Biomedical subjects

Aaron E Bair

Publications and source records attributed to Aaron E Bair.

10 recordsLinked to original sources

PubMed2006

Electrocardiogram differentiation of benign early repolarization versus acute myocardial infarction by emergency physicians and cardiologists.

OBJECTIVES: ST-segment elevation (STE) related to benign early repolarization (BER), a common normal variant, can be difficult to distinguish from acute myocardial infarction (AMI). The authors compared the electrocardiogram (ECG) interpretations of these two entities by emergency physicians (EPs) and cardiologists. METHODS: Twenty-five cases (13 BER, 12 AMI) of patients presenting to the emergency department with chest pain were identified. Criteria for BER required four of the following: 1) widespread STE (precordial greater than limb leads), 2) J-point elevation, 3) concavity of initial up-sloping portion of ST segment, 4) notching or irregular contour of J point, and 5) prominent, concordant T waves. Additional BER criteria were 1) stable ECG pattern, 2) negative cardiac injury markers, and 3) normal cardiac stress test or angiography. AMI criteria were 1) regional STE, 2) positive cardiac injury markers, and 3) identification of culprit coronary artery by angiography in less than eight hours of presentation. The 25 ECGs were distributed to 12 EPs and 12 cardiologists (four in academic medicine, four in community practice, and four in community academics [health maintenance organization] in each physician group). The physicians were informed of the patients' age, gender, and race, and they then interpreted the ECGs as BER or AMI. Undercalls (AMI misdiagnosed as BER) and overcalls (BER misdiagnosed as AMI) were calculated for each physician group. RESULTS: Cardiologists correctly interpreted 90% of ECGs, and EPs correctly interpreted 81% of ECGs. The proportion of undercalls (missed AMI/total AMI) was 2.8% for cardiologists (95% confidence interval [CI] = 0.09% to 5.5%) compared with 9.7% for EPs (95% CI = 4.8% to 14.6%) (p = 0.02). The proportion of overcalls (missed BER/total BER) was 17.3% for cardiologists (95% CI = 11.4% to 23.3%) versus 27.6% for EPs (95% CI = 20.6% to 34.6%) (p = 0.03). The mean number of years in practice was 19.8 for cardiologists (95% CI = 19 to 20.5) and 11 years for EPs (95% CI = 10.5 to 12.0) (p < 0.001). CONCLUSIONS: Although correct interpretation was high in both groups, cardiologists, who had significantly more years of practice, had fewer misinterpretations than EPs in distinguishing BER from AMI electrocardiographically.

Atrial Function↗

PubMed2005

Ultrasound detection of blunt urological trauma: a 6-year study.

The objective of this study was to assess the utility of emergency ultrasonography in the detection of blunt urological injury. A retrospective review was conducted of all consecutive emergency blunt trauma ultrasonograms (US) obtained at a level I trauma centre from January 1995 to January 2001. Among the 4320 emergency ultrasonograms performed, 596 patients (14%) had intraabdominal injury and, of these, 99 patients (17%) had urological injuries. The sensitivity of ultrasound for all urological injuries was 67%, and specificity was 99.8%. For isolated urological injuries, sensitivity and specificity were 55.6 and 99.8%, respectively. Ultrasound was most accurate in the detection of grade III renal injuries, identifying 14/15 (93%), and 13 underwent laparotomy. For isolated urological injuries, 15 of 25 (60%) patients with a true-positive US underwent laparotomy compared to 3 of 20 (15%) with a false-negative US. Isolated urological injury was significantly associated with an ultrasonographic pattern of free fluid in the left upper quadrant and the left pericolic gutter (odds ratio=55.1; P<0.001), followed by isolated fluid in the left pericolic gutter (odds ratio=8.6; P=0.04). Although emergency ultrasonography is useful in the triage of patients with blunt urological trauma, it may miss significant urological injury requiring further intervention. As most renal injuries may be managed non-operatively, further studies such as contrast-enhanced CT or angiography should be obtained in the stable patient with suspected blunt urological injury.

Abdominal Injuries↗

PubMed2005

An assessment of a tracheal tube introducer as an endotracheal tube placement confirmation device.

INTRODUCTION: Early detection of an inadvertent esophageal intubation can be particularly challenging in cases when the current standard of care, carbon dioxide detection, is unreliable. We sought to determine the sensitivity and specificity of an inexpensive and portable device, the gum elastic bougie (Eschmann Tracheal Tube Introducer, SIMS Portex, Inc, Keene, NH), as an endotracheal tube placement confirmation device. METHODS: We conducted a prospective blinded trial in 20 human cadavers. Each cadaver was randomized to a mixed series of 5 esophageal and 5 tracheal intubations. Each intubation was assessed with the bougie twice, once by a novice to the technique, and once by an assessor who was constant through the trial. Assessors used the bougie to "feel" for "clicks" of the tracheal rings and to appreciate "hang up" of the bougie as it was advanced into the smaller airways. Absence of these findings was presumed to indicate an esophageal intubation. Actual placement was confirmed by bronchoscopy. Each assessor made an independent determination of tube location. Descriptive statistics were used to summarize the data. RESULTS: Overall, 93% (95% confidence interval [CI], 86%-97%) of tracheal placements were correctly identified. The constant assessor was able to correctly identify 98% (95% CI, 90%-100%). Tracheal rings were detected in 92% of tracheal placements. Ring clicks were 95% specific for tracheal intubation. Hang up was reported in 100% of tracheal placements with a specificity of 84%. Overall, 95% (95% CI, 88%-98%) of esophageal intubations were detected. The constant assessor detected 100% of esophageal intubations. CONCLUSION: In the cadaver model used in this study, the gum elastic bougie (Eschmann Tracheal Tube Introducer) shows promise as an endotracheal tube confirmation device.

Air Ambulances↗

PubMed2005

Intubation confirmation techniques associated with unrecognized non-tracheal intubations by pre-hospital providers.

This study examined pre-hospital intubations performed by paramedics, which were later determined to be non-tracheal upon arrival at an urban, academic emergency department (ED). The aim was to characterize the various confirmation techniques used among these unrecognized non-tracheal intubations. A retrospective review of the emergency medical services (EMS) quality assurance database was conducted over a period of 65 months. Paramedic patient care reports and hospital medical records were reviewed with regard to techniques used for airway evaluation. Simple descriptive statistics are used to summarize the data. During this study period, paramedics intubated 1643 patients. There were 35 (2%) intubations that were ultimately determined to be non-tracheal by receiving physicians. Among these, 20 (57%) were intubations for trauma indications. Seven patients (20%) were children (< 10 years). Fifteen patients (43%) did not have a pulse before intubation attempts. Overall, 21 (60%) had multiple confirmatory techniques employed by paramedics. The most commonly documented was 'equal lung sounds' (91%), followed by 'visualized cords' (52%). Per protocol, colorimetric end tidal CO2 was used selectively among patients with pulses, 9/20 (45%). Aspiration techniques were not used among this study population. Based on paramedic documentation, 17 (49%) of the non-tracheal intubations were potentially recognizable. An unrecognized, non-tracheal intubation is a potentially devastating consequence of failed airway management. We report a small, but important experience with failed pre-hospital airway management. In this EMS system, more frequent use of multiple confirmatory techniques (including end tidal CO2 detection) may help to reduce the incidence of this potentially life-threatening scenario.

Carbon Dioxide↗

PubMed2005

The fast is positive, now what? Derivation of a clinical decision rule to determine the need for therapeutic laparotomy in adults with blunt torso trauma and a positive trauma ultrasound.

INTRODUCTION: The object of this study was to derive a clinical decision rule for therapeutic laparotomy among adult blunt trauma patients with a positive abdominal ultrasound for trauma (FAST) examination. METHODS: We retrospectively reviewed the trauma registry and medical records of all critical trauma patients who underwent a FAST examination in the emergency department (ED) in a university Level I trauma center over a 3-year period. Blunt trauma patients aged >16 years who had a positive FAST examination (defined as the presence of intraperitoneal fluid) were eligible. We selected seven clinical and ultrasound variables available during ED resuscitation for analysis: age, presence of an episode of hypotension (systolic blood pressure <90 torr in the ED), presence of abdominal tenderness, chest injury, pelvic fracture, femur fracture, and FAST fluid location (right upper quadrant [RUQ] only; RUQ plus other location; other location only). The primary outcome variable was whether a laparotomy was performed and whether this laparotomy was needed to provide the definitive surgical intervention ("therapeutic laparotomy"). We analyzed the variables using binary recursive partitioning analysis to create a decision rule. RESULTS: There were 2336 FAST examinations performed during the study period, resulting in 230 (9.8%) positive examinations in patients meeting inclusion criteria. There were 135 patients who had therapeutic laparotomies and 95 who did not need laparotomy. The groups were similar in baseline characteristics. In the recursive partitioning analysis, the first node in the decision tree was the presence of fluid in the RUQ. Of the 144 patients with RUQ fluid, 105 (73%, 95% confidence interval [CI] 64%-80%) required therapeutic laparotomy. Of the 86 patients without RUQ fluid, 30 (35%, 95% CI 25%-46%) nevertheless required therapeutic laparotomies, and the variables blood pressure, femur fracture, abdominal tenderness, and age further divided these patient into high- and low-risk groups. Of the 12 patients without RUQ fluid who had normal blood pressures, no femur fractures, no abdominal tenderness, and were aged 60 years and younger, none (95% CI 0%-22%) required therapeutic laparotomy. In conclusion, given a positive FAST examination, the presence of fluid in the RUQ is an important predictor of the need for therapeutic laparotomy. CONCLUSION: In the absence of fluid in the RUQ, there are other clinical variables that may allow for the development of a clinical decision rule regarding the need for therapeutic laparotomy.

Abdominal Injuries↗

PubMed2004

An evaluation of a blind rotational technique for selective mainstem intubation.

OBJECTIVES: Although rare, massive hemoptysis and major bronchial disruptions are associated with high mortality. Selective ventilation of the uninvolved lung can increase the likelihood of survival. Specialized devices used for single lung ventilation are often not readily available and can be difficult to place in the emergency department. The authors evaluated a blind rotational technique for selective mainstem intubation using either a standard endotracheal tube (ET) or a directional-tip endotracheal tube (DTET). METHODS: This was a prospective, randomized trial on 25 human cadavers. The desired side of mainstem intubation was determined by randomization. Each cadaver was used for four ET, four DTET, and four control intubations. In the ET group, the trachea was intubated. The tube was then rotated 90 degrees in the direction of the desired placement and advanced until resistance was met. In the DTET group, the technique was identical, except the trigger was activated to flex the tip during advancement. In the control group, an ET was advanced in neutral alignment until resistance was met. A bronchoscopist blinded to the desired placement determined tube position. Comparison testing was performed using Pearson's chi-square test. RESULTS: When attempting to intubate the left mainstem, use of the ET with the rotational technique was successful 72.3% of the time (95% confidence interval [95% CI] = 57% to 84%). Intubation of the left mainstem using the DTET was successful 68.5% of the time (95% CI = 54% to 81%; p = 0.67). Attempts to selectively intubate the right mainstem using the rotational technique were highly successful in both groups: 94% for the ET (95% CI = 84% to 99%) versus 97.8% for the DTET (95% CI = 89% to 100%). Among controls, the right mainstem was intubated 93% of the time (95% CI = 86% to 97%). CONCLUSIONS: In a cadaveric model, the left mainstem bronchus can be selectively intubated with moderate reliability using this rotational technique. Use of a DTET confers no significant advantage. The ability to generalize these findings to living subjects is unknown.

Cadaver↗

PubMed2004

Discrete event simulation of emergency department activity: a platform for system-level operations research.

OBJECTIVES: This article explores the potential of discrete event simulation (DES) methods to advance system-level investigation of emergency department (ED) operations. To this end, the authors describe the development and operation of Emergency Department SIMulation (EDSIM), a new platform for computer simulation of ED activity at a Level 1 trauma center. The authors also demonstrate one potential application of EDSIM by using simulated ED activity to compare two patient triage methods. METHODS: The Extend DES modeling package was used to develop a model of ED activity for a five-day period in July 2003. Model input includes staffing levels, facility characteristics, and patient data drawn from electronic patient tracking databases, billing records, and a detailed review of 674 ED charts. The accuracy of model output was tested by comparing predicted and known patient service times. The EDSIM model was then used to compare the fast-track triage approach with an alternative acuity ratio triage (ART) approach whereby patients were assigned to staff on an acuity ratio basis. RESULTS: The EDSIM model predicts average patient service times within 10% of actual values. The accuracy of individual patient paths, however, was variable. In the authors' model, 28% of individual patient treatment times had an absolute error of less than one hour, and 59% less than three hours. A preliminary comparison of two triage methods showed that the ART approach reduced imaging bottlenecks and average treatment times for high-acuity patients, but resulted in an overall increase in average service time for low-acuity patients. CONCLUSIONS: The EDSIM model provides a flexible platform for studying ED operations as they relate to average treatment times for ED patients, but the model will require further refinement to predict individual patient times. A comparative study of triage methods suggests that ART provides a mix of benefits and drawbacks, but further investigation will be required to substantiate these preliminary findings.

Appointments and Schedules↗

PubMed2003

Cricothyrotomy: a 5-year experience at one institution.

We describe the prevalence, primary indications and immediate complications of emergency cricothyrotomy (cric) techniques, in a single institution's Emergency Department (ED) and associated air-medical transport service. This is a retrospective review at an academic, level-one trauma center with an annual ED census of 65,000 and an associated air-medical transport service (AMTS). All patients undergoing cric in the field or in the ED between July 1995 and June 2000 were included. Expert reviewers from Emergency Medicine, Trauma Surgery and the AMTS prospectively defined the complication criteria. All charts with a possible complication underwent a blinded evaluation by reviewers representing each of the three clinical services. Descriptive statistics were used to summarize the data. Fifty crics were performed over 5 years. Seventy-six percent of crics were performed in trauma patients. The prevalence of cric in patients requiring airway management in the ED was 1.1% (95% CI, 0.7-1.6) and 10.9% (95% CI, 6.9-16.1) in the field by the AMTS. The prevalence of complications was 14% (95% CI, 4-32.6) in ED patients and 54.5% (95% CI, 32-75.6) for prehospital patients. The overall inter-rater agreement for complication rate was excellent (kappa =.87). Overall, 77% of crics were performed using the rapid four-step technique (RFST). There were no reports of complications associated with the RFST when performed in the ED. Non-RFST crics in the ED had an associated complication rate of 25% (95% CI, 2.8-60). Emergency cricothyrotomy was performed in approximately 1% of all emergency airway cases in the ED and at a higher rate by the AMTS. The most frequent indications were trauma related. Additionally, the RFST was the most commonly used technique for cric at this institution. The complication rate of cric was significantly higher in the prehospital environment than in the ED.

Cricoid Cartilage↗

PubMed2003

Cricoid ring integrity: implications for cricothyrotomy.

STUDY OBJECTIVES: The rapid 4-step technique for cricothyrotomy was originally described as making use of a single traction hook on the cricoid ring. However, it is possible that such hook placement could lead to damage of the cricoid ring. As an alternative, a double-hook device was developed to augment the rapid 4-step technique by dispersing forces applied to the cricoid ring. The objectives of this study were to compare the requisite forces for intubation and the structural tolerances of the cricoid ring between the single- and double-hook techniques. METHODS: We randomized 56 human cadaver specimens to undergo either cricothyrotomy with intubation followed by cricoid ring breakage or cricoid ring breakage alone. We randomized those cadaver specimens undergoing cricothyrotomy with intubation with respect to the initial hook technique used and then crossed over to the alternate technique for repeat intubation and subsequent cricoid ring breakage. We performed all cricothyrotomies in a similar manner with a consistent technique. We measured the intubation and breakage forces for the single- and double-hook techniques and calculated 95% confidence intervals (CIs). RESULTS: The mean force to intubate with the single-hook technique was 18 N (95% CI 14 to 22 N), and the mean force to intubate with the double-hook technique was 23 N (95% CI 17 to 29 N). There was a significant difference between the mean forces required to break the cricoid ring with the single-hook technique (54 N; 95% CI 47 to 62 N) versus with the double-hook technique (101 N; 95% CI 89 to 113 N; difference in means 47 [95% CI 34 to 60 N]). CONCLUSION: When applying the rapid 4-step technique for cricothyrotomy, the force required to intubate with either the single- or double-hook technique is small. The cricoid ring, however, tolerates significantly more force without breakage when the double-hook technique is used.

Airway Obstruction↗

PubMed2002

The failed intubation attempt in the emergency department: analysis of prevalence, rescue techniques, and personnel.

The aims of this study were: To describe the prevalence of Emergency Department (ED) airway management failures requiring rescue maneuvers, to describe successful rescue methods used when the primary method chosen is unsuccessful, and to characterize the roles of emergency physicians and other specialists in rescue airway management. A prospective observational study was conducted of ED airway management in 30 hospitals in the USA, Canada, and Singapore participating in the National Emergency Airway Registry (NEAR) database project. Patients were entered in the study if they underwent ED airway management, the first method chosen was not successful in achieving intubation, and a rescue technique was required. Data were collected on a structured data form for entry into a relational database with subsequent search for subjects fulfilling inclusion and exclusion criteria. Descriptive statistics were used for analysis of these data. There were 7,712 patients identified who underwent emergency intubation during the study period from January 1998 to February 2001. A total of 207 (2.7%) patient intubations met the inclusion criteria. Of these, 102 (49%) patients underwent rescue rapid sequence intubation (RSI). RSI was used after failure of oral intubation with sedation alone (n = 29), oral intubation without medications (n = 37), or blind nasotracheal intubation (n = 36). Forty-three (21%) patients underwent rescue cricothyrotomy after failure of RSI (n = 26) or other intubation methods (n = 17). Seventy-nine percent of rescue RSIs and 53% of rescue surgical airways were performed by emergency physicians. In conclusion, a total of 2.7% of emergency intubations required rescue. RSI is the most commonly used first line technique for ED airway management and is also the principal back-up technique when other oral or nasal intubation methods fail. Emergency physicians manage the majority of ED intubations, including those requiring rescue techniques.

Cricoid Cartilage↗