Compressions during defibrillator charging shortens shock pause duration and improves chest compression fraction during shockable out of hospital cardiac arrest.
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. 3.5s; Δ 11.5; 95% CI: 6.81, 16.19), post-shock pause (4.0 vs. 3.0s; Δ 1.0; 95% CI: -2.57, 4.57), and peri-shock pause (21.0 vs. 9.0s; 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.
Sunnybrook Centre for Prehospital Medicine, Toronto, ON, Canada; University of Toronto, Division of Emergency Medicine, Toronto, ON, Canada; Rescu Li Ka Shing Knowledge Institute, St. Michaels Hospital, Toronto, ON, Canada. Electronic address: Sheldon.Cheskes@sunnybrook.ca.
Sheldon
S
Cheskes
Rescu Li Ka Shing Knowledge Institute, St. Michaels Hospital, Toronto, ON, Canada; Institute of Medical Science, University of Toronto, Toronto, ON, Canada.
Matthew R
MR
Common
Rescu Li Ka Shing Knowledge Institute, St. Michaels Hospital, Toronto, ON, Canada.
P Adam
PA
Byers
Rescu Li Ka Shing Knowledge Institute, St. Michaels Hospital, Toronto, ON, Canada.
Cathy
C
Zhan
University of Toronto, Division of Emergency Medicine, Toronto, ON, Canada; Rescu Li Ka Shing Knowledge Institute, St. Michaels Hospital, Toronto, ON, Canada.
Laurie J
LJ
Morrison
D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004554:Electric Countershock / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006336:Heart Massage / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000628:therapy*; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D016896:Treatment Outcome
Cardiopulmonary resuscitation; Heart arrest; Resuscitation; Survival