Early defibrillation is critical for ventricular fibrillation, but limited preclinical data and one human trial suggest that performing cardiopulmonary resuscitation before defibrillation may increase the likelihood of defibrillation success and improve patient outcome. These investigators conducted a prospective, randomized study to evaluate CPR before defibrillation in patients with out-of-hospital (not witnessed by ambulance personnel) VF.
Two hundred patients received either standard care with immediate defibrillation or CPR for 3 minutes followed by defibrillation. In the standard-care group, if initial defibrillation was not successful, patients received CPR for 1 minute before defibrillation was attempted again. The CPR and standard-care groups did not differ in the primary outcome measure of survival to discharge (22% vs. 15%) or in the secondary outcome measures of return of spontaneous circulation (ROSC; 56% vs. 46%) and 1-year survival (20% vs. 15%). In a subgroup of 81 patients with ambulance response times less than 5 minutes, there also were no differences between the CPR and standard-care groups. However, in a subgroup of 119 patients with ambulance response times greater than 5 minutes, the CPR group had significantly higher rates than did the standard-care group in survival to discharge (22% vs. 4%), ROSC (58% vs. 38%), and 1-year survival (20% vs. 4%).
Comment: In patients with VF arrest for whom out-of-hospital care is delayed for more than 5 minutes, the lack of oxygen and depletion of metabolic substrates and high-energy phosphate stores may diminish the effectiveness of applied electricity. The promising result -- that CPR was beneficial in patients with longer response times -- must be corroborated before we stratify patients into different management pathways.
— John A. Marx, MD, FACEP
Published in Journal Watch Emergency Medicine May 14, 2003