Abstract 287: What Is the Optimal Chest Compression Depth During Resuscitation from Out-of-Hospital Cardiac Arrest in Adult Patients?

Abstract

Introduction: The 2010 AHA/ILCOR recommendations suggested an increase in CPR compression depth for adults, with a target >50 mm and no upper limit. This target is based upon limited evidence and, hence, we sought to determine the optimal compression depth range for adult patients. Methods: We studied emergency medical services treated OOHCA patients from the Resuscitation Outcomes Consortium ROC PRIMED clinical trial and Epistry - Cardiac Arrest database for whom electronic CPR compression depth data were available, from June 2007 to December 2010. We calculated anterior chest wall depression in millimeters for each minute of CPR. We controlled for 10 covariates including compression rate and calculated adjusted odds ratios for survival to hospital discharge, 24-hour survival, and any return of circulation (ROSC). Smoothing splines were used to explore the relationship between average compression depth and outcome for all patients as well as men and women separately. Results: We included 9,142 adult patients from 9 U.S. and Canadian cities with these characteristics: mean age 67.5 years; male 64 %; bystander witnessed 44%; bystander CPR 42%; initial rhythms - VF/VT 24%, PEA 20%, asystole 49%, other non-shockable 6%; outcomes - ROSC 31.3%, 1-day survival 22.8%, survival to hospital discharge 7.3%. For all patients, mean compression rate was 108 per minute; mean compression fraction 0.68; mean compression depth 41.9 mm with ranges: <38 mm 37%, 38-51 mm 45%, >51 mm 18%. Adjusted odds ratios for survival to discharge, with depth >51mm as reference, were <38 mm - 0.69 (95% CI 0.53, 0.90) and 39-51 mm - 1.03 (0.81, 1.30). Results were similar for the intermediate outcomes of ROSC and 1-day survival. Covariate-adjusted spline curves revealed that the maximum survival was associated with a depth of 45.8 mm followed by a decline in survival by 50 mm (optimal interval 44-49 mm). We also found no differences in the spline curves between males and females. Conclusions: This study found that more than one-third of patients received very low compression depth. The optimal CPR compression depth for survival appears to be 46 mm (44-49) for both males and female adults but falls off after 50 mm. These findings conflict with the 2010 international guideline recommendations.