Robert J. Rydman

Value of Posterior and Right Ventricular Leads in Comparison to the Standard 12-Lead Electrocardiogram in Evaluation of ST-Segment Elevation in Suspected Acute Myocardial Infarction

In this multicenter prospective trial, we studied posterior (V7 to V9) and right ventricular (V4R to V6R) leads to assess their accuracy compared with standard 12-lead electrocardiograms (ECGs) for the diagnosis of acute myocardial infarction (AMI). Patients aged >34 years with suspected AMI received posterior and right ventricular leads immediately after the initial 12-lead ECG. ST elevation of 0.1 mV in 2 leads was blindly determined and inter-rater reliability estimated. AMI was diagnosed by World Health Organization criteria. The diagnostic value of nonstandard leads was determined when 12-lead ST elevation was absent and present and multivariate stepwise regression analysis was also performed. Of 533 study patients, 64.7% (345 of 533) had AMI and 24.8% received thrombolytic therapy. Posterior and right ventricular leads increased sensitivity for AMI by 8.4% (p = 0.03) but decreased specificity by 7.0% (p = 0.06). The likelihood ratios of a positive test for 12, 12 + posterior, and 12 + right ventricular ECGs were 6.4, 5.6, and 4.5, respectively. Increased AMI rates (positive predictive values) were found when ST elevation was present on 6 nonstandard leads (69.1%), on 12 leads only (88.4%), and on both 6 and 12 leads (96.8%; p <0.001). Treatment rates with thrombolytic therapy increased in parallel with this electrocardiographic gradient. Logistic regression analysis showed that 4 leads were independently predictive of AMI (p <0.001): leads I, II, V3, V5R; V9 approached statistical significance (p = 0.055). The standard ECG is not optimal for detecting ST-segment elevation in AMI, but its accuracy is only modestly improved by the addition of posterior and right ventricular leads.

A national survey of emergency department chest pain centers in the United States

Although chest pain centers are promoted as improving emergency cardiac care, no data exist on their structure and processes. This national study determines the 1995 prevalence rate for emergency department (ED)-based chest pain centers in the United States and compares organizational differences of EDs with and without such centers. A mail survey was directed to 476 EDs randomly selected from the American Hospital Associations database of metropolitan hospitals (n = 2,309); the response rate was 63%. The prevalence of chest pain centers was 22.5% (95% confidence interval 18% to 27%), which yielded a projection of 520 centers in the United States in 1995. EDs with centers had higher overall patient volumes, greater use of high-technology testing, lower treatment times for thrombolytic therapy, and more advertising (all p <0.05). Hospitals with centers had greater market competition and more beds per annual admissions, cardiac catheterization, and open heart surgery capability (all p <0.05). Logistic regression identified open heart surgery, high-admission volumes, and nonprofit status as independent predictors of hospitals having chest pain centers. Thus, chest pain centers have a moderate prevalence, offer more services and marketing efforts than standard EDs, and tend to be hosted by large nonprofit hospitals.

Assessing the diagnostic value of an ECG containing leads V4R, V8, and V9: The 15-Lead ECG

STUDY OBJECTIVES To assess sensitivity, specificity, and odds ratios of ECG findings on leads V4R, V8, and V9 for acute myocardial infarction. DESIGN Prospective, two-stage cohort study. SETTING A 660-bed university-affiliated community hospital. TYPE OF PARTICIPANTS One hundred forty-nine admitted patients with suspected myocardial infarction or unstable angina. INTERVENTIONS Standard 12-lead ECG followed immediately by V4R, V8, and V9. MEASUREMENTS Initial ECG findings of ST-segment displacement, Q waves, T-wave inversion, and eligibility for thrombolytic therapy. RESULTS Major abnormalities (ST-segment deviation, T-wave inversion, Q waves) were found on the extra three leads in 28.9% (43 of 149) of patients. Sensitivity of ST-segment elevation for acute myocardial infarction on 12 versus 15 leads increased from 47.1% to 58.8%, respectively, with no decrease in specificity. McNemars pair-matched analysis for ST-segment elevation on myocardial infarction subgroup showed an association of ST elevation with the 15-lead ECG (P < .05). An eightfold increase in the odds of detecting ST elevation was found (90% confidence interval, 1.42 to 14.58); 22% of patients negative for ST elevation on 12 leads were positive on 15 leads. Analysis of ECG criteria for thrombolytic therapy presenting uniquely on extra leads showed an increased sensitivity from 35.3% to 44.1% on 12 versus 15 leads, respectively; there was a sixfold increase in the odds of meeting ECG thrombolytic therapy criteria (90% confidence interval, 0.34 to 11.66); 13.5% of patients not meeting criteria on 12 leads did so on 15 leads. CONCLUSION The 15-lead ECG provides increased sensitivity and odds of detecting ST-segment elevation in acute myocardial infarction patients with no loss of specificity; its use may expand the selection of thrombolytic therapy candidates and provide a fuller ECG description of the extent of myocardial injury and necrosis.

Patient Satisfaction with an Emergency Department Chest Pain Observation Unit

STUDY OBJECTIVE Patient satisfaction is an essential outcome measure in the diagnosis and treatment of acute chest pain in the emergency department. We compared patient satisfaction with the diagnostic protocol of a chest pain observation unit (CPOU) and standard inpatient hospitalization. METHODS We prospectively studied patients who presented to the ED with chest pain and were found to have a low risk of acute myocardial infarction (AMI) but who still might have benefited from a diagnostic protocol to rule out AMI. Consenting patients (N = 104) were randomized to the CPOU (experimental) arm or the hospital inpatient (control) arm and assessed for satisfaction by means of an interview before hospital discharge. RESULTS The CPOU protocol scored higher on four summary ratings of overall patient satisfaction. Correlations between overall satisfaction, number, and type of problems with care, and patient characteristics demonstrated content validity and revealed strengths and improvements that might be made in CPOUs. CONCLUSION Patients were more satisfied with rapid diagnosis in the CPOU than with inpatient stays for acute chest pain. Our findings add important information to the standard practice of weighing clinical and cost outcomes between two medical care alternatives.

Outcomes of offering rapid point-of-care HIV testing in a sexually transmitted disease clinic.

Background:Delays in receipt of positive HIV test results and in entry into HIV care are common problems in clinics; in public venues, up to 33% of patients with negative results and 25% of those with positive results never learn their results. Methods:Patients aged 18 years or older at an urban sexually transmitted disease (STD) clinic were offered rapid HIV testing between October 1999 and August 2000. Specimens were tested using the rapid Single Use Diagnostic System for HIV-1 (SUDS; Abbott/Murex, Norcross, GA), and results were confirmed by conventional enzyme immunoassay and Western blot (WB) analysis. Trained health educators performed all HIV counseling, phlebotomy, and rapid testing. Results:Of 1977 eligible patients, 1581 (80%) agreed to HIV testing; of these, 1372 (87%) accepted rapid testing and 1357 (99%) received same-visit results and posttest counseling. Thirty-seven (2.7%) were HIV-positive as confirmed by WB analysis. One of these HIV-positive participants died, but the remaining 36 went to their first clinic appointment. Conclusion:Rapid HIV testing was acceptable and feasible in this STD clinic and facilitated entry of newly identified HIV-infected patients into health care.

Emergency Department Observation Unit versus hospital inpatient care for a chronic asthmatic population: a randomized trial of health status outcome and cost.

OBJECTIVES This study was designed to determine if an accelerated treatment protocol administered to acute asthmatics presenting to a Hospital Emergency Department Observation Unit (EDOU) can offset the need for inpatient admissions and reduce total cost per episode of care without sacrificing patient quality of life. METHODS The authors used a prospective randomized controlled trial comparing postintervention patient quality of life for EDOU care versus standard inpatient care as measured by the standardized Medical Outcomes Study (MOS) SF-36 instrument. Other measures reported include: clinical status as measured by peak flow rates, total cost per treatment arm using microcosting techniques, and relapse-free survival 8 weeks after treatment. Eligible patients (n = 113) were assigned randomly to an EDOU or inpatient care from a consecutive sample of 250 acute asthmatic patients presenting to an urban hospital emergency department who could not resolve their acute asthma exacerbation after 3 hours of emergency department therapy. RESULTS Patients assigned to the EDOU had lower mean costs of treatment (EDOU =

The Pulse Oximetry Gap in Carbon Monoxide Intoxication

1,202 versus Hospital Inpatient =

Prediction of relapse within eight weeks after an acute asthma exacerbation in adults

2,247) and higher quality of life outcomes after intervention in five of eight domains measured by the MOS SF-36: Physical Functioning, Role Functioning-Emotional, Social Functioning, Mental Health, and Vitality. No differences were found in clinical outcomes as measured by peak flow rates or postintervention relapse-free survival. Univariate comparative findings were re-examined and confirmed through multivariable analysis when baseline SF-36 scores and postintervention peak expiratory flow rates clinical status were used as covariates. CONCLUSIONS The study showed that the EDOU was a lower cost and more effective treatment alternative for a refractory asthmatic population presenting to the Emergency Department. Several baseline MOS SF-36 domains proved useful in predicting or validating posttreatment clinical status, relapse, and total costs of care. Outcome SF-36 domain scores were also useful in identifying patients with the most favorable clinical, cost, and relapse rate outcomes at the study endpoint.

Practice variations in treating urban minority asthmatics in Chicago

STUDY OBJECTIVE Pulse oximetry has been reported to be falsely elevated in the presence of carbon monoxide (CO). However, the degree to which pulse oximetry overestimates measured oxyhemoglobin saturation (O2Hb) has not been investigated in patients with CO exposure. This study quantifies the effect of CO on pulse oximetry and O2Hb in a series of patients with elevated carboxyhemoglobin (COHb) levels. METHODS A prospective case series of 25 pulse oximetry measurements, with concurrent arterial blood gas sampling, were obtained on 16 adults with CO exposure. RESULTS COHb levels (mean, 16.1%; SD, 11.6%; range, 2.2% to 44%) did not significantly correlate with pulse oximetry saturation (mean, 97.7%; SD, 1.5%; range 96% to 100%) (r = .45; P = .1 [NS]). Compared with COHb, a pulse oximetry gap (mean, 17.5%; SD, 1.5%; range, 2.3% to 42%), defined as pulse oximetry saturation minus O2Hb, yielded a linear regression model: pulse oximetry gap = 1.82 + 0.94 x COHb (SEM = 0.07; F = 204; R2 = .90; P < .0001). CONCLUSION Oxygen saturation as measured by pulse oximetry failed to decrease to less than 96% despite COHb levels as high as 44%. Regression between the pulse oximetry gap and COHb suggests that pulse oximetry overestimates O2Hb by the amount of COHb present. Pulse oximetry is unreliable in estimating O2Hb saturation in CO-exposed patients and should be interpreted with caution when used to estimate oxygen saturation in smokers.

The Rate and Risk of Heat-Related Illness in Hospital Emergency Departments During the 1995 Chicago Heat Disaster

Associations between historical, presenting, and treatment-related characteristics and relapse within 8 weeks after a moderate to severe asthma exacerbation were studied in a cohort of 284 adult asthmatics. Data were collected prospectively, and a multivariate model was developed and internally validated. Within 10 days, only 8% had relapsed, increasing to 45% by 8 weeks. Three variables that could be identified at the time of discharge were independently associated with relapse. These included: having made three or more visits to an emergency department in the prior 6 months (hazard ratio (HR) = 2.3, 95% CI = 1.6-3.4); difficulty performing work or activities as a result of physical health in the 4 weeks prior (HR = 2.7, 95% CI = 1.6-4.3); discontinuing hospital-based treatment for the exacerbation within 24 hours without having achieved a peak expiratory flow rate of at least 50% of predicted (HR = 2.6, 95% CI = 1.6-4.1). These risk factors may help to identify patients with poorly controlled asthma in need of more intensive and comprehensive management.