest that threshold currents used for motor response from nerve stimulation under general anaesthesia might be higher than those used in awake patients.

    View details for DOI 10.1111/anae.12540

    View details for Web of Science ID 000332923100014

    View details for PubMedID 24641644

  • Keys to minimizing the risk of spinal cord trauma during a lumbar approach to thoracic epidural CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C. 2014; 61 (4): 289-294

    View details for DOI 10.1007/s12630-014-0120-2

    View details for Web of Science ID 000333058000001

    View details for PubMedID 24477465

  • Reducing and Washing Off Local Anesthetic for Continuous Interscalene Block REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Dillane, D. 2014; 39 (2): 175-176

    View details for Web of Science ID 000336394300017

    View details for PubMedID 24553308

  • ED placement of perineural catheters for femoral fracture pain management AMERICAN JOURNAL OF EMERGENCY MEDICINE Herring, A. A., Liu, B., Kiefer, M. V., Nagdev, A. D., Tsui, B. C. 2014; 32 (3)

    Abstract

    Regional nerve blocks provide superior analgesia over opioid-based pain management regimens for traumatic injuries such as femur fractures. An ultrasound-guided regional nerve block is placed either as a single-shot injection or via a perineural catheter that is left in place. Although perineural catheters are commonplace in the perioperative setting, their use by emergency physicians (EPs) for emergency pain management in adults has not been previously described. Perineural catheters allow prolonged and titratable delivery of local anesthetic directly targeted to the injured extremity, resulting in opioid sparing while maintaining high-quality pain relief with improved alertness. Despite these advantages, most EPs do not currently place perineural catheters, likely due to the widespread perception that the procedure is both excessively time consuming and too technically difficult to be practical in a busy emergency department (ED). A catheter-over-needle kit, resembling a peripheral intravenous line, is now available and may be familiar to EPs than traditional catheter-needle assemblies. Recent studies also suggest excellent analgesic outcomes with intermittent perineural bolusing of local anesthetic, thereby dispensing with the need for complex and expensive infusion pumps. Herein, we describe our successful placement of perineural femoral catheters at a busy inner-city public hospital ED. Our experience suggests that this is a promising new technique for emergency pain management of acute extremity injuries.

    View details for DOI 10.1016/j.ajem.2013.09.036

    View details for Web of Science ID 000332525500028

    View details for PubMedID 24239494

  • Estimation of equivalent threshold currents using different pulse widths for the epidural stimulation test in a porcine model CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Tsui, J. H., Corry, G. N. 2014; 61 (3): 249-253

    Abstract

    The epidural stimulation test can help detect if a catheter is correctly positioned in the epidural space. Previous studies showed that a current of up to 16 mA was required to elicit a motor response, but few peripheral nerve stimulators can produce a current this high. Manipulating pulse width can produce a positive response at a lower current. To clarify the effects of pulse width on the epidural stimulation test, we performed a single-blinded study in a porcine model to estimate the equivalent current needed at varying pulse widths.After obtaining local ethics approval, an 18G insulated Tuohy needle was advanced into the epidural space at the lower lumbar spinal level, and a 20G stimulating epidural catheter was advanced 30 cm cephalad. A gradually increasing electrical current was applied, and a motor response was elicited at pulse widths of 0.1, 0.2, 0.3, 0.5, and 1 msec. This was followed by a 1-2 cm catheter withdrawal, and the process was repeated for a total of 15 locations per pig.Recorded threshold currents ranged from 0.36-9.5 mA at a pulse width of 0.2 msec. Our results show a linear relationship between threshold current and pulse width.In situations where different pulse widths are needed, the nomograms presented here may be useful to estimate the equivalent threshold current which is required to elicit a motor response according to previously published criteria for epidural stimulation tests.

    View details for DOI 10.1007/s12630-013-0096-3

    View details for Web of Science ID 000331998500006

    View details for PubMedID 24347355

  • Postintubation arytenoid dislocation/subluxation in CHARGE infants PEDIATRIC ANESTHESIA Chowdhury, F., Siddiqui, U., Tsui, B. C., El-Hakim, H. 2014; 24 (2): 225-227

    View details for DOI 10.1111/pan.12288

    View details for Web of Science ID 000329300800017

    View details for PubMedID 24387151

  • Learning the 'traceback' approach for interscalene block ANAESTHESIA Tsui, B. C., Lou, L. 2014; 69 (1): 83-85

    View details for DOI 10.1111/anae.12549

    View details for Web of Science ID 000327902100018

    View details for PubMedID 24320862

  • The catheter-over-needle assembly offers greater stability and less leakage compared with the traditional counterpart in continuous interscalene nerve blocks: a randomized patient-blinded study CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Ip, V. H., Rockley, M. C., Tsui, B. C. 2013; 60 (12): 1272-1273

    View details for DOI 10.1007/s12630-013-0032-6

    View details for Web of Science ID 000327870700014

    View details for PubMedID 24043379

  • Impact of anesthesia for cancer surgery: Continuing Professional Development CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Green, J. S., Tsui, B. C. 2013; 60 (12): 1248-1269

    Abstract

    A number of original publications and review articles have addressed the issue of perioperative immune modulation and cancer outcome. The objective of this module is to review current understanding surrounding the pathways involved and the evidence implicating commonly used anesthetic agents.Drugs commonly used in anesthetic practice have been shown to affect various components of the immune system in laboratory animal and human in vitro models. It has been hypothesized that these effects may favour tumour recurrence and metastasis formation. Inhalational agents and opiates have potential negative immunomodulatory effects; on the other hand, regional anesthesia and propofol may have positive effects on immune function modulation. However, the clinical relevance of these studies to human cancer outcome is unknown since clinical trials are equivocal, and results of in vitro and animal model studies cannot be extrapolated to clinical practice. Furthermore, there is a lack of rigorous clinical trials demonstrating clinical outcome benefit for one technique over another. It remains unclear how anesthetic drugs influence the immune system in relation to tumour cell elimination and clinical cancer outcome.Recommendations for a specific anesthetic technique based on cancer outcome alone cannot be made. A pragmatic solution would be to offer regional anesthesia in isolation or combined with propofol infusion to cancer patients if appropriate and if local expertise is available. Regional anesthesia offers excellent analgesia, a low incidence of postoperative nausea and vomiting, and a favourable immunological profile based on current understanding of laboratory evidence.

    View details for DOI 10.1007/s12630-013-0037-1

    View details for Web of Science ID 000327870700011

    View details for PubMedID 24165829

  • The electrophysiological principles of the electrical stimulation test in the epidural compartment CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C. 2013; 60 (12): 1270-1271

    View details for DOI 10.1007/s12630-013-0033-5

    View details for Web of Science ID 000327870700012

    View details for PubMedID 24105620

  • Intermittent hoarseness with continuous interscalene brachial plexus catheter infusion due to deficient carotid sheath ACTA ANAESTHESIOLOGICA SCANDINAVICA Shakespeare, T. J., Tsui, B. C. 2013; 57 (8): 1085-1086

    View details for DOI 10.1111/aas.12147

    View details for Web of Science ID 000323075000020

    View details for PubMedID 23808964

  • Catheter-over-needle method facilitates effective continuous infraclavicular block CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Shakespeare, T. J., Tsui, B. C. 2013; 60 (9): 948-949

    View details for DOI 10.1007/s12630-013-9993-8

    View details for Web of Science ID 000323340700014

    View details for PubMedID 23801025

  • Reproducibility of current perception threshold with the Neurometer(A (R)) vs the Stimpod NMS450 peripheral nerve stimulator in healthy volunteers: an observational study CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Shakespeare, T. J., Leung, D. H., Tsui, J. H., Corry, G. N. 2013; 60 (8): 753-760

    Abstract

    Current methods of assessing nerve blocks, such as loss of perception to cold sensation, are subjective at best. Transcutaneous nerve stimulation is an alternative method that has previously been used to measure the current perception threshold (CPT) in individuals with neuropathic conditions, and various devices to measure CPT are commercially available. Nevertheless, the device must provide reproducible results to be used as an objective tool for assessing nerve blocks.We recruited ten healthy volunteers to examine CPT reproducibility using the Neurometer(®) and the Stimpod NMS450 peripheral nerve stimulator. Each subject's CPT was determined for the median (second digit) and ulnar (fifth digit) nerve sensory distributions on both hands - with the Neurometer at 5 Hz, 250 Hz, and 2000 Hz and with the Stimpod at pulse widths of 0.1 msec, 0.3 msec, 0.5 msec, and 1.0 msec, both at 5 Hz and 2 Hz. Intraclass correlation coefficients (ICC) were also calculated to assess reproducibility; acceptable ICCs were defined as ≥ 0.4.The ICC values for the Stimpod ranged from 0.425-0.79, depending on pulse width, digit, and stimulation; ICCs for the Neurometer were 0.615 and 0.735 at 250 and 2,000 Hz, respectively. These values were considered acceptable; however, the Neurometer performed less efficiently at 5 Hz (ICCs for the second and fifth digits were 0.292 and 0.318, respectively).Overall, the Stimpod device displayed good to excellent reproducibility in measuring CPT in healthy volunteers. The Neurometer displayed poor reproducibility at low frequency (5 Hz). These results suggest that peripheral nerve stimulators may be potential devices for measuring CPT to assess nerve blocks.

    View details for DOI 10.1007/s12630-013-9965-z

    View details for Web of Science ID 000322009800003

    View details for PubMedID 23690134

  • Comparison of blind and electrically guided tracheal needle insertion in human cadavers ANAESTHESIA Tsui, B. C., Neufeld, A., WALJI, A. H. 2013; 68 (7): 689-693

    Abstract

    The purpose of this study was to investigate whether an electrically guided needle insertion technique would enable greater success at intratracheal needle tip insertion than the traditional, aspiration-of-air technique. Twenty-seven anaesthesiology residents were assessed in their ability to place a needle tip in the trachea of cadavers using the two methods. Success of needle placement, time to placement and confidence in placement were recorded. Correct intratracheal needle placement was achieved by 22% of residents (6/27) using the aspiration-of-air method vs 82% (22/27) using the electrically guided method (p<0.001). For the instances of success, there was no significant difference between the two methods in the median (IQR [range]) time taken (28 (24-49 [18-63]) s aspiration vs 32 (19-49 [15-84]) s electrical; p=0.93). The electrically guided method provides an acceptably quick and accurate way of placing a needle tip into the tracheal lumen and can be learnt easily by anaesthesiology residents.

    View details for DOI 10.1111/anae.12283

    View details for Web of Science ID 000320384400004

    View details for PubMedID 23672675

  • The safety of an interscalene catheter-over-needle technique ANAESTHESIA Ip, V., Tsui, B. 2013; 68 (7): 774-775

    View details for DOI 10.1111/anae.12304

    View details for Web of Science ID 000320384400018

    View details for PubMedID 24044390

  • Injection Through the Paraneural Sheath Rather Than Circumferential Spread Facilitates Safe, Effective Sciatic Nerve Block REGIONAL ANESTHESIA AND PAIN MEDICINE Ip, V., Tsui, B. 2013; 38 (4): 373-373

    View details for Web of Science ID 000330473700022

    View details for PubMedID 23788078

  • The catheter-over-needle assembly facilitates delivery of a second local anesthetic bolus to prolong supraclavicular brachial plexus block without time-consuming catheterization steps: a randomized controlled study CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Ip, V. H., Tsui, B. C. 2013; 60 (7): 692-699

    Abstract

    Single-shot delivery of a supraclavicular brachial plexus block is effective for providing outpatient surgical anesthesia; however, patients generally must use oral analgesics to control pain shortly after discharge from the hospital. Catheterized delivery of supraclavicular blocks can be challenging to perform. We aimed to show that administering a second postoperative bolus of local anesthetic through a catheter placed by a catheter-over-needle assembly not only avoids time-consuming steps but also provides an extended analgesic effect compared with the traditional single-shot approach.Patients were randomized into two groups: one group received a single-shot supraclavicular block with 25-30 mL of local anesthetic (1.5% lidocaine and 0.125% bupivacaine mixture), while the other group received a supraclavicular block via a catheter-over-needle assembly with the same volume and concentration of local anesthetic as for the single-shot block, which was followed by a second bolus of analgesic solution (0.2 % ropivacaine 20 mL) administered postoperatively through the catheter before its removal. The duration between the initial bolus and onset of pain was measured as well as the duration of pain relief from the last bolus.Thirty patients were enrolled and randomized into the single-shot supraclavicular block group (n = 15) and the catheter-over-needle group (n = 15). One patient withdrew from the study, and five patients were lost to follow-up. We observed no significant difference between the two groups in time to perform the blocks. The mean (standard deviation [SD]) times were 3.1 (1.9) min and 4.4 (2.7) min for the top-up group and single-shot group, respectively (single-shot took 1.3 min longer than the catheter-over-needle group; 95% confidence interval [CI]: -0.65 to 3.25; P = 0.17). The mean (SD) duration of analgesia, measured from the beginning of the local anesthetic bolus to the onset of pain requiring rescue analgesia was 617.5 (288) min in the catheter-over-needle group and 377.2 (161.3) min in the single-shot control group (difference = 240.3 min; 95% CI: 46.8 to 433.8; P = 0.03).Using the catheter-over-needle assembly for supraclavicular brachial plexus block facilitated effective delivery of a supplementary bolus of local anesthetic without extending the time to perform the block or increasing the number of steps. It also prolonged analgesia significantly compared with the single-shot approach. This trial was registered at: ClinicalTrials.gov, ID: NCT01522066.

    View details for DOI 10.1007/s12630-013-9951-5

    View details for Web of Science ID 000320374500011

    View details for PubMedID 23637033

  • Color Flow Doppler Ultrasonography Can Distinguish Caudal Epidural, Injection from Intrathecal Injection ANESTHESIA AND ANALGESIA Tsui, B., Leipoldt, C., Desai, S. 2013; 116 (6): 1376-1379

    Abstract

    Color flow Doppler ultrasonography has been used to confirm caudal epidural injection, but its ability to detect accidental intrathecal injection is unknown. We hypothesized that, when using color flow Doppler, the injection of fluid into the epidural space would result in turbulent flow which would appear as a burst of color while intrathecal injection would show an absence of a color flow Doppler signal.Two groups of pediatric patients (up to 6 years of age) were prospectively enrolled for this observational study during a 2-month period. One group (group E) consisted of patients suitable for elective surgery using caudal epidural analgesia, and the other (group I) included patients receiving lumbar puncture for intrathecal chemotherapeutic injection. After induction of general anesthesia and placement of the patient in the lateral position, an 8 MHz curved array probe (Sonosite TITAN, Bothell, WA) was applied to obtain a transverse image of the lumbar region (L1-L3). Real-time images using color flow Doppler were obtained and recorded during initial injections of 2 consecutive (20 seconds apart) aliquots of 0.1 mL/kg medication of local anesthetic (0.25% bupivacaine) or chemotherapy drugs (mixture of methotrexate, cytarabine, and hydrocortisone) at a rate of 0.5 to 1.0 mL/s. After obtaining the study images, the rest of the medication was injected in standard fashion. A blinded anesthesiologist later evaluated the recorded images to determine a positive or negative result (positive = presence of turbulence as illustrated by a medley of color; negative = no turbulence or color). Sensitivity, specificity, and positive and negative predictive values were calculated for those patients who had successful analgesia (group E) and intrathecal (group I) injections.Forty recorded images from 41 patients (group E, n = 21; group I, n = 20) were included in the analysis. The observed sensitivity, specificity, positive predictive value, and negative predictive values were all 100%. The lower 95% confidence limits were 0.832.In the context of this study, color flow Doppler could differentiate epidural from intrathecal injection into the caudal space of children up to 6 years of age using a 0.1 mL/kg injection volume and injection rate of 0.5 to 1.0 mL/s.

    View details for DOI 10.1213/ANE.0b013e31828e5e93

    View details for Web of Science ID 000319710800028

    View details for PubMedID 23558836

  • Lower interscalene approach for elbow surgery CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Ip, V. H., Tsui, B. C. 2013; 60 (6): 600-601

    View details for DOI 10.1007/s12630-013-9913-y

    View details for Web of Science ID 000319416000012

    View details for PubMedID 23460188

  • Airway Sonography in Live Models and Cadavers JOURNAL OF ULTRASOUND IN MEDICINE Tsui, B., Ip, V., Walji, A. 2013; 32 (6): 1049-1058

    Abstract

    Sonography using cadavers is beneficial in teaching and learning sonoanatomy, which is particularly important because imaging of the airway can be challenging due to the cartilaginous landmarks and air artifacts. In this exploratory study, we have attempted to compare the airway sonoanatomy of cadavers and live models. Our observations support the use of cadavers as teaching tools for learning airway sonoanatomy and practicing procedures involving airway structures, such as superior laryngeal nerve blocks, transtracheal injections, and needle cricothyroidotomy, before performance on patients in clinical situations. We believe this process will improve patient safety and enhance the competency of trainees and practitioners in rare procedures such as needle cricothyroidotomy.

    View details for DOI 10.7863/ultra.32.6.1049

    View details for Web of Science ID 000319895500019

    View details for PubMedID 23716527

  • Adductor canal nerve catheter for post-operative management of medial ankle pain following ankle fusion ACTA ANAESTHESIOLOGICA SCANDINAVICA Green, J. S., Dillane, D., Tsui, B. C. 2013; 57 (2): 264-264

    View details for DOI 10.1111/aas.12007

    View details for Web of Science ID 000313253800021

    View details for PubMedID 23294056

  • Ultrasound visualization of anatomical structures through a sterile transparent dressing CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Hogan, M., Shakespeare, T., Tsui, B. 2013; 60 (1): 87-88

    View details for DOI 10.1007/s12630-012-9805-6

    View details for Web of Science ID 000313446200013

    View details for PubMedID 23264009

  • Potential contamination of the surgical site caused by leakage from an interscalene catheter with the patient in a seated position: a case report CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Ip, V., Bouliane, M., Tsui, B. 2012; 59 (12): 1125-1129

    Abstract

    Continuous catheterized nerve blockade has been used for many years to provide effective analgesia postoperatively. We report a potential complication of interscalene nerve block performed with the traditional catheter-through-needle insertion technique. Specifically, leakage from the catheter insertion site posed a risk of contamination to the sterile surgical field. We also describe an alternative catheter design to overcome this leakage problem.We present a case of leakage from the catheter insertion site during the course of an interscalene nerve block with the patient in a beach chair position for shoulder arthroplasty. Using the traditional catheter-through-needle technique, an 18G 100-mm Tuohy needle was inserted between the C6 and C7 roots under ultrasound guidance. After confirming the needle tip position, 20 mL of local anesthetic (1% ropivacaine and 0.25% bupivacaine 1:1) were injected. A 20G catheter was then threaded through the Tuohy needle and carefully secured with tape and dressing. In the operating room, leakage from the catheter insertion site started to disturb the adhesives of the surgical drapes and threatened the sterility of the surgical field. The catheter was removed prior to surgery upon the surgeon's request. Upon completion of the operation, a catheter was reinserted using an alternative catheter-over-needle method. Postoperatively, no leakage was seen at or around the catheter entry site.This case report serves as a reminder that leakage from the catheter entry site remains a troublesome and hazardous issue during continuous peripheral nerve block. Leakage from the catheter insertion site often occurs due to the loose fit of the catheter in the larger diameter hole left by the Tuohy needle. We have also shown the successful use of an alternative catheter-over-needle design to minimize the risk of leakage from the catheter entry site. This technique resulted in being particularly vital for shoulder surgery with the patient in the beach chair position.

    View details for DOI 10.1007/s12630-012-9798-1

    View details for Web of Science ID 000312142400007

    View details for PubMedID 23055036

  • Less leakage and dislodgement with a catheter-over-needle versus a catheter-through-needle approach for peripheral nerve block: an ex vivo study CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Tsui, J. 2012; 59 (7): 655-661

    Abstract

    The objective of this study was to compare the catheter-through-needle (CTN) and catheter-over-needle (CON) catheterization techniques ex vivo by measuring leak pressure around the catheter and the catheter's resistance to pulling force.Using an ex vivo porcine limb model, we compared the conventional CTN design with the CON design with respect to the ability to resist leakage at the catheter insertion site under high injection pressure and the force required to withdraw the catheter from tissue. One CON assembly (MultiSet, Pajunk) and three CTN assemblies (Contiplex, B.Braun; StimuCath, Arrow; Stimulong Sono, Pajunk) were studied. Ten porcine hind limbs were used to test leakage and another ten were used to measure withdrawal force. Catheters were placed at angles of 15° and 30° at depths of 3 cm and 5 cm. Leakage was assessed visually at the insertion site, and pressure was measured at the moment leakage occurred. Withdrawal force was measured by pulling the catheter from the tissue.No evidence of leakage was detected at the CON catheter insertion site at the highest pressure applied (1,000 mmHg) (n = 40). The CON assembly withstood significantly higher injection pressure than the CTN catheters without causing leaks at the catheter insertion site [CON, mean (standard deviation) > 1,000 (0) mmHg; B.Braun, 596 (92) mmHg; Pajunk Stimulong, 615 (107) mmHg; and Arrow, 422 (104) mmHg; P < 0.001 CON vs CTN]. The force required to withdraw the catheter from the porcine limb was greater with CON catheters [3.8 (0.8) N] than with any of the CTN catheters [range, 0.4 (0.2) - 0.8 (0.2) N], depending on depth, angle, and manufacturer (P < 0.001 CON vs CTN).In the porcine leg model, CON catheterization provides greater resistance to leakage under high injection pressure and greater holding force in tissue than traditional CTN catheters.

    View details for DOI 10.1007/s12630-012-9713-9

    View details for Web of Science ID 000305234300005

    View details for PubMedID 22565332

  • A trigonometric method to confirm needle tip position during out-of-plane ultrasound-guided regional blockade CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C. 2012; 59 (5): 501-502

    View details for DOI 10.1007/s12630-012-9686-8

    View details for Web of Science ID 000302574200012

    View details for PubMedID 22368078

  • Continuous interscalene block: the good, the bad and the refined spread ACTA ANAESTHESIOLOGICA SCANDINAVICA Ip, V. H., Tsui, B. C. 2012; 56 (4): 526-530

    Abstract

    Continuous interscalene block is popular for shoulder surgery, but there are several challenges when performing this continuous block. The interscalene catheter is susceptible to incidental dislodgement and migration due to movement of the head and neck. Another important consideration is phrenic nerve involvement; the phrenic nerve is susceptible to being incidentally anaesthetised with local anaesthetic during interscalene block, owing to its close proximity to the interscalene groove. We present two cases: firstly, a case demonstrating an interscalene catheter insertion approach that provides an effective spread of local anaesthetic perineurally within the interscalene groove, with the additional benefit of preventing catheter dislodgement. Secondly, we present a case in which ultrasound-guided interscalene catheter insertion resulted in phrenic nerve palsy in an asthmatic patient, where dilution or 'wash-off' of local anaesthetic with normal saline and repositioning of the catheter under ultrasound guidance resulted in rapid recovery of respiratory function and adequate pain control.

    View details for DOI 10.1111/j.1399-6576.2012.02650.x

    View details for Web of Science ID 000301334500018

    View details for PubMedID 22338616

  • A flexible gel pad as an effective medium for scanning irregular surface anatomy CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Tsui, J. 2012; 59 (2): 226-227

    View details for DOI 10.1007/s12630-011-9623-2

    View details for Web of Science ID 000299295800011

    View details for PubMedID 22052289

  • Rapid percutaneous tracheal catheterization using electrical guidance CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Tsui, J. 2012; 59 (1): 116-117

    View details for DOI 10.1007/s12630-011-9602-7

    View details for Web of Science ID 000298608000017

    View details for PubMedID 21989553

  • Is there still a place for the use of nerve stimulation? PEDIATRIC ANESTHESIA Dillane, D., Tsui, B. C. 2012; 22 (1): 102-108

    Abstract

    The introduction of nerve stimulation as a method of nerve localization sparked a new beginning in regional anesthesia. It was an epochal development akin to the utilization of ultrasound in more recent times. Many experts now consider ultrasound-guided peripheral nerve blockade to be more efficient, less painful, and more successful than landmark and nerve stimulation techniques. However, inadvertent intraneural injection continues to occur despite the widespread use of ultrasound and nerve stimulation. Both of these technologies allow for only limited elucidation of needle position relative to the target nerve and are unable to reliably identify intraneural position of the needle. This article will review the role of nerve stimulation in modern regional anesthesia techniques in light of the introduction of ultrasound technology.

    View details for DOI 10.1111/j.1460-9592.2011.03729.x

    View details for Web of Science ID 000298263300016

    View details for PubMedID 22050512

  • Development of an electronic database for Acute Pain Service outcomes PAIN RESEARCH & MANAGEMENT Love, B. L., Jensen, L. A., Schopflocher, D., Tsui, B. C. 2012; 17 (1): 25-30

    Abstract

    Quality assurance is increasingly important in the current health care climate. An electronic database can be used for tracking patient information and as a research tool to provide quality assurance for patient care.An electronic database was developed for the Acute Pain Service, University of Alberta Hospital (Edmonton, Alberta) to record patient characteristics, identify at-risk populations, compare treatment efficacies and guide practice decisions.Steps in the database development involved identifying the goals for use, relevant variables to include, and a plan for data collection, entry and analysis. Protocols were also created for data cleaning quality control. The database was evaluated with a pilot test using existing data to assess data collection burden, accuracy and functionality of the database. A literature review resulted in an evidence-based list of demographic, clinical and pain management outcome variables to include. Time to assess patients and collect the data was 20 min to 30 min per patient. Limitations were primarily software related, although initial data collection completion was only 65% and accuracy of data entry was 96%.The electronic database was found to be relevant and functional for the identified goals of data storage and research.

    View details for Web of Science ID 000300218500004

    View details for PubMedID 22518364

    View details for PubMedCentralID PMC3299031

  • Reusable Phantom With Feedback Signal for Ultrasound Needle Tip Control REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Tsui, J. 2011; 36 (6): 630-631

    View details for DOI 10.1097/AAP.0b013e31822e0d75

    View details for Web of Science ID 000296532100018

    View details for PubMedID 22024703

  • Paramedian thoracic epidural training model CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Tsui, J. 2011; 58 (11): 1051-1052

    View details for DOI 10.1007/s12630-011-9571-x

    View details for Web of Science ID 000295981000012

    View details for PubMedID 21845485

  • Kill 2 Birds With 1 Stone Injection at the Bifurcation During Popliteal Sciatic Nerve Block REGIONAL ANESTHESIA AND PAIN MEDICINE Ip, V. H., Tsui, B. C. 2011; 36 (6): 633-634

    View details for DOI 10.1097/AAP.0b013e31822afe9d

    View details for Web of Science ID 000296532100023

    View details for PubMedID 22024708

  • Practical concepts in nerve stimulation: impedance and other recent advances. International anesthesiology clinics Byrne, K., Tsui, B. C. 2011; 49 (4): 81-90

    View details for DOI 10.1097/AIA.0b013e31821775a8

    View details for PubMedID 21956079

  • 2011 Canadian Journal of Anesthesia Guide for Authors CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Backman, S., Baker, A., Beattie, S., Brasher, P., Bryson, G., Cheng, D., Crawford, M., Deschamps, A., Donati, F., Drolet, P., Gelb, A. W., Grocott, H., Hare, G., Hebert, P., Karkouti, K., Lessard, M., Mazer, D., de Medicis, E., Merry, A., Miller, D. R., Moher, D., Morley-Forster, P., Plaud, B., Preston, R., Rashiq, S., Sladen, R., Tsui, B., Werner, C. 2011; 58 (7): 670-696
  • Ultrasound beyond regional anesthesia: formal training? CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Ip, V. H. 2011; 58 (6): 499-503

    View details for DOI 10.1007/s12630-011-9490-x

    View details for Web of Science ID 000290730100003

    View details for PubMedID 21432003

  • Physiological considerations related to the pediatric airway CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C. 2011; 58 (5): 476-477

    View details for DOI 10.1007/s12630-011-9464-z

    View details for Web of Science ID 000289684400014

    View details for PubMedID 21308427

  • Guidelines for fellowship training in Regional Anesthesiology and Acute Pain Medicine: Second Edition, 2010. Regional anesthesia and pain medicine 2011; 36 (3): 282-288

    Abstract

    The Regional Anesthesiology and Acute Pain Medicine Fellowship Directors Group develops and maintains guidelines for fellowship training in the subspecialty. These guidelines update the original guidelines that were published in 2005. The guidelines address 3 major topic areas: organization and resources, the educational program, and the evaluation process.

    View details for DOI 10.1097/AAP.0b013e31820d439f

    View details for PubMedID 21519314

  • Type of anaesthesia during cancer surgery and cancer recurrence BMJ-BRITISH MEDICAL JOURNAL Tsui, B. C., Green, J. S. 2011; 342

    View details for DOI 10.1136/bmj.d1605

    View details for Web of Science ID 000289200800002

    View details for PubMedID 21447588

  • Injection of Injectates Is More Than Just for "Opening the Perineural Space" REGIONAL ANESTHESIA AND PAIN MEDICINE Ip, V. H., Tsui, B. C. 2011; 36 (1): 89-90

    View details for DOI 10.1097/AAP.0b013e3182007539

    View details for Web of Science ID 000292774300019

    View details for PubMedID 21169760

  • Novelty without toxicity: a quest for a safer local anesthetic CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE Ip, V. H., Tsui, B. C. 2011; 58 (1): 8-13

    View details for DOI 10.1007/s12630-010-9409-y

    View details for Web of Science ID 000286102300002

    View details for PubMedID 21042902

  • From basic concepts to emerging technologies in regional anesthesia CURRENT OPINION IN ANESTHESIOLOGY Dillane, D., Tsui, B. C. 2010; 23 (5): 643-649

    Abstract

    The present article details how our understanding of the basic concepts of regional anesthesia has recently evolved. We will appraise current technological advances and question the commensurate nature of the relationship between tradition and innovation.Ultrasound localization has enhanced our understanding of the needle-nerve relationship. Intraneural injection of local anesthetic may occur with greater frequency than previously thought without inevitably leading to neurological complications. The ratio of neural to non-neural tissue varies both between and within nerves and may be an important determinant of neural injury. Ultrasonographic evidence of intraneural injection is subject to observer expertise and the resolution of the ultrasound image. Current ultrasound resolution capability does not reliably permit differentiation between intrafascicular and extrafascicular drug injection. Perineural electrical impedance may be a determinant of current threshold and conceivably distinguish between intraneural and extraneural tissue. Technology that enhances the sonographic image of both procedure needle and target nerve is the focus of current endeavors in ultrasound innovation.There is inconclusive evidence that the use of ultrasound technology has reduced the incidence of local anesthetic toxicity. Lipid emulsion therapy is now an accepted treatment for systemic local anesthetic toxicity. There are new reports on the development of an ultra long-acting local anesthetic agent that would permit lower doses and superannuate catheter-based continuous regional anesthesia techniques.Over the past decade, our understanding of the fundamental concepts of regional anesthesia continues to be challenged by emerging experimental and clinical evidence.

    View details for DOI 10.1097/ACO.0b013e32833d9513

    View details for Web of Science ID 000281560500019

    View details for PubMedID 20689412

  • Applications of ultrasonography in ENT: airway assessment and nerve blockade. Anesthesiology clinics Green, J. S., Tsui, B. C. 2010; 28 (3): 541-553

    Abstract

    This article presents a comprehensive narrative review of the published literature relating to ultrasound imaging relevant to anesthesia for ear, nose, and throat (ENT) surgery. The review comprises 2 main subject areas: the use of ultrasonography related to assessment and management of the airway, and the use of ultrasonography related to nerve blockade for ENT surgery. The relevant sonoanatomy and suitable probe placement are illustrated in relation to applicable regional anatomy (they are not discussed). The possible value of the use of ultrasonography to improve existing clinical practice in these areas is explored.

    View details for DOI 10.1016/j.anclin.2010.07.012

    View details for PubMedID 20850084

  • Minimally Invasive Parathyroidectomy under Local Anesthesia: Patient Satisfaction and Overall Outcome JOURNAL OF OTOLARYNGOLOGY-HEAD & NECK SURGERY Chau, J. K., Hoy, M., Tsui, B., Harris, J. R. 2010; 39 (4): 361-369

    Abstract

    To compare minimally invasive parathyroidectomy (MIP) under local anesthesia (MIPULA) to minimally invasive parathyroidectomy performed under general anesthesia (MIPUGA) in terms of postoperative pain, postanesthetic side effects, patient satisfaction, and overall outcome.Prospective comparative cohort study.Consecutive consenting patients presenting to a single surgeon's practice were enrolled into MIPULA or MIPUGA groups if inclusion criteria were satisfied. A standard anesthesia and surgical protocol was followed for all included patients. Subjective outcome measurements (pain, overall satisfaction, and other variables) were achieved through questionnaires. Objective outcomes were also measured.Seventy-four patients were enrolled: 58 in the MIPULA group and 16 in the MIPUGA group. Operative time and hospital stay were significantly shorter in the MIPULA group. Subjectively, the MIPULA group was significantly more ready for discharge versus the MIPUGA group. No significant difference in overall satisfaction between groups was noted. Biochemical cure and conversion (MIPULA to general anesthesia open exploration) rates for our cohort were 100% and 4%, respectively.MIPULA confers significantly shorter operative time and hospital stay with no significant difference in subjective postoperative pain, patient satisfaction, overall outcome, or cure rate when compared to MIPUGA. Provided that appropriate preoperative localization and surgical experience are present, MIPULA can be offered to patients as a safe and reasonable alternative to MIPUGA.

    View details for DOI 10.2310/7070.2010.090204

    View details for Web of Science ID 000284046200008

    View details for PubMedID 20643000

  • No change in impedance upon intravascular injection of D5W CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Chin, J., Tsui, B. C. 2010; 57 (6): 559-564

    Abstract

    Electrical impedance increases following test injections of non-conducting solutions around nerves; however, this increase should diminish rapidly with intravascular needle placement, wherein the systemic circulation will dissipate the solution. For this observational study, we hypothesized that the impedance increases significantly at the perineural space after an injection of 5% dextrose in water (D5W), but that it does not increase correspondingly at the intravascular locationAfter Ethics Research Board approval, electrical impedance was measured by a nerve stimulator displaying resistance, Stimuplex HNS 12, before and during (30 sec) an injection of D5W 3 mL: 1) during intravenous cannula placement using an insulated stimulating needle sheathed in its plastic cannula, MultiSet NanoLine with 18G needle; and 2) during needle placement (Pajunk 22G insulated) for an ultrasound-guided supraclavicular block in patients undergoing hand surgery. The impedance changes at each location were analyzed and compared.Data were collected from 16 patients. Baseline impedance was lower intravascularly (mean 16.5 +/- standard deviation 7.2 kOmega) compared with perineurally (23.5 +/- 8.3 kOmega) (P = 0.037). Peak impedance after intravascular D5W injection was 20.1 +/- 6.8 kOmega, which was not a significant change (P = 0.15). In contrast, peak impedance after perineural D5W injection was 58.6 +/- 29.1 kOmega, an increase of 35.1 +/- 26.4 kOmega (155 +/- 117%), and then it reached a plateau of 36.7 +/- 19.6 kOmega. The increase in impedance was significantly greater at the perineural location (P < 0.0001).The absence of a significant increase in impedance upon injection of D5W prior to injection of local anesthetic may provide useful information to warn of intravascular injection.

    View details for DOI 10.1007/s12630-010-9293-5

    View details for Web of Science ID 000277425800005

    View details for PubMedID 20221859

  • Evidence-Based Medicine: Assessment of Ultrasound Imaging for Regional Anesthesia in Infants, Children, and Adolescents REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Pillay, J. J. 2010; 35 (2): S47-S54

    Abstract

    This review was performed to evaluate and discuss the quality and outcomes of studies assessing ultrasound imaging in pediatric regional anesthesia. Literature searches were conducted using MEDLINE and EMBASE, combining the search term "ultrasonography" with "regional anesthesia," "nerve block," "epidural anesthesia," and "spinal anesthesia," with the limit of 0 to 18 years. Additional literature was sought from departmental files and recent issues of several major anesthesiology journals. Meta-analyses/systematic reviews, randomized controlled trials, clinical studies without either randomization or control (eg, comparative studies), and case series (n > 10) were collected, reviewed, and graded for their quality (Jadad scores) and level of evidence (Grades of Recommendation). The search resulted in 211 total publications in pediatric literature, of which 12 were included in the evaluation of peripheral nerve blocks and 12 in the evaluation of neuraxial anesthesia. Although there is some evidence to support ultrasound for various outcomes in pediatric regional anesthesia, more randomized controlled studies with sufficient power are required to further support these findings and to evaluate the potential for ultrasound to reduce complications for regional anesthesia in children.

    View details for DOI 10.1097/AAP.0b013e3181d32770

    View details for Web of Science ID 000275384900007

    View details for PubMedID 20216025

  • The ASRA Evidence-Based Medicine Assessment of Ultrasound-Guided Regional Anesthesia and Pain Medicine Executive Summary REGIONAL ANESTHESIA AND PAIN MEDICINE Neal, J. M., Brull, R., Chan, V. W., Grant, S. A., Horn, J., Liu, S. S., McCartney, C. J., Narouze, S. N., Perlas, A., Salinas, F. V., Sites, B. D., Tsui, B. C. 2010; 35 (2): S1-S9

    Abstract

    The American Society of Regional Anesthesia and Pain Medicine charged an expert panel to examine the evidence basis for ultrasound guidance as a nerve localization tool in the clinical practices of regional anesthesia and interventional pain medicine.The panel searched, examined, and assessed the literature of ultrasound-guided regional anesthesia (UGRA) from the past 20 years. The qualities of studies were graded using the Jadad score. Strength of evidence and recommendations were graded using an accepted rating tool.The panel made specific literature-based assessments concerning the relative advantages and limitations of UGRA relative to traditional nerve localization methods as they pertained to block characteristics and complications. Assessments and recommendations were made for upper and lower extremity, neuraxial, and truncal blocks and include pediatrics and interventional pain medicine.Ultrasound guidance improves block characteristics (particularly performance time and surrogate measures of success) that are often block specific and that may impart an efficiency advantage depending on individual practitioner circumstances. Evidence for UGRA impacting patient safety is currently limited to the demonstration of improvements in the frequency of surrogate events for serious complications.

    View details for DOI 10.1097/AAP.0b013e3181d22fe0

    View details for Web of Science ID 000275384900001

    View details for PubMedID 20216019

  • Ultrasound Imaging for Regional Anesthesia in Infants, Children, and Adolescents A Review of Current Literature and Its Application in the Practice of Neuraxial Blocks ANESTHESIOLOGY Tsui, B. C., Suresh, S. 2010; 112 (3): 719-728

    Abstract

    Complementary to a previous publication related to pediatric extremity and trunk blockade, the authors present a comprehensive narrative review of the literature pertaining to techniques described and outcomes evaluated for ultrasound imaging in pediatric neuraxial anesthesia. The sonoanatomy related to each block is also described and illustrated to serve as a foundation for better understanding the block techniques described. For neuraxial blockade, ultrasound may fairly reliably predict the depth to loss of resistance and can enable a dynamic view of the needle and catheter after entry into the spinal canal. Particularly, in young infants, direct visualization of the needle and catheter tip may be possible, whereas in older children surrogate markers including the displacement of dura mater by the injection of fluid may be necessary for confirming needle and catheter placement. More outcome-based, prospective, randomized, controlled trials are required to prove the benefits of ultrasound when compared with conventional methods.

    View details for DOI 10.1097/ALN.0b013e3181c5e03a

    View details for Web of Science ID 000275266800029

    View details for PubMedID 20179511

  • Epidural anesthesia and cancer recurrence rates after radical prostatectomy CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Rashiq, S., Schopflocher, D., Murtha, A., Broemling, S., Pillay, J., Finucane, B. T. 2010; 57 (2): 107-112

    Abstract

    To determine the effect of adjunctive epidural local anesthetic and opioid infusion on disease recurrence following radical prostatectomy for adenocarcinoma under general anesthesia.This article describes a secondary analysis of subjects undergoing radical prostatectomy who had participated previously in a randomized controlled trial evaluating pain control, blood loss, and the need for perioperative allogeneic blood transfusion. The patients were randomly allocated to receive either general anesthesia alone (control group; n = 50) or combined general/epidural anesthesia (study group; n = 49). A long-term follow-up chart review was undertaken to determine clinically evident or biochemical (Prostate Specific Antigen > 0.2 ng x mL(-1)) recurrence of prostate cancer. Comparison by group was undertaken using survival analysis.Median disease-free survival for the study as a whole was 1644 days, and the longest recorded survival was 3403 days. Biochemical recurrence of prostate cancer was observed in 11/49 study subjects and 17/50 control subjects. There was one death from prostate cancer in each group and a total of five deaths in the study group and six deaths in the control group. The hazard ratio for recurrence in the study group compared with the control group was 1.33 (95% confidence intervals 0.64-2.77; P = 0.44 by log-rank test).No difference was observed between the epidural and control groups in disease-free survival at a median follow-up time of 4.5 years. There is a need for large randomized controlled trials to determine the ability of epidural analgesia to alter disease recurrence rates following radical prostatectomy.

    View details for DOI 10.1007/s12630-009-9214-7

    View details for Web of Science ID 000273846700003

    View details for PubMedID 19911247

  • Ultrasound Imaging for Regional Anesthesia in Infants, Children, and Adolescents A Review of Current Literature and Its Application in the Practice of Extremity and Trunk Blocks ANESTHESIOLOGY Tsui, B. C., Suresh, S. 2010; 112 (2): 473-492

    Abstract

    The use of ultrasound guidance has provided an opportunity to perform many peripheral nerve blocks that would have been difficult to perform in children based on pure landmark techniques due to the potential for injection into contiguous sensitive vascular areas. This review article provides the readers with techniques on ultrasound-guided peripheral nerve blocks of the extremities and trunk with currently available literature to substantiate the available evidence for the use of these techniques. Ultrasound images of the blocks with corresponding line diagrams to demonstrate the placement of the ultrasound probe have been provided for all the relevant nerve blocks in children. The authors hope that this review will stimulate further research into ultrasound-guided regional anesthesia in infants, children, and adolescents and stimulate more randomized controlled trials to provide a greater understanding of the anatomy and physiology of regional anesthesia in pediatrics.

    View details for Web of Science ID 000274046400028

    View details for PubMedID 20068455

  • Ultrasound imaging to localize foramina for superficial trigeminal nerve block CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C. 2009; 56 (9): 704-706

    View details for DOI 10.1007/s12630-009-9129-3

    View details for Web of Science ID 000269186900011

    View details for PubMedID 19504162

  • Dextrose 5% in Water as an Alternative Medium to Gel for Performing Ultrasound-Guided Peripheral Nerve Blocks REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C. 2009; 34 (5): 525-527

    View details for Web of Science ID 000270157900026

    View details for PubMedID 19749591

  • Challenges in sublingual airway ultrasound interpretation CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Hui, C. M. 2009; 56 (5): 393-394

    View details for DOI 10.1007/s12630-009-9077-y

    View details for Web of Science ID 000265382400012

    View details for PubMedID 19259756

  • Ultrasound-Guided Transsartorial Perifemoral Artery Approach for Saphenous Nerve Block REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Ozelsel, T. 2009; 34 (2): 177-178

    View details for Web of Science ID 000264128600013

    View details for PubMedID 19282716

  • The potential use of intralipid to minimize propofol's cardiovascular effects CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Gragasin, F. S., Davidge, S. T., Tsui, B. C. 2009; 56 (2): 170-171

    View details for DOI 10.1007/s12630-008-9031-4

    View details for Web of Science ID 000263478100013

    View details for PubMedID 19247766

  • Migration of a Thoracic Epidural Catheter into the Intercostal Space via the Intervertebral Foramen ANESTHESIA AND ANALGESIA Tsui, B. C., Kulkarni, P. 2009; 108 (1): 371-373

    Abstract

    We describe a documented migration of a thoracic epidural catheter into the thoracic cage in a 5-wk-old with DiGeorge's syndrome and an uncorrected acyanotic Tetralogy of Fallot who underwent laparotomy for malrotation, gastric fundoplication, and gastrostomy tube insertion under combined general and epidural anesthesia. A 20-gauge stimulating catheter was inserted caudally and advanced cephalad to the thoracic level while applying a low electrical current (1-10 mA) to confirm epidural placement at approximately T5-6. Despite good pain control through the third postoperative day, using an epidural infusion of bupivacaine 0.1% at 1-1.2 mL/h, radiography demonstrated catheter migration into the seventh intercostal space.

    View details for DOI 10.1213/ane.0b013e31818e0ee2

    View details for Web of Science ID 000261963000056

    View details for PubMedID 19095876

  • Case series: ultrasound-guided supraclavicular block using a curvilinear probe in 104 day-case hand surgery patients CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Doyle, K., Chu, K., Pillay, J., Dillane, D. 2009; 56 (1): 46-51

    Abstract

    To report our experiences regarding the implementation of a combined ultrasound and nerve stimulation guidance technique for supraclavicular blockade in day-case hand surgery patients at our institution.We retrospectively reviewed 104 patient charts from the first 6 months of our clinical practice of using this block approach for upper extremity surgery. Block success, completion and recovery time, post-block analgesia requirement, acute complication rate, and duration of hospital stay were evaluated and categorized based on the practitioner who performed the block (fellow/staff anesthesiologists and residents), as well as the body mass index of the patient (when available). During the performance of each block, the brachial plexus was viewed using a curvilinear probe, and the needle was advanced in-plane in an anterolateral-to-posteromedial direction. The plexus, needle, and spread of local anesthetic could be clearly visualized in each case. Surgical regional anesthesia was achieved in 94.2% of blocks. The block was the sole method of postoperative analgesia in 85.6% of patients, and the overall block completion time was 20.2 +/- 9.2 min. There were no occurrences of clinical pneumothorax during the study period.We report our successful experience using ultrasound guidance and nerve stimulation during supraclavicular blockade. The curvilinear probe enables a large field of view, adequate resolution in larger patients, and excellent needle visibility that allows access to the plexus while avoiding the pleura and subclavian artery.

    View details for DOI 10.1007/s12630-008-9006-5

    View details for Web of Science ID 000263012800007

    View details for PubMedID 19247777

  • Continuing medical education: Ultrasound guidance for regional blockade - basic concepts CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Dillane, D. 2008; 55 (12): 869-874

    View details for Web of Science ID 000261940200010

    View details for PubMedID 19050091

  • Sublingual airway ultrasound imaging CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Hui, C. M. 2008; 55 (11): 790-791

    View details for Web of Science ID 000261044600015

    View details for PubMedID 19138924

  • Electrical impedance to distinguish intraneural from extraneural needle placement in porcine nerves during direct exposure and ultrasound guidance ANESTHESIOLOGY Tsui, B. C., Pillay, J. J., Chu, K. T., Dillane, D. 2008; 109 (3): 479-483

    Abstract

    Intraneural injection during peripheral nerve blockade can cause neurologic injury. Current approaches to prevent or detect intraneural injection lack reliability and consistency, or only signal intraneural injection upon the event. A change in electrical impedance (EI) could be indicative of intraneural needle placement before injection.After animal care committee approval, eight pigs were anesthetized and kept spontaneously breathing. In four pigs (part 1), the sciatic nerves were exposed bilaterally for direct needle placement; in a further four pigs (part 2), the tissue was kept intact for ultrasound-guided needle placement. An insulated needle (Sprotte 24 gauge; Pajunk GmbH Medizintechnologie, Geisingen, Germany), attached to a nerve stimulator displaying EI (Braun Stimuplex HNS 12; B. Braun Medical, Bethlehem, PA), was placed extraneurally and then advanced to puncture the nerve sheath. Five punctures within approximately a 1-cm length of each nerve were performed. For each Part, overall EI at each compartment and EI after individual punctures were compared using a general linear model, with post hoc analysis using the Duncan multiple range test.The EI was lower extraneurally compared with intraneurally during open dissection (12.1 +/- 1.8 vs. 23.2 +/- 4.4 kOmega; P < 0.0001; n = 8) and when using ultrasound guidance (10.8 +/- 2.9 vs. 18.2 +/- 6.1 kOmega; P < 0.0001; n = 7 nerves were visualized adequately). The EI difference was maintained despite performing five sequential punctures.With further study, EI could prove to be a quantifiable warning signal to alert clinicians to intraneural needle placement, preventing local anesthetic injection and subsequent nerve injury.

    View details for Web of Science ID 000258793700017

    View details for PubMedID 18719446

  • Ultrasound-guided anterior sciatic nerve block using a longitudinal approach: "Expanding the view" REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Ozelsel, T. J. 2008; 33 (3): 275-276

    View details for DOI 10.1016/j.rapm.2007.11.008

    View details for Web of Science ID 000255617400017

    View details for PubMedID 18433684

  • Reduced injection pressures using a compressed air injection technique (CAIT): An in vitro study REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Knezevich, F. P., Pillay, J. J. 2008; 33 (2): 168-173

    Abstract

    High injection pressures have been associated with intraneural injection and persistent neurological injury in animals. Our objective was to test whether a reported simple compressed air injection technique (CAIT) would limit the generation of injection pressures to below a suggested 1,034 mm Hg limit in an in vitro model.After ethics board approval, 30 consenting anesthesiologists injected saline into a semiclosed system. Injection pressures using 30 mL syringes connected to a 22 gauge needle and containing 20 mL of saline were measured for 60 seconds using: (1) a typical "syringe feel" method, and (2) CAIT, thereby drawing 10 mL of air above the saline and compressing this to 5 mL prior to and during injections. All anesthesiologists performed the syringe feel method before introduction and demonstration of CAIT.Using CAIT, no anesthesiologist generated pressures above 1,034 mm Hg, while 29 of 30 produced pressures above this limit at some time using the syringe feel method. The mean pressure using CAIT was lower (636 +/- 71 vs. 1378 +/- 194 mm Hg, P = .025), and the syringe feel method resulted in higher peak pressures (1,875 +/- 206 vs. 715 +/- 104 mm Hg, P = .000).This study demonstrated that CAIT can effectively keep injection pressures under 1,034 mm Hg in this in vitro model. Animal and clinical studies will be needed to determine whether CAIT will allow objective, real-time pressure monitoring. If high pressure injections are proven to contribute to nerve injury in humans, this technique may have the potential to improve the safety of peripheral nerve blocks.

    View details for DOI 10.1016/j.rapm.2007.10.006

    View details for Web of Science ID 000253781700012

    View details for PubMedID 18299098

  • Patient-con trolled oral airway insertion to facilitate awake fibreoptic intubation CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Dillane, D., Yee, M. 2008; 55 (3): 194-195

    View details for Web of Science ID 000254110300019

    View details for PubMedID 18310637

  • Ultrasound imaging in cadavers: training in imaging for regional blockade at the trunk CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B., Dillane, D., Pillay, J., Walji, A. 2008; 55 (2): 105-111

    Abstract

    The unique strategy of using cadaveric models for teaching ultrasound-guided blocks has been described for blocks of the upper and lower extremities. This report considers the parallels between cadaveric and live imaging relevant to scanning of the trunk. The inter-individual variation between subjects (particularly for epidural blocks) is also considered, for practicing ultrasound-guided or supported trunk and central neuraxial techniques.Ultrasound images using a portable machine C60 5-2 MHz curved array probe or HFL38 13-6 MHz linear array probe were obtained from scanning the trunk of a male adult cadaver, and were compared with ultrasound and magnetic resonance images from an adult male volunteer.Ultrasound imaging at the midline of the spine in the transverse/coronal plane provided an overview of the vertebral column, while scanning in a medial-to-lateral direction using longitudinal/sagittal plane sequentially localized the spinous, articular and transverse process. At the thoracic spine, further lateral longitudinal scanning will identify costal structures with the rib necks alternating with the hyperechoic ligamentous tissue of the costovertebral joints. Ultrasound imaging in the live subject in the paramedian longitudinal plane could be used at the thoracic and lumber spinal levels to capture the optimal ultrasound window of the epidural space. Imaging in the cadaver, especially when viewing the epidural space, is primarily limited by the tissue rigidity and lack of spine flexibility.Cadavers may provide viable training options for practicing ultrasound imaging and real-time ultrasound needle guidance for nerve blocks at the trunk and epidural space. The training can be performed in a stress-free pre-clinical environment without time constraints and the potential for patient discomfort.

    View details for Web of Science ID 000253139500005

    View details for PubMedID 18245070

  • Pharmacokinetics and metabolism of diltiazem in rats: Comparing single vs repeated subcutaneous injections in vivo BIOPHARMACEUTICS & DRUG DISPOSITION Yeung, P. K., Alcos, A., Tang, J., Tsui, B. 2007; 28 (7): 403-407

    Abstract

    The objective of the study was to determine the effect of repeated administration on the pharmacokinetics and metabolism of diltiazem (DTZ) using an in vivo rat model. Male SD rats (n = 6-10 per group) weighing 350-450 g were used. Each rat received either a single 20 mg/kg dose of DTZ by subcutaneous (s.c.) injection or 5 mg/kg s.c. twice daily for five doses. Plasma concentrations of DTZ and its major metabolites were determined by HPLC for up to 8 h. Compared with the single dose, repeated administration resulted in higher dose normalized plasma concentrations of DTZ (AUC 26.4+/-14.2 vs 13.9+/-11.5 microg-h/ml), longer apparent half-life (t(1/2) = 12.5+/-14.6 vs 3.7+/-1.4 h) and lower systemic clearance (CL = 1.1+/-1.0 vs 2.9+/-2.7 l/h/kg). Higher dose normalized plasma concentrations, longer t(max), but shorter apparent t(1/2) of the major metabolites were observed following the repeated administration. The results also suggest that possible binding of DTZ may occur at the site of injection when administered subcutaneously in the higher dose.

    View details for DOI 10.1002/bdd.568

    View details for Web of Science ID 000250662700007

    View details for PubMedID 17668417

  • Cadaveric ultrasound imaging for training in ultrasound-guided peripheral nerve blocks: lower extremity CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Dillane, D., Pillay, J., Ramji, A., Walji, A. H. 2007; 54 (6): 475-480

    View details for Web of Science ID 000246993100011

    View details for PubMedID 17541078

  • Cadaveric ultrasound imaging for training in ultrasound-guided peripheral nerve blocks: upper extremity CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Dillane, D., Walji, A. H. 2007; 54 (5): 392-396

    View details for Web of Science ID 000246329600011

    View details for PubMedID 17470892

  • Adjunct continuous intravenous ketamine infusion for postoperative pain relief following posterior spinal instrumentation for correction of scoliosis: a case report PEDIATRIC ANESTHESIA Tsui, B. C., Wagner, A., Mahood, J., Moreau, M. 2007; 17 (4): 383-386

    Abstract

    Providing effective analgesia is challenging for correction of idiopathic scoliosis, as nonsteroidal anti-inflammatory drugs and epidural anesthesia are controversial and large-dose opioids can cause significant side effects. Perioperative adjuvant low-dose ketamine has been shown to provide good supplementary analgesia as well as to potentially spare opioid consumption. Ketamine may also improve early ease of mobility without addition of any noticeable adverse effects. This case describes the combined use of a continuous low-dose ketamine infusion and patient-controlled analgesia (PCA) morphine for postoperative analgesia in an adolescent girl undergoing posterior spinal instrumentation and correction of scoliosis. The patient had excellent postoperative analgesia and was able to participate in early rehabilitation. The opioid-sparing effect of ketamine was not demonstrated in this case. Further study of continuous low-dose ketamine infusions in this patient population would be beneficial to provide more evaluation of the efficacy and tolerability of ketamine and of its opioid-sparing potential.

    View details for DOI 10.1111/j.1460-9592.2006.02134.x

    View details for Web of Science ID 000244742900014

    View details for PubMedID 17359410

  • Ultrasound-guidance and nerve stimulation: implications for the future practice of regional anesthesia CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. 2007; 54 (3): 165-170

    View details for Web of Science ID 000245113600001

    View details for PubMedID 17331926

  • Cervical epidural analgesia via a thoracic approach using nerve-stimulation guidance in adult patients undergoing total shoulder replacement surgery ACTA ANAESTHESIOLOGICA SCANDINAVICA Tsui, B. C., Bury, J., Bouliane, M., Ganapathy, S. 2007; 51 (2): 255-260

    Abstract

    Continuous cervical epidural anesthesia can provide excellent peri- and post-operative analgesia, although several factors prevent its widespread use. Advancing catheters from thoracic levels to the cervical region may circumvent these barriers, provided they are accurately positioned. We hypothesize that guiding catheters from thoracic to cervical regions using low-current epidural stimulation will have a high success rate and enable excellent analgesia in adults undergoing total shoulder arthroplasty.After Institutional Review Board approval, adult patients were studied consecutively. A 17-G Tuohy needle was inserted into the thoracic epidural space using a right paramedian approach with loss of resistance. A 20-G styletted epidural catheter, with an attached nerve stimulator, was primed with saline and a 1-10 mA current was applied as it advanced in a cephalad direction towards the cervical spine. Muscle twitch responses were observed and post-operative X-ray confirmed final placement. After a test dose, an infusion (2-8 ml/h) of ropivacaine 2 mg/ml and morphine 0.05 mg/ml (or equivalent) was initiated. Verbal analog pain scale scores were collected over 72 h.Cervical epidural anesthesia was performed on 10 patients. Average current required to elicit a motor response was 4.8 +/- 2.0mA. Post-operative X-ray of catheter positions confirmed all catheter tips reached the desired region (C4-7). The technical success rate for catheter placement was 100% and excellent pain control was achieved. Catheters were positioned two to the left, four to the right and four to the midline.This epidural technique provided highly effective post-operative analgesia in a patient group that traditionally experiences severe post-operative pain and can benefit from early mobilization.

    View details for DOI 10.1111/j.1399-6576.2006.1184.x

    View details for Web of Science ID 000243561900019

    View details for PubMedID 17096670

  • Facilitating needle alignment in-plane to an ultrasound beam using a portable laser unit REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C. 2007; 32 (1): 84-88

    Abstract

    Ultrasound guidance can increase success with peripheral nerve blocks. Accurate anesthetic injection is optimized with both clear visualization and fine adjustment of the needle tip at the target area. Good needle alignment with the ultrasound beam and using a freehand technique are both desirable for these conditions. The purpose of this report is to describe how a unique, in-plane laser guide may be used to improve the alignment of injection needles with ultrasound beams in order to promote best needle tip visualization.By using a small, battery-operated laser unit mounted onto an ultrasound transducer, a method to align the ultrasound scanning plane and laser-line projection plane was developed. Such alignment was further demonstrated and illustrated in a water bath model. Ultrasound was then used to show how clearly the needle shaft and tip can be visualized after needle alignment to the ultrasound beam using the laser line shining on the shaft of the needle.This in vitro demonstration describes the potential use of a readily available laser-line unit to assist with in-plane needle alignment with the ultrasound plane in order to ultimately improve needle visibility during ultrasound-guided peripheral nerve block. It requires minimum specialized training and may allow for maximum flexibility with freehand needle insertions in a sterile fashion.

    View details for DOI 10.1016/j.rapm.2006.09.009

    View details for Web of Science ID 000243311100015

    View details for PubMedID 17196498

  • Needle puncture site and a "walkdown" approach for short-axis alignment during ultrasound-guided blocks REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Dillane, D. 2006; 31 (6): 586-587

    View details for DOI 10.1016/j.rapm.2006.08.001

    View details for Web of Science ID 000242698700022

    View details for PubMedID 17138208

  • "Credentials" in ultrasound-guided regional blocks REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C. 2006; 31 (6): 587-588

    View details for DOI 10.1016/j.rapm.2006.08.003

    View details for Web of Science ID 000242698700023

    View details for PubMedID 17138209

  • Compressed air injection technique to standardize block injection pressures CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Li, L. X., Pillay, J. J. 2006; 53 (11): 1098-1102

    Abstract

    Presently, no standardized technique exists to monitor injection pressures during peripheral nerve blocks. Our objective was to determine if a compressed air injection technique, using an in vitro model based on Boyle's law and typical regional anesthesia equipment, could consistently maintain injection pressures below a 1293 mmHg level associated with clinically significant nerve injury.Injection pressures for 20 and 30 mL syringes with various needle sizes (18G, 20G, 21G, 22G, and 24G) were measured in a closed system. A set volume of air was aspirated into a saline-filled syringe and then compressed and maintained at various percentages while pressure was measured. The needle was inserted into the injection port of a pressure sensor, which had attached extension tubing with an injection plug clamped "off". Using linear regression with all data points, the pressure value and 99% confidence interval (CI) at 50% air compression was estimated.The linearity of Boyle's law was demonstrated with a high correlation, r = 0.99, and a slope of 0.984 (99% CI: 0.967-1.001). The net pressure generated at 50% compression was estimated as 744.8 mmHg, with the 99% CI between 729.6 and 760.0 mmHg. The various syringe/needle combinations had similar results.By creating and maintaining syringe air compression at 50% or less, injection pressures will be substantially below the 1293 mmHg threshold considered to be an associated risk factor for clinically significant nerve injury. This technique may allow simple, real-time and objective monitoring during local anesthetic injections while inherently reducing injection speed.

    View details for Web of Science ID 000241826900008

    View details for PubMedID 17079636

  • Compressed air injection technique to standardize block injection pressures : [La technique d'injection d'air comprimé pour normaliser les pressions d'injection d'un blocage nerveux]. Canadian journal of anaesthesia = Journal canadien d'anesthesie Tsui, B. C., Li, L. X., Pillay, J. J. 2006; 53 (11): 1098-1102

    Abstract

    Presently, no standardized technique exists to monitor injection pressures during peripheral nerve blocks. Our objective was to determine if a compressed air injection technique, using an in vitro model based on Boyle's law and typical regional anesthesia equipment, could consistently maintain injection pressures below a 1293 mmHg level associated with clinically significant nerve injury.Injection pressures for 20 and 30 mL syringes with various needle sizes ( 18G, 20G, 21 G, 22G, and 24G) were measured in a closed system. A set volume of air was aspirated into a saline-filled syringe and then compressed and maintained at various percentages while pressure was measured. The needle was inserted into the injection port of a pressure sensor, which had attached extension tubing with an injection plug clamped "off". Using linear regression with all data points, the pressure value and 99% confidence interval (CI) at 50% air compression was estimated.The linearity of Boyle's law was demonstrated with a high correlation, r = 0.99, and a slope of 0.984 (99% CI: 0.967-1.001). The net pressure generated at 50% compression was estimated as 744.8 mmHg, with the 99% CI between 729.6 and 760.0 mmHg. The various syringe/needle combinations had similar results.By creating and maintaining syringe air compression at 50% or less, injection pressures will be substantially below the 1293 mmHg threshold considered to be an associated risk factor for clinically significant nerve injury. This technique may allow simple, real-time and objective monitoring during local anesthetic injections while inherently reducing injection speed.Présentement, aucune technique normalisée ne permet de vérifier les pressions d'injection pendant les blocages nerveux périphériques. Nous voulions vérifier si une technique d'injection d'air comprimé, utilisant un modèle in vitro fondé sur la loi de Boyle et du matériel propre à l'anesthésie régionale, pouvait maintenir avec régularité les pressions d'injection sous les 1293 mmHg, pression associée à une lésion nerveuse cliniquement significative. MéTHODE: Les pressions d'injection pour des seringues de 20 et 30 mL et diverses tailles d'aiguilles (18G, 20G, 21G, 22G et 24G) ont été mesurées dans un système fermé. Un volume défini d'air a été aspiré dans une seringue rempli de solution saline, puis comprimé et maintenu à des pourcentages variés pendant la mesure de la pression. L'aiguille a été insérée dans l'ouverture à injection d'un détecteur de pression muni d'une extension avec un bouchon d'injection en position fermée. La valeur de la pression et l'intervalle de confiance de 99 % (IC) pour une compression d'air à 50 % ont été évalués en utilisant une régression linéaire avec tous les points de données. RéSULTATS: La linéarité de la loi de Boyle a été démontrée avec une forte corrélation, r = 0,99 et une pente de 0,984 (IC de 99 % : 0,967-1,001) La pression nette générée sous une compression de 50% a été de 744,8 mmHg avec un IC de 99 % entre 729,6 et 760,0 mmHg. Les diverses combinaisons de seringues et d'aiguilles ont présenté des résultats similaires.En créant et en maintenant dans la seringue une compression d'air à 50% ou moins, les pressions d'injection seront dans l'ensemble sous le seuil des 1293 mmHg associé à un facteur de risque de lésion nerveuse cliniquement significative. Cette technique peut permettre une surveillance simple, objective et en temps réel pendant les injections d'anesthésiques locaux tout en réduisant fondamentalement la vitesse d'injection.

    View details for PubMedID 27771909

  • Innovative approaches to neuraxial blockade in children: the introduction of epidural nerve root stimulation and ultrasound guidance for epidural catheter placement. Pain research & management Tsui, B. C. 2006; 11 (3): 173-180

    Abstract

    Continuous epidural blockade remains the cornerstone of pediatric regional anesthesia. However, the risk of catastrophic trauma to the spinal cord when inserting direct thoracic and high lumbar epidural needles in anesthetized or heavily sedated pediatric patients is a concern. To reduce this risk, research has focused on low lumbar or caudal blocks (ie, avoiding the spinal cord) and threading catheters from distal puncture sites in a cephalad direction. However, with conventional epidural techniques, including loss-of-resistance for localization of the needle, optimal catheter tip placement is difficult to assess because considerable distances are required during threading. Novel approaches include electrical epidural stimulation for physiological confirmation and segmental localization of epidural catheters, and ultrasound guidance for assessing related neuroanatomy and real-time observation of the needle puncture and, potentially, catheter advancement. The present article provides a brief and focused review of these two advances, and outlines recent clinical experiences relevant to pediatric epidural anesthesia.

    View details for PubMedID 16960634

    View details for PubMedCentralID PMC2539001

  • Epidural stimulation test criteria ANESTHESIA AND ANALGESIA Tsui, B. C. 2006; 103 (3): 775-776
  • The importance of ultrasound landmarks: A "traceback" approach using the popliteal blood vessels for identification of the sciatic nerve REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Finucane, B. T. 2006; 31 (5): 481-482

    View details for DOI 10.1016/j.rapm.2006.03.008

    View details for Web of Science ID 000240881700017

    View details for PubMedID 16952825

  • Thoracic epidural catheters via the caudal and lumbar approaches using styletted multiple port catheters in pediatric patients: a report of three cases ACTA ANAESTHESIOLOGICA SCANDINAVICA Tsui, B. C., Usher, A., Kulkarni, P. R., Scott, S. L. 2006; 50 (4): 514-517

    Abstract

    Advancing catheters from the lumbar and caudal epidural spaces to the thoracic level has been reported to be an alternative to the direct thoracic approach. However, as children grow, the threading of catheters in the epidural space becomes increasingly difficult. This report describes three cases of thoracic epidural placement using a multiport catheter threaded from the caudal and lumbar spaces using electrical stimulation guidance. In the first case, a multiport catheter was threaded 22 cm from the lumbar space to T8 following a failed attempt with a single-port catheter in a 9-year-old boy scheduled to undergo a right nephrectomy. In the second case, a multiport catheter was threaded 26 cm from the caudal space to T9 in a 3-year-old girl undergoing fundoplication. In the last case, a multiport catheter was inserted at the completion of a fundoplication in a 2-year-old girl after it had been confirmed that the single-port catheter inserted prior to surgery had not advanced to the desired thoracic level. The multiport catheter was threaded 17 cm without resistance from the caudal space to T9. In all cases, electrical stimulation was used to confirm the location of the catheter tip at the time of insertion. The position of the catheters was later confirmed by X-ray. The multiport catheter incorporates a stylet, which extends to a closed distal tip, within a catheter body that ejects fluid from three lateral holes in a direction perpendicular to the advancing catheter. These properties may facilitate the reliable advancement of catheters in the epidural space.

    View details for DOI 10.1111/j.1399-6576.2005.00969.x

    View details for Web of Science ID 000236069900018

    View details for PubMedID 16548868

  • Verifying spinal needle location in the a presence of a "dry tap" CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C. 2006; 53 (4): 424-425

    View details for Web of Science ID 000236596500023

    View details for PubMedID 16575050

  • Targeted thoracic epidural blood patch placed under electrical stimulation guidance (Tsui test) CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Morley-Forster, P. K., Abotaiban, A., Ganapathy, S., Moulin, D. E., Leung, A., Tsui, B. 2006; 53 (4): 375-379

    Abstract

    This case report describes the use of electrical epidural stimulation (Tsui test) to confirm accurate placement of a thoracic epidural catheter when administering an epidural blood patch for headache management in a patient suffering from spontaneous intracranial hypotension.A 41-yr-old female presented to the Chronic Pain Clinic with a history of postural headache symptoms worsening in severity over several years. Two previous blood patches performed at T11-12 and T10-11 respectively provided short-term relief only. The presumed diagnosis of a spontaneous dural tear was confirmed by a nuclear flow test to be at T2-T4. The epidural site was accessed at T6 with a Tuohy needle. To accurately place the epidural blood patch at the level of the dural tear, the Arrow catheter with electrode adapter was advanced under nerve stimulation guidance to T4. Ten millilitres of autologous blood injected through the catheter was confirmed on magnetic resonance imaging, one hour postprocedure, to lie between T3 and T9. Sustained headache relief was achieved.The use of electrical stimulation guidance may be useful when precise epidural blood patch placement is required.

    View details for Web of Science ID 000236596500009

    View details for PubMedID 16575036

  • Visualization of the brachial plexus in the supraclavicular region using a curved ultrasound probe with a sterile transparent dressing REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C. 2006; 31 (2): 182-184

    View details for DOI 10.1016/j.rapm.2005.12.002

    View details for Web of Science ID 000236599500018

    View details for PubMedID 16543109

  • Declining randomized clinical trials from Canadian anesthesia departments? CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Li, L. X., Ma, V., Wagner, A. M., Finucane, B. T. 2006; 53 (3): 226-235

    Abstract

    The research productivity was estimated by publications from anesthesiology departments at Canadian universities over a five-year period, and the articles published were classified into several study designs.In this observational study, the MEDLINE database was searched for publications listed by anesthesiology departments at Canadian universities as the primary corresponding source from 2000-2004. Abstracts were reviewed and each publication categorized into its respective methodological design. Impact factors of the journals in which the articles appeared were taken into consideration. "Total impact score" was defined as the total number of articles from a particular journal in a particular year multiplied by the impact factor value. Changes in overall publication numbers over the five-year period were compared and analyzed using Pearson correlation coefficients.Total Canadian anesthesia publications remained constant from 2000-2004. In this five-year time frame, the University of Toronto had the highest number of publications (271) followed by the University of Montreal (86), and McGill University (84). These universities conducted primarily randomized controlled trials (RCTs) whereas smaller Canadian universities mainly published case reports, reviews, and cohort studies. The number of RCTs conducted seems to be decreasing whereas the number of case reports and reviews being published are remaining constant over the five-year period.Although overall numbers in anesthesia publications do not suggest a significant decline, the number of RCTs decreased during the years 2000-2004. The quality of anesthesia research appears to be comparable to those in other medical specialties, with larger institutions conducting RCTs and smaller institutions publishing more case reports.

    View details for Web of Science ID 000235697000003

    View details for PubMedID 16527785

  • Epidural stimulation test vs epidural ECG test for checking epidural catheter placement BRITISH JOURNAL OF ANAESTHESIA Tsui, B. C. 2005; 95 (6): 837-837

    View details for DOI 10.1093/bja/aei613

    View details for Web of Science ID 000233400400024

    View details for PubMedID 16286354

  • Epidural test dose. How to be sure it is safe? Acta anaesthesiologica Scandinavica Tsui, B. C. 2005; 49 (10): 1579-1580

    View details for PubMedID 16223418

  • Can continuous low current electrical stimulation distinguish insulated needle position in the epidural and intrathecal spaces in pediatric patients? PEDIATRIC ANESTHESIA Tsui, B. C., Wagner, A. M., Cunningham, K., Perry, S., Desai, S., Seal, R. 2005; 15 (11): 959-963

    Abstract

    Muscle twitches elicited with electrical stimulation (6-17 mA) during epidural insertion indicate correct epidural needle placement while muscle twitches at a lower current (<1 mA) may indicate intrathecal needle placement. This study examined whether applying continuous electrical stimulation at 6 mA could indicate needle entry into the epidural space without inadvertently penetrating the intrathecal space.After institutional review board (IRB) approval, 10 pediatric patients scheduled for lumbar puncture were studied. Following sedation with propofol, an insulated 24-gauge Pajunck unipolar needle was inserted through an 18-gauge introducer needle placed at the L4-5 interspace. The needle was first connected to a nerve stimulator (6 mA) and advanced. At the first sign of muscle twitching, needle advancement was stopped and the threshold current for motor activity was determined. The current was then turned off, the stylet was removed and the needle checked for cerebrospinal fluid (CSF). If CSF was not present, the needle was advanced into the intrathecal space (as confirmed by the presence of CSF). Ten pediatric patients (ASA II or III) aged 7.8 +/- 4.3 years (2.8-16.0 years) were studied.All patients had two distinguishable threshold currents as the needle advanced. The mean threshold current to elicit muscle twitch in the presumed epidural space was 3.84 +/- 0.99 mA. CSF was not present in any of the patients at this location. The mean threshold current in the intrathecal space was 0.77 +/- 0.32 mA. The average estimated distance from the first threshold location to the intrathecal space was 3 mm. All muscle twitches were at the L3-5 myotomes. Nine muscle twitches were unilateral and one was bilateral.Monitoring with an insulated needle with electrical stimulation at 6 mA may prevent unintentional placement of epidural needles into the intrathecal space.

    View details for DOI 10.1111/j.1460-9592.2005.01622.x

    View details for Web of Science ID 000232659600009

    View details for PubMedID 16238557

  • Dextrose 5% in water: fluid medium for maintaining electrical stimulation of peripheral nerves during stimulating catheter placement ACTA ANAESTHESIOLOGICA SCANDINAVICA Tsui, B. C., Kropelin, B., Ganapathy, S., Finucane, B. 2005; 49 (10): 1562-1565

    Abstract

    It is well documented that a higher electrical current is required to elicit a motor response following a normal saline (NS) injection during the placement of stimulating catheters for peripheral nerve block. We present three cases of continuous brachial plexus catheter placement in which Dextrose 5% in water (D5W) was used to dilate the perineural space instead of NS. Three brachial plexus blocks (two interscalene and one axillary) were performed in three different patients for pain relief. In each case, an insulated needle was advanced towards the brachial plexus. A corresponding motor response was elicited with a current less than 0.5 mA after needle repositioning. A stimulating catheter was advanced with ease after 3-5 ml of D5W was injected to dilate the perineural space. A corresponding motor response was maintained when the current applied to the stimulating catheter was less than 0.5 mA. Local anesthetic was then injected and the motor response immediately ceased. All blocks were successful and provided excellent pain relief with the continuous infusion of local anesthetics.

    View details for DOI 10.1111/j.1399-6576.2005.00736.x

    View details for Web of Science ID 000232557500026

    View details for PubMedID 16223407

  • Practical recommendations for improving needle-tip visibility under ultrasound guidance? REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Finucane, B. 2005; 30 (6): 596-597

    View details for DOI 10.1016/j.rapm.2005.07.181

    View details for Web of Science ID 000233977900026

    View details for PubMedID 16326357

  • An in vitro comparison of the electrical conducting properties of multiport versus single-port epidural catheters for the epidural stimulation test ANESTHESIA AND ANALGESIA Tsui, B. C., Sze, C. K. 2005; 101 (5): 1528-1530

    Abstract

    Effective conduction of electricity through a catheter is essential for the success of the epidural stimulation test. In this in vitro study we examined the electrical conductivity of single and multiport epidural catheters (with and without embedded metal elements) after being primed with normal saline. Seven different types of 19-gauge catheters (n = 5), either single-port or multiport catheters, with or without embedded metal elements, were studied. The proximal end of each epidural catheter was connected to the cathode of a nerve stimulator via an electrode adapter. The catheter, primed with normal saline, was placed at the bottom of a syringe filled with 5 different volumes of saline (1, 2, 3, 4 and 5 mL) and attached to an electrode adapter. The voltage of the peripheral nerve stimulator was measured using an oscilloscope. The electrical resistance between the proximal and distal end of the catheter was calculated using Ohm's Law. In catheters without metal elements the electrical resistances were too high to be measured. In catheters that had metal elements, the mean electrical resistances of the same catheter design (single-port or multiport) were similar. However, the electrical resistances of the multiport metal reinforced epidural catheters were significantly lower (P < 0.05) than the single-port metal coil reinforced epidural catheters. The volume of saline in the syringe had no impact on the measured electrical resistances. This study suggests that multiport metal reinforced epidural catheters have low electrical resistances and, thus, are a reasonable alternative to single-port catheters for transmitting sufficient current for performing the epidural stimulation test. On the other hand, epidural catheters without metal elements (single-port or multiport) are not suitable for performing the stimulation test.

    View details for DOI 10.1213/01.ANE.0000181006.36917.3E

    View details for Web of Science ID 000232782800049

    View details for PubMedID 16244025

  • The sine qua non of a subdural block? REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C. 2005; 30 (6): 592-593

    View details for DOI 10.1016/j.rapm.2005.06.012

    View details for Web of Science ID 000233977900020

    View details for PubMedID 16326352

  • New tool for checking epidural catheter location CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C. 2005; 52 (8): 890-890

    View details for Web of Science ID 000233024300027

    View details for PubMedID 16189351

  • Can direct spinal cord injury occur without paresthesia? A report of delayed spinal cord injury after epidural placement in an awake patient ANESTHESIA AND ANALGESIA Tsui, B. C., Armstrong, K. 2005; 101 (4): 1212-1214

    Abstract

    We discuss the etiology of a delayed spinal cord injury after epidural anesthesia without paresthesia. The description of such a case in an awake, adult patient who underwent a Whipple resection is provided. An epidural was performed at approximately the T8-9 interspace with the patient in the sitting position after 1 mg of midazolam was administered. On the first attempt, a dural puncture occurred. The patient did not report any paresthesia or pain. The needle was withdrawn and a second attempt was made one interspace lower. At this level, the epidural catheter was advanced into the epidural space uneventfully. Postoperatively, the patient suffered decreased motor function in the right leg. Magnetic resonance imaging revealed high signal intensity within the spinal cord, indicating cord edema compatible with direct needle trauma. An extradural fluid collection consistent with a hematoma was also noted. Although it may be impossible to confirm if the spinal cord injury was a result of direct needle trauma, hematoma, or a combination of needle trauma and hematoma, these events clearly raise the important question of whether an awake patient will always report paresthesia secondary to spinal cord trauma.This case reminds anesthesiologists that we should not simply assume paresthesia will always occur and be reported if a needle encroaches on the spinal cord even in an awake patient.

    View details for DOI 10.1213/01.ANE.0000175764.16650.85

    View details for Web of Science ID 000232115400051

    View details for PubMedID 16192547

  • The electrophysiological effect of dextrose 5% in water on single-shot peripheral nerve stimulation ANESTHESIA AND ANALGESIA Tsui, B. C., Kropelin, B. 2005; 100 (6): 1837-1839

    Abstract

    When performing regional anesthesia, a small volume of local anesthetic or normal saline abolishes a motor response induced by a low current (0.5 mA). In this case series we describe the electrophysiological effect of a nonconducting (dextrose 5% in water, D5W) injectate on a motor response elicited by low current electrical stimulation. Twenty-nine peripheral nerve blocks were performed in 20 patients using insulated needles. Each needle was primed with D5W. The needle was advanced towards the target nerve until corresponding motor responses were observed using a current of 0.5 mA or less. Once the needle position was optimally placed, 1 mL of D5W was injected followed by a predetermined dose of local anesthetic. The effects of the injectates (D5W and local anesthetic) on the motor response were observed at all needle insertion sites. In all cases, the motor response was at least maintained or augmented (96%) immediately after the injection of D5W. All motor responses diminished after the injection of local anesthetic (100%). All blocks were considered clinically successful.

    View details for DOI 10.1213/01.ANE.0000153020.84780.A5

    View details for Web of Science ID 000229305600050

    View details for PubMedID 15920223

  • Caudal analgesia and anesthesia techniques in children. Current opinion in anaesthesiology Tsui, B. C., Berde, C. B. 2005; 18 (3): 283-288

    Abstract

    Caudal epidural blockade remains the cornerstone of pediatric regional anesthesia. In this article we provide a comprehensive review of the recent developments in caudal anesthesia in infants and children.Research has focused on prolonging the duration of single-shot caudal blocks and accurately positioning continuous caudal catheters. New local anesthetics with similar potencies but less toxicity have been introduced. Opioids prolong the duration of analgesia of local anesthetic, but have also been associated with unacceptable side effects, particularly in pediatric outpatients. Various non-opioid adjuncts with more favorable side-effect profiles may increase the duration of analgesia. New ultrasound and nerve-stimulation techniques have been developed to accurately guide epidural catheters to a specific spinal level.The addition of ketamine or clonidine to a caudal local anesthetic prolong the duration of the block. However, a preservative-free preparation of ketamine that is suitable for neuraxial use is not widely available. Ultrasound imaging and electrical stimulation are promising options to accurately position a caudal needle. However, because ultrasound imaging is more difficult in older children, nerve stimulation is a more-suitable technique to accurately guide caudal catheters in this patient population. Although complications associated with caudal block are rare, the risks and benefits must be carefully considered on an individual basis.

    View details for PubMedID 16534352

  • The use of electrical stimulation to monitor epidural needle advancement in a porcine model ANESTHESIA AND ANALGESIA Tsui, B. C., Emery, D., Uwiera, R. R., Finucane, B. 2005; 100 (6): 1611-1613

    Abstract

    Muscle twitches elicited with electrical stimulation (ES) during epidural insertion may indicate epidural needle location. We examined the potential application of ES at 5 mA as a continuous method of monitoring the response to epidural needle advancement in a porcine model. Five 20-kg pigs were used in this study. A needle with a stimulating current of 5 mA was inserted at 20 separate levels in each pig. The needle was advanced until a muscle twitch was observed without loss-of-resistance (LOR). The needle position was then assessed using LOR. At the end of the experiment, an autopsy was performed to assess the spinal cord for injury. A total of 100 needle insertions were performed in the 5 pigs. The threshold current in the epidural space was 3.6 +/- 0.6 mA. In 59 of the needle insertions, LOR was not obtained at the depth at which a muscle twitch was initially observed. However, after advancing these 59 needles another 1-2 mm, LOR was obtained. In the other 41 insertions, LOR was observed without further advancement of the needle. Autopsies indicated there were no dural punctures or spinal cord damage in any of the pigs. These observations suggest that ES can be used to signal that the epidural needle is in or approaching the epidural space. However, the high false positive predictive value (59%) makes it impractical and unreliable to detect the precise entry of a needle into the epidural space in pigs.

    View details for DOI 10.1213/01.ANE.0000150600.28332.72

    View details for Web of Science ID 000229305600009

    View details for PubMedID 15920182

  • Combined propofol and remifentanil intravenous anesthesia for pediatric patients undergoing magnetic resonance imaging PEDIATRIC ANESTHESIA Tsui, B. C., Wagner, A., Usher, A. G., Cave, D. A., Tang, C. 2005; 15 (5): 397-401

    Abstract

    A prospective observational case series of children receiving light general anesthesia for magnetic resonance imaging (MRI) was performed. Our purpose was to examine the merit of anesthesia and recovery/discharge times of combined remifentanil and propofol total intravenous anesthesia (TIVA) in spontaneously breathing children.After IRB approval and informed consent, 56 patients receiving Remi/Propofol TIVA (Remifentanil 10 microg.ml(-1) Propofol 10 mg.ml(-1)) were observed. Blood pressure, respiratory rate, endtidal CO(2) (P(E)CO(2)), oxygen saturation and temperature were recorded at the start and finish of anesthesia. In addition, induction and recovery times were noted. Recovery time was from scan completion until discharge from the initial recovery area. Discharge time was from scan completion to discharge home.Fifty-six patients received Remi/Propofol TIVA. The mean Remi/Propofol recovery and discharge times were 8.9 and 28.2 min, respectively. There was a statistically significant decrease in respiratory rate and increase in CO(2) from the start to the end of the procedure. During the scan, seven patients moved. One patient experienced postprocedure nausea and or vomiting.The combination of remifentanil and propofol for TIVA may be an effective method of light general anesthesia in pediatric patients undergoing MRI.

    View details for DOI 10.1111/j.1460-9592.2005.01462.x

    View details for Web of Science ID 000228310200008

    View details for PubMedID 15828991

  • Thoracic epidural analgesia via the lumbar approach using nerve stimulation in a pediatric patient with Down syndrome ACTA ANAESTHESIOLOGICA SCANDINAVICA Tsui, B. C., Entwistle, L. 2005; 49 (5): 712-714

    Abstract

    This case illustrates the threading of an epidural catheter with electrical stimulation guidance from the lumbar epidural space to the thoracic space in a pediatric patient. A 17-year-old boy with Down syndrome, weighing 48 kg, was scheduled to undergo a laparotomy for duodenal obstruction and gastrostomy tube insertion. Combined general and continuous epidural anesthesia was selected for his anesthetic. Following the induction of general anesthesia and tracheal intubation, a 17G Tuohy needle (Arrow International, Inc., Reading, PA) was inserted into the lumbar space (L3-4) using loss of resistance with air. A 20G styletted epidural catheter was then inserted and threaded cranially. As the catheter was advanced, a low electrical current (1-10mA) was applied to the catheter. Motor response was observed from the lower limb muscles to the upper abdominal muscles as the catheter advanced cranially. After 22 cm of the epidural catheter had been inserted, intercostal muscle movement (T9 - 10) was observed at 3.0 mA. Radiographical imaging later confirmed the catheter tip at T10. The patient awoke without distress and was discharged to the ward with subsequent good pain control from a continuous epidural infusion of bupivacaine 0.1% with 1 microg ml(-1) fentanyl at 4-6 ml(-1).

    View details for DOI 10.1111/j.1399-6576.2005.00684.x

    View details for Web of Science ID 000228397600021

    View details for PubMedID 15836690

  • Lateral cervical epidural catheter placement using nerve stimulation for continuous unilateral upper extremity analgesia following a failed continuous peripheral nerve block ACTA ANAESTHESIOLOGICA SCANDINAVICA Prusinkiewicz, C., Lang, S., Tsui, B. C. 2005; 49 (4): 579-582

    Abstract

    This case report describes the application of electrical stimulation (Tsui test) to confirm placement of a cervical epidural catheter for postoperative pain management in a patient with a failed brachial plexus block who underwent upper extremity surgery. An epidural catheter was easily advanced under nerve stimulation guidance to the surgical dermatome C4 level without any resistance from the C7-T1 level. Successful analgesia was achieved with a bolus of 2 mg ml(-1) ropivacaine 2 ml and fentanyl 20 microg, followed by a continuous infusion of 2 mg ml(-1) ropivacaine with 2 microg ml(-1) of fentanyl at a rate of 2 ml h(-1). This case reminds the clinician that cervical epidural analgesia may serve as an alternative to a difficult continuous peripheral nerve block. Electrical stimulation may also help to confirm cervical epidural catheter placement at the appropriate dermatome to provide effective analgesia with minimal side-effects.

    View details for Web of Science ID 000227773700025

    View details for PubMedID 15777311

  • Umbilical vein catheterization under electrocardiogram guidance PEDIATRIC ANESTHESIA Tsui, B. C., Richards, G. J., Van Aerde, J. 2005; 15 (4): 297-300

    Abstract

    In the neonate, umbilical venous catheters (UVC) are inserted and advanced blindly to a predetermined length from the umbilicus. The reported rates for UVC misplacement into the liver (and occasionally the spleen) range from 20 to 37%. Radiographs are routinely used to confirm the positioning of UVCs. This involves movement of often critically ill infants, as well as radiation exposure. This pilot study examines the potential value of confirming UVC placement in neonates using ECG.In critically ill neonates, a conductive Johans ECG adapter was connected to a UVC. A satisfactory tracing (lead II) was obtained (right arm lead connected to the adapter) when the UVC was filled with saline solution allowing the catheter tip to become a unipolar ECG electrode. The UVC was then advanced from the umbilicus until the tip reached the inferior vena cava (IVC) within the thoracic region, as demonstrated by appearance of normal sized QRS complexes with small P-waves. A small QRS indicated the catheter was below the diaphragm. The appearance of a tall positive P-wave indicated the tip was at the right atrium level. The UVC was then withdrawn until the P-wave size returned to normal. The final UVC position was later confirmed by X-ray.Eight neonates were studied. The figure shows typical ECG tracings when the UVC was placed in the liver, IVC, and right atrium, respectively. Three malpositioned catheters were detected (2 into liver and 1 into spleen).Based on these cases, the insertion of UVCs in neonates can be guided with ECG by observing sequential and characteristic alterations in P-waves and QRS complexes, thereby reducing the use of X-rays. In addition, this technique could prove to be beneficial in remote healthcare facilities where X-ray machines may not be readily available and quick intravenous access is required to transport sick neonates to major centers.

    View details for DOI 10.1111/j.1460-9592.2005.01433.x

    View details for Web of Science ID 000227775400006

    View details for PubMedID 15787920

  • Threshold current of an insulated needle in the intrathecal space in pediatric patients ANESTHESIA AND ANALGESIA Tsui, B. C., Wagner, A. M., Cunningham, K., Perry, S., Desai, S., Seal, R. 2005; 100 (3): 662-665

    Abstract

    A threshold current of <1 mA has been suggested to be sufficient to produce a motor response to electrical stimulation in the intrathecal space. We designed this study to determine the threshold current needed to elicit motor activity for an insulated needle in the intrathecal space. Twenty pediatric patients aged 7.3 +/- 3.9 yr scheduled for lumbar puncture were recruited. After sedation with propofol, patients were turned to the lateral position and an 18-gauge or 20-gauge introducer needle was placed at the L4-5 level through which an insulated 24-gauge Pajunck unipolar needle (with a Sprotte tip and stylet) was inserted. The needle was advanced into the intrathecal space as suggested by the presence of a "pop." At this point, a nerve stimulator was attached to the insulated needle and the current was gradually increased until motor activity was evident. The needle hub was checked for cerebrospinal fluid. If cerebrospinal fluid was not present, the needle was advanced further until cerebrospinal fluid was present. The threshold current was retested. The mean current in the intrathecal space required to elicit a motor response was 0.6 +/- 0.3 mA (range, 0.1-1 mA). In 19 patients, the twitches were observed at the L4-5 myotomes and 1 patient had twitches at L2. Twitches were observed unilaterally in 19 children and bilaterally in one child. This confirms the hypothesis that the threshold current in the intrathecal space is <1 mA and that it differs significantly from the threshold currents reported for electrical stimulation in the epidural space.

    View details for DOI 10.1213/01.ANE.0000143953.31973.5F

    View details for Web of Science ID 000227221100010

    View details for PubMedID 15728047

  • Propofol total intravenous anesthesia for MRI in children PEDIATRIC ANESTHESIA Usher, A. G., Kearney, R. A., Tsui, B. C. 2005; 15 (1): 23-28

    Abstract

    The aim of this study was to assess clinical signs of airway patency, airway intervention requirements and adverse events in 100 children receiving propofol total intravenous anesthesia for magnetic resonance imaging, with spontaneous ventilation and oxygenation via nasal prongs.Airway patency was clinically assessed and stepwise interventions were performed until a satisfactory airway was achieved. Propofol requirements, vital signs, procedure times and adverse events were also recorded.Ninety-three per cent of children had no signs of airway obstruction when positioned with a shoulder roll only, two required a chin lift, four required an oral airway and one required lateral positioning. The mean propofol induction dose was 3.9 mg.kg(-1) (range 1.8-6.4 mg.kg(-1)). The mean propofol infusion rate was 193 microg.kg(-1).min(-1) (range 150-250 microg.kg(-1).min(-1)). The initial and final mean respiratory rates were 26 and 23 b.min(-1) (P < 0.05). Movement was more likely at lower infusion rates (mean 175 microg.kg(-1).min(-1)). There were no respiratory or cardiovascular complications (calculated risk: 95% CI = 0-3%). The mean time from end of scan to discharge home was 44 min.This study demonstrates good preservation of upper airway patency and rapid recovery using general anesthetic doses of propofol in children.

    View details for DOI 10.1111/j.1460-9592.2004.01390.x

    View details for Web of Science ID 000226426000005

    View details for PubMedID 15649159

  • Failed spinal anesthesia after a psoas compartment block CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Lang, S. A., Prusinkiewicz, C., Tsui, B. C. 2005; 52 (1): 74-78

    Abstract

    To report the case of a patient who experienced failed spinal anesthesia following a psoas compartment block (PCB) and discuss its implications.A 70-yr-old male was scheduled for a right total hip arthroplasty. He agreed to a PCB for postoperative analgesia and a spinal anesthetic. The spinal anesthetic was performed after completion of the PCB. Free flow of clear fluid was demonstrated at the beginning and at the end of the presumed intrathecal injection. General anesthesia had to be induced because of failure of the spinal anesthetic. The patient awoke from his general anesthetic with a functional PCB and no evidence of residual neuraxial anesthesia. The possibility of epidural spread of local anesthetic from the PCB impairing the ability to perform spinal anesthesia is discussed and reviewed. We hypothesize that local anesthetic in the epidural space may have falsely reassured the anesthesiologist that the needle was properly placed.We describe a case of failed spinal anesthesia following a PCB and discuss its implications.

    View details for Web of Science ID 000226480500013

    View details for PubMedID 15625260

  • Intravenous ketamine infusion as an adjuvant to morphine in a 2-year-old with severe cancer pain from metastatic neuroblastoma JOURNAL OF PEDIATRIC HEMATOLOGY ONCOLOGY Tsui, B. C., Davies, D., Desai, S., Malherbe, S. 2004; 26 (10): 678-680

    Abstract

    A 2.8-year-old female patient (11.6 kg) was admitted to the hospital for uncontrolled pain and swelling in the left leg relating to a metastatic neuroblastoma. Initially, her pain was managed with oral morphine 2 mg (approx. 0.2 mg/kg) every 4 hours. Because she was quite somnolent but still in significant pain, analgesia was then changed to methadone 1 mg orally every 6 hours (approximately 0.1 mg/kg/dose) and was eventually increased over 36 hours to 2 mg every 6 hours (approximately 0.2 mg/kg/dose). She received oral methadone 0.6 mg (approximately 0.05 mg/kg) every 4 hours as needed for breakthrough pain. She continued to have severe pain and experienced side effects, including respiratory depression, sedation, visual hallucinations, and vomiting. An intravenous ketamine infusion was started at 100 microg/kg/hour. Regular opioid administration was ceased, but she was given intravenous morphine 0.5 to 0.75 mg for breakthrough pain. She required only zero to three doses of breakthrough morphine per day, initially. After starting the ketamine infusion, her pain control improved and her symptoms of opioid toxicity abated. She was more alert and able to partake in limited activities. As a result of pain from progressive disease, the ketamine infusion was increased to 200 microg/kg/hour after 6 days with positive results. Her condition continued to deteriorate. An intravenous morphine infusion was initiated 2 weeks after starting the ketamine infusion and was eventually increased to 50 microg/kg/hour. One week later, she died with reasonable pain control. This case illustrates the use of ketamine as an effective analgesic in an adjuvant setting in a pediatric patient with advanced poorly controlled cancer pain. Ketamine not only eased the child's suffering while preserving life but also improved her quality of life by maintaining the child's ability to communicate and engage in activities.

    View details for Web of Science ID 000224308800013

    View details for PubMedID 15454842

  • Threshold current for an insulated epidural needle in pediatric patients ANESTHESIA AND ANALGESIA Tsui, B. C., Wagner, A., Cave, D., Seal, R. 2004; 99 (3): 694-696

    Abstract

    We designed this study to determine the threshold current for nerve stimulation of an insulated needle in the epidural space. The intended dermatome was identified using the bony landmarks of the spine. An 18-gauge insulated Tuohy needle was inserted perpendicularly to the skin and advanced until "loss of resistance" was felt. A nerve stimulator was then connected to the insulated needle. Twenty patients were studied using an insulated Tuohy needle and one patient was studied using a noninsulated Tuohy needle. Muscle twitch was elicited with a current of 11.1 +/- 3.1 mA (mean +/- sd) in all patients in which an insulated needle was used. Muscle twitches were within 2 myotomes of the intended level (based on bony landmarks). Muscle twitch was not elicited with a noninsulated needle. After catheter threading, positive stimulation tests were elicited via epidural catheters in all patients (4.9 +/- 2.3 mA). Postoperative radiograph confirmed all catheter placements within 2 myotomes of the muscle twitches. Electrical stimulation may be a useful adjuvant tool to loss of resistance for confirming proper thoracic epidural needle placement. The threshold current criteria for an insulated needle (6-17 mA) would be higher than the original Tsui test criteria described for an epidural catheter (1-10 mA) in the epidural space.

    View details for DOI 10.1213/01.ANE.0000130617.79600.05

    View details for Web of Science ID 000223430300012

    View details for PubMedID 15333396

  • The threshold current in the intrathecal space to elicit motor response is lower and does not overlap that in the epidural space: a porcine model CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Wagner, A., Finucane, B. 2004; 51 (7): 690-695

    Abstract

    Using electrical epidural stimulation, a current of 1 to 10 mA is required to confirm the presence of the tip of an epidural catheter in the epidural space. The purpose of this study was to examine the hypothesis that the threshold current required to elicit a motor response in the intrathecal space is significantly lower than that in the epidural space in a porcine model.Four 20-kg pigs were used in this experiment. Eighteen gauge, insulated, Tuohy needles were advanced into the epidural space using the loss of resistance technique at five different spinal levels in each pig. When the epidural space was entered, an electrical current was applied to the needle and increased progressively until a motor response was elicited. The needle was then further advanced until cerebrospinal fluid (CSF) was observed or until the needle had been advanced a maximum of 1 cm. At this point, the current was reapplied and increased until motor activity was evident.A total of 20 needles were inserted in four pigs. The current required to produce a motor response in the epidural space was 3.45 +/- 0.73 mA (mean +/- SD). The current required to produce a motor response in the intrathecal space (entry confirmed by the presence of CSF) was 0.38 +/- 0.19 mA (mean +/- SD). Two needles were advanced 1 cm without obtaining CSF but the current thresholds were similar to those obtained when CSF was evident (0.4 mA and 0.3 mA, respectively).The threshold current of an insulated needle required to elicit a motor response in the intrathecal space, was significantly (P < 0.01) lower than that in the epidural space in a porcine model.

    View details for Web of Science ID 000224044600009

    View details for PubMedID 15310637

  • Cervical epidural analgesia via a thoracic approach using nerve stimulation guidance in an adult patient undergoing elbow surgery REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Bateman, K., Bouliane, M., Finucane, B. 2004; 29 (4): 355-360

    Abstract

    This case report describes the placement of a cervical epidural catheter via the thoracic approach, using nerve stimulation, in a patient undergoing elbow surgery.An epidural catheter was easily advanced to the C5 dermatome level from the T4-5 interspace, using nerve stimulation guidance. Successful perioperative analgesia was accomplished using an infusion of ropivacaine 0.2% with 0.05 mg/mL morphine at 4 mL/h.This case report suggests that electrical stimulation may allow one to accurately position epidural catheters in the central neuraxial space to provide reliable, effective analgesia of the upper extremity. This approach might be an alternative way to deliver cervical epidural analgesia for patients undergoing upper extremity surgery.

    View details for DOI 10.1016/j.rapm.2004.03.010

    View details for Web of Science ID 000222987800010

    View details for PubMedID 15305256

  • Inadvertent cervical epidural catheter placement via the caudal route using electrical stimulation ANESTHESIA AND ANALGESIA Tsui, B. C., Malherbe, S. 2004; 99 (1): 259-261

    Abstract

    Inadvertent placement of an epidural catheter in the cervical region via the caudal route is described in an infant who underwent revision of a fundoplication. We attempted electrical stimulation (the Tsui test) via the epidural catheter to confirm correct placement and positioning of the catheter tip. In this case, the epidural catheter was inadvertently advanced to the cervical region, resulting in stimulation of the phrenic nerve. These diaphragmatic twitches were misinterpreted as chest wall twitches, and it was incorrectly assumed that the catheter was in the thoracic region. To avoid misinterpretation of the stimulation level, the catheter should be continuously stimulated while it is advanced. We also recommend that the catheter length be estimated before insertion (although doing so did not help in this case) and that the catheter position be radiographically confirmed after surgery.

    View details for DOI 10.1213/01.ane.0000120082.85977.f7

    View details for Web of Science ID 000222256400050

    View details for PubMedID 15281541

  • Fiberoptic endotracheal intubation after topicalization with in-circuit nebulized lidocaine in a child with a difficult airway ANESTHESIA AND ANALGESIA Tsui, B. C., Cunningham, K. 2004; 98 (5): 1286-1288

    Abstract

    This case report describes the successful fiberoptic intubation of an uncooperative child with a difficult airway due to gross burn scarring in the facial and neck region by administering 4% end-tidal sevoflurane and simultaneously delivering 4% nebulized lidocaine via a small-volume nebulizer that was connected to the inspiratory limb of the circle system via a T-piece adapter. This case suggests that simultaneously administering a volatile anesthetic with nebulized lidocaine might be an alternative way to deliver lidocaine and might provide better topical anesthesia for uncooperative patients.An in-circuit nebulization system to deliver topical lidocaine may facilitate fiberoptic-assisted intubation in anesthetized, spontaneously breathing children with compromised airways.

    View details for DOI 10.1213/01.ANE.0000108486.70256.E8

    View details for Web of Science ID 000221041800017

    View details for PubMedID 15105202

  • Electrophysiologic effect of injectates on peripheral nerve stimulation REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Wagner, A., Finucane, B. 2004; 29 (3): 189-193

    Abstract

    A small volume of local anesthetic or normal saline abolishes the muscle twitch induced by a 1ow current (0.5 mA) during electrolocation. This study examines the hypothesis that the mechanism of this phenomenon is primarily the electrophysiologic effect of the injectate on the electrical current density at the needle tip.Five pigs were studied. An insulated Tuohy needle was inserted in each pig toward the left and right brachial plexuses and the left and right femoral nerves. The needle was advanced until corresponding motor responses were observed at each site, using a current of 0.5 mA. The effect of injecting 1 mL each of normal saline and 5% dextrose in water (NS and D5W) on muscle twitch was investigated at all 20 needle insertion sites. Changes in the conductive area induced by the injectates were also demonstrated using gel electrophoresis.In all cases, the muscle twitches were abolished immediately after the injection of NS and recovered instantaneously after a subsequent injection of D5W. The electrical resistance between the needle and the ground electrodes decreased instantly after the NS injection. The resistance not only recovered but also increased after the injection of D5W. In the gel electrophoresis experiment, the results demonstrated that the expanded conductive area induced by the saline column surrounding the insulated needle was similar to that observed with the uninsulated needle.The injection of a conducting solution (i.e., NS) rendered the current that was previously sufficient to elicit a motor response (0.5 mA) ineffective. The most likely reason for this change is that the conductive area surrounding the stimulating needle expanded after the injection and dispersion of the conducting solution (i.e., NS), thereby reducing the current density at the target nerve. This effect can be reversed by injecting a nonconducting solution (i.e., D5W) via the stimulating needle.

    View details for DOI 10.1016/j.rapm.2004.02.002

    View details for Web of Science ID 000221532800002

    View details for PubMedID 15138901

  • Thoracic and lumbar epidural analgesia via the caudal approach using electrical stimulation guidance in pediatric patients - A review of 289 patients ANESTHESIOLOGY Tsui, B. C., Wagner, A., Cave, D., Kearney, R. 2004; 100 (3): 683-689

    Abstract

    Nerve stimulation guidance (Tsui test) has been reported to be an effective alternative to radiographic imaging for proper catheter placement. The purpose of this study was to examine the success rate and complications of continuous caudal epidural analgesia since the implementation of routine use of the Tsui test at the authors' institution.The authors examined prospectively collected data in their pediatric pain service database from 289 children who had attempted caudal placement of a lumbar or thoracic catheter between 1999 and 2002.In five patients (aged 5 months-1.6 yr), the catheter did not thread to the desired level and was abandoned in the operating room (technical success rate, 98.2%). Of the remaining 284 patients, the overall analgesic success rate of all caudal route epidural analgesia procedures was 84.9%. There was no significant difference in adequate pain control (success) in infants (aged 1 day-1 yr) versus older children (aged younger than 1 yr). The most common adverse effects were pruritus (26.1%) and nausea and vomiting (16.9%). Of the patients in our study, 57.7% had urinary catheters in situ; of those who did not have a catheter placed, 20.8% experienced urinary retention. The incidence of respiratory depression was 4.2%, but the administration of naloxone for severe respiratory depression was never necessary. Three percent of catheters were removed because of suspected contamination, but no epidural abscesses or systemic infection were noted.The results of this study suggest that epidural catheter placement via the caudal approach using the Tsui test is an effective and reasonable alternative to direct lumbar and thoracic epidural analgesia in pediatric patients.

    View details for Web of Science ID 000189251700031

    View details for PubMedID 15108986

  • Argatroban as anticoagulant in cardiopulmonary bypass in an infant and attempted reversal with recombinant activated factor VII ANESTHESIOLOGY Malherbe, S., Tsui, B. C., Stobart, K., Koller, J. 2004; 100 (2): 443-445

    View details for Web of Science ID 000188438500036

    View details for PubMedID 14739823

  • The incidence of laryngospasm with a "No touch" extubation technique after tonsillectomy and adenoidectomy ANESTHESIA AND ANALGESIA Tsui, B. C., Wagner, A., Cave, D., Elliott, C., El-Hakim, H., Malherbe, S. 2004; 98 (2): 327-329

    Abstract

    In this case series, we evaluated the incidence of laryngospasm using a clearly defined awake tracheal extubation technique in 20 children undergoing elective tonsillectomy with or without adenoidectomy. This technique required patients to be turned to the recovery position at the end of the procedure before discontinuing the volatile anesthetics. No further stimulation, besides continuous oximetry monitoring, was allowed until the patients spontaneously woke up ("no touch" technique). The incidence of laryngospasm, oxygen saturation, and coughing was recorded. No cases of laryngospasm, oxygen desaturation, or severe coughing occurred in our patient population.This study re-emphasizes the importance of a sound anesthetic technique in tracheally extubating pediatric patients.

    View details for DOI 10.1213/01/ANE.0000097185.70171.89

    View details for Web of Science ID 000188438700010

    View details for PubMedID 14742363

  • Reversal of an unintentional spinal anesthetic by cerebrospinal lavage ANESTHESIA AND ANALGESIA Tsui, B. C., Malherbe, S., Koller, J., Aronyk, K. 2004; 98 (2): 434-436

    Abstract

    In this case report, we describe the use of cerebrospinal fluid lavage as a successful treatment of an inadvertent intrathecally placed epidural catheter in a 14-yr-old girl who underwent a combination of epidural anesthesia and general anesthesia for orthopedic surgery. In this case, a large amount of local anesthetic was injected (the total possible intrathecal injection was 200 mg of lidocaine and 61 mg of bupivacaine), resulting in apnea and fixed dilated pupils in the patient at the end of surgery. Twenty milliliters of cerebrospinal fluid was replaced with 10 mL of normal saline and 10 mL of lactated Ringer's solution from the "epidural" catheter. Spontaneous respiration returned 5 min later, and the patient was tracheally extubated after 30 min. No signs of neurological deficit or postdural puncture headache were noted after surgery.Cerebrospinal lavage may be a helpful adjunct to the conventional supportive management of patients in the event of an inadvertent total spinal.

    View details for DOI 10.1213/01.ANE.0000095152.81728.DC

    View details for Web of Science ID 000188438700030

    View details for PubMedID 14742383

  • Thoracic epidural catheter placement in infants via the caudal approach under electrocardiographic guidance: Simplification of the original technique ANESTHESIA AND ANALGESIA Tsui, B. C. 2004; 98 (1): 273-273
  • Regional anaesthesia in the elderly - A clinical guide DRUGS & AGING Tsui, B. C., Wagner, A., Finucane, B. 2004; 21 (14): 895-910

    Abstract

    The number of elderly patients presenting for anaesthesia and surgery has increased exponentially in recent years. Regional anaesthesia is frequently used in elderly patients undergoing surgery. Although the type of anaesthesia (general versus regional anaesthesia) has no substantial effect on perioperative morbidity and mortality in any age group; it intuitively makes sense that elderly patients would benefit from regional anaesthesia because they remain minimally sedated throughout the procedures and awaken with excellent postoperative pain control. However, a multitude of factors influence the outcome, such as the type, duration and invasiveness of the operation, co-existing medical and mental status of the patient and the skill and expertise of the anaesthesiologist and surgeon. These factors make it difficult to decide if and when one technique is equivocally better than another. Thus, it is more important to optimise the overall management of the patient during the perioperative period and, in most cases, it is the quality of the anaesthetic administered rather than the type of anaesthetic which is most important. Sedatives used for regional anaesthesia in the elderly should be short acting, easy to administer, have a low adverse effect profile and high safety margin. Midazolam, lorazepam, ketamine, propofol and low-dose opioids have been successfully used for sedation in the elderly. Aging affects the pharmacokinetics and pharmacodynamics of local anaesthetics, composition and characteristics of tissues and organs within the body, and physiological functions of the body. Changes in the systematic absorption, distribution and clearance of local anaesthetics lead to an increased sensitivity, decreased dose requirement and a change in the onset and duration of action in the elderly. Decreases in neural population, neural conduction velocity and inter-Schwann cell distance can lead to an increased sensitivity to local anaesthetics in the elderly. The addition of an opioid and epinephrine (adrenaline) has been shown to be useful in central neuraxial blockade. Epinephrine also can prolong the duration of peripheral nerve blocks. However, caution must be exercised as epinephrine has the potential for causing ischaemic neurotoxicity in peripheral nerves. Regional anaesthesia appears to be safe and beneficial in elderly patients; however, every anaesthetic administered must be assessed on a case-by-case basis and particular consideration should be given to the health status of the patient, the operation being performed and the expertise of the anaesthesiologist.

    View details for Web of Science ID 000225648200001

    View details for PubMedID 15554749

  • Tensile strength of 19-and 20-gauge Arrow epidural catheters ANESTHESIA AND ANALGESIA Tsui, B. C., Finucane, B. 2003; 97 (5): 1524-1526

    Abstract

    There are no data about the mechanical properties of the 20-gauge reinforced Arrow epidural catheter, which has a similar design to the 19-gauge reinforced Arrow catheter. In this study, we compared the mechanical properties of 19- and 20-gauge Arrow epidural catheters at 22 degrees C and 37 degrees C. The distal 12 cm of each catheter was suspended in an enclosed chamber maintained at either 22 degrees C or 37 degrees C. A pair of forceps was applied to each catheter 5 cm from the distal end (fixed site). Another pair of forceps was applied 15 cm from the catheter tip (traction site). The catheter was pulled. At 22 degrees C, the mean fracture force was 2.24 kg (range, 1.96 - 2.41 kg) for 5 19-gauge catheters and 2.17 kg (range, 2.04-2.41 kg) for 5 20-gauge catheters. At 37 degrees C, the mean force was 1.98 kg (range 1.84- 2.15 kg) for 5 19-gauge catheters and 1.99 kg (range, 1.81-2.09 kg) for 5 20-gauge catheters. There were no significant differences in tensile strength between the two different gauge catheters at either temperature. All the 19-gauge catheters fractured at the same "fixed site" at both temperatures. All the 20-gauge catheters elongated at the "fixed site" but fractured at the "traction site." We conclude that using the smaller-gauge catheter (20-gauge) is not associated with a more frequent rate of fracture.The 20-gauge Arrow epidural catheters had similar tensile strengths as the 19-gauge epidural catheters but fractured at the traction site rather than at the fixed site. Thus, the 20-gauge Arrow catheter may be a reasonable alternative to the 19-gauge Arrow catheter.

    View details for DOI 10.1213/01.ANE.0000086724.96661.8F

    View details for Web of Science ID 000186143600055

    View details for PubMedID 14570679

  • Confirmation of direct epidural catheter placement using nerve stimulation in pediatric anesthesia ANESTHESIA AND ANALGESIA Goobie, S. M., Montgomery, C. J., Basu, R., McFadzean, J., O'Connor, G. J., Poskitt, K., Tsui, B. C. 2003; 97 (4): 984-988

    Abstract

    We evaluated the success rate of using low current electrical stimulation (the Tsui test) to identify and confirm direct epidural catheter placement in a pediatric population. Thirty subjects received a standard anesthetic and administration of the Tsui test on epidural placement. The distribution of myotomal activity was recorded. The intended and actual level of the epidural catheter was compared. Myotomal activity was seen in all patients but one. The median current resulting in myotomal activity was 5.3 mA. The median difference between the intended and actual level as confirmed on radiograph was 1.8 levels. The clinical success rate was 93.9%. The positive predictive value of the Tsui test was 82%; i.e., in 23 of 28 cases, the Tsui test correctly identified the position of the epidural catheter tip within 2 vertebral levels. The test did not offer any added advantage when used in the setting of directly placed epidural catheters in our institution over "blind" methods already used to confirm catheter position when using cutaneous landmarks and test dosing.A new technique to confirm epidural catheter position uses low current electrical stimulation in pediatric patients. This study evaluated the use of electrical stimulation in 30 pediatric patients for directly placed catheters. Electrical stimulation did not provide any advantage over conventional methods (e.g., cutaneous landmarks) for confirmation of catheter position.

    View details for DOI 10.1213/01.ANE.0000080609.05942.38

    View details for Web of Science ID 000185492300012

    View details for PubMedID 14500145

  • Nebulization of lidocaine with varied oxygen flow rates ANESTHESIA AND ANALGESIA Tsui, B. C., Malherbe, S. 2003; 97 (1): 302-302
  • New avenues of epidural research ANESTHESIA AND ANALGESIA Lang, S. A., Tsui, B., Grau, T. 2003; 97 (1): 292-293
  • Discoloration of parenteral ondansetron ANESTHESIA AND ANALGESIA Tsui, B. C., Cave, D. 2003; 96 (4): 1239-1239
  • Thoracic epidural catheter placement via the caudal approach in infants by using electrocardiographic guidance ANESTHESIA AND ANALGESIA Tsui, B. C., Seal, R., Koller, J. 2002; 95 (2): 326-330

    Abstract

    We examined the success of inserting epidural catheters via the caudal route in infants by using electrocardiographic guidance. A case series of 20 patients with thoracic epidural analgesia was studied. After the induction of general anesthesia, an 18-gauge IV catheter was inserted into the caudal space to allow threading of a 20-gauge epidural catheter. The electrocardiogram (ECG) tracings via the epidural catheter, as well as the surface ECG at the target spine level, were recorded simultaneously with a modified two-channel five-lead ECG system. The epidural catheter was advanced from the caudal space until the tip reached the target level as demonstrated by a match in the configuration of the epidural ECG tracing to that of the surface ECG tracing at the target level. The catheter tip location was verified by postoperative radiographs. All catheter tips were located within two vertebrae of the target level, and satisfactory intraoperative epidural anesthesia was achieved in all subjects.Epidural electrocardiography may be used to guide the positioning of the thoracic epidural catheter tip via the caudal approach to the appropriate dermatome for optimum analgesia.

    View details for DOI 10.1213/01.ANE.0000018560.51224.99

    View details for Web of Science ID 000176964200016

    View details for PubMedID 12145046

  • Verifying accurate placement of an epidural catheter tip using electrical stimulation ANESTHESIA AND ANALGESIA Tsui, B. C., Finucane, B. 2002; 94 (6): 1670-1671

    View details for Web of Science ID 000175890900063

    View details for PubMedID 12032053

  • Thoracic epidural catheter placement via the caudal approach under electrocardiographic guidance CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C. 2002; 49 (2): 216-217

    View details for Web of Science ID 000173999100026

    View details for PubMedID 11823409

  • Thoracic epidural analgesia via the caudal approach in pediatric patients undergoing fundoplication using nerve stimulation guidance ANESTHESIA AND ANALGESIA Tsui, B. C., Seal, R., Koller, J., Entwistle, L., Haugen, R., Kearney, R. 2001; 93 (5): 1152-1155

    Abstract

    Epidural catheter placement using electrical stimulation guidance is an alternative approach for positioning the catheter into the thoracic region via the caudal space. This easily performed clinical assessment provides optimization of catheter tip positioning for achieving effective pain control.

    View details for Web of Science ID 000171820500015

    View details for PubMedID 11682385

  • Predicting caudal epidural analgesia using nerve stimulation ANAESTHESIA Tsui, B. C. 2001; 56 (8): 816-817

    View details for Web of Science ID 000170399000044

    View details for PubMedID 11494425

  • Cardiac arrest and myocardial infarction induced by postpartum intravenous ergonovine administration ANESTHESIOLOGY Tsui, B. C., Stewart, B., Fitzmaurice, A., WILLIAMS, R. 2001; 94 (2): 363-364

    View details for Web of Science ID 000166694900029

    View details for PubMedID 11176106

  • Detection of subdural placement of epidural catheter using nerve stimulation CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Gupta, S., Emery, D., Finucane, B. 2000; 47 (5): 471-473

    Abstract

    To report the detection of a subdural catheter placement using nerve stimulation through an epidural catheter.An 85-yr-old gentleman was scheduled for radical cystectomy and creation of an ileal conduit. Combined general anesthesia and regional technqiue was selected. An epidural catheter (19 G Arrow Flextip Plus) was inserted prior to induction of general anesthesia. Intra-operatively, the patient received 5 mg morphine and 10 ml bupivacane 0.5% via the epidural catheter. The patient remained hemodynamically stable throughout the operation and did not require intravenous opioids. The patient was discharged to the ward with an order for epidural morphine for pain control. The next day, the patient remained comfortable. As an ongoing quality assessment to survey the success rate of epidural catheters at our institution, all patients are invited to have their catheter assessed using an electrical epidural stimulation test. Electrical stimulation (1-10 mA) with a segmental motor response (truncal or extremities movement) indicates that the catheter is in the epidural space. No motor response indicates that it is not. In this case, subdural catheter placement was suspected because a diffuse motor response including right anterior chest wall, back muscle, and bilateral lower extremities was observed using only 0.3 mA. Subdural catheter placement was subsequently confirmed by a radiograph showing a very thin film of dye spreading cephalad and caudad over many segments.This new electrical test helps to detect subdural placement objectively.

    View details for Web of Science ID 000089776400017

    View details for PubMedID 10831207

  • Determining epidural catheter location using nerve stimulation with radiological confirmation REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Guenther, C., Emery, D., Finucane, B. 2000; 25 (3): 306-309

    Abstract

    The use of epidural stimulation to confirm epidural catheter placement has been shown. This case report describes the benefits and problems of using the epidural stimulation test to confirm epidural catheter placement and provides supporting evidence for these observations using radiological imaging.A nerve stimulator was connected to the proximal end of an epidural catheter via an adapter. The cathode lead was connected to the adapter. The anode lead was connected to an electrode placed on the upper extremity as a grounding site. Using 1 to 10 mA current, a segmental motor response indicated that the catheter was in the epidural space. The absence of a motor response indicated that it was not.In the first patient, the new test predicted subcutaneous epidural catheter placement, which was subsequently confirmed radiologically. In the second patient, the catheter tip was found to be lying near a nerve root, which was again confirmed radiologically. In the third case, a negative test was initially observed with only local muscle movement over the biceps area (T2). After relocation of the grounding electrode to the lower extremity, segmental intercostal muscle movement (T4-5 level) was observed. The catheter placement was radiologically shown to be in the T4-5 region.This report illustrates some of the potential benefits and problems of using the nerve stimulation test to confirm epidural catheter placement, with radiological verification.

    View details for Web of Science ID 000087128100018

    View details for PubMedID 10834789

  • Thoracic epidural analgesia via the caudal approach using nerve stimulation in an infant with CATCH22 CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Seal, R., Entwistle, L. 1999; 46 (12): 1138-1142

    Abstract

    To illustrate insertion of an epidural catheter via caudal route in a small infant under electrical stimulation guidance.A six month old boy, weighting 4.25 kg, with a diagnosis of CATCH22 (Cardiac abnormality/abnormal faces, T cell deficit due to thymic hypoplasia, cleft palate, hypocalcemia due to hypoparathyroidism resulting from 22q11 deletion) was scheduled for fundoplication and gastrostomy tube (G-tube) insertion. A combined light general anesthesia and continuous epidural anesthesia technique was selected. Following induction of general anesthesia and tracheal intubation with 1.5 mg midazolam, 10 microg fentanyl and 10 mg succinylcholine, a 16G intravenous catheter was inserted into the caudal space. A 19G epidural catheter (Arrow Flextip Plus) epidural catheter was then inserted up cranially. A low electrical current (1-10mA) was then applied through the catheter. The level of motor movement was advanced from the lower limb muscles to the upper abdominal muscles as the catheter was threaded cranially. After 19 cm of epidural catheter had been inserted, intercostal muscle movement (T9-10 level) was observed at 4.2mA. The tip of the catheter was later confirmed to be at the T9-10 interspace by radiographical imaging. The patient awakened without distress and the trachea was extubated the same evening. The infant was discharged to the ward next morning with good pain relief from a continuous epidural infusion of bupivacane 0.1% with 1 microg x ml(-1) at 1.6 ml(-1).Epidural stimulation may help placement of the epidural catheter at the appropriate dermatome for effective anesthesia and analgesia.

    View details for Web of Science ID 000083998100007

    View details for PubMedID 10608207

  • Confirmation of caudal needle placement using nerve simulation ANESTHESIOLOGY Tsui, B. C., Tarkkila, P., Gupta, S., Kearney, R. 1999; 91 (2): 374-378

    Abstract

    The study was designed to examine a new method of confirming proper caudal needle placement using nerve stimulation.Thirty-two pediatric patients were studied. A 22-gauge insulated needle was inserted into the caudal canal via the sacral notch until a "pop" was felt. The needle placement was classified as correct or incorrect depending upon the presence or absence of anal sphincter contraction (S2-S4) to electrical simulation (1 to 10 mA).Three patients were excluded, two because they inadvertently received neuromuscular blockers and one because the patient's anatomy precluded any attempt at a caudal block. The sensitivity and specificity of the test were both 100% in predicting clinical outcomes of the caudal block. Six patients had a negative stimulation test after the first attempt to place the needle. Four of these went on to receive a second attempt of needle insertion after a subcutaneous bulge or resistance to local anesthetic injection were observed. Following needle reinsertion, positive stimulation tests were elicited. These patients received the local anesthetic injection with ease and had good analgesia postoperatively. No attempt was made to reinsert the needle in the remaining two patients with a negative stimulation test, as they did not show subcutaneous bulge or resistance upon injection. These patients had poor analgesia postoperatively. The positive predictive value of the test was greater than the presence of a "pop" alone (P < 0.05) but not significantly different (P = 0.492) over the presence of "pop" and easy injection.This test may be used as a teaching and adjuvant tool in performing caudal block.

    View details for Web of Science ID 000081726300009

    View details for PubMedID 10443599

  • Detection of subarachnoid and intravascular epidural catheter placement CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Gupta, S., Finucane, B. 1999; 46 (7): 675-678

    Abstract

    To report the detection of subarachnoid and intravascular catheter placement using nerve stimulation through an epidural catheter.Electrical stimulation (1-10 mA) was applied through the catheter. A positive motor response (truncal or limb movement) indicated that the catheter was in the epidural space. Absence of a motor response indicated that it was not. A low milliamperage (<1 mA) with bilateral response indicated subarachnoid placement. Intravascular catheter placement was indicated by a positive response to the test, which remains at or returns to the baseline levels (i.e. prior to any local anesthetic injection), despite the administration of local anesthetics. In the first patient, the test confirmed subarachnoid catheter placement during attempts at continuous spinal anaesthesia even though CSF could not be aspirated. Bilateral motor response in the legs was observed at 0.2 mA. In the second patient, inadvertent subarachnoid placement was detected during attempted lumbar epidural block by observing bilateral motor response in the legs at 0.3 mA. In the third patient, intravascular placement was suspected and confirmed by failure to obliterate the motor response despite repeated local anesthetic injection.The new test provides objective information in managing epidural catheters when their position is uncertain.

    View details for Web of Science ID 000081366900010

    View details for PubMedID 10442964

  • Loss of resistance to saline - does the dripping bother you? CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Gupta, S., Finucane, B. 1999; 46 (6): 615-616

    View details for Web of Science ID 000080818000019

    View details for PubMedID 10391615

  • Estimation of desflurane concentration using isoflurane channel in optical infrared analyzer CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Jolly, D. T., Clanachan, A. S. 1999; 46 (2): 192-195

    Abstract

    To estimate desflurane concentration on the isoflurane channel in an optical infrared analyzer using a simple regression equation.Desflurane in concentrations of 0% to 3% in 0.5% increments and 3% to 12% in 1% increments in 2 L.min-1 oxygen was delivered simultaneously to an Ohmeda 5250 RGM desflurane channel, an Ohmeda 5250 RGM isoflurane channel, and a Datex Capnomac Ultima isoflurane channel at room temperature and atmospheric pressure. For each concentration increment, the displayed gas concentrations were recorded. By comparing the readings from the desflurane channel of Ohmeda RGM and the isoflurane channels from Ohmeda RGM and Datex Capnomac Ultima respectively, the linear regression relationship and the slope of the fitted line (conversion factor) between two channels were obtained. Similar measurements were performed using 2 L.min-1 mixture of nitrous oxide 50% and oxygen 50%. The measurements were repeated with different monitors three months later.All four analysers tested were linear (r2 > 0.9) for measuring desflurane using isoflurane channels over the range of concentrations studied on two different days. The accuracy of the estimation using the mean conversion factor of the four monitors was within 10% error from the readings of the commercially available desflurane channel analyzer. There was no noticeable effect on the slope (conversion factor) of the linear regression with O2 100% or 50/50 mixture of N2O and O2.The concentration of desflurane can be estimated by a simple conversion factor using an isoflurane channel of an infrared system.

    View details for Web of Science ID 000078928600018

    View details for PubMedID 10084004

  • Determination of epidural catheter placement using nerve stimulation in obstetric patients REGIONAL ANESTHESIA AND PAIN MEDICINE Tsui, B. C., Gupta, S., Finucane, B. 1999; 24 (1): 17-23

    Abstract

    Peripheral nerve and spinal cord stimulation techniques have been used for many years. However, electrical stimulation methods rarely have been used to confirm epidural catheter placement. This study examines the practicality of this technique to confirm epidural catheter placement in obstetric patients.Thirty-nine obstetric patients in labor were studied. An electrocardiography (ECG) adapter (Arrow-Johans) was attached to the proximal end of the epidural catheter (19-gauge Arrow Flextip plus). Then, the lowest milliamperage (1-10 mA) necessary to produce a motor response (truncal or limb movement) was applied using this setup. A positive motor response indicated that the catheter was in the epidural space. This test was performed initially after catheter insertion and repeatedly after incremental local anesthetic doses.The sensitivity and specificity of the new test was 100% and 100%, respectively, with 38 true positive tests and 1 true negative test. The threshold current required to produce a positive test increased after incremental doses of local anesthetic. A case of intravascular epidural catheter migration was detected using this new test. In this case, the patient's increased threshold milliamperage returned to the baseline value within 1 hour, despite having received local anesthetic. Intravascular epidural catheter migration was subsequently confirmed by a positive epinephrine test dose. Thus, this test appears to be a potentially useful method to detect intravascular catheter placement.This study demonstrates that this test may have a role in improving the success rate of epidural anesthesia.

    View details for Web of Science ID 000078163700005

    View details for PubMedID 9952090

  • Confirmation of epidural catheter placement using nerve stimulation CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Gupta, S., Finucane, B. 1998; 45 (7): 640-644

    Abstract

    To examine the reliability of low current electrical epidural stimulation to confirm epidural catheter placement.Forty patients with epidural catheters (19G Arrow Flextip plus) already in place for post-operative pain management were studied. An adapter (Arrow-Johans ECG Adapter) was attached to the connector of the epidural catheter. The epidural catheter and adapter were filled with normal saline. The cathode lead of the nerve stimulator was attached to the metal hub of the adapter. Catheter placement was judged to be correct or incorrect, depending upon the presence or absence of truncal or limb movement to 1 Hz stimulation (1-10 mA). A standard test dose (3 ml lidocaine 1.5% with 1:200,000 epinephrine) was then injected. The efficacy of the epidural morphine was assessed independently.The sensitivity and specificity of the test was 100% and 91.6% compared with the standard test dose. The positive and negative predictive value was 96% and 100%. In predicting the clinical effect of epidural morphine, the sensitivity and specificity was 96.1% and 76.9%. The positive and negative predictive value was 89% and 90%. The correlation of unilateral or bilateral motor response from the test and sensory response from the lidocaine test with sensitivity and specificity was 91.6% and 53.0%. The predictive value for unilateral response was 61% and for bilateral was 88%.This study establishes this test as a simple, objective and reliable technique for confirmation of epidural catheter placement.

    View details for Web of Science ID 000075263300008

    View details for PubMedID 9717595

  • A rapid precurarization technique using rocuronium CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C., Reid, S., Gupta, S., Kearney, R., Mayson, T., Finucane, B. 1998; 45 (5): 397-401

    Abstract

    To evaluate a rapid and time-saving precurarization technique using rocuronium to prevent succinylcholine-induced myalgia.In a prospective, double blind randomized study, 42 ASA 1-2 patients were assigned to one of three pretreatment groups: 0.01 ml.kg-1 normal saline, 0.1 mg.kg-1 atracurium, and 0.1 mg.kg-1 rocuronium. Anaesthesia commenced with 1.5 micrograms.kg-1 fentanyl and 0.5 mg.kg-1 lidocaine at time zero. Pretreatment was administered 60 sec later, followed by 2.5 mg.kg-1 propofol. At 90 sec, 1.5 mg.kg-1 succinylcholine was injected and 30 sec later, the trachea was intubated and the ease of intubation was graded. The patient was observed for the presence and severity of fasciculations. Myalgias were recorded on postoperative days 1, 2 and 7.The incidence of fasciculations in the rocuronium group (21.4%) was lower (P < 0.001) than atracurium (78.5%) or placebo (92.8%) groups. On postoperative day 1, the incidence of postoperative myalgia in the rocuronium group (14.2%) was less than the placebo group (78.2%; P < 0.002) and atracurium group (85.7%; P < 0.001). The incidence of myalgia in the rocuronium group (7.1%) was lower than in the placebo group (78.5%; P < 0.001) but not different from the atracurium group (42.8%; P = 0.077) on postoperative day 2. On postoperative day 7, there was no difference among the three groups. Fasciculations were related to postoperative myalgia. There was no difference in intubating conditions among the three groups.Rocuronium pretreatment given just before induction of anaesthesia with propofol reduces fasciculations and succinylcholine-induced myalgia.

    View details for Web of Science ID 000073543400003

    View details for PubMedID 9598252

  • Pharmacokinetics and haemodynamic effect of diltiazem in rats: Effect of route of administration JOURNAL OF PHARMACY AND PHARMACOLOGY Tsui, B. C., Feng, J. D., Yeung, P. K. 1998; 50 (2): 183-188

    Abstract

    Diltiazem is a calcium antagonist widely used for the treatment of angina and hypertension. Previous studies in patients have shown that the haemodynamic effects of diltiazem are greater after parenteral rather than oral administration. The rat has been used as an animal model to determine the effect of the route of administration on the pharmacokinetic and haemodynamic effects of diltiazem. The results showed that plasma concentrations of diltiazem were more than 10 times higher after the intra-arterial dose. The plasma concentrations of the major metabolites were also higher after intra-arterial administration, although only for deacetyl diltiazem (M1) did the difference reach statistical significance (P < 0.05). The haemodynamic effects (on blood pressure and heart rate) of diltiazem were considerably greater after intra-arterial administration; this was attributed mainly to the much higher plasma concentrations of diltiazem. The hypotensive and chronotropic effects of diltiazem were similar; Emax and EC50 for diastolic blood pressure were 72+/-19% and 4.4+/-5.9 microg mL(-1); for heart rate they were 77+/-32% and 10.0+/-11.7 microg mL(-1), respectively. The haemodynamic effects of diltiazem are much greater after intra-arterial administration, mainly because of the much higher plasma concentrations of the drug. The contribution by the metabolites would be minimal after this route of administration.

    View details for Web of Science ID 000072423400009

    View details for PubMedID 9530986

  • A simple method with no additional cost for monitoring ETCO2 using a standard nasal cannulae CANADIAN JOURNAL OF ANAESTHESIA-JOURNAL CANADIEN D ANESTHESIE Tsui, B. C. 1997; 44 (7): 787-788

    View details for Web of Science ID A1997XH98700026

    View details for PubMedID 9232317

  • Occult liver abscess following clinically unsuspected ingestion of foreign bodies CANADIAN JOURNAL OF GASTROENTEROLOGY Tsui, B. C., Mossey, J. 1997; 11 (5): 445-448

    Abstract

    Two uncommon cases of foreign body (a wooden clothespin and a toothpick) perforation of the gur with associated pyogenic liver abscesses are presented. These cases illustrate the difficulties of preoperative diagnosis. The lack of history of ingestion of foreign bodies, variable clinical presentation of the conditions and radiolucent natures of the foreign bodies all play a role in impeding the diagnosis preoperatively. This report emphasizes the role of ultrasound and computed tomographic scan in evaluating similar cases. Any patient with known risk factors for ingestion of foreign body should arouse suspicion and be investigated further.

    View details for Web of Science ID A1997XT66500011

    View details for PubMedID 9286481

  • Anorectal fistula: an unusual presentation in a Crohn's disease patient. journal of emergency medicine Tsui, B. C., Cummings, G. E. 1997; 15 (1): 39-43

    Abstract

    An unusual case of an anorectal fistula presenting with hip pain and extensive lower limb muscle wasting in a patient with Crohn's disease is reported. This report emphasizes the important role of a thorough history, a complete physical examination, and a thorough search for evaluating such cases. Any progressive local irritation and pain in a Crohn's disease patient may indicate possible fistulous involvement. Nonspecific laboratory findings such as leukocytosis, anemia, decreased albumin level, and thrombocytosis may be considered as supportive indicators. Barium contrast studies and enhanced computed tomography scan may be helpful but can be falsely negative in the presence of a fistula, as in this case. These findings illustrate that the clinician must not be dissuaded from the diagnosis simply based on negative radiological findings because the presence of a fistula may be impossible to determine preoperatively.

    View details for PubMedID 9017486

  • ASSESSMENT OF ARYLAMINE N-ACETYLTRANSFERASE (NAT1) ACTIVITY IN MONONUCLEAR LEUKOCYTES OF CYSTIC-FIBROSIS PATIENTS BRITISH JOURNAL OF CLINICAL PHARMACOLOGY Cribb, A. E., Tsui, B., Isbrucker, R., Michael, R. T., Gillespie, C. T., BROWNBONOMO, J., Barrett, P., LeVatte, T., Renton, K. W. 1995; 39 (1): 85-89

    Abstract

    The clearance of sulphamethoxazole (SMX), a compound metabolised primarily by the N-acetyltransferase NAT1, is increased in cystic fibrosis (CF) patients. We assessed the activity and kinetic properties of NAT1 in lysates of peripheral blood mononuclear leukocytes (MNL) from CF (n = 17) and control (n = 22) subjects using SMX and p-aminobenzoic acid (PABA) as test substrates. The Km and Vmax values of both substrates in MNL from CF patients and control subjects were not significantly different. The acetylation of PABA (100 microM) by intact MNL from CF patients (n = 4) was not different from the observed in intact MNL from controls (n = 9) (25 +/- 3 pmol h-1 per 10(6) MNL vs 27 +/- 4 pmol h-1 per 10(6) MNL). These results suggest that there are not systemic changes in this enzyme in CF. The increased metabolic clearance of SMX may therefore be related to factors other than alterations in the level of activity of the N-acetyltransferase NAT1.

    View details for Web of Science ID A1995QA72500014

    View details for PubMedID 7756106

    View details for PubMedCentralID PMC1364987

  • PHARMACOKINETICS AND METABOLISM OF DILTIAZEM IN RATS FOLLOWING A SINGLE INTRAARTERIAL OR SINGLE ORAL DOSE EUROPEAN JOURNAL OF DRUG METABOLISM AND PHARMACOKINETICS Tsui, B. C., Feng, J. D., Buckley, S. J., Yeung, P. K. 1994; 19 (4): 369-373

    Abstract

    Diltiazem (DTZ) 20 mg/kg was given to male Sprague-Dawley rats either orally (p.o.) or intra-arterially (i.a.) over a 5 min period (n = 6 for each group). Plasma concentrations of DTZ and its major basic metabolites were determined by high performance liquid chromatography assay (HPLC) as previously described over a 10 h period. The major metabolites found in the rat plasma were M2, followed by M6, MA, M1, and then M4. The metabolite Mx was measurable only in some of the plasma samples, and MB was not detected in this species. The mean apparent half-life (t1/2) of the measurable metabolites were longer than the parent DTZ. The metabolism profiles were qualitatively similar between the two routes of administration. Quantitatively, however, the plasma concentrations of the metabolites were higher after the i.a. route. These results are in agreement with a previous study reported in rabbits, and suggest that deacetylation of DTZ and MA in the blood is extremely important in this species.

    View details for Web of Science ID A1994QE50000010

    View details for PubMedID 7737239

  • ACETYLATOR PHENOTYPING - THE URINARY CAFFEINE METABOLITE RATIO IN SLOW ACETYLATORS CORRELATES WITH A MARKER OF SYSTEMIC NAT1 ACTIVITY PHARMACOGENETICS Cribb, A. E., Isbrucker, R., LeVatte, T., Tsui, B., Gillespie, C. T., Renton, K. W. 1994; 4 (3): 166-170

    Abstract

    Eighteen healthy Caucasians were evaluated for the systemic acetylation of a caffeine metabolite using the urinary caffeine metabolite ratio 5-acetylamino-6-formylamino-3-methyluracil (AFMU) to 1-methylaxanthine (1X) and for N-acetyltransferase activity in peripheral blood mononuclear leukocytes (MNL) using p-aminobenzoic acid (PABA). These are markers for systemic NAT2 and NAT1 N-acetyltransferase activities, respectively. Fourteen slow acetylators and four fast acetylators (the NAT2 polymorphism) were identified by the caffeine metabolite ratio. In slow acetylators who have decreased levels of hepatic NAT2, the AFMU/1X ratio was significantly correlated with PABA acetylation in MNL (r = 0.8; p = 0.0002). These results suggest that significant variation in the acetylation of arylamine substrates susceptible to the classical acetylator polymorphism is attributable to variation in NAT1 activity in the slow acetylator phenotype.

    View details for Web of Science ID A1994NW01700009

    View details for PubMedID 7920698

  • OPTIMAL IMAGING TECHNIQUES FOR LOCATING LEAFLETS AFTER ESCAPE FROM PROSTHETIC HEART-VALVES CANADIAN ASSOCIATION OF RADIOLOGISTS JOURNAL-JOURNAL DE L ASSOCIATION CANADIENNE DES RADIOLOGISTES Tsui, B. C., KINLEY, C. E., Miller, R. M. 1994; 45 (2): 93-96

    Abstract

    The authors report two cases of leaflets escaping from an Edwards-Duromedics bileaflet prosthetic heart valve (Baxter-Edwards Division, Baxter Healthcare Corp., Irvine, Calif.). Several imaging techniques were used in attempts to locate the leaflets. Only computed tomography (CT) led to conclusive results. Because progressive extrusion through the arterial wall was documented surgically in these cases, the authors recommend that CT be performed as early as possible after a leaflet escapes, even in asymptomatic patients. Extrusion through the arterial wall precludes percutaneous intravascular movement or retrieval of escaped leaflets.

    View details for Web of Science ID A1994NG03900002

    View details for PubMedID 8149278

  • A RELIABLE TECHNIQUE FOR CHRONIC CAROTID ARTERIAL CATHETERIZATION IN THE RAT JOURNAL OF PHARMACOLOGICAL METHODS Tsui, B. C., MOSHER, S. J., Yeung, P. K. 1991; 25 (4): 343-352

    Abstract

    A reliable and simple method for cannulating the carotid artery of rats is described. The rat was anesthetized with halothane. The right carotid artery located between the omohyoideus and sternohyoideus muscles was exposed through a 2-cm ventral neck incision. The catheter was made of Silastic tubing and a monofilament line, which served as an obturator and internal support. The line was then filled with a viscous mixture of heparin, polyvinylpyrrolidinone and normal saline to prevent the formation of blood clots. The catheter was advanced through the carotid artery towards the heart by a predetermined distance (15-20 mm) depending on the size of the rat. The catheter was well tolerated by the rats and the success rate was 95%. Its patency lasted for at least 7 days postsurgery without any special maintenance care. With the described method one would be able to perform repetitive blood sampling and arterial blood pressure measurements in unanesthetized and unrestrained rats for prolonged period after catheterization.

    View details for Web of Science ID A1991FR31700008

    View details for PubMedID 1886417

  • HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ASSAY OF DILTIAZEM AND 6 OF ITS METABOLITES IN PLASMA - APPLICATION TO A PHARMACOKINETIC STUDY IN HEALTHY-VOLUNTEERS JOURNAL OF PHARMACEUTICAL SCIENCES Yeung, P. K., Montague, T. J., Tsui, B., McGregor, C. 1989; 78 (7): 592-597

    Abstract

    A sensitive and specific reversed-phase high-performance liquid chromatographic assay for simultaneous determination of plasma concentrations of diltiazem and six of its metabolites known to occur in humans is reported. Using 2 mL of plasma, the lower limit of quantitation of the assay was less than 10 ng/mL of diltiazem and each of the metabolites, with coefficients of variation of less than 10%. The assay was successfully applied to determine the kinetics of diltiazem and its major metabolites in four healthy volunteers after each received a single 90-mg oral dose of diltiazem. In addition to the previously reported two major metabolites in humans, deacetyl diltiazem (M1) and N-monodemethyl diltiazem (MA), another previously unreported major metabolite, deacetyl N-monodemethyl diltiazem (M2), was present at comparable concentrations to M1 and MA in all four volunteers. In addition, another metabolite, deacetyl diltiazem N-oxide (M1-NO), which was previously found most abundant in urine, was also estimated in the plasma of two volunteers. Two other known human metabolites, deacetyl O-demethyl diltiazem (M4) and deacetyl N,O-didimethyl diltiazem (M6), were not detected in any of the four study subjects. The average maximum plasma concentrations of M1, M2, MA, and M1-NO were 10, 15, 26, and 13%, respectively, of the mean maximum diltiazem concentrations.

    View details for Web of Science ID A1989AF19000017

    View details for PubMedID 2778663