We learned over a decade ago from the Arizona investigators that compression continuity was the most important metric for survival. A new study in Circulation, using a different analytical approach, confirmed the association:
Methods and Results—In 319 patients with ventricular tachycardia/fibrillation out-of-hospital cardiac arrest, we analyzed recordings from all defibrillators used during resuscitation and measured durations of all CPR pauses. Median (25th, 75th percentile) durations in seconds were 32 (22, 52) for the longest pause for any reason, 23 (14, 34) for the longest peri-shock pause, and 24 (11, 38) for the longest non-shock pause. Multivariable regression models showed lower odds for survival per five second increase of the longest overall pause (OR 0.89, 95%CI 0.83-0.95), longest peri-shock pause (OR 0.85, 95%CI 0.77-0.93), and longest non-shock pause (OR 0.83, 95%CI 0.75-0.91). In 36% of cases, the longest pause was a non-shock pause; this subgroup had lower survival than cases where the longest pause was a peri-shock pause (27% vs 44% respectively, p less than 0.01) despite a higher chest compression fraction. Pre-shock pauses were 8 seconds (4, 17) for shock that terminated ventricular fibrillation and 7 seconds (4, 13) for shocks that did not (p=0.18).