Abstract 266: The Impact of Chest Compression Release Velocity on Outcomes From Out-of-Hospital Cardiac Arrest

Abstract

BACKGROUND: Previous studies have demonstrated significant relationships between CPR quality metrics and survival to hospital discharge from out-of hospital (OHCA) cardiac arrest. Recently a new metric, chest compression release velocity (CCRV) has been associated with improved survival from OHCA. OBJECTIVE: To determine the impact of CCRV on clinical outcomes from OHCA. METHODS: We performed a retrospective review of prospectively collected data on all treated adult OHCA occurring over a one year period (Jan 2012 - Jan 2013) in two Canadian EMS agencies. CPR metrics of chest compression fraction (CCF), compression rate, compression depth, shock pause duration and CCRV were abstracted from impedance channel measurements during each resuscitation. Cases of public access defibrillation, EMS witnessed arrest and those missing any Utstein variable or discharge status data were excluded. We performed a multivariable regression analysis to determine the impact of CCRV on survival to hospital discharge. Secondary outcome measures were the impact of CCRV on return of spontaneous circulation (ROSC) and neurologically intact survival (MRS ≤ 3). RESULTS: Among 908 treated OHCA, 611met inclusion criteria. The median (IQR) age was 71.7 (60.7, 81.6) with 395 (64.6%) being male. 140 (22.9%) presented in ventricular fibrillation, 122 (20%) pulseless electrical activity and 349 (57.1%) asystole. The median (IQR) CPR quality metrics were: CCF 0.81 (0.73, 0.85), compression rate 105/minute (101, 115), compression depth 49.9 mm (42.5, 56.7), pre-shock pause 13.5 secs (8, 19) and post-shock pause 3.5 secs (2.8, 5). The median (IQR) CCRV (mm/sec) amongst 49 survivors was 135.9 (115.4, 156.5) compared to 120 (102.9, 140) in 562 non survivors (p=0.009). When adjusted for CPR metrics and Utstein variables, the odds of survival to hospital discharge for each 5 mm/sec increase in CCRV was 1.02 (95% CI: 0.97, 1.08). Similarly the odds of ROSC and neurologically intact survival were 1.02 (95% CI: 0.99, 1.05) and 1.03 (95% CI: 0.98, 1.08), respectively. CONCLUSIONS: When adjusted for Utstein variables and CPR quality metrics, CCRV was not significantly associated with outcomes from OHCA. Our findings may have been impacted by the sample size of our study.