Compression depth measured by accelerometer vs. outcome in patients with out-of-hospital cardiac arrest

Background: Analyses of data recorded by monitor-defibrillators that measure CPR depth with dierent methods show significant relationships between the process and outcome of CPR. Our objective was to evaluate whether chest compression depth was significantly associated with outcome based on accelerometer-recordings obtained with monitor-defibrillators from a single manufacturer, and to assess whether an accelerometer based analysis corroborated evidence-based practice guidelines on performance of CPR. Methods and results: We included 5434 adult patients treated from seven US and Canadian cities between January 2007 and May 2015. These had mean (SD) age of 64.2 (17.2) years, mean compression depth of 45.9 (12.7) mm, ROSC sustained to ED arrival of 26%, and survival to hospital discharge of 8%. For survival to discharge, the adjusted odds ratios were 1.15 (95% CI, 0.86, 1.55) for cases within 2005 depth range (38-51 mm), and 1.17 (95% CI, 0.91, 1.50) for cases within 2010 depth range (>50 mm) compared to those with an average depth of <38 mm. The adjusted odds ratio of survival was 1.33 (95% CI, 1.01, 1.75) for cases within 2015 depth range (50 to 60 mm) for at least 60% of minutes. Conclusions: This analysis of patients with OHCA demonstrated that increased chest compression depth measured by accelerometer is associated with better survival. It confirms that current evidence-based recommendations to compress within 50-60 mm are likely associated with greater survival than compressing to another depth.