Compressions during defibrillator charging shortens shock pause duration and improves chest compression fraction during shockable out of hospital cardiac arrest

Abstract

Background: Previous studies have demonstrated significant relationships between shock pause duration and survival to hospital discharge from shockable out-of hospital (OHCA) cardiac arrest. Compressions during defibrillator charging (CDC) has been proposed as a technique to shorten shock pause duration. Objective: We sought to determine the impact of CDC on shock pause duration and CPR quality measures in shockable OHCA. Methods: We performed a retrospective review of all treated adult OHCA occurring over a 1 year period beginning August 1, 2011 after training EMS agencies in CDC. We included OHCA patients with an initial shockable rhythm, available CPR process data and shock pause data for up to the first three shocks of the resuscitation. CDC by EMS personnel was confirmed by review of impedance channel measures. We evaluated the relationship between CDC and shock pause duration as the primary outcome measure. Secondary outcome measures investigated the association between CDC and CPR quality measures. Results: Among 747 treated OHCA 149 (23.4%) presented in a shockable rhythm of which 129 (81.6%) met study inclusion criteria. Seventy (54.2%) received CDC. There was no significant difference between the CDC and no CDC group with respect to Utstein variables. Median pre-shock pause (15.0 vs. 3.5. s; δ 11.5; 95% CI: 6.81, 16.19), post-shock pause (4.0 vs. 3.0. s; δ 1.0; 95% CI: -2.57, 4.57), and peri-shock pause (21.0 vs. 9.0. s; δ 12.0; 95% CI: 5.03, 18.97) were all lower for those who received CDC. Mean chest compression fraction was significantly greater (0.77 vs. 0.70, δ 0.07; 95% CI: 0.03, 0.11) with CDC. No significant difference was noted in compression rate or depth with CDC. Clinical outcomes did not differ between the two approaches (return of spontaneous circulation 62.7% vs. 62.9% p= 0.98, survival 25.4% vs. 27.1% p= 0.82), although the study was not powered to detect clinical outcome differences. Conclusions: Compressions during defibrillator charging may shorten shock pause duration and improves chest compression fraction in shockable OHCA. Given the impact on shock pause duration, further study with a larger sample size is required to determine the impact of this technique on clinical outcomes from shockable OHCA. © 2014 Elsevier Ireland Ltd.