Abstract P192: What is the Role of Chest Compression Depth during Out-of-Hospital CPR?
Introduction: Current CPR compression depth guidelines were empirically derived. We sought to study patterns of CPR compression depth and their associations with patient outcomes in out-of-hospital cardiac arrest (OOHCA).
Methods: We studied OOHCA patients from the Resuscitation Outcomes Consortium Epistry - Cardiac Arrest for whom electronic CPR data were available from proprietary accelerometer technology attached to the prehospital defibrillators. We calculated anterior chest wall depression in millimeters and the period of active CPR (chest compression fraction [CCF]) for each minute of CPR. We controlled for covariates including compression rate and calculated adjusted odds ratios (OR) for any return of circulation (ROSC) and 24 hour survival. We calculated unadjusted OR for hospital discharge.
Results: We included 615 adult patients from 6 U.S. and Canadian cities with these characteristics: mean age 68.9; male 62 %; witnessed 43%; bystander CPR 31%; initial rhythms - VF/VT 25%, PEA 17%, asystole 43%, unspecified non-shockable 15%; mean compression rate 103/min; mean compression depth <38mm 51%, 38–51mm 39%, >51mm 11%; median CCF 0.66; outcomes - ROSC 57%, 24 hour survival 18%, discharge 5%. We found an inverse association between depth and compression rate (P<0.0001; see Table⇓), no association between depth and CCF (P=0.30), and a positive association between CCF and rate (P<0.0001). ORs with 95% CIs for each 5mm increment in compression depth and the outcomes were: 1) ROSC - adjusted OR 1.06 (0.97–1.16), 2) 24 hour survival - adjusted OR 1.01 (0.98–1.03), 3) discharge - unadjusted OR 1.13 (0.95–1.34).
Conclusions: We found half of patients received suboptimal compression depth, an inverse association between compression depth and rate, and no clear association between survival and increased compression depth. Further study is required to determine the optimum chest compression depth and its interaction with rate and CCF in order to maximize outcomes.