To the Editor.
—Dr Stiell and colleagues1 published a study comparing the effect of active compression-decompression (ACD) cardiopulmonary resuscitation (CPR) and standard CPR on outcomes of in-hospital and out-of-hospital victims of cardiac arrest. They concluded that ACD CPR did not improve survival or neurologic outcomes in any group of patients with cardiac arrest. However, testing ACD CPR in a system in which the ambulance services did not have the capability for endotracheal intubation is biased against successful application of ACD CPR. Since previous animal studies tested the method under conditions that included endotracheal intubation, it is a significant methodological error not to control for intubation.Intubation is an integral part of CPR research because, among other advantages, it ensures a patent airway and allows air to move freely in and out of the lungs. The ACD CPR technique involves the use of a suction-cup device applied to the sternum