Clinical Associate Professor, Anesthesiology, Perioperative and Pain Medicine
Airway Management Physician, San Francisco 49ers Football Club (2021 - Present)
Neuroanesthesia Division Clinical Director, Department of Anesthesiology, Stanford University (2021 - Present)
Honors & Awards
Article of the Month (January), OpenAnesthesia (2021)
Teaching Scholar Award, Department of Anesthesiology, Stanford University (2017)
Board Certification: Royal College of Physicians and Surgeons, Anesthesia (2013)
Neuroanesthesia Fellowship, Stanford University (2015)
Anesthesia Residency, University of Saskatchewan (2013)
Medical Education: National University of Ireland (2008) Ireland
Fosaprepitant Does Not Interfere With Commonly Used Intraoperative Neuromonitoring Modalities Under General Anesthesia: A Preliminary Study.
Journal of neurosurgical anesthesiology
BACKGROUND: Fosaprepitant [Emend], a neurokinin type-1 [NK-1] receptor antagonist, is a highly effective for the prophylaxis of postoperative nausea and vomiting [PONV] after general anesthesia; it is particularly effective in patients undergoing neurosurgical procedures. Based on the widespread distribution of NK-1 receptors in the central and peripheral nervous systems, we sought to determine whether fosaprepitant administration would interfere with commonly used intraoperative neurophysiologic monitoring modalities during general anesthesia.METHODS: Eleven patients having propofol-based general anesthesia for interventional neuroradiology procedures were administered 150mg fosaprepitant intravenously after baseline electroencephalogram [EEG], transcranial motor evoked potential [TcMEP], and somatosensory evoked potential [SSEP] recordings were obtained. Recordings of these neuromonitoring modalities at 30, 60, and 90 min after fosaprepitant administration were compared to baseline.RESULTS: Fosaprepitant did not have a significant effect on SSEP/TcMEP amplitudes or latencies, or on TcMEP morphology. There were also no changes in EEG voltage, frequency, or symmetry.CONCLUSION: Fosaprepitant does not appear to markedly interfere with SSEP, TcMEP, or EEG neuromonitoring modalities during propofol-based general anesthesia.
View details for DOI 10.1097/ANA.0000000000000865
View details for PubMedID 36006662
- Tension Pneumocephalus. Journal of neurosurgical anesthesiology 2022
Intraoperative Anaphylaxis: Definition Determines Detection Response
ANESTHESIA AND ANALGESIA
2021; 132 (5): E78
View details for Web of Science ID 000639311200014
Rapid Blood Transfusion: The Importance of Hemodilution and Needleless Connectors.
2021; 13 (3): e13999
Large-bore cannulas are critical to administering IV fluids and blood products during resuscitation and treatment of hemorrhage. Although catheter flow rates for crystalloid solutions are well defined, rapid administration of blood products is poorly characterized. In this in vitro study, we examined the effects of hemodilution and needleless connectors on red blood cell (RBC) flow rates. To determine RBC flow rates through large-bore cannulae, a crystalloid solution (Normosol®, Hospira, Lake Forest, IL) or RBC units were warmed and delivered under pressure (360 mmHg) using a Level 1 H-1200 Fast Flow Fluid Warmer (Smiths Medical, St. Paul, MN). Flow rates for crystalloid, packed RBCs and diluted RBCs were determined using a stopwatch. Additionally, the effect of the MaxPlus® clear needleless connector (CareFusion, San Diego, CA) was measured in all three infusion groups. Flow rates for undiluted RBC units were 53% slower than crystalloid solution (220 mL/min vs. 463 mL/min; p=0.0003), however, when RBC units were diluted to a hematocrit of ~30% flow rate improved to 369 mL/min (p=0.005). The addition of the MaxPlus® needleless connector reduced flow of crystalloid solution by 47% (245 mL/min; p=0.0001), undiluted RBCs by 64% (78 mL/min; p=0.01), and diluted RBCs by 51% (180 mL/min; p=0.00003). Compared to undiluted RBC units, hemodilution increased RBC delivery rate through a MaxPlus® connector by 130% (p=0.004) and by 68% (p=0.02) when the catheter was directly connected to the Level 1 tubing (MaxPlus® excluded). In settings requiring rapid transfusion of RBC units, needleless connectors should not be used and hemodilution should be considered in order to decrease the time required to deliver an equivalent red cell mass.
View details for DOI 10.7759/cureus.13999
View details for PubMedID 33880314
View details for PubMedCentralID PMC8053387
- Enhancing Perioperative Care of Patients Undergoing Major Complex Spinal Instrumentation Surgery: Clinical Practice Guidelines from the Society for Neuroscience in Anesthesiology and Critical Care Journal of Neurosurgical Anesthesiology 2021
- Antiepileptic and Other Neurologically Active Drugs Stoelting's Pharmacology and Physiology in Anesthetic Practice Wolters Kluer. 2021; 6
Accidental Injection of Propofol Into a Lumbar Drain
Journal of Neurosurgical Anesthesiology
View details for DOI 10.1097/ANA.0000000000000693
Incidence of Anaphylaxis to Sugammadex in a Single-Center Cohort of 19,821 Patients
Anesthesia and Analgesia
View details for DOI 10.1213/ANE.0000000000004752
- Accidental Injection of Propofol Into a Lumbar Drain: The Role of ISO 80369-6 Compliant Neuro Connectors. Journal of neurosurgical anesthesiology 2020
- Neurointensive Care Unit: Clinical Practice and Organization. Anesthesia and analgesia 2020; 131 (5): e225–e226
- The use of end-tidal argon to detect venous air embolism: foiled by "fake oxygen!" JOURNAL OF CLINICAL MONITORING AND COMPUTING 2019; 33 (5): 925–26
- Effect of Head Rotation on Jugular Vein Patency Under General Anesthesia CANADIAN JOURNAL OF NEUROLOGICAL SCIENCES 2019; 46 (3): 355–57
- Excipients in Anesthesia Medications ANESTHESIA AND ANALGESIA 2019; 128 (5): 891–900
Acetaminophen Does Not Reduce Postoperative Opiate Consumption in Patients Undergoing Craniotomy for Cerebral Revascularization: A Randomized Control Trial.
2019; 11 (1): e3863
Background Postoperative management in patients undergoing craniotomy is unique and challenging. We utilized apopulation of patients who underwent bilateral extracranial-to-intracranial (EC-IC bypass) revascularization procedures for moyamoya disease and hypothesized that 1 gram (gm) of intravenous (IV) acetaminophen given immediately after intubation and again 45 minutes prior to the end of craniotomymay be more effective than saline in minimizing opiate consumption and decreasing pain scores. Methods In a double-blind, randomized, placebo-controlled crossover pilot study, 40 craniotomies in 20 patients were studied. A random number generator assigned patients to receive either 1 gram of IV acetaminophen or an equal volume of normal saline immediately after intubation and again 45 minutes prior to the end of their first operation. For the second surgery, patients received the study drug (IV acetaminophen or normal saline) that they did not receive during their first surgery. Results In the IV acetaminophen group, the average 24-hour postoperative fentanyl equivalent consumption was decreased but the difference was not statistically significant: 228 micrograms compared to 312 micrograms in the placebo group (Figure 1;p = 0.09). Pain scores did not significantly differ between the IV acetaminophen group and the placebo group in postoperative hours 0-12 (Figure 2; p = 0.44) or 24 (Figure 3;p = 0.77). Conclusion Our study demonstrates that in patients receiving bilateral craniotomies for moyamoya disease, IV acetaminophen when given immediately after intubation and again 45 minutes prior to closuredoes not significantly decrease 12- or 24-hour postoperative opiate consumption.
View details for PubMedID 30899614
Intraoperative Kirschner Wire Migration during Robotic Minimally Invasive Spine Surgery.
Case reports in anesthesiology
2019; 2019: 9581285
We present the case of a 58-year-old woman who underwent a minimally invasive robotic-assisted L4-S1 instrumentation and fusion which was complicated by a Kirschner wire (K-wire) fracture and migration into the abdominal cavity necessitating emergent exploratory laparotomy. Retrieval of the K-wire proceeded without incident, and the patient had an otherwise uneventful surgery and recovery. This is the first such case description reported in the literature. As minimally invasive robotic-assisted spine procedures become more common, it is essential for the anesthesiologist to be familiar with potential complications to manage such patients in the perioperative period optimally.
View details for DOI 10.1155/2019/9581285
View details for PubMedID 31871795
View details for PubMedCentralID PMC6906877
- Intracranial Neurosurgery Anesthesiologist's Manual of Surgical Procedures Wolters Kluwer. 2019; 6
An Anesthesia Attempt to Be Green: How Do You Waste Your Carbon Dioxide Absorbers?
Operating room waste is categorized as noncontaminated solid waste (SW) and regulated medical waste (RMW). RMW is treated by autoclaving at an increased economic and environmental cost. We evaluated these costs with a focus on the disposable carbon dioxide (CO2) absorbers. At our institution, exhausted CO2 absorbers were discarded as RMW. We collaborated with product representatives, anesthesia and perioperative staff, and waste management personnel to identify opportunities and barriers for recycling and waste reduction. Ultimately, we agreed to discard CO2 absorbers as SW instead of RMW, a strategy that is practical, less expensive, and more environmentally appropriate.
View details for DOI 10.1213/XAA.0000000000001113
View details for PubMedID 31609724
Paradoxical Critical Hyperkalemia After Acetazolamide for Cerebrovascular Reactivity Study: A Case Report.
We present the case of a 42-year-old man with moyamoya disease presenting for cerebral revascularization surgery who developed critical hyperkalemia following a single intravenous (iv) dose of 1000 mg of acetazolamide 1 day preoperatively for a cerebrovascular reactivity study. His potassium increased from 5.1 to 6.7 mmol/L. Prompt treatment of this abnormality allowed this patient to undergo surgery the next day uneventfully. A paradoxical, critical increase in potassium can result from a single 1000-mg iv dose of acetazolamide.
View details for DOI 10.1213/XAA.0000000000001148
View details for PubMedID 31770135
- Performance of Litholyme compared with Sodasorb carbon dioxide absorbents in a standard clinical setting. British journal of anaesthesia 2019; 122 (1): e11–e12
A novel use of the precordial Doppler for verification of central venous access.
Korean J Anesthesiol.
2019; 72 (76-77)
View details for DOI 10.4097/kja.d.18.00252
Intraoperative Transcranial Motor-evoked Potential Stimulation Does Not Seem to Cause Seizures.
Journal of neurosurgical anesthesiology
Intraoperative neurophysiological monitoring is of critical importance in evaluating the functional integrity of the central nervous system during surgery of the central or peripheral nervous system. In a large recent study, transcranial motor-evoked potentials (TcMEPs) were found to be associated with a 0.7% risk of inducing a seizure as diagnosed by clinical observation and electromyography in patients having general anesthesia with intravenous anesthetics. The gold standard for seizure diagnosis, however, is electroencephalography (EEG). The aim of this single-institution retrospective study is to ascertain the risk of intraoperative seizures detected using EEG during surgeries in adult patients undergoing intraoperative monitoring with TcMEPs.The authors retrospectively reviewed the intraoperative EEG records of 1175 patients anesthetized with a variety of anesthetic agents, including volatile and intravenous anesthetics, to ascertain the rate of EEG-diagnosed seizures attributable to TcMEPs.Our analysis did not reveal a single seizure event attributable to TcMEPs in 1175 patients.The intraoperative use of TcMEPs does not seem to cause seizures.
View details for DOI 10.1097/ANA.0000000000000671
View details for PubMedID 31876633
Inaccurate Blood Pressure Readings in the Intensive Care Unit: An Observational Study.
2018; 10 (12): e3716
Measuring and monitoring cerebral perfusion pressure (CPP) is important in the management of patients with certain neurological conditions. To accurately reflect blood pressure at the circle of Willis, the arterial line transducer should be leveled at the tragus. This study measured the relative distance of the transducer to the tragus in 100 intensive care unit (ICU) patients in the mixed ICU at our institution, of which 44 patients had a pressure-sensitive neurological diagnosis. For neurological patients, the average distance was 10.9 cm and for non-neurological patients, the average distance was 11.4 cm (p-value: 0.60). This suggests that the arterial line transducer was leveled at approximately the same level regardless of pathology, potentially leading to falsely elevated CPP readings in patients with pressure-sensitive neurological pathology.
View details for PubMedID 30906677
Case Report of an Awake Craniotomy in a Patient With Eisenmenger Syndrome.
2018; 10 (9): 219-222
We present a detailed report of an awake craniotomy for recurrent third ventricular colloid cyst in a patient with severe pulmonary arterial hypertension in the setting of Eisenmenger syndrome, performed 6 weeks after we managed the same patient for a more conservative procedure. This patient has a high risk of perioperative mortality and may be particularly susceptible to perioperative hemodynamic changes or fluid shifts. The risks of general anesthesia induction and emergence must be balanced against the risks inherent in an awake craniotomy on a per case basis.
View details for DOI 10.1213/XAA.0000000000000664
View details for PubMedID 29708913
View details for PubMedCentralID PMC6309536
Fluid management concepts for severe neurological illness: an overview.
Current opinion in anaesthesiology
The acute care of a patient with severe neurological injury is organized around one relatively straightforward goal: avoid brain ischemia. A coherent strategy for fluid management in these patients has been particularly elusive, and a well considered fluid management strategy is essential for patients with critical neurological illness.In this review, several gaps in our collective knowledge are summarized, including a rigorous definition of volume status that can be practically measured; an understanding of how electrolyte derangements interact with therapy; a measurable endpoint against which we can titrate our patients' fluid balance; and agreement on the composition of fluid we should give in various clinical contexts.As the possibility grows closer that we can monitor the physiological parameters with direct relevance for neurological outcomes and the various complications associated with neurocritical illness, we may finally move away from static therapy recommendations, and toward individualized, precise therapy. Although we believe therapy should ultimately be individualized rather than standardized, it is clear that the monitoring tools and analytical methods used ought to be standardized to facilitate appropriately powered, prospective clinical outcome trials.
View details for PubMedID 30015638
- Dermographism: A rare cause of intraoperative hypotension and urticaria 100 Selected Case Reports from Anesthesia & Analgesia Wolters Kluer. 2018; 1
- Intraoperative tonic-clonic seizure under general anesthesia captured by electroencephalogram. 100 Selected Case Reports from Anesthesia & Analgesia Wolters Kluer. 2018; 1
- High Risk of Aspiration in Patients With ReShape Intragastric Balloon Weight Loss System. Anesthesia and analgesia 2017; 124 (2): 703
- At What Hematocrit Should We Transfuse in Craniotomy? You're Wrong I'm Right: Dueling Authors Re-Examine Classic Teachings in Anesthesia 2017
- High Flow Nasal Cannula, A Novel Approach to Airway Management in Awake Craniotomies. Journal of neurosurgical anesthesiology 2017
Intraoperative Tonic-Clonic Seizure Under General Anesthesia Captured by Electroencephalography: A Case Report
A and A Case Reports
We present the case of a 34-year-old man undergoing craniotomy for arteriovenous malformation resection under general anesthesia who suffered a tonic-clonic seizure captured by intraoperative electroencephalograph. The seizure was extinguished with a propofol bolus. This patient had no previous history of seizures, and no precipitating cause was identified. Intraoperative electroencephalographic seizures under general anesthesia have been recorded previously in the literature, but our observation is the first to demonstrate this with overt motor manifestations. We also discuss the differential diagnosis of an intraoperative seizure under general anesthesia and provide guidance to the anesthesiologist who encounters this event.
View details for DOI 10.1213/XAA.0000000000000509
Ventriculoperitoneal Shunt Insertion Under Monitored Anesthesia Care in a Patient With Severe Pulmonary Hypertension.
A & A case reports
2016; 7 (2): 27-29
A 32-year-old man with severe pulmonary arterial hypertension and Eisenmenger syndrome secondary to congenital ventricular septal defects presented for ventriculoperitoneal shunt insertion. Consultation between surgical and anesthesia teams acknowledged the extreme risk of performing this case, but given ongoing symptoms related to increased intracranial pressure from a large third ventricle colloid cyst, the case was deemed urgent. After a full discussion with the patient, including an explanation of anesthetic expectations and perioperative risks, the case was performed under monitored anesthesia care. Anesthetic management included high-flow nasal cannula oxygen with capnography and arterial blood pressure monitoring, dexmedetomidine infusion, boluses of midazolam and ketamine, and local anesthetic infiltration of the cranial and abdominal incisions as well as the catheter track. Hemodynamic support was provided with an epinephrine infusion, small vasopressin boluses, and inhaled nitric oxide. The patient recovered without any significant problems and was discharged home on postoperative day 3.
View details for DOI 10.1213/XAA.0000000000000329
View details for PubMedID 27224039
Dermographism: A Rare Cause of Intraoperative Hypotension and Urticaria.
A & A case reports
2016; 7 (2): 41-43
A 54-year-old man with dermographism presented for spine surgery, and shortly after induction of anesthesia, he experienced severe hypotension and urticaria, resulting in cancellation of the case on suspicion of allergic reaction. For subsequent ventral hernia repair, a perioperative management strategy was devised, which resulted in an uneventful perioperative course. This case report is the first to demonstrate severe intraoperative hypotension and urticaria from dermographism. We discuss the strategy that made the subsequent surgery a success and provide guidance for practitioners who face a patient with a severe form of this chronic disease.
View details for DOI 10.1213/XAA.0000000000000336
View details for PubMedID 27434310
- Exparel®: A New Local Anesthetic with Special Safety Concerns. Anesthesia and analgesia 2015; 121 (4): 1113-1114
- Antiepileptic and Other Neurologically Active Drugs Stoelting's Pharmacology and Physiology in Anesthetic Practice Wolters Kluer. 2015; 5
Awake craniotomy in a developmentally delayed blind man with cognitive deficits
CANADIAN JOURNAL OF ANESTHESIA-JOURNAL CANADIEN D ANESTHESIE
2013; 60 (4): 399-403
To describe the complex perioperative considerations and anesthetic management of a cognitively delayed blind adult male who underwent awake craniotomy to remove a left anterior temporal lobe epileptic focus.A 28-yr-old left-handed blind cognitively delayed man was scheduled for awake craniotomy to resect a left anterior temporal lobe epileptic focus due to intractable epilepsy despite multiple medications. His medical history was also significant for retinopathy of prematurity that rendered him legally blind in both eyes and an intracerebral hemorrhage shortly after birth that resulted in a chronic brain injury and developmental delay. His cognitive capacity was comparable with that of an eight year old. Since patient cooperation was the primary concern during the awake electrocorticography phase of surgery, careful assessment of the patient's ability to tolerate the procedure was undertaken. There was extensive planning between surgeons and anesthesiologists, and a patient-specific pharmacological strategy was devised to facilitate surgery. The operation proceeded without complication, the patient has remained seizure-free since the procedure, and his quality of life has improved dramatically.This case shows that careful patient assessment, effective interdisciplinary communication, and a carefully tailored anesthetic strategy can facilitate an awake craniotomy in a potentially uncooperative adult patient with diminished mental capacity and sensory deficits.
View details for DOI 10.1007/s12630-013-9893-y
View details for Web of Science ID 000316293900009
View details for PubMedID 23361899
- Health Quality Improvement Using Instructional Communication and Teamwork Videos: An Outcome Study Creative Education 2013; 5 (1)
- Teamwork and Communication in Acute Care: A Teaching Resource for Healthcare Professionals MedEd Portal. 2012
The long-term functional outcome of type II odontoid fractures managed non-operatively
EUROPEAN SPINE JOURNAL
2010; 19 (10): 1635-1642
Odontoid fractures currently account for 9-15% of all adult cervical spine fractures, with type II fractures accounting for the majority of these injuries. Despite recent advances in internal fixation techniques, the management of type II fractures still remains controversial with advocates still supporting non-rigid immobilization as the definitive treatment of these injuries. At the NSIU, over an 11-year period between 1 July 1996 and 30 June 2006, 66 patients (n = 66) were treated by external immobilization for type II odontoid fractures. The medical records, radiographs and CT scans of all patients identified were reviewed. Clinical follow-up evaluation was performed using the Cervical Spine Outcomes Questionnaire (CSOQ). The objectives of this study were to evaluate the long-term functional outcome of patients suffering isolated type II odontoid fractures managed non-operatively and to correlate patient age and device type with clinical and functional outcome. Of the 66 patients, there were 42 males and 24 females (M:F = 1.75:1) managed non-operatively for type II odontoid fractures. The mean follow-up time was 66 months. Advancing age was highly correlated with poorer long-term functional outcomes when assessing neck pain (r = 0.19, P = 0.1219), shoulder and arm pain (r = 0.41, P = 0.0007), physical symptoms (r = 0.25, P = 0.472), functional disability (r = 0.24, P = 0.0476) and psychological distress (r = 0.41, P = 0.0007). Patients >65 years displayed a higher rate of pseudoarthrosis (21.43 vs. 1.92%) and established non-union (7.14 vs. 0%) than patients <65 years. The non-operative management of type II odontoid fractures is an effective and satisfactory method of treating type II odontoid fractures, particularly those of a stable nature. However, patients of advancing age have been demonstrated to have significantly poorer functional outcomes in the long term. This may be linked to higher rates of non-union.
View details for DOI 10.1007/s00586-010-1391-0
View details for Web of Science ID 000282825800004
View details for PubMedID 20364276