Background: Animal models have demonstrated that interruptions in chest compressions are associated with decreased survival and worse neurologic outcome in cardiac arrests. Observational studies in humans have suggested that for out-of-hospital cardiac arrests, continuous compressions result in improved survival.
Study Design: Unblinded, randomized, cluster design with crossover.
Setting: One hundred fourteen emergency medical service (EMS) agencies across eight clinical sites in North America.
Synopsis: Patients with out-of-hospital cardiac arrest received either continuous chest compressions with asynchronous positive-pressure ventilations or interrupted compressions at a rate of 30 compressions to two ventilations. EMS agencies were divided into clusters and randomly assigned to deliver either resuscitation strategy. Twice per year, each cluster switched treatment strategies.
During the active enrollment phase, 12,653 patients were enrolled in the intervention arm and 11,058 were enrolled in the control arm. The primary outcome of survival to hospital discharge was comparable between the two groups, with 9.0% survival rate in the intervention group as compared to 9.7% in the control group (P=0.07). The secondary outcome of survivorship with favorable neurologic status was similar at 7.0% in the intervention group and 7.7% in the control group.
There was only a small difference in the proportion of minutes devoted to compressions between the two groups, so the similarity in outcomes may be reflective of high-quality chest compressions. Additional limitations include a lack of standardization of post-resuscitation care and a lack of measurement of oxygen or ventilation delivered.
Bottom line: For out-of-hospital cardiac arrests, continuous chest compressions with positive-pressure ventilation did not increase survival or improve neurologic outcome compared to interrupted chest compressions.
Citation: Nichol G, Lerou B, Wang H, et al. Trial of continuous or interrupted chest compressions during CPR. N Engl J Med. 2015;373(23):2203-2214.