Can USMLE and COMLEX-USA Scores Predict At-Risk Emergency Medicine Residents' Performance on In-Training Examinations?

PURPOSE

The United States Medical Licensing Examination (USMLE) and Comprehensive Osteopathic Medical Licensing Examination (COMLEX) scores are standard methods used to determine residency candidates' medical knowledge. The authors were interested in using the USMLE and COMLEX part 2 scores in our emergency medicine (EM) residency program to identify at-risk residents who may have difficulty on the in-training exam (ITE) and to determine the cutoff values under which an intern could be given an individualized study plan to ensure medical knowledge competency.

METHODS

The authors abstracted the USMLE and COMLEX part 2 scores and the American Board of Emergency Medicine (ABEM) ITE scores for a cohort of first-year EM residents graduating years 2010-2022, converting raw scores to percentiles, and compared part 2 and ABEM ITE scores with Pearson's correlation, a Bland-Altman analysis of bias and 95% limits of agreement, and ROC analysis to determine optimal the cut-off values for predicting ABEM ITE < 50th percentile and the estimated test characteristics.

RESULTS

Scores were available for 152 residents, including 93 USMLE and 88 COMLEX exams. The correlations between part 2 scores and ABEM ITE were r = 0.36 (95%CI: 0.17, 0.52; p < 0.001) for USMLE and r = 0.50 (95%CI: 0.33, 0.64; p < 0.001) for COMLEX. Bias and limits of agreement for both part 2 scores were -14 ± 63% for USMLE and 13 ± 50% for COMLEX in predicting the ABEM ITE scores. USMLE < 37th percentile and COMLEX < 53rd percentile identified 42% (N = 39) and 27% (N = 24) of EM residents, respectively, as at risk, with a sensitivity of 61% and 49% and specificity of 71% and 92%, respectively.

CONCLUSION

USMLE and COMLEX part 2 scores have a very limited role in identifying those at risk of low ITE performance, suggesting that other factors should be considered to identify interns in need of medical knowledge remediation.

Orbital compartment syndrome: Pearls and pitfalls for the emergency physician

Orbital compartment syndrome (OCS) is a rare, vision-threatening diagnosis that requires rapid identification and immediate treatment for preservation of vision. Because of the time-sensitive nature of this condition, the emergency physician plays a critical role in the diagnosis and management of OCS, which is often caused by traumatic retrobulbar hemorrhage. In this review, we outline pearls and pitfalls for the identification and treatment of OCS, highlighting lateral canthotomy and inferior cantholysis (LCIC), a crucial skill for the emergency physician. We recommend adequate preparation for the diagnosis and procedure, early consultation to ophthalmology, clear and thorough documentation of the physical examination, avoidance of iatrogenic injury during LCIC, and complete division of the inferior canthal tendon. Emergency physicians should avoid failing to make the diagnosis of OCS, delaying definitive surgical treatment, overrelying on imaging, failing to decrease intraocular pressure, and failing to exclude globe rupture. The emergency physician should be appropriately trained to identify signs and symptoms of OCS and perform LCIC in a timely manner.

Independent evaluation of a simple clinical prediction rule to identify right ventricular dysfunction in patients with shortness of breath

BACKGROUND

Many patients have unexplained persistent dyspnea after negative computed tomographic pulmonary angiography (CTPA). We hypothesized that many of these patients have isolated right ventricular (RV) dysfunction from treatable causes. We previously derived a clinical decision rule (CDR) for predicting RV dysfunction consisting of persistent dyspnea and normal CTPA, finding that 53% of CDR-positive patients had isolated RV dysfunction. Our goal is to validate this previously derived CDR by measuring the prevalence of RV dysfunction and outcomes in dyspneic emergency department patients.

METHODS

A secondary analysis of a prospective observational multicenter study that enrolled patients presenting with suspected PE was performed. We included patients with persistent dyspnea, a nonsignificant CTPA, and formal echo performed. Right ventricular dysfunction was defined as RV hypokinesis and/or dilation with or without moderate to severe tricuspid regurgitation.

RESULTS

A total of 7940 patients were enrolled. Two thousand six hundred sixteen patients were analyzed after excluding patients without persistent dyspnea and those with a significant finding on CTPA. One hundred ninety eight patients had echocardiography performed as standard care. Of those, 19% (95% confidence interval [CI], 14%-25%) and 33% (95% CI, 25%-42%) exhibited RV dysfunction and isolated RV dysfunction, respectively. Patients with isolated RV dysfunction or overload were more likely than those without RV dysfunction to have a return visit to the emergency department within 45 days for the same complaint (39% vs 18%; 95% CI of the difference, 4%-38%).

CONCLUSION

This simple clinical prediction rule predicted a 33% prevalence of isolated RV dysfunction or overload. Patients with isolated RV dysfunction had higher recidivism rates and a trend toward worse outcomes.

Evaluation of pulmonary embolism in the emergency department and consistency with a national quality measure: quantifying the opportunity for improvement

BACKGROUND

The National Quality Forum (NQF) has endorsed a performance measure designed to increase imaging efficiency for the evaluation of pulmonary embolism (PE) in the emergency department (ED). To our knowledge, no published data have examined the effect of patient-level predictors on performance.

METHODS

To quantify the prevalence of avoidable imaging in ED patients with suspected PE, we performed a prospective, multicenter observational study of ED patients evaluated for PE from 2004 through 2007 at 11 US EDs. Adult patients tested for PE were enrolled, with data collected in a standardized instrument. The primary outcome was the proportion of imaging that was potentially avoidable according to the NQF measure. Avoidable imaging was defined as imaging in a patient with low pretest probability for PE, who either did not have a D-dimer test ordered or who had a negative D-dimer test result. We performed subanalyses testing alternative pretest probability cutoffs and imaging definitions on measure performance as well as a secondary analysis to identify factors associated with inappropriate imaging. χ(2) Test was used for bivariate analysis of categorical variables and multivariable logistic regression for the secondary analysis.

RESULTS

We enrolled 5940 patients, of whom 4113 (69%) had low pretest probability of PE. Imaging was performed in 2238 low-risk patients (38%), of whom 811 had no D-dimer testing, and 394 had negative D-dimer test results. Imaging was avoidable, according to the NQF measure, in 1205 patients (32%; 95% CI, 31%-34%). Avoidable imaging owing to not ordering a D-dimer test was associated with age (odds ratio [OR], 1.15 per decade; 95% CI, 1.10-1.21). Avoidable imaging owing to imaging after a negative D-dimer test result was associated with inactive malignant disease (OR, 1.66; 95% CI, 1.11-2.49).

CONCLUSIONS

One-third of imaging performed for suspected PE may be categorized as avoidable. Improving adherence to established diagnostic protocols is likely to result in significantly fewer patients receiving unnecessary irradiation and substantial savings.

Factors associated with positive D-dimer results in patients evaluated for pulmonary embolism

OBJECTIVES

Available D-dimer assays have low specificity and may increase radiographic testing for pulmonary embolism (PE). To help clinicians better target testing, this study sought to quantify the effect of risk factors for a positive quantitative D-dimer in patients evaluated for PE.

METHODS

This was a prospective, multicenter, observational study. Emergency department (ED) patients evaluated for PE with a quantitative D-dimer were eligible for inclusion. The main outcome of interest was a positive D-dimer. Odds ratio (ORs) and 95% confidence intervals (CIs) were determined by multivariable logistic regression. Adjusted estimates of relative risk were also calculated.

RESULTS

A total of 4,346 patients had D-dimer testing, of whom 2,930 (67%) were women. A total of 2,500 (57%) were white, 1,474 (34%) were black or African American, 238 (6%) were Hispanic, and 144 (3%) were of other race or ethnicity. The mean (+/-SD) age was 48 (+/-17) years. Overall, 1,903 (44%) D-dimers were positive. Model fit was adequate (c-statistic = 0.739, Hosmer and Lemeshow p-value = 0.13). Significant positive predictors of D-dimer positive included female sex; increasing age; black (vs. white) race; cocaine use; general, limb, or neurologic immobility; hemoptysis; hemodialysis; active malignancy; rheumatoid arthritis; lupus; sickle cell disease; prior venous thromboembolism (VTE; not under treatment); pregnancy and postpartum state; and abdominal, chest, orthopedic, or other surgery. Warfarin use was protective. In contrast, several variables known to be associated with PE were not associated with positive D-dimer results: body mass index (BMI), estrogen use, family history of PE, (inactive) malignancy, thrombophilia, trauma within 4 weeks, travel, and prior VTE (under treatment).

CONCLUSIONS

Many factors are associated with a positive D-dimer test. The effect of these factors on the usefulness of the test should be considered prior to ordering a D-dimer.

Clinical features from the history and physical examination that predict the presence or absence of pulmonary embolism in symptomatic emergency department patients: results of a prospective, multicenter study

STUDY OBJECTIVE

Prediction rules for pulmonary embolism use variables explicitly shown to estimate the probability of pulmonary embolism. However, clinicians often use variables that have not been similarly validated, yet are implicitly believed to modify probability of pulmonary embolism. The objective of this study is to measure the predictive value of 13 implicit variables.

METHODS

Patients were enrolled in a prospective cohort study from 12 centers in the United States; all had an objective test for pulmonary embolism (D-dimer, computed tomographic angiography, or ventilation-perfusion scan). Clinical features including 12 predefined previously validated (explicit) variables and 13 variables not part of existing prediction rules (implicit) were prospectively recorded at presentation. The primary outcome was venous thromboembolism (pulmonary embolism or deep venous thrombosis), diagnosed by imaging up to 45 days after enrollment. Variables with adjusted odds ratios from logistic regression with 95% confidence intervals not crossing unity were considered significant.

RESULTS

Seven thousand nine hundred forty patients (7.2% venous thromboembolism positive) were enrolled. Mean age was 49 years (standard deviation 17 years) and 67% were female patients. Eight of 13 implicit variables were significantly associated with venous thromboembolism; those with an adjusted odds ratio (OR) greater than 1.5 included non-cancer-related thrombophilia (OR 1.99), pleuritic chest pain (OR 1.53), and family history of venous thromboembolism (OR 1.51). Implicit variables that predicted no venous thromboembolism outcome included substernal chest pain, female sex, and smoking. Nine of 12 explicit variables predicted a positive outcome of venous thromboembolism, including patient history of pulmonary embolism or deep venous thrombosis in the past, unilateral leg swelling, recent surgery, estrogen, hypoxemia, and active malignancy.

CONCLUSION

In symptomatic outpatients being considered for possible pulmonary embolism, non-cancer-related thrombophilia, pleuritic chest pain, and family history of venous thromboembolism increase probability of pulmonary embolism or deep venous thrombosis. Other variables that are part of existing pretest probability systems were validated as important predictors in this diverse sample of US emergency department patients.

Potential impact of adjusting the threshold of the quantitative D-dimer based on pretest probability of acute pulmonary embolism

OBJECTIVES

The utility of D-dimer testing for suspected pulmonary embolism (PE) can be limited by test specificity. The authors tested if the threshold of the quantitative D-dimer can be varied according to pretest probability (PTP) of PE to increase specificity while maintaining a negative predictive value (NPV) of >99%.

METHODS

This was a prospective, observational multicenter study of emergency department (ED) patients in the United States. Eligible patients had a diagnostic study ordered to evaluate possible PE. PTP was determined by the clinician's unstructured estimate and the Wells score. Five different D-dimer assays were used. D-dimer test performance was measured using 1) standard thresholds and 2) variable threshold values: twice (for low PTP patients), equal (intermediate PTP patients), or half (high PTP patients) of standard threshold. Venous thromboembolism (VTE) within 45 days required positive imaging plus decision to treat.

RESULTS

The authors enrolled 7,940 patients tested for PE, and clinicians ordered a quantitative D-dimer for 4,357 (55%) patients who had PTPs distributed as follows: low (74%), moderate (21%), or high (4%). At standard cutoffs, across all PTP strata, quantitative D-dimer testing had a test sensitivity of 94% (95% confidence interval [CI] = 91% to 97%), specificity of 58% (95% CI = 56% to 60%), and NPV of 99.5% (95% CI = 99.1% to 99.7%). If variable cutoffs had been used the overall sensitivity would have been 88% (95% CI = 83% to 92%), specificity 75% (95% CI = 74% to 76%), and NPV 99.1% (95% CI = 98.7% to 99.4%).

CONCLUSIONS

This large multicenter observational sample demonstrates that emergency medicine clinicians currently order a D-dimer in the majority of patients tested for PE, including a large proportion with intermediate PTP and high PTP. Varying the D-dimer's cutoff according to PTP can increase specificity with no measurable decrease in NPV.

Prospective multicenter evaluation of the pulmonary embolism rule-out criteria

BACKGROUND

Over-investigation of low-risk patients with suspected pulmonary embolism (PE) represents a growing problem. The combination of gestalt estimate of low suspicion for PE, together with the PE rule-out criteria [PERC(-): age < 50 years, pulse < 100 beats min(-1), SaO(2) >or= 95%, no hemoptysis, no estrogen use, no surgery/trauma requiring hospitalization within 4 weeks, no prior venous thromboembolism (VTE), and no unilateral leg swelling], may reduce speculative testing for PE. We hypothesized that low suspicion and PERC(-) would predict a post-test probability of VTE(+) or death below 2.0%.

METHODS

We enrolled outpatients with suspected PE in 13 emergency departments. Clinicians completed a 72-field, web-based data form at the time of test order. Low suspicion required a gestalt pretest probability estimate of <15%. The main outcome was the composite of image-proven VTE(+) or death from any cause within 45 days.

RESULTS

We enrolled 8138 patients, 85% of whom had a chief complaint of either dyspnea or chest pain. Clinicians reported a low suspicion for PE, together with PERC(-), in 1666 patients (20%). At initial testing and within 45 days, 561 patients (6.9%, 95% confidence interval 6.5-7.6) were VTE(+), and 56 others died. Among the low suspicion and PERC(-) patients, 15 were VTE(+) and one other patient died, yielding a false-negative rate of 16/1666 (1.0%, 0.6-1.6%). As a diagnostic test, low suspicion and PERC(-) had a sensitivity of 97.4% (95.8-98.5%) and a specificity of 21.9% (21.0-22.9%).

CONCLUSIONS

The combination of gestalt estimate of low suspicion for PE and PERC(-) reduces the probability of VTE to below 2% in about 20% of outpatients with suspected PE.

Self-reported pain scores in the emergency department: lack of association with vital signs

BACKGROUND

Some practitioners and investigators have presumed relationships between pain scores and heart rate, blood pressure, or respiratory rate. Previous literature has not adequately addressed the association of pain and vital signs.

OBJECTIVES

To identify any association between self-reported pain and heart rate, blood pressure, or respiratory rate.

METHODS

In this retrospective, observational study, emergency department patients older than 17 years of age presenting between May 2004 and April 2005 with verifiable painful diagnoses (including nephrolithiasis, myocardial infarction, small bowel obstruction, fracture, burn, crush injury, stab wound, amputation, corneal abrasion, and dislocation) were identified. Data were extracted from the hospital's database, including patients' age, gender, emergency department diagnosis, self-reported pain score, heart rate, blood pressure, and respiratory rate.

RESULTS

Among 1,063 subjects, the most common diagnoses were nephrolithiasis (25%; n = 267) and fracture (23%; n = 249). The mean (+/- SD) triage pain score was 7 (+/- 3). The mean (+/- SD) heart rate was 85 (+/- 16) beats/min, mean (+/- SD) systolic blood pressure was 141 (+/- 23) mm Hg, and mean (+/- SD) respiratory rate was 19 (+/- 3) breaths/min. There were no clinically significant differences in mean vital signs across the individual pain scores, as demonstrated by overlapping confidence intervals across pain scores.

CONCLUSIONS

No clinically significant associations were identified between self-reported triage pain scores and heart rate, blood pressure, or respiratory rate.

The verbal numeric pain scale: effects of patient education on self-reports of pain

BACKGROUND

Emergency department (ED) patients are frequently asked to provide a self-report of the level of pain experienced using a verbal numeric rating scale.

OBJECTIVES

To determine the effects of patient education regarding the verbal numeric rating scale on self-reports of pain among ED patients.

METHODS

In this prospective, interventional study, 310 eligible ED patients with pain, aged 18 years and older, were randomized to view either a novel educational video (n = 155) or a novel print brochure (n = 155) as an educational intervention, both developed to deliver educational information about the verbal numeric pain scale and its use. Participants initially rated their pain on a scale from 0 to 10 and then were administered the educational intervention. Following the educational intervention, participants completed a survey that included demographic information, postinterventional pain score, prior pain experience, and subjective rating of the helpfulness of the educational intervention. Fifty-five consecutive participants were enrolled as controls and received no educational intervention but gave a self-reported triage pain score and a second pain score at an equivalent time interval. Clinical significance was defined as a decrease in pain of 2 or more points following the education.

RESULTS

Following the educational interventions, there were statistically significant, although not clinically significant, decreases in mean pain scores within each intervention group (video: mean change, 1 point [95% confidence interval [CI] = 0.7 to 1.2]; printed brochure: mean change, 0.6 points [95% CI = 0.4 to 0.8]). For participants in the control group (no intervention), there was no significant change (mean change, 0.2 points [95% CI = -0.2 to 0.5]). A clinically significant decrease in pain was seen in 28% of the video group, 23% of the brochure group, and 5% of controls. Most patients had no change (71% of the video group, 73% of the brochure group, and 89% of controls). Participants rated the helpfulness of the video educational intervention as 7.1 (95% CI = 6.7 to 7.5) and the print educational intervention as 6.7 (95% CI = 6.2 to 7.1) on a scale from 0 (least effective) to 10 (most helpful).

CONCLUSIONS

Among ED participants with pain, both educational interventions (video and printed brochure) resulted in statistically and clinically significant decreased self-reported pain scores by 2 or more points in 26% of participants compared with 5% of controls. The educational interventions were rated as helpful by participants, with no appreciable difference between the two intervention groups.

Comparison of oxycodone and hydrocodone for the treatment of acute pain associated with fractures: a double-blind, randomized, controlled trial

BACKGROUND

Previous studies have demonstrated the efficacy of oxycodone and hydrocodone for the treatment of acute pain. However, to the best of the authors' knowledge, no previous reports have compared the efficacies of these commonly prescribed agents.

OBJECTIVES

To compare the efficacies of oxycodone and hydrocodone for the treatment of acute pain associated with fractures in emergency department (ED) patients.

METHODS

This prospective, double-blind, randomized, controlled trial was conducted at an urban trauma center with an annual census of 65,000. Eligible participants included ED patients over the age of 12 years with fractures who consented to participate. Subjects were randomized to receive either oxycodone (5 mg orally [po]) with acetaminophen, or hydrocodone (5 mg po) with acetaminophen. Measurements included demographic information; pain scores on a verbal numeric rating scale at baseline and at 30 and 60 minutes; vital signs at baseline and at 30 and 60 minutes; and adverse effects. Ninety-five-percent confidence intervals (95% CIs) constructed about means and proportions were used to assess differences between the oxycodone and hydrocodone groups in analgesic efficacy and side effects.

RESULTS

Seventy-three subjects were randomized to receive oxycodone or hydrocodone. Sixty-seven subjects completed the ED study period (n = 35, oxycodone; n = 32, hydrocodone). There was no difference between the two groups in age, weight, gender, ethnicity, diagnoses, baseline pain scores, or vital signs. Patients in both groups had pain relief from baseline to 30 minutes (oxycodone mean change 3.7, 95% CI = 2.9 to 4.6; hydrocodone mean change 2.5, 95% CI = 1.7 to 3.3), and from baseline to 60 minutes (oxycodone mean change 4.4, 95% CI = 3.2 to 5.6; hydrocodone mean change 3.0, 95% CI = 2.1 to 3.9). There was no difference in pain between the patients treated with oxycodone and hydrocodone at 30 minutes (mean difference between groups -0.6, 95% CI = -1.8 to 0.5) or at 60 minutes (mean difference -0.5, 95% CI = -2.0 to 1.0). There was no difference between the groups in nausea, vomiting, itching, or drowsiness; however, the hydrocodone patients had a higher incidence of constipation (oxycodone 0%, hydrocodone 21%, difference in proportions 21%, 95% CI = 3% to 39% more with hydrocodone).

CONCLUSIONS

Treatment with acetaminophen and either oxycodone, 5 mg po, or hydrocodone, 5 mg po, resulted in pain relief among ED patients with acute fractures, and there was no difference between the two agents at 30 and 60 minutes. Adverse effect profiles were similar, with the exception of a higher incidence of subsequent constipation with the use of hydrocodone. These results suggest that oxycodone and hydrocodone have similarly potent analgesic effects in the first hour of treatment for ED patients with acute fractures.

Diagnostic accuracy of a bedside D-dimer assay and alveolar dead-space measurement for rapid exclusion of pulmonary embolism: a multicenter study

CONTEXT

A previous study suggested that the combination of a normal D-dimer assay and normal alveolar dead-space fraction is a highly sensitive screening test for pulmonary embolism (PE).

OBJECTIVE

To determine if the combination of a normal alveolar dead-space fraction (volume of alveolar dead space/tidal volume </=20%) and a normal whole-blood agglutination D-dimer assay can exclude PE in emergency department (ED) patients.

DESIGN

Prospective, noninterventional study conducted in 1998-1999. Study data were obtained prior to standard testing for PE, consisting of radionuclide lung scanning or contrast-enhanced computed tomography and 6-month follow-up plus selective use of venous ultrasonography and pulmonary angiography. Imaging studies were interpreted by blinded observers.

SETTING

Six urban teaching hospitals in the United States.

PATIENTS

A total of 380 hemodynamically stable ED patients aged 18 years or older with suspected acute PE.

MAIN OUTCOME MEASURES

Sensitivity and specificity for PE with a positive test defined as having either alveolar dead-space fraction or D-dimer assay results abnormal. Alveolar dead-space fraction was determined by subtracting airway dead space from physiological dead space (determined using the modified Bohr equation) and D-dimer assay, assayed at bedside using 20 microL of arterial blood.

RESULTS

Pulmonary embolism was diagnosed in 64 patients (16.8%), of those 20 had an abnormal D-dimer assay result, 3 had an abnormal alveolar dead-space fraction, 40 had abnormal results in both, and 1 had normal results for both tests. The sensitivity for diagnosis of PE was 98.4% (95% confidence interval [CI], 91.6%-100.0%). Among the 316 patients without PE, both D-dimer and dead-space results were normal in 163, for a specificity of 51.6% (95% CI, 46.1%-57.1%). Posterior probability of PE with normal results on both tests was 0.75% (95% CI, 0%-3.4%).

CONCLUSION

In this multicenter study of ED patients, a normal D-dimer assay result plus a normal alveolar dead-space fraction was associated with a low prevalence of PE.

Collaboration among emergency medicine physician researchers and statisticians: resources and attitudes

We examined the statistical resources within emergency medicine residency programs, and the attitudes of emergency medicine physician researchers toward activities wherein collaboration with a statistician is useful. Anonymous surveys were mailed to 104 emergency medicine physician researchers (1/program). Sixty-four (62%) responses were analyzed. Sixty-seven percent of respondents were their program's research director. Their highest level of statistical training was self-taught/nondegree course work for 88% of respondents. Forty-two percent said they were the person used most often by their program for statistical expertise. One-quarter of programs employed a full-time statistician. Collaboration among researchers and statisticians was considered sometimes or always useful for protocol development (aims 84%, design 99%, outcomes 99%, procedures 73%, sampling 97%, inclusion criteria 93%, number of subjects 100%); data entry 73%; statistical analysis 100%; and manuscript preparation 86%. Although most emergency medicine residencies lacked statistical resources within their program, physician researchers expressed positive attitudes toward collaboration with a statistician for all aspects of research.

The false-positive rate of thoracic outlet syndrome shoulder maneuvers in healthy subjects

OBJECTIVE

To estimate the incidence of false-positive findings of thoracic outlet syndrome (TOS) shoulder maneuvers, Adson's test (AT), costoclavicular maneuver (CCM), elevated arm stress test (EAST), and supraclavicular pressure (SCP) in healthy subjects.

METHODS

A cross-sectional, observational study was performed in a medical school and affiliated emergency medicine residency program setting. Participants included healthy adult volunteers without symptoms of TOS. The shoulder maneuvers AT, CCM, EAST, and SCP were performed in randomized order for 30 sec, 30 sec, 3 min, and 30 sec, respectively. Pulse quality and the presence and timing of pain or paresthesias were assessed.

RESULTS

53 subjects were enrolled, including 27 women, aged 29.7 +/- 6.4 years (range 21-58 years). AT, CCM, EAST, and SCP resulted in an altered pulse in 11%, 11%, 62%, and 21%; pain in 0%, 0%, 21%, and 2%; and paresthesias in 11%, 15%, 36%, and 15% of cases, respectively. The following outcomes had reasonable false-positive rates (upper 95% confidence limit): pain with the AT (7%), CCM (7%), SCP (10%), or any 2 TOS shoulder maneuvers (10%); discontinuing the EAST because of symptoms (16%); or any symptom with 3 (13%) or 4 (7%) TOS shoulder maneuvers.

CONCLUSIONS

In a study of TOS shoulder maneuvers in healthy subjects, the outcomes of pulse alteration or paresthesias were unreliable in general. However, TOS shoulder maneuvers have reasonably low false-positive rates when a positive outcome is defined as pain after AT, CCM, or SCP; discontinuation of the EAST secondary to pain; pain in the same arm with > or =2 maneuvers; or any symptom in the same arm with > or =3 maneuvers.

Serum creatine kinase is an unreliable predictor of ectopic pregnancy

OBJECTIVE

To compare serum creatine kinase (CK) values in patients with ectopic pregnancy vs patients with threatened miscarriage or normal pregnancy.

METHODS

An observational case-control study was performed at an urban teaching hospital. Pregnant women with a quantitative beta-hCG obtained for suspicion of ectopic pregnancy were evaluated. Excluded were cases with recent trauma, i.m. injections, surgery, or history of heart, liver, or muscle disease. The serum beta-hCG and CK values were recorded and compared between groups with 1-way ANOVA and Tukey's multiple comparison procedure at the overall 0.05 level.

RESULTS

The 15 ectopic, 28 threatened miscarriage, and 21 normal pregnancy cases were of similar gestational ages (p = 0.2), ranging from 3 to 12 weeks. Although the CK values for ectopic pregnancy (88.8 +/- 33.6 IU/L) exceeded those for threatened miscarriage (65.9 +/- 59.0 IU/L) and normal pregnancy (56.0 +/- 38.1 U/L) (p = 0.02), there was significant overlap between groups. CK values were at or above a cutoff of 74 IU/L in 80% (95% confidence interval: 52-96%) of ectopic pregnancies, 25% (11-45%) of threatened miscarriages, and 14% (3-36%) of normal pregnancies.

CONCLUSIONS

Although the ectopic pregnancy population is characterized by a higher mean CK than are patients with threatened miscarriage or a normal pregnancy, a significant overlap in CK values makes use of this serum marker unreliable for detecting ectopic pregnancy.

Effects of simulated mouth-to-mouth ventilation during external cardiac compression or active compression-decompression in a swine model of witnessed cardiac arrest

STUDY OBJECTIVE

To assess the effects of simulated mouth-to-mouth (MTM) ventilation on blood gases, gas exchange, and minute ventilation during external cardiac compression (ECC) or active compression-decompression (ACD) in a swine model of witnessed cardiac arrest and bystander CPR.

METHODS

Twenty swine were anesthetized, intubated, ventilated with room air, and monitored for aortic and right atrial pressure and blood gas sampling. After 1 minute of ventricular fibrillation cardiac arrest, ECC or ACD was manually performed at a rate of 100 per minute for 12 minutes. Animals in the room air group had their endotracheal tubes open to air, whereas those in the MTM group were mechanically ventilated with a gas mixture of 16% oxygen and 4% carbon dioxide. Arterial and venous PO2, PCO2, and pH values; oxygen consumption (VO2); carbon dioxide production (VCO2); and minute ventilation (VE) were measured at baseline and 1, 5, 9, and 13 minutes after induction of cardiac arrest.

RESULTS

MTM ventilation did not alter arterial or venous PO2 values in comparison with room air but did result in higher arterial PCO2 values at 5 and 9 minutes (although the mean PCO2 was 40 mm Hg or less [5.3 kPa] in all groups) and significant central venous hypercarbic acidosis at 9 and 13 minutes. Arterial PO2 values were greater in the ACD than the ECC groups at 5, 9, and 13 minutes, although all groups maintained acceptable PO2 (mean values > or = 60 mm Hg [8.0 kPa]) through 9 minutes of CPR and through 13 minutes in all but the ECC-room air group. PCO2 values were lower in the ACD groups beyond 1 minute, with the ACD-room air group showing extreme hyperventilation (mean PCO2 < or = 20 mm Hg [2.7 kPa]). MTM ventilation resulted in negative VO2 and VCO2 for the first few minutes, reflecting changes in pulmonary gas stores. As equilibrium was approached, VO2 and VCO2 approached zero in all groups, reflecting low cardiac output. MTM ventilation did not improve VE over room air at any time during ACD. It did improve VE during ECC, but only at the 12th interval.

CONCLUSION

In this swine model of witnessed CPR, simulated MTM ventilation was not beneficial for blood gases, gas exchange, or ventilation during ECC or ACD CPR.

Cervical prevertebral soft-tissue measurements and chest radiographic findings in acute traumatic aortic injury

Acute traumatic aortic injury (ATAI) results in several characteristic chest radiographic findings, most notably mediastinal widening. This study was based on the hypothesis that blood or fluid in the widened mediastinum might track up into the neck and be detected on lateral cervical radiographs. In a blinded, retrospective, case-control review of radiology files, 13 consecutive adult cases of ATAI were identified and compared with 19 cases of negative aortography (NAO) and 18 multiple trauma victims (MT) without aortography. Cases with inadequate cervical films or cervical injury were excluded. Measurements included the cervical soft-tissue (ST) width at the third (C3) and sixth (C6) cervical vertebrae, mediastinal width, mediastinal-chest width ratio, and the presence of several characteristic chest radiograph findings of ATAI. The C3 ST measurements averaged 9.1 +/- 2.8 mm, 8.5 +/- 2.7 mm, and 6.9 +/- 2.2 mm for the ATAI, NAO, and MT groups, respectively. The C6 ST measurements averaged 19.2 +/- 4.5 mm, 18.6 +/- 3.9, and 16.5 +/- 3.8 mm for the ATAI, NAO, and MT groups, respectively. These cervical ST values were not significantly different between groups at either C3 (P = .188) or C6 (P = .148). The incidence of abnormal ST swelling of >7 mm at C3 was 38%, 53%, and 33% for the ATAI, NAO, and MT groups, respectively. The incidence of abnormal ST swelling of >20 mm at C6 was 54%, 42%, and 11% for the ATAI, NAO, and MT groups, respectively. Cervical ST measurements at C3 or at C6 did not correlate with mediastinal-chest width ratios. Mediastinal widening, aortopulmonic window opacification, and blurring of the aortic knob were the most sensitive chest radiography findings in ATAI, although each of these lacked useful specificity and accuracy. Cervical ST swelling is not a useful marker for ATAI.

Shock index as a marker for significant injury in trauma patients

OBJECTIVE

To determine whether the shock index (SI), defined as the ratio of heart rate (HR) to systolic blood pressure (SBP), is a useful marker for significant injury in trauma patients.

METHODS

A retrospective database analysis was used to relate the SI to the clinical measures: death within 24 hours, injury severity score (ISS) > or = 16, intensive care unit (ICU) stay > or = 1 day, and amount of blood transfused (BT) > or = 2 units. Consecutive trauma patients seen at one level I trauma center over a 24-month period were reviewed; excluded were patients not requiring trauma team consultation, or those with either incomplete records, severe head injury (Glasgow Coma Scale score < or = 8), or age < 14 years. The SI was calculated from ED admission vital signs. Receiver operating characteristic (ROC) curves were used to find the value of the SI that maximized the sum of sensitivity and specificity for predicting each measure, separately; a separate analysis was done to determine the optimal SI threshold for predicting any of the severity measures.

RESULTS

1,101 cases met study criteria. The optimal SI values (by ROC analysis) for predicting the severity measures were: 1.10 for death < 24 hours, 0.71 for ISS > or = 16, 0.77 for ICU > or = 1 day, and 0.85 for BT > or = 2 units. The optimal SI value (by ROC analysis) for any of the above measures was 0.83; use of this SI cutoff provided a sensitivity of 37% (95% CI 32-42%), a specificity of 83% (95% CI 80-87%), and a negative predictive value of 58% (95% CI 54-61%) for any measure. This SI threshold predicted between 24% fewer cases and 4% more cases of poor outcome than did the optimal thresholds HR and SBP, respectively.

CONCLUSION

The optimal SI threshold performed similarly to the optimal threshold HR or SBP for prediction of injury severity.

Emergency physician use of ultrasonography in blunt abdominal trauma

OBJECTIVE

To evaluate the diagnostic utility of abdominal diagnostic ultrasonography (DUS) performed by emergency physicians for intraperitoneal fluid caused by blunt abdominal trauma (BAT).

METHODS

The design was a prospective, blind, observational study. During a 15-month period, a convenience sample of patients presenting to the ED with BAT necessitating CT scan of the abdomen, diagnostic peritoneal lavage (DPL), or laparotomy was studied. Scans were performed by an emergency medicine (EM) attending, or a resident supervised by an attending, using a real-time sector ultrasound scanner with a 3.5-MHz probe. Training in DUS included a 1-hour didactic session and 1 hour of practice on human volunteers. Free intraperitoneal fluid was defined as an anechoic stripe in the hepatorenal, bladder-rectal, or splenorenal space, and constituted a positive DUS study. Free intraperitoneal fluid detected on abdominal CT scan, DPL, and/or laparotomy was the criterion standard.

RESULTS

Of 110 patients scanned, 13 were excluded secondary to technical difficulty or lack of diagnostic follow-up modalities. Of the remaining 97 patients, there were 24 females and 73 males, ranging from ages 2 to 78 years. DUS detected intraperitoneal fluid in 21 subjects, including 3 false positives. There were 6 false-negative DUS examinations. DUS had a sensitivity of 75% (95% CI 53-90%), a specificity 96% of (95% CI 89-99%), and an accuracy of 91% (95% CI 83-96%). No false-positive or false-negative DUS study occurred after the first 67 cases. The mean interval for a DUS scan was 4.9 +/- 2.9 minutes, ranging from 0.5 to 16 minutes, and the mean intervals were not different between the positive and the negative studies. The accuracies of DUS were similar in the pediatric patients, 97% (95% CI 83-100%), and in the adults, 88% (95% CI 78-95%). The hepatorenal view provided the highest sensitivity as well as the least number of uninterpretable scans of the 3 DUS views.

CONCLUSION

Emergency physicians with minimal training can use DUS with fair sensitivity and good specificity and accuracy to detect free intraperitoneal fluid in both pediatric and adult BAT victims. The hepatorenal view provides the highest sensitivity for intraperitoneal fluid, although the 3-view series (with hepatorenal, bladder-rectal, and splenorenal spaces) can typically be performed within 5 minutes and may increase the specificity and accuracy.

Intrasound vibration testing in acute ankle injuries

OBJECTIVES

To determine the accuracy of intrasound vibration testing (IVT) in comparison with plain radiography in the diagnosis of acute ankle fractures.

METHODS

A group-sequential, nonrandomized, double-blind, observational study design was used. A convenience sample of patients were studied, aged > or = 10 years, with acute ankle injuries, undergoing ankle radiography, evaluated at a community teaching hospital ED. Excluded were cases involving injuries of > 24 hours' duration, inadequate documentation, protocol violation, or positive IVT on the uninjured ankle. IVT was performed with the intrasound apparatus placed on the anterior and posterior aspects of the medial and lateral malleoli of the uninjured and injured ankles; positive IVT was defined as patient withdrawal secondary to pain.

RESULTS

Of 105 patients enrolled, 8 were excluded; 1 for inadequate documentation, 5 for protocol violation, and 2 for positive IVT of the uninjured ankle. Of the 97 patients analyzed, 13 had fractures identified by radiography, including 9 lateral malleolar, 1 medial malleolar, 1 bimalleolar, and 2 talar fractures. Only 5 of the 13 fractures were detected with IVT (sensitivity = 39%; 95% CI: 14-68%). Seventy of 84 nonfractured ankles had negative IVT (specificity = 83%; 95% CI: 74-91%). Of the 19 with positive IVT, 5 had fractures (positive predictive value of 26%; 95% CI: 9-51%). Of the 78 with negative IVT, 70 had no fracture (negative predictive value of 90%; 95% CI: 81-96%). Overall, 75 of 97 IVTs were correct (77%), most of which were among patients without fractures.

Evaluation of capnography in nonintubated emergency department patients with respiratory distress

OBJECTIVE

To evaluate the ability of noninvasive capnographic measurement of end-tidal CO2 tension (PetCO2) to predict arterial CO2 tension (PaCO2) in nonintubated ED patients with respiratory distress.

METHODS

A prospective, nonblind study was performed in a level I trauma center/community teaching hospital ED. Participants included all nonintubated adult patients with respiratory distress requiring measurement of arterial blood gases (ABGs); 29 patients were enrolled. PetCO2 was measured with a capnography monitor, using both baseline tidal volumes and forced expiratory volumes. The bias between PetCO2 values and simultaneous measurements of PaCO2 by ABG was assessed.

RESULTS

PetCO2, measured with forced expiration, and PaCO2 agreed well, with bias (i.e., average difference) = 0.44 +/- 0.52 kPa (3.3 +/- 3.9 torr). PetCO2 measured with the tidal volume breath produced an unacceptably high bias of 0.82 +/- 0.70 kPa (6.1 +/- 5.2 torr). Levels of agreement between PaCO2 were similar for smokers and nonsmokers and for men and women. The arterial-end-tidal CO2 tension (Pa-etCO2) difference was not related to PaCO2. Pa-etCO2 correlated with age (r = 0.473; p = 0.01), and was significantly higher in patients with pulmonary disease (1.32 +/- 0.56 kPa; 9.9 +/- 4.2 torr) than it was in those without pulmonary disease (0.46 +/- 0.55 kPa; 3.5 +/- 4.1 torr; p < 0.001).

CONCLUSIONS

Noninvasive PetCO2 monitoring may adequately predict PaCO2 in nonintubated ED patients with respiratory distress who are able to produce a forced expiration. PetCO2 is less accurate for PaCO2 with tidal volume breathing and in patients with pulmonary disease.

Hematologic safety of intraosseous blood transfusion in a swine model of pediatric hemorrhagic hypovolemia

OBJECTIVE

To assess the risk of hemolysis, disseminated intravascular coagulation (DIC), or fat embolism syndrome (FES) with pressurized intraosseous (IO) blood transfusion following hemorrhage.

METHODS

A controlled, repeated-measures, randomized animal study with blinded pathologic evaluations was conducted. Sixteen pentobarbital-anesthetized, instrumented immature swine underwent a 20-mL/kg hemorrhage into citrate-phosphate-dextrose bags, then received autologous blood transfusion via a 16-ga i.v. catheter (eight), or via a 15-ga IO needle in the proximal tibia (eight) under maximal manual pressure using a 30-mL syringe. At baseline and at one hour and 48 hours posttransfusion, blood samples were assayed for hemoglobin (Hb), schistocytes, free Hb in plasma, bilirubin, lactate dehydrogenase, platelets, fibrinogen, and alveolar-arteriolar O2 gradient. Lung sections were examined for inflammation after hematoxylin/eosin stain, and for fat emboli after oil red-O-stain. Kidney sections were examined for inflammation using hematoxylin/eosin stain.

RESULTS

Though the IO transfusion rate of 21 +/- 6 mL/min was slower than the i.v. rate of 35 +/- 5 mL/min (p = 0.0012), all the animals returned to baseline blood pressure within 15 minutes and survived. The presence of schistocytes and mildly elevated free Hb in plasma was noted in both groups at baseline and each time period, and was presumed to be due to sampling from the arterial catheter. All other laboratory values remained within normal limits and without intergroup differences at any time period. No fat embolus was noted, and all lung and kidney specimens were free of inflammation.

CONCLUSIONS

In this model, pressurized IO blood transfusion appears to be hematologically safe, i.e., without risk of appreciable hemolysis, DIC, or FES.

Delayed tension pneumothorax complicating central venous catheterization and positive pressure ventilation

Pneumothorax is the most common complication after central venous catheterization. The diagnosis of pneumothorax may be delayed for hours or days, in some instances because of minimal clinical symptoms or radiographic signs on initial evaluation, or in other instances because of late presentation precipitated by positive pressure ventilation. A case is presented in which a patient developed a tension pneumothorax while under general anesthesia 10 days after central venous line placement. A review of the literature suggests that delayed pneumothorax has an incidence of approximately 0.4% of all central venous access attempts, is much more common after subclavian than internal jugular approaches, especially in difficult or multiple attempts, is asymptomatic in 22%, and results in tension pneumothorax in 22%. End-expiratory upright chest radiographs, the optimal radiographic technique for detection of small pneumothoraces, were obtained in only 19% of reviewed cases. Supine views, the least sensitive radiographic technique, should be carefully reviewed for evidence of basilar hyperlucency, a deep sulcus sign, or a double diaphragm sign. In patients unable to tolerate the upright position, supine views should be supplemented with lateral decubitus, oblique, or cross-table lateral views. Emergency physicians should be aware of the possibility of delayed pneumothorax, as well as optimal radiographic technique for demonstration of small pneumothoraces, and subtle radiographic findings in supine or semirecumbent patients.

Benign cervical prevertebral soft tissue swelling in traumatic asphyxia

Two cases of benign cervical prevertebral soft tissue swelling following traumatic asphyxia are presented. Neither were associated with neck pain, neck tenderness, or mechanism of injury associated with cervical injury, and each resolved spontaneously. Traumatic asphyxia, which results in significant craniofacial swelling, may also result in swelling of the retropharyngeal soft tissues, which may be detected on cervical radiography. Cervical prevertebral soft tissue swelling in the setting of traumatic asphyxia should not be misinterpreted as suggestive of spinal injury in the absence of other findings.

Hemodynamic effects of 3,4-diaminopyridine in a swine model of verapamil toxicity

STUDY HYPOTHESIS

3,4-Diaminopyridine (3,4-DAP) may reverse the hemodynamic effects of severe verapamil toxicity.

DESIGN

A nonblinded acute animal preparation.

INTERVENTIONS

Eighteen chloralose-anesthetized and instrumented swine were poisoned with verapamil at 10 mg/kg/hr for five minutes and then 5 mg/kg/hr until a systolic blood pressure of 55 mm Hg was achieved. Heart rate, lead II ECG, mean arterial pressure, left ventricular dP/dT max, and cardiac index were monitored. Nine control animals received 0.2 mL/kg/min infusion of normal saline, and nine treatment animals received similar volumes of 1 mg/kg/min 3,4-DAP until systolic blood pressure reached 100 mm Hg, an elapsed time of 30 minutes, or death.

RESULTS

Verapamil toxicity was produced in all animals following an average dose of 1.38 +/- 0.44 mg/kg verapamil, and resulted in diminished mean arterial pressure, dP/dT max, cardiac index, and heart rate to average values of 47%, 32%, 46%, and 88% of baseline values, respectively. Transient atrioventricular dissociation was noted in only 22% of cases. 3,4-DAP treatment (with an average dose of 14 +/- 5.6 mg/kg) resulted in significant increases in mean arterial pressure, dP/dT max, cardiac index, and heart rate to 136%, 298%, 149%, and 158% of baseline values, respectively. Mortality was unchanged (22% in both groups). 3,4-DAP treatment was complicated by muscle twitching, tachycardia (rate of more than 180) and hypertension (diastolic blood pressure of more than 110 mm Hg) each in 44% of cases.

CONCLUSION

Although 3,4-DAP reversed the hypotensive and negative inotropic effects of verapamil toxicity, it failed to improve survival and resulted in several complications including muscle twitching, tachycardia, and hypertension.

Compliance with emergency department referral: the effect of computerized discharge instructions

STUDY OBJECTIVE

To examine the effect of computerized discharge instructions on emergency department patient referral recommendations.

DESIGN

Prospective, descriptive analysis and clinical trial.

SETTING

Emergency medicine residency-affiliated urban hospital with 568 beds and 29,000 annual visits.

TYPE OF PARTICIPANTS

One thousand ED patients discharged to an outpatient referral network during a six-week period.

INTERVENTION

Mandatory referral was provided in written or computerized (Logicare Corp, Eau Claire, Wisconsin) format for each 500-patient group. Demographic data and compliance, measured as appointment completion within 30 days, were analyzed using chi 2 with Yates' correction, Fisher's exact, and odds ratio comparisons (P < .05, 95% confidence interval).

MEASUREMENTS AND MAIN RESULTS

The institution of computerized discharge instructions resulted in increased overall patient compliance from 26.2% to 36.2% (P < .0008) with odds ratio of 1.59 (1.2 to 2.1). Subset analysis showed increased compliance in patients who were more than 40 years old (32.5% to 61.1%), were female (28.7% to 39.7%) with a private physician (36.4% to 53.9%), established hospital relationship (26.1% to 38.9%), had nonurgent complaints (26.5% to 36.2%), were specifically diagnosed with strain or contusion (17.0% to 36.8%), or were referred to obstetrics/gynecology clinic (13.2% to 48.6%) (P < .001).

CONCLUSION

Computerized discharge instructions were associated with improved compliance with ED referral recommendations, based on historic and contemporary controls.

Emergency abdominal radiography

Plain abdominal radiographs are rarely diagnostic when the patient presents with acute abdominal pain. Emergency physicians, therefore, should be aware of the appropriate indications and limitations of abdominal films in this setting and should be skilled in their interpretation to exclude the rare cases of pneumoperitoneum, pneumobilia, hepatic-portovenous gas, small and large bowel obstruction, toxic megacolon, volvulus and intramural gas.

An evaluation of cannulae and oxygen sources for pediatric jet ventilation

The authors evaluated the cannulae and oxygen sources available for pediatric translaryngeal ventilation. Peak flow rates were measured and maximum tidal volumes (MTV) calculated for each combination of cannula and oxygen source. Standard 22, 20, 18, and 16 gauge intravenous catheters and a 14 gauge cannula designed for pediatric jet ventilation were tested. The oxygen sources evaluated included an adult bag-valve device; a continuous flow source regulated between 6 to 15 L/min; and a high pressure jet source regulated between 5 to 50 psi. Mean calculated MTV delivered to the cannula tip (22 g to 14 g) were: 26 to 235 mL with the bag-valve source; 91 to 236 mL with the continuous flow sources; and 58 to 1034 mL with the jet sources. Assuming that in normal subjects approximately 70% of the flow from the tip of a translaryngeal cannula reaches the distal respiratory tree, the authors conclude that bag-valve and continuous flow low pressure sources are unlikely to deliver sufficient tidal volumes to sustain normal ventilation in apneic children when coupled with standard cannulae. Jet oxygen sources with standard cannulae provide a wide range of tidal volumes sufficient to sustain normal ventilation in apneic pediatric patients.

Manual translaryngeal jet ventilation and the risk of aspiration in a canine model

STUDY OBJECTIVES

Manual translaryngeal jet ventilation (TLJV) is a safe and effective method of maintaining normal ventilation in apneic subjects. Little data exist on the amount of airway protection afforded with this technique of airway management. We sought to evaluate the risk of aspiration during manual TLJV.

SETTING

Data were collected in a laboratory animal model.

DESIGN

A prospective, nonrandomized, controlled trial was performed.

PARTICIPANTS

Seventeen adult apneic mongrel dogs were enrolled.

INTERVENTIONS

Intratracheal Gastrograffin was instilled and radiographic changes assessed during ventilation using a 0 to 3 scale (none to severe). Thirty-six trials were performed, with equal numbers at both 30 degrees and 45 degrees head elevation. The three groups studied were animals without airway protection (control), animals with a cuffed endotracheal tube (tube), and animals with a percutaneous TLJV cannula and a 50-psi oxygen source ventilated at a rate of 20 breaths per minute (jet).

MEASUREMENTS AND MAIN RESULTS

Significantly less radiographic evidence of aspiration was noted in the jet and tube groups at 30 degrees and 45 degrees compared with control animals (P = .002 each). At 45 degrees head elevation a trend toward increased aspiration scores in the jet group compared with the tube group (P = .065) was observed.

CONCLUSION

In our model, manual TLJV at 20 breaths per minute and an I:E ratio of 1:2 provided protection from aspiration comparable to that observed with a cuffed endotracheal tube at 30 degrees head elevation. At 45 degrees elevation, this protection was diminished.

Altered host response and special infections in the elderly

Infection remains one of the most common causes for Emergency Department evaluation and hospital admission in the elderly. Unfortunately, aged individuals may not manifest the typical symptoms and signs as their younger counterparts. The emergency physician must recognize that the elderly individual may exhibit a less vigorous physiologic response to infectious states, which can delay or make diagnosis difficult. This article attempts to explain the apparent dysfunctions in the elderly that places this important population at greater risk for certain infections.