Risk stratification according to the initial electrocardiogram in patients with suspected acute myocardial infarction.

Previously developed initial electrocardiogram (ECG) prediction rules were modified to stratify 426 patients with suspected acute myocardial infarction into low-, intermediate-, and high-risk groups (normal, abnormal, and positive ECG categories) for development of acute myocardial infarction and complications of coronary ischemia. Compared with patients with normal ECGs, patients with positive ECGs had a 2.9 times greater risk of interventions, a greater risk of life-threatening complications, and a 14.2 times greater risk of acute myocardial infarction. Compared with patients with abnormal ECGs, patients with positive ECGs had a 1.7 times greater risk of interventions, a 2.6 times greater risk of life-threatening complications, and a 4.9 times greater risk of acute myocardial infarction. This prediction scheme was further improved by assigning "high" risk to any patient requiring an acute intervention during the initial evaluation in the emergency department. Otherwise, risk was assigned according to the ECG category, with normal, abnormal, and positive ECGs corresponding to "low," "intermediate," and high risk, respectively. Hospitals with limited intensive care beds may be able to use these prediction rules as an aid in determining in-hospital disposition of patients with suspected acute myocardial infarction.

Misoprostol for cervical ripening and labor induction: a meta-analysis.

OBJECTIVE: To analyze published randomized trials assessing the safety and efficacy of misoprostol for cervical ripening and labor induction. DATA SOURCES: We supplemented a search of entries in electronic data bases with references cited in original studies and review articles to identify randomized trials of misoprostol for cervical ripening and labor induction. METHODS OF STUDY SELECTION: Two blinded investigators performed independent trial quality evaluation and data abstraction of randomized clinical trials assessing the efficacy of misoprostol as a cervical ripening and labor-inducing agent. TABULATION, INTEGRATION, AND RESULTS: We calculated an estimate of the odds ratio (OR) and risk difference for dichotomous outcomes, using both a random- and fixed-effects model. Continuous outcomes were pooled using a variance-weighted average of the within-study difference in means. Of 16 studies identified, eight met our criteria for meta-analysis. These eight trials included 966 patients (488 received misoprostol and 478 were controls). Women who received misoprostol for cervical ripening and labor induction had a significantly lower overall cesarean rate (OR 0.67, 95% confidence interval [CI] 0.48, 0.93) and a higher incidence of vaginal delivery within 24 hours of misoprostol application (OR 2.64, 95% CI 1.87, 3.71). Use of misoprostol was associated with a higher incidence of tachysystole (OR 2.70, 95% CI 1.80, 4.04) but not hyperstimulation (OR 1.91, 95% CI 0.98, 3.73). The incidences of abnormal 5-minute Apgar scores and admissions to the neonatal intensive care unit were similar in the misoprostol and control groups. The pooled estimate of the mean interval from start of induction to delivery was 4.6 hours fewer (95% CI -3.5, -5.7) in the misoprostol group. CONCLUSION: Published data confirm the safety and efficacy of intravaginal misoprostol as an agent for cervical ripening and labor induction.

Setting the educational agenda and curriculum for error prevention in emergency medicine.

Graduate and postgraduate medical education currently teaches safety in patient care by instilling a deep sense of personal responsibility in student practitioners. To increase safety, medical education will have to begin to introduce new concepts from the "safety sciences," without losing the advantages that the values of commitment and responsibility have gained. There are two related educational goals. First, we in emergency medicine (EM) must develop a group of safety-educated practitioners who can understand and implement safe practice innovations in their clinical settings, and will be instrumental in changing our professional culture. Second, EM must develop a group of teachers and researchers who can begin to deeply understand how safety is maintained in emergency care, develop solutions that will work in emergency department settings, and pass on those insights and innovations. The specifics of what should be taught are outlined briefly. Work is currently ongoing to identify more specifically the core content that should be included in educational programs on patient safety in emergency care. Finally, careful attention will have to be paid to the way in which these principles are taught. It seems unlikely that a series of readings and didactic lectures alone will be effective. The analysis of meaningful cases, perhaps supplemented by high-fidelity simulation, seems to hold promise for more successful education in patient safety.

Ethical dilemmas in a randomized trial of asthma treatment: can Bayesian statistical analysis explain the results?

OBJECTIVES: The original objective was to determine whether the use of bilevel positive airway pressure (BiPAP) ventilation would reduce the need for endotracheal intubation, the length of hospital stay, and hospital charges in patients with status asthmaticus. The development of physician treatment bias made patient enrollment difficult. The article subsequently describes the use of Bayesian statistics to explain study results when this bias occurs. METHODS: This study was a prospective, randomized controlled clinical trial conducted over a 34.5-month period at an urban university hospital with an emergency department census of 94,000 annual visits. Patients remaining in status asthmaticus after initial standard treatment with inhaled beta-agonists and steroids were randomized to receive BiPAP ventilation plus standard treatment versus standard treatment alone (non-BiPAP), with intubation for either group as needed. Patients with concurrent cardiac or other pulmonary diseases were excluded. The primary outcome measures were endotracheal intubation rate and length of hospital stay. Secondary outcome measures included vital signs (respiratory rate, pulse rate, blood pressure), changes in expiratory peak flow, changes in pulse oximetry values, and hospital charges. Data were analyzed using Fisher's exact test, Mann-Whitney tests, and Bayesian statistics. For patients enrolled in the study more than once, data analysis was performed on the first enrollment only. RESULTS: Nineteen patients were enrolled in the BiPAP group and 16 patients in the non-BiPAP group. Patients were frequently enrolled more than once and the data from the subsequent enrollments were excluded from the analysis. A marked decrease in enrollment, due to physician treatment bias, led to a premature termination of the study. Demographics showed that the groups were similar in age, sex, initial peak flow rate, and arterial blood gas measurements. There was a 7.3% increase (95% CI = -22 to +45) in the intubation rate in the non-BiPAP group (n = 2) compared with that for the BiPAP group (n = 1). No significant difference was seen in length of hospital stay or hospital charges, although there was a favorable trend toward the BiPAP group. Complications encountered in the BiPAP group included one patient with discomfort associated with the nasal BiPAP mask. Bayesian analysis demonstrated that in order for the collected data to be convincing at the 95% confidence level, the prior conviction among treating physicians that BiPAP was a successful treatment modality would have had to be 98.9%. CONCLUSIONS: In this study, BiPAP appeared to have no deleterious effects in patients with status asthmaticus, with a trend toward decreased endotracheal intubation rate, decreased length of hospital stay, and decreased hospital charges. Although further study with more patients is needed to determine the clinical and statistical significance of this intervention, ethical concerns regarding withholding BiPAP treatment from the patients in the control group forced a premature termination of the study in the authors' institution.

Effect of exogenous melatonin on mood and sleep efficiency in emergency medicine residents working night shifts.

OBJECTIVE: To determine whether melatonin taken prior to attempted daytime sleep sessions will improve daytime sleep quality, nighttime sleepiness, and mood state in emergency medicine (EM) residents, changing from daytime to nighttime work schedules. METHODS: A prospective, randomized, double-blind crossover design was used in an urban emergency department. Emergency medicine residents who worked two strings of nights, of at least three nights' duration each, and separated by at least one week of days were eligible. Subjects were randomized to receive either melatonin 1 mg or placebo, 30 to 60 minutes prior to their daytime sleep session, for three consecutive days after each night shift. Crossover to the other agent occurred during their subsequent night shifts. Objective measures of quality of daytime sleep were obtained using the Actigraph 1000. This device measures sleep motion and correlates with sleep efficiency, total sleep time, time in bed, and sleep latency. The Profile of Mood States (POMS) and the Stanford Sleepiness Scale (SSS) were also used to quantify nighttime mood and sleepiness. RESULTS: Among the 19 volunteers studied, there was no difference in sleep efficiency (91.16% vs 90.98%, NS), sleep duration (379.6 min vs 342.7 min, NS), or sleep latency (7.59 min vs 6.80 min, NS), between melatonin and placebo, respectively. In addition, neither the POMS total mood disturbance (5.769 baseline vs 12.212 melatonin vs 5.585 placebo, NS) nor the SSS (1.8846 baseline vs 2.2571 melatonin vs 2.1282 placebo, NS) demonstrated a statistical difference in nighttime mood and sleepiness between melatonin and placebo. CONCLUSIONS: There are no beneficial effects of a 1-mg melatonin dose on sleep quality, alertness, or mood state during night shift work among EM residents.

Objective determination of the optimal red blood cell count in diagnostic peritoneal lavage done for abdominal stab wounds.

The purpose of this study was to determine objectively the optimal value or positivity criterion for red blood cell counts in diagnostic peritoneal lavage in stab wounds to the anterior abdomen. Our study group consisted of 91 consecutive adults with abdominal stab wounds who underwent peritoneal lavage. We excluded those patients who met criteria for immediate laparotomy and those with negative stab wound exploration. We divided the patients into two groups based on outcome. Group 1 consisted of those who had undergone laparotomy and had findings that required surgical intervention. Group 2 patients had either undergone laparotomy but had no injury requiring surgical intervention or had no surgery and a benign hospital course and follow-up. Receiver operator characteristic analysis was done on the diagnostic peritoneal lavage RBC counts for both groups. The overlap between the groups was minimal, with 75% of patients in Group 1 having > 120,000 RBC/mm3 and 75% of patients in Group 2 having < 486 RBC/mm3 in the lavage effluent. Using the observed probability of 23.1% of patients with abdominal stab wounds requiring surgery, a RBC count of 50,000/mm3 discriminated best those patients who required surgery from those who did not.

The utility of the presence or absence of chest pain in patients with suspected acute myocardial infarction.

In 422 patients admitted from the emergency department (ED) for suspected acute myocardial infarction, the hypothesis that chest pain that persists on arrival in the ED or recurs during the initial ED evaluation is a useful predictor of acute myocardial infarction (AMI) and complications of coronary ischemia was tested. Compared with patients whose chest pain spontaneously ceased before arrival in the ED, patients whose chest pain persisted or recurred during the initial ED evaluation had a 2.3 times greater risk of interventions (P less than .001), a 1.7 times greater risk of complications (P = .045), a 3.8 times greater risk of life-threatening complications (P = .04), and a 2.4 times greater risk of AMI (P = .005). A third group of patients with suspected AMI never experienced chest pain. This group of patients who never experienced chest pain had a three times higher risk of death (P = .02) compared with patients whose chest pain persisted or recurred in the ED, and a 2.1 times greater risk of intervention (P = .01), a 5.2 times greater risk of life-threatening complication (P = .015), and a 7.9 times greater risk of death (P = .025) compared with patients whose chest pain resolved before arrival in the ED. It was concluded that patients with chest pain that resolves spontaneously before arrival to the ED have a better in-hospital prognosis than any other group.

Load and go versus stay and play: analysis of prehospital i.v. fluid therapy by computer simulation.

A computer-simulation model of prehospital hemorrhage and fluid resuscitation was used to determine under what circumstances it is advantageous to begin fluid resuscitation in the field instead of immediately transporting to the hospital. Four hypothetical bleeding rates (15, 25, 50, and 100 mL/min) were examined for short and long prehospital times. No significant difference in survival was noted for bleeding rates of 15 mL/min for either short or long time; a small but statistically significant increase in survival was noted for bleeding rates of 25 mL/min and long transport times. For both short and long times, all higher bleeding rates showed greater survival with prehospital fluid resuscitation and higher blood pressure at the onset of definitive care.

Prophylactic antibiotics for the prevention of infectious complications including empyema following tube thoracostomy for trauma: results of meta-analysis.

Since 1977, six clinical trials have been performed on the subject of routine antibiotic prophylaxis in patients requiring tube thoracostomy for trauma. No definitive conclusions have been reached regarding the efficacy of antibiotic use in this setting. The results of these clinical trials were pooled to generate an unbiased estimate of the efficacy of antibiotic prophylaxis for tube thoracostomy using the technique of meta-analysis. Meta-analysis is a statistical method for synthesizing results from separate but similar experiments, grouping them, and comparing each to the null hypothesis. Meta-analysis allows synthesis of all of the available data on antibiotic prophylaxis for tube thoracostomy to resolve the controversy surrounding this issue generated by different but similar clinical studies with conflicting results. Despite different conclusions of value when taken individually, the combined analysis does not support the null hypothesis (no effect of antibiotics). The statistical method is highly significant despite different mechanisms of injury, pathologic findings, and antibiotics employed.

A simple method for evaluating the safety of high-yield criteria.

High-yield criteria for selecting patients for further investigation or treatment sometimes may be associated with an increase in the false-negative rate (decrease in sensitivity), when compared with conventional methods of selection. A simple method, suitable for use by nonstatisticians, is presented. It enables the determination of the sample size required to measure the false-negative rate to a given degree of precision, or the smallest increase in false-negative rate that a study of a given size is likely to detect. Examples of use are provided.

An introduction to the Bayesian analysis of clinical trials.

Although most clinical trials comparing therapies are analyzed using classical hypothesis testing and P values, such methods do not yield the information most useful to the clinician, that is, the probability that one treatment is more efficacious than another. Bayesian inference can yield this probability but only if we quantify our prior beliefs about the possible efficacies of the treatments studied. This article gives a brief introduction to Bayesian methods and contrasts them with classical hypothesis testing. It shows that the quantification of prior beliefs is a common and necessary part of the interpretation of clinical information, whether from a laboratory test or published clinical trial. Advantages of Bayesian analysis over classical analysis of clinical trials include the ability to incorporate prior information regarding treatment efficacies into the analysis; the ability to make multiple unscheduled inspections of accumulating data without increasing the error rate of the study; and the ability to calculate the probability that one treatment is more effective than another. Because it is likely that Bayesian methods will be used more often in the analysis of future clinical trials, investigators and readers should be aware of the two schools of statistical thought and the strengths and weaknesses of each.