Effectiveness of Bystander CPR-Reply

In Reply.  —Dr Weil and colleagues comment on three pertinent issues in our article. First, regarding the relative importance of compressions vs ventilations in CPR, our data are entirely compatible with the hypothesis that effective ventilations are less crucial to survival than effective compressions during CPR. This concept has been suggested by Noc et al¹ and Berg et al,² but we did not comment on it for both methodological and statistical reasons.Exploring this hypothesis with our data would have represented a post hoc subset analysis, and we did not wish to mix hypothesis-generating work with a priori hypothesis testing. Moreover, as previously reported,³ overall survival rates from cardiac arrest in New York City are so poor (1.4%) that we lacked sufficient statistical power to detect survival differences in stratified subsets or to demonstrate convincingly that no differences exist. As experienced investigators such as Weil are well