Cardiac marker sensitivity depends on chest pain duration at the time of sampling. Our objective was to estimate the sensitivity, specificity, and likelihood ratios of early CK–MB and myoglobin assays in patients presenting to the emergency department (ED) with nondiagnostic ECGs, stratified by the duration of ongoing chest pain at the time of ED assessment.

This was a prospective observational study carried out in 10 US and 2 Canadian EDs. Patients >25 years of age with ongoing chest pain and nondiagnostic ECGs were stratified by pain duration (0–4 h, 4–8 h, 8–12 h, >12 h). CK–MB and myoglobin assays were drawn at T = 0 (ED assessment) and T = 1 hr. Patients were followed for 7–14 days to identify all cases of acute myocardial infarction (AMI). ED test results were correlated with patient outcomes.

Of 5005 eligible patients, 565 had AMI. Pain duration was 0–4 h in 3014 patients, 4–8 h in 961, 8–12 h in 487, and >12 h in 543. Marker sensitivity increased with pain duration, ranging from 28%–77% for CK–MB and 39%–73% for myoglobin. The maximal sensitivity achieved by a T = 0 assay was 73%, and this was in patients with 8–12 or >12 h of ongoing pain. No combination of tests achieved 90% sensitivity in any pain duration strata.

Regardless of chest pain duration, single assays and early serial markers (0+1 hr) do not rule out AMI; therefore, serial assays over longer observation periods are required. Likelihood ratios derived in this study will help physicians who use Bayesian analysis to determine post-test AMI likelihood in patients with chest pain.

To determine if peripheral venous blood gas values for pH, partial pressure of carbon dioxide (PCO2) and the resultant calculated bicarbonate (HCO3) predict arterial values accurately enough to replace them in a clinical setting.

This prospective observational study was performed in a university tertiary care emergency department from June to December 1998. Patients requiring arterial blood gas analysis were enrolled and underwent simultaneous venous blood gas sampling. The following data were prospectively recorded: age, sex, presenting complaint, vital signs, oxygen saturation, sample times, number of attempts and indication for testing. Correlation coefficients and mean differences with 95% confidence intervals (CIs) were calculated for pH, PCO2 and HCO3. A survey of 45 academic emergency physicians was performed to determine the minimal clinically important difference for each variable.

The 218 subjects ranged in age from 15 to 90 (mean 60.4) years. The 2 blood samples were drawn within 10 minutes of each other for 205 (96%) of the 214 patients for whom data on timing were available. Pearson’s product–moment correlation coefficients between arterial and venous values were as follows: pH, 0.913; PCO2, 0.921; and HCO3, 0.953. The mean differences (and 95% CIs) between arterial and venous samples were as follows: pH, 0.036 (0.030–0.042); PCO2, 6.0 (5.0–7.0) mm Hg; and HCO3, 1.5 (1.3–1.7) mEq/L. The mean differences (± 2 standard deviations) were greater than the minimum clinically important differences identified in the survey.

Arterial and venous blood gas samples were strongly correlated, and there were only small differences between them. A survey of emergency physicians suggested that the differences are too large to allow for interchangeability of results; however, venous values may be valid if used in conjunction with a correction factor or for trending purposes.

To determine the inter-observer agreement on triage assignment by first-time users with diverse training and background using the Canadian Emergency Department Triage and Acuity Scale (CTAS).

Twenty emergency care providers (5 physicians, 5 nurses, 5 Basic Life Support paramedics and 5 Advanced Life Support paramedics) at a large urban teaching hospital participated in the study. Observers used the 5-level CTAS to independently assign triage levels for 42 case scenarios abstracted from actual emergency department patient presentations. Case scenarios consisted of vital signs, mode of arrival, presenting complaint and verbatim triage nursing notes. Participants were not given any specific training on the scale, although a detailed one-page summary was included with each questionnaire. Kappa values with quadratic weights were used to measure agreement for the study group as a whole and for each profession.

For the 41 case scenarios analyzed, the overall agreement was significant (quadratic-weighted κ = 0.77, 95% confidence interval, 0.76–0.78). For all observers, modal agreement within one triage level was 94.9%. Exact modal agreement was 63.4%. Agreement varied by triage level and was highest for Level I (most urgent). A reasonably high level of intra- and inter-professional agreement was also seen.

Despite minimal experience with the CTAS, inter-observer agreement among emergency care providers with different backgrounds was significant.

This study evaluated the incidence of subarachnoid hemorrhage (SAH) and the use of computed tomography (CT) and lumbar puncture (LP) in a cohort of emergency department (ED) patients with acute headache.

Health records from a tertiary care ED were used to identify all patients over 15 years of age who presented with headache over a 10-month period. Patients were excluded if they had been referred with confirmed SAH or if they had recurrent headache, head trauma, decreased level of consciousness or new neurologic deficits. Outcome measures included ED diagnosis, use of CT or LP, and ED length of stay. Analysis included descriptive statistics, 95% confidence intervals (CIs) and analysis of variance for length of stay.

The mean age of the 891 patients was 41.9 years. Ten (1.1%) of the patients had SAH, 313 (35.1%) underwent CT, and 85 (9.5%) underwent LP. Only 9 (2.9%) of the CT scans and 2 (2.4%) of the LPs were positive for SAH. Of the 296 patients with normal CT results, 232 (78.4%) did not undergo subsequent LP. The mean length of stay was 4.0 hours (95% CI, 3.8–4.1) if no diagnostic testing was performed, 5.0 hours (95% CI, 4.7–5.4) if CT was performed and 7.1 hours (95% CI, 6.3–7.9) if LP was performed (p = 0.001).

Diagnostic testing was associated with substantially prolonged lengths of stay. CT and LP had low diagnostic yields, which suggests the need for a clinical decision rule to rule out SAH in ED patients with acute headache.