Ontario Prehospital Advanced Life Support - OPALS


The goal of the trial was to evaluate adding a program of advanced life support to a program of rapid defibrillation for treatment of patients with out-of-hospital cardiac arrest.

Study Design

Study Design:

Patients Enrolled: 5,638
Mean Follow Up: Through hospital discharge
Mean Patient Age: Mean age 69 years
Female: 33

Patient Populations:

Age ≥16 years and had an out-of-hospital cardiac arrest for which resuscitation was attempted


Age <16 years, persons who were dead, patients with trauma, and others with disorders that clearly had a noncardiac cause

Primary Endpoints:

Survival to hospital discharge

Secondary Endpoints:

Return of spontaneous circulation and admission to the hospital

Drug/Procedures Used:

The study was desiged as a "before-after" trial, in which survival was assessed in patients enrolled in the trial during the 12-month rapid-defibrillation phase ("before" initiation of advanced-life-support programs; n=1,391) and during the 36-month advanced-life-support phase ("after"; n=4,247). For the advanced-life-support phase, paramedics were trained to perform endotracheal intubation, insert intravenous lines, and administer intravenous medications.

Principal Findings:

There was no difference in the primary endpoint of rate of survival to hospital discharge (5.0% for rapid-defibrillation phase vs. 5.1%, p=0.83 for advanced-life-support phase). However, the rate of hospital admission increased from the rapid-defibrillation phase to the advanced-life-support phase (10.9% vs. 14.6%, p<0.001), as did the rate of return of spontaneous circulation (12.9% vs. 18.0%, p<0.001).

In a multivariate model, the odds ratio (OR) for survival after advanced life support was not significantly related to survival (OR 1.1, 95% confidence interval [CI] 0.8-1.5), but other factors were related to survival, including arrest witnessed by a bystander (OR 4.4, 95% CI 3.1-6.4), cardiopulmonary resuscitation administered by a bystander (OR 3.7, 95% CI 2.5-5.4), and rapid defibrillation (OR 3.4, 95% CI 1.4-8.4). No subgroup was shown to have improvement in the rate of survival with the use of advanced life support.


Among patients with out-of-hospital cardiac arrest, addition of a program of advanced life support to a program of rapid defibrillation was not associated with an increase in survival to hospital discharge compared with a program of rapid defibrillation only. It should be noted that the rapid defibrillation program itself was considered optimal, with a rapid-defibrillation time of ≤8 minutes in 90% of patients with cardiac arrest, paramedic response in 95% of patients, arrival at the scene by paramedics within 11 minutes for 80% of patients, and successful endotracheal intubation in 90% of patients.

Another recently published trial, the PAD trial, demonstrated that survival was improved with training of laypersons to perform cardiopulmonary resuscitation, to call 911, and to use automated external defibrillators, suggesting resources may be better spent on training laypersons than providing advanced life support training to paramedics.


Stiell IG, Wells GA, Field B, et al. Advanced cardiac life support in out-of-hospital cardiac arrest. N Engl J Med 2004;351:647-56.

Clinical Topics: Arrhythmias and Clinical EP, Implantable Devices, SCD/Ventricular Arrhythmias

Keywords: Odds Ratio, Defibrillators, Out-of-Hospital Cardiac Arrest, Advanced Cardiac Life Support, Intubation, Intratracheal, Heart Arrest, Confidence Intervals

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