- Emergency Medicine
Clinical Assistant Professor, Emergency Medicine
Assistant Program Director for Research, Department of Emergency Medicine San Antonio Uniformed Health Education Consortium (2013 - 2014)
Member, Institutional Review Board, San Antonio Military Medical Center (2013 - 2014)
Associate Medical Director, Department of Emergency Medicine San Antonio Military Medical Center (2012 - 2014)
Co-Director, Emergency Ultrasound, Department of Emergency Medicine San Antonio Uniformed Services Health Education Consortium (2011 - 2014)
Honors & Awards
Highly Cited Research - One of 5 most highest cited papers published, Elsevier - American Journal of Emergency Medicine (2016)
Research Award Nominee, American Academy of Emergency Ultrasound (2016)
Outstanding Reviewer, American Journal of Emergency Medicine (2016)
Patient Service Champion, Duke University Medical Center (2009)
Leadership and Service Award, Society of Orange County Emergency Physiicians (2006)
Honor Society Member, Phi Beta Kappa (2000)
Summa Cum Laude, University of California, Davis (2000)
Boards, Advisory Committees, Professional Organizations
Research Officer, Academy of Emergency Ultrasound, Society for Academic Emergency Medicine (2016 - 2018)
Reviewer, Clinical Ultrasound Accreditation Program, American College of Emergency Physicians (2015 - Present)
Secretary, Academy of Emergency Ultrasound, Society for Academic Emergency Medicine (2013 - 2015)
Member, American Heart Association (2013 - Present)
Fellow, American College of Emergency Physicians (2011 - Present)
Board Certification: Emergency Medicine, American Board of Emergency Medicine (2011)
Fellowship, Hospital of the University of Pennsylvania, Emergency Ultrasound (2010)
Residency, Duke University Medical Center, Emergency Medicine (2009)
M.D., University of California, Irvine School of Medicine, Medicine (2006)
B.S., University of California, Davis, Neurobiology, Physiology, and Behavior (2000)
Community and International Work
Texas Two Step: How to Save a Life Campaign, Multiple Texas Communities
Hands Only CPR
American College of Emergency Physicians, Texas College of Emergency Physicians, Texas Medical Association, Health Corps
Opportunities for Student Involvement
New Horizons, Haiti & Suriname
general and specialized medical and dental services
United States Air Force
Opportunities for Student Involvement
Current Research and Scholarly Interests
- Cardiac massage for trauma patients in the battlefield: An assessment for survivors RESUSCITATION 2019; 138: 20–27
A Traumatic Pulseless Electrical Activity Model: Mortality Increases With Hypovolemia Time.
The Journal of surgical research
2019; 243: 301–8
There currently are no well-defined animal models for traumatic pulseless electrical activity (PEA). Our objective was to develop a swine model of traumatic PEA that would be useful for laboratory research where mortality is an outcome of interest. In this pilot study, we hypothesized that animals that remained in PEA without intervention for a longer period would have increased mortality.Sixteen Yorkshire swine were alternately allocated to either 5 or 10 min of traumatic PEA without intervention. After the nonintervention period, basic life support (BLS) with mechanical cardiopulmonary resuscitation was initiated and performed for 10 min followed by advanced life support (ALS) for an additional 10 min. Hemodynamic and laboratory values are reported for baseline, posthemorrhage, end of BLS, and end of ALS periods.Mortality in the 10-min PEA group (100%) was higher than the 5-min group (38%) (P = 0.03). Animals in the 5-min group had improved aortic diastolic blood pressure, coronary perfusion pressure, and end-tidal CO2 at the end of both the BLS (P = 0.02, 0.002, and 0.02, respectively) and ALS (P = 0.009, 0.005, and 0.008, respectively). The 10-min animals had increased hyperkalemia at the end of the BLS (P = 0.004) and ALS (P = 0.005) periods. All animals in the 10-min group developed ventricular fibrillation (VF) and 38% of the 5-min animals developed VF (P = 0.03).In our pilot study of traumatic PEA in a swine model, a shorter period of nonintervention resulted in increased survival, improved hemodynamics during resuscitation, decreased hyperkalemia, and less incidence of conversion to VF arrest.
View details for DOI 10.1016/j.jss.2019.05.037
View details for PubMedID 31254903
- Asymptomatic ST elevation myocardial infarction HEART & LUNG 2018; 47 (4): 363–65
Left Ventricular Compressions Improve Return of Spontaneous Circulation and Hemodynamics in a Swine Model of Traumatic Cardiopulmonary Arrest.
The journal of trauma and acute care surgery
BACKGROUND: Prehospital cardiopulmonary resuscitation, including closed chest compressions, has commonly been considered ineffective in traumatic cardiopulmonary arrest (TCPA) because traditional chest compressions do not produce substantial cardiac output. However, recent evidence suggests that chest compressions located over the left ventricle produce greater hemodynamics when compared to traditional compressions. We hypothesized that chest compressions located directly over the left ventricle would improve return of spontaneous circulation (ROSC) and hemodynamics, when compared to traditional chest compressions, in a swine model of traumatic cardiopulmonary arrest (TCPA).METHODS: Transthoracic echocardiography was used to mark the location of the aortic root (traditional compressions), and the center of the left ventricle (LV) on animals (n=26) which were randomized to receive chest compressions in one of the two locations. After hemorrhage, ventricular fibrillation (VF) was induced. After ten minutes of VF, basic life support (BLS) with mechanical CPR was initiated and performed for ten minutes followed by advanced life support (ALS) for an additional ten minutes. During BLS the area of maximal compression was verified using transesophageal echocardiography. Hemodynamic variables were averaged over the final two minutes of BLS and ALS periods.RESULTS: Five of the left ventricle group (38%) achieved ROSC compared to zero of the aortic root group (p=0.04). Additionally, there was an increase in aortic systolic blood pressure (SBP), aortic diastolic blood pressure (DBP) and coronary perfusion pressure (CPP) at the end of both the BLS (95% CI SBP -49 to -21, DBP -14 to -5.6 and CPP -15 to -7.4) and ALS (95% CI SBP -66 to -21, DBP -49 to -6.8 and CPP -51 to -7.5) resuscitation periods among the LV group.CONCLUSIONS: In our swine model of TCPA, chest compressions performed directly over the left ventricle improved ROSC and hemodynamics when compared to traditional chest compressions.LEVEL OF EVIDENCE: Therapeutic Animal Model, Level I.
View details for PubMedID 29613954
Airway ultrasound for the confirmation of endotracheal tube placement in cadavers by military flight medic trainees - A pilot study.
The American journal of emergency medicine
Confirming correct endotracheal tube (ETT) placement is a key component of successful airway management. Ultrasound (US) as a tool for the confirmation of ETT placement has been investigated in the hospital setting but not in the pre-hospital setting. We hypothesized that after a short educational session, military flight medic trainees would be able to accurately identify ETT placement in a cadaver model.We conducted a prospective, randomized trial in a human cadaver model. Participants received a brief didactic and hands-on presentation on airway US techniques. Each participant then performed transtracheal US on cadaver models which were randomly assigned to tracheal or esophageal intubation; time to verbalize ETT location was also recorded. Participants were then asked whether they felt airway US would be a useful adjunctive skill in their practice.Thirty-two military flight medic trainees were enrolled. US had a sensitivity of 66.7% and a specificity of 76.4% for identification of esophageal intubations. The positive predictive value was 71.4% and the negative predictive value was 72.2%. Mean time to report ETT placement was 47.3s. Time did not vary between medics with accurate identification versus inaccurate identification (p=0.176). 83% of participants felt airway US would be a useful adjunctive skill for the confirmation of ETT placement.Military flight medic trainees can rapidly use airway US to identify ETT placement after a short educational session with moderate sensitivity and specificity. These advanced military medics are interested in learning and implementing this skill into their practice.
View details for PubMedID 29478724
- A 49-year-old man who presents with abdominal pain Visual Journal of Emergency Medicine 2018; 11: 74-75
Adult Male With Scrotal Swelling and Pain.
Annals of emergency medicine
2018; 71 (6): e113–e114
View details for PubMedID 29776509
Point-of-Care Ultrasound in Austere Environments A Complete Review of Its Utilization, Pitfalls, and Technique for Common Applications in Austere Settings
EMERGENCY MEDICINE CLINICS OF NORTH AMERICA
2017; 35 (2): 409-?
With the advent of portable ultrasound machines, point-of-care ultrasound (POCUS) has proven to be adaptable to a myriad of environments, including remote and austere settings, where other imaging modalities cannot be carried. Austere environments continue to pose special challenges to ultrasound equipment, but advances in equipment design and environment-specific care allow for its successful use. This article describes the technique and illustrates pathology of common POCUS applications in austere environments. A brief description of common POCUS-guided procedures used in austere environments is also provided.
View details for DOI 10.1016/j.emc.2016.12.007
View details for PubMedID 28411935
Left Ventricular Compressions Improve Hemodynamics in a Swine Model of Out-of-Hospital Cardiac Arrest
PREHOSPITAL EMERGENCY CARE
2017; 21 (2): 272-280
We hypothesized that chest compressions located directly over the left ventricle (LV) would improve hemodynamics, including coronary perfusion pressure (CPP), and return of spontaneous circulation (ROSC) in a swine model of cardiac arrest.Transthoracic echocardiography (echo) was used to mark the location of the aortic root and the center of the left ventricle on animals (n = 26) which were randomized to receive chest compressions in one of the two locations. After a period of ten minutes of ventricular fibrillation, basic life support (BLS) with mechanical cardiopulmonary resuscitation (CPR) was initiated and performed for ten minutes followed by advanced cardiac life support (ACLS) for an additional ten minutes. During BLS the area of maximal compression was verified using transesophageal echo. CPP and other hemodynamic variables were averaged every two minutes.Mean CPP was not significantly higher in the LV group during all time intervals of resuscitation; mean CPP was significantly higher in the LV group during the 12-14 minute interval of BLS and during minutes 22-30 of ACLS (p < 0.05). Aortic systolic and diastolic pressures, right atrial systolic pressures, and end-tidal CO2 (ETCO2) were higher in the LV group during all time intervals of resuscitation (p < 0.05). Nine of the left ventricle group (69%) achieved ROSC and survived to 60 minutes compared to zero of the aortic root group (p < 0.001). In our swine model of cardiac arrest, chest compressions over the left ventricle improved hemodynamics and resulted in a greater proportion of animals with ROSC and survival to 60 minutes.
View details for DOI 10.1080/10903127.2016.1241328
View details for Web of Science ID 000395748100017
View details for PubMedID 27918847
- Gastric perforation causing severe abdominal pain Visual Journal of Emergency Medicine 2017; 9: 65-66
The ability of renal ultrasound and ureteral jet evaluation to predict 30-day outcomes in patients with suspected nephrolithiasis
AMERICAN JOURNAL OF EMERGENCY MEDICINE
2015; 33 (10): 1402-1406
We sought to identify findings on bedside renal ultrasound that predicted need for hospitalization in patients with suspected nephrolithiasis.A convenience sample of patients with suspected nephrolithiasis was prospectively enrolled and underwent bedside ultrasound of the kidneys and bladder to determine the presence and degree of hydronephrosis and ureteral jets. Sonologists were blinded to any other laboratory and imaging data. Patients were followed up at 30 days by phone call and review of medical records.Seventy-seven patients with suspected renal colic were included in the analysis. Thirteen patients were admitted. Reasons for admission included intractable pain, infection, or emergent urologic intervention. All 13 patients requiring admission had hydronephrosis present on initial bedside ultrasound. Patients with moderate hydronephrosis had a higher admission rate (36%) than those with mild hydronephrosis (24%), P<.01. Of patients without hydronephrosis, none required admission within 30 days. The sensitivity and specificity of hydronephrosis for predicting subsequent hospitalization were 100% and 44%, respectively. Loss of the ipsilateral ureteral jet was not significantly associated with subsequent hospital admission and did not improve the predictive value when used in combination with the degree of hydronephrosis.No patients with suspected renal colic and absence of hydronephrosis on bedside ultrasound required admission within 30 days. Ureteral jet evaluation did not help in prediction of 30-day outcomes and may not be useful in the emergency department management of renal colic.
View details for DOI 10.1016/j.ajem.2015.07.014
View details for Web of Science ID 000361839300014
View details for PubMedID 26279392
The utility of transvaginal ultrasound in the ED evaluation of complications of first trimester pregnancy
AMERICAN JOURNAL OF EMERGENCY MEDICINE
2015; 33 (6): 743-748
For patients with early intrauterine pregnancy (IUP), the sonographic signs of the gestation may be below the resolution of transabdominal ultrasound (TAU); however, it may be identified by transvaginal ultrasound (TVU). We sought to determine how often TVU performed in the emergency department (ED) reveals a viable IUP after a nondiagnostic ED TAU and the impact of ED TVU on patient length of stay (LOS).This was a retrospective cohort study of women presenting to our ED with complications of early pregnancy from January 1, 2007 to February 28, 2009 in a single urban adult ED. Abstractors recorded clinical and imaging data in a database. Patient imaging modality and results were recorded and compared with respect to ultrasound (US) findings and LOS.Of 2429 subjects identified, 795 required TVU as part of their care. Emergency department TVU was performed in 528 patients, and 267 went to radiology (RAD). Emergency department TVU identified a viable IUP in 261 patients (49.6%). Patients having initial ED US had shorter LOS than patients with initial RAD US (median 4.0 vs 6.0 hours; P < .001). Emergency department LOS was shorter for women who had ED TVU performed compared with those sent for RAD TVU regardless of the findings of the US (median 4.9 vs 6.7 hours; P < .001). There was no increased LOS for patients who needed further RAD US after an indeterminate ED TVU (7.0 vs 7.1 hours; P = .43). There was no difference in LOS for those who had a viable IUP confirmed on ED TAU vs ED (median 3.1 vs 3.2 hours, respectively; P < .32).When an ED TVU was performed, a viable IUP was detected 49.6% of the time. Emergency department LOS was significantly shorter for women who received ED TVU after indeterminate ED TAU compared with those sent to RAD for TVU, with more marked time savings among those with live IUP diagnosed on ED TVU. For patients who do not receive a definitive diagnosis of IUP on ED TVU, this approach does not result in increased LOS.
View details for DOI 10.1016/j.ajem.2015.02.023
View details for Web of Science ID 000356601400001
View details for PubMedID 25817202
- Portable Ultrasound in Disaster and Emergency Settings Global Point of Care: Strategies for Disasters, Emergencies and Public Health Resilience AACC Press. 2015
- Point-of-care ultrasound diagnoses acute decompensated heart failure in the ED regardless of examination findings AMERICAN JOURNAL OF EMERGENCY MEDICINE 2014; 32 (4): 385-388
- Quantifying B-Lines on Lung Sonography: Insufficient Evidence as an Objective, Constructive, and Educational Tool Reply JOURNAL OF ULTRASOUND IN MEDICINE 2014; 33 (2): 363-365
Diagnosing heart failure among acutely dyspneic patients with cardiac, inferior vena cava, and lung ultrasonography
AMERICAN JOURNAL OF EMERGENCY MEDICINE
2013; 31 (8): 1208-1214
Rapid diagnosis (dx) of acutely decompensated heart failure (ADHF) may be challenging in the emergency department (ED). Point-of-care ultrasonography (US) allows rapid determination of cardiac function, intravascular volume status, and presence of pulmonary edema. We test the diagnostic test characteristics of these 3 parameters in making the dx of ADHF among acutely dyspneic patients in the ED.This was a prospective observational cohort study at an urban academic ED. Inclusion criteria were as follows: dyspneic patients, at least 18 years old and able to consent, whose differential dx included ADHF. Ultrasonography performed by emergency sonologists evaluated the heart for left ventricular ejection fraction (LVEF), the inferior vena cava for collapsibility index (IVC-CI), and the pleura sampled in each of 8 thoracic regions for presence of B-lines. Cutoff values for ADHF were LVEF less than 45%, IVC-CI less than 20%, and at least 10 B-lines. The US findings were compared with the final dx determined by 2 emergency physicians blinded to the US results.One hundred one participants were enrolled: 52% male, median age 62 (25%-75% interquartile, 53-91). Forty-four (44%) had a final dx of ADHF. Sensitivity and specificity (including 95% confidence interval) for the presence of ADHF were as follows: 74 (65-90) and 74 (62-85) using LVEF less than 45%, 52 (38-67) and 86 (77-95) using IVC-CI less than 20%, and 70 (52-80) and 75 (64-87) using B-lines at least 10. Using all 3 modalities together, the sensitivity and specificity were 36 (22-51) and 100 (95-100). As a comparison, the sensitivity and specificity of brain natriuretic peptide greater than 500 were 75 (55-89) and 83 (67-92).In this study, US was 100% specific for the dx of ADHF.
View details for DOI 10.1016/j.ajem.2013.05.007
View details for Web of Science ID 000323163400010
View details for PubMedID 23769272
Inter-Rater Reliability of Quantifying Pleural B-Lines Using Multiple Counting Methods
JOURNAL OF ULTRASOUND IN MEDICINE
2013; 32 (1): 115-120
Sonographic B-lines are a sign of increased extravascular lung water. Several techniques for quantifying B-lines within individual rib spaces have been described, as well as different methods for "scoring" the cumulative B-line counts over the entire thorax. The interobserver reliability of these methods is unknown. This study examined 3 methods of quantifying B-lines for inter-rater reliability.Videotaped pleural assessments of adult patients presenting to the emergency department with dyspnea and suspected acute heart failure were reviewed by 3 blinded pairs of emergency physicians. Each pair performed B-line counts within single rib spaces using 1 of the following 3 predetermined methods: 1, individual B-lines are counted over an entire respiratory cycle; 2, as per method 1, but confluent B-lines are counted as multiple based on the percentage of the rib space they occupy; and 3, as per method 2, but the count is made at the moment when the most B-lines are seen, not over an entire respiratory cycle. A single-measures interclass correlation coefficient was used to assess inter-rater reliability for the 3 definitions of B-line counts.A total of 456 video clips were reviewed. The interclass correlation coefficients (95% confidence intervals) for methods 1, 2, and 3 were 0.84 (0.81-0.87), 0.87 (0.85-0.90), and 0.89 (0.87-0.91), respectively. The difference between methods 1 and 3 was significant (P = .003).All methods of B-line quantification showed substantial inter-rater agreement. Method 3 is more reliable than method 1. There were no other significant differences between the methods. We recommend the use of method 3 because it is technically simpler to perform and more reliable than method 1.
View details for Web of Science ID 000313607400013
View details for PubMedID 23269716
Cardiac Evaluation for Structural Abnormalities May Not Be Required in Patients Presenting With Syncope and a Normal ECG Result in an Observation Unit Setting
ANNALS OF EMERGENCY MEDICINE
2012; 60 (4): 478-484
Patients with syncope are frequently managed in observation units and receive serial examinations, monitoring for arrhythmias, and structural analysis of the heart. The primary aim of this study is to determine the utility of structural analysis of the heart in syncope patients who are being managed in an observation unit and have a normal ECG result.This is a retrospective, observational chart review of all consecutive adult patients observed during 18 months at an urban, academic medical center. A case report form with demographics, ECG interpretations, and structural analysis of the heart data was generated and all variables were defined before data extraction. Subjects with an ECG demonstrating any arrhythmia, premature atrial contraction, premature ventricular contraction, pacing, second- and third-degree blocks, and left bundle branch block were excluded from the normal ECG group. An abnormal cardiac structure was defined as an ejection fraction less than 45%, severe hypertrophy, or severe valvular abnormality. Ten percent of cases were evaluated by a second extractor to verify accuracy. Descriptive statistics with confidence intervals (CIs) and interquartile ranges (IQRs; 25%, 75%) are used.Three hundred twenty-three subjects were managed in the observation unit for syncope, 48% were men, and their median age was 66 years (25%, 75% IQR 52, 80). Two of 323 (0.6%; 95% CI 0.2% to 2.2%) had an arrhythmia; 1 of 323 had a non-ST-segment myocardial infarction (0.3%; 95% CI 0.1% to 1.7%). Of the 323 patients, 267 had a normal ECG result and 235 (88%) had their cardiac structure evaluated. Forty-eight percent of the normal ECG group were men, and the median age was 65 years (25%, 75% IQR 52, 79). Zero of 235 patients (0%; 95% CI 0% to 1.6%) had a structural abnormality identified on evaluation, and 2 of 18 (11%; 95% CI 3.1% to 32.8%) had an abnormal stress echocardiogram result.Structural abnormalities are unlikely in syncope patients with a normal ECG result. Care should focus on excluding arrhythmias and acute coronary syndrome.
View details for DOI 10.1016/j.annemergmed.2012.04.023
View details for Web of Science ID 000309636000017
View details for PubMedID 22632775
The effect of vessel depth, diameter, and location on ultrasound-guided peripheral intravenous catheter longevity
AMERICAN JOURNAL OF EMERGENCY MEDICINE
2012; 30 (7): 1134-1140
Ultrasound-guided peripheral intravenous catheters (USGPIVs) have been observed to have poor durability. The current study sets out to determine whether vessel characteristics (depth, diameter, and location) predict USGPIV longevity.A secondary analysis was performed on a prospectively gathered database of patients who underwent USGPIV placement in an urban, tertiary care emergency department. All patients in the database had a 20-gauge, 48-mm-long catheter placed under ultrasound guidance. The time and reason for USGPIV removal were extracted by retrospective chart review. A Kaplan-Meier survival analysis was performed.After 48 hours from USGPIV placement, 32% (48/151) had failed prematurely, 24% (36/151) had been removed for routine reasons, and 44% (67/151) remained in working condition yielding a survival probability of 0.63 (95% confidence interval [CI], 0.53-0.70). Survival probability was perfect (1.00) when placed in shallow vessels (<0.4 cm), moderate (0.62; 95% CI, 0.51-0.71) for intermediate vessels (0.40-1.19 cm), and poor (0.29; 95% CI, 0.11-0.51) for deep vessels (≥1.2 cm); P < .0001. Intravenous survival probability was higher when placed in the antecubital fossa or forearm locations (0.83; 95% CI, 0.69-0.91) and lower in the brachial region (0.50; 95% CI, 0.38-0.61); P = .0002. The impact of vessel depth and location was significant after 3 hours and 18 hours, respectively. Vessel diameter did not affect USGPIV longevity.Cannulation of deep and proximal vessels is associated with poor USGPIV survival. Careful selection of target vessels may help improve success of USGPIV placement and durability.
View details for DOI 10.1016/j.ajem.2011.07.027
View details for Web of Science ID 000308541100019
View details for PubMedID 22078967
TRAFFIC LAW KNOWLEDGE DISPARITY BETWEEN HISPANICS AND NON-HISPANIC WHITES IN CALIFORNIA
JOURNAL OF EMERGENCY MEDICINE
2011; 40 (6): 687-695
The Hispanic population is one group that is involved in a disproportionately high percentage of fatal motor vehicle collisions in the United States.This study investigated demographic factors contributing to a lack of knowledge and awareness of traffic laws among Hispanic drivers involved in motor vehicle collisions (MVCs) in southern California.The cross-sectional study enrolled adults (n = 190) involved in MVCs presenting to a Level I trauma center in southern California over a 7-month period. Subjects completed a survey about California traffic law knowledge (TLK) consisting of eight multiple-choice questions. The mean number of questions answered correctly was compared between groups defined by demographic data.The mean number of TLK questions answered correctly by Hispanic and non-Hispanic white groups were significantly different at 4.13 and 4.62, respectively (p = 0.005; 95% confidence interval -0.83 to -0.15). Scores were significantly lower in subjects who were not fluent in English, had less than a high school education, did not possess a current driver's license, and received their TLK from sources other than a driver's education class or Department of Motor Vehicle materials. Analysis of variance showed that the source of knowledge was the strongest predictor of accurate TLK.Source of TLK is a major contributing factor to poor TLK in Hispanics. An emphasis on culturally specific traffic law education is needed.
View details for DOI 10.1016/j.jemermed.2009.07.007
View details for Web of Science ID 000291960500020
View details for PubMedID 19748200
Foreign Bodies in the Gastrointestinal Tract and Anorectal Emergencies
EMERGENCY MEDICINE CLINICS OF NORTH AMERICA
2011; 29 (2): 369-?
Of all ingested foreign bodies (FBs) brought to the attention of physicians (probably a small minority of the total), 80% to 90% pass spontaneously; however, 10% to 20% require endoscopic removal, and about 1% require surgery. The article divides the GI tract into regions in which the anatomy, presentation, clinical findings, and management of FBs are distinct. The final third of this article describes the management of anorectal emergencies. An understanding of anatomy and common pathological conditions allows the emergency physician to make a diagnosis and provide relief and/or resolution in most cases.
View details for DOI 10.1016/j.emc.2011.01.009
View details for Web of Science ID 000291124300013
View details for PubMedID 21515184
- Pleural and Lung Ultrasound Encyclopedia of Intensive Care Medicine Springer. 2011; 1st Edition
- Topic A14. Fracture Assessment. In: American College of Emergency Physicians Emergency Ultrasound Fellowship Guidelines; Appendix: Core Content of Clinical Ultrasonography Fellowship Training. American College of Emergency Physicians. 2011
- Topic A4. Advanced Ocular Ultrasound. In: American College of Emergency Physicians Emergency Ultrasound Fellowship Guidelines; Appendix: Core Content of Clinical Ultrasonography Fellowship Training. American College of Emergency Physicians. 2011
- Soft Tissue and Extremity Ultrasound Handbook of Critical Care and Emergency Ultrasound McGraw Hill. 2011
- Acute Care and Sports Injury Oxford American Handbook of Sports Medicine Oxford University Press. 2010
Antinociception induced by chronic exposure of rats to cigarette smoke
2004; 366 (1): 86-91
To investigate if chronic exposure to cigarette smoke induces analgesia, rats were exposed to concentrated cigarette smoke in an environmental chamber over four successive 5-day blocks (6 h/day), with 2 smoke-free days between blocks. A control group was exposed to room air. Tail flick latencies increased significantly (analgesia) during each smoke exposure block, with a relative decline in analgesia across blocks (tolerance) and a return to control levels during the first three smoke-free interludes while remaining higher after the conclusion of the 4-week exposure period. Mechanical (von Frey) withdrawal thresholds declined over time in smoke-exposed and control groups, with the smoke-exposed group showing significantly lower thresholds. Plasma nicotine reached 95.4 +/- 32 (S.D.) ng/ml at the end of weekly smoke exposure and declined to 44.9 +/- 10.6 ng/ml 24 h after withdrawal. Rats lost weight during smoke exposure and quickly regained weight during smoke-free interludes and at the cessation of smoke exposure. Analgesia may contribute to the initiation of smoking, and rapid reversal of the analgesic effect following acute exposure may contribute to the difficulty in quitting smoking.
View details for DOI 10.1016/j.neulet.2004.05.020
View details for Web of Science ID 000223026000019
View details for PubMedID 15265596
The selective group mGlu2/3 receptor agonist LY379268 suppresses REM sleep and fast EEG in the rat
PHARMACOLOGY BIOCHEMISTRY AND BEHAVIOR
2002; 73 (2): 467-474
Studies of ionotropic receptors indicate that glutamate (Glu) neurotransmission plays a role in sleep. Here, we show for the first time that metabotropic 2/3 Glu (mGlu2/3) receptors play an active or permissive role in the control of REM sleep. The potent, selective, and systemically active mGlu2/3 receptor agonist LY379268 was administered systemically in doses of 1.0 and 0.25 mg/kg sc. The drug produced a dose-dependent suppression of rapid eye movement (REM) sleep and fast (10-50 Hz) EEG in non-rapid eye movement (NREM) sleep. The 1.0-mg/kg effect on REM sleep was remarkably powerful: REM sleep was totally suppressed in the 6-h postinjection and reduced by 80% in the next 6 h. NREM duration was unchanged during the REM suppression in spite of the strong and unusual depression of EEG power in fast NREM frequencies. These sleep and EEG effects were unaccompanied by motor or behavioral abnormalities. We hypothesize that the REM and the fast EEG suppression were both caused by a depression of brain arousal levels by LY379268. If correct, depressing arousal by reducing excitatory neurotransmission with an mGlu2/3 receptor agonist produces electrophysiological effects that differ drastically from those produced by depressing arousal by enhancing neural inhibition with GABAergic drugs. This different approach to modifying the excitation/inhibition balance in the brain might yield novel therapeutic actions.
View details for Web of Science ID 000177501500022
View details for PubMedID 12117602
Analgesia induced by chronic nicotine infusion in rats - Differences by gender and pain test
2001; 157 (1): 40-45
Acute administration of nicotine induces analgesia with subsequent development of tolerance. In human studies, females are less sensitive to the analgesic effects of nicotine than males. Few previous animal studies have investigated analgesic effects of chronic nicotine administration or addressed gender differences.To investigate whether chronic administration of nicotine induces analgesia in male and female rats as assessed by a battery of standard pain assays, if tolerance develops, and if hyperalgesia occurs following cessation of nicotine.Nicotine (free base; 6 mg/kg/day i.v.) or saline was administered for 2 weeks via implanted osmotic pumps. Pain behavior was assessed before, during, and for 3 weeks after nicotine infusion by measuring tail flick latency, hot-plate latency, and thermal paw withdrawal latency. The paw-withdrawal threshold to non-noxious mechanical stimuli was also measured. Effects of nicotine infusion, gender, and time were assessed by three-way analyses of variance.Both male and female rats exhibited a comparable degree of analgesia in the hot-plate test with development of tolerance during the 2-week infusion period. Males, but not females, showed analgesia in the tail flick test. Analgesia was not observed for thermally evoked paw withdrawal in either males or females, nor did nicotine affect non-noxious mechanically evoked paw withdrawals. Males and females showed cessation of weight gain during the first week of nicotine infusion.Chronic nicotine-induced analgesia was confirmed in both male and female rats as assessed using the hot-plate test which reflects integrated pain behavior. Males, but not females, exhibited analgesia in a nociceptive withdrawal reflex test (tail flick), indicating that nicotine-induced analgesia may depend on both the type of pain test and gender. The lack of nicotine-induced analgesia assessed by the tail flick reflex test in female rats is consistent with recent human studies showing that nicotine reduces pain elicited by brief noxious cutaneous stimulation in male but not female subjects.
View details for Web of Science ID 000170825600005
View details for PubMedID 11512041