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.

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.

The laryngeal mask airway (LMA™ airway) provides adequate ventilation and offers a suitable alternative for airway management in patients with cardiac arrest if primary care paramedics do not have intubation skills or are unable to intubate. Training in the use of the LMA usually occurs in the operating room.

To describe the use of the LMA by paramedics in prehospital adult non-traumatic cardiac arrest patients after classroom mannequin training. The study took place in a suburban rural emergency medical service.

This is a 2-phase observational study of the effect of paramedic training for LMA insertion using a mannequin and the success rate in the prehospital setting. All paramedics successfully completed classroom mannequin training. All subsequent prehospital adult non-traumatic cardiac arrest patients from mid-February 1999 to Mar. 31, 2000, were eligible. Subjective assessment of chest expansion, ease of ventilation and auscultation defined adequacy of ventilation. Data collected included the number of insertion attempts, reasons for failure, ease of insertion, adverse events and reasons for not attempting intubation. Statistical analysis comprised descriptive frequencies, chi-squared tests for comparison of categorical variables and analysis of variance for continuous variables.

208 paramedics (100%) successfully completed training. The mean number of attempts was 1, and only 4 (2.1%) paramedics required a second attempt with a mannequin. The paramedics’ perception of ease of use comparing the LMA with a bag valve mask (BVM) was evenly distributed across the 3 descriptors: 70 (39%) scored the LMA as easier to use, 57 (31%) as more difficult, and 54 (30%) stated there would be no difference. Of the 291 arrests during the study period, insertion of the LMA was attempted in 283 (97.3%) and was successful in 199 (70%) patients. The LMA became dislodged in 5 (2.5%) cases and was removed in 12 (6%) to clear vomit from the airway. The overall success rate was 182 (64%). The incidence of regurgitation prior to attempted insertion of the LMA was 28% (79 patients). Success rates did not vary significantly with the incidence of vomiting prior to insertion (p = 0.11). The majority of the paramedics evaluated LMA insertion as Very easy 49/220 (22.3%) or Easy 87/220 (39.6%). Paramedic evaluation of ease of use varied with success (p = 0.001).

This study reports a 100% training success rate with a mannequin and a 64% success with LMA insertion and ventilation in the field by paramedics among adult out-of-hospital non-traumatic cardiac arrest patients.