Abstract 14869: Survivors of Adult Out-of-Hospital Cardiac Arrest Are Likely to be Neurologically Intact Despite Prolonged Prehospital Resuscitation

Abstract

Introduction: Preliminary data suggest that adult out-of-hospital cardiac arrest (OHCA) patients may survive neurologically intact with duration of prehospital resuscitation (DOPR) exceeding previous guidelines. We assess how DOPR affects neurologically intact survival (NIS) from OHCA. Methods: We conducted an observational study of all OHCA patients in our urban/suburban advanced life support EMS system (pop 1,000,000) from 2005-2014. Excluded were resuscitations not attempted, age < 16, trauma patients, and EMS-witnessed arrests. DOPR was measured from time of dispatch to end of prehospital resuscitation, defined by first return of spontaneous circulation, en-route hospital, or death. Primary outcome was NIS, defined as cerebral performance category (CPC) 1 or 2. Multiple modelling approaches including decision trees and multivariate logistic regression were used to determine predictors of NIS. Results: Of 3814 eligible OHCA, patients were: mean age 64.3 years and 60.4% male, 38.2% bystander witnessed, and 43.3% bystander assisted. Median time to first arriving professional response unit was 4.6 min (IQR 3.4-6.0). We controlled for resuscitation protocol changes over time, with median CPR fraction of 96% (IQR 93-96) and median compression rate 114 (103-137) during the most recent phase. Overall, 467 survived (12.2%) and 392 had NIS (83.9% of survivors). The median DOPR for NIS was 18 min (12-25), and the 90th percentile for NIS was 35 min, with 39 patients surviving neurologically intact with DOPR > 35 min. The adjusted OR (95% CI) for the continuous variable DOPR was 0.99 (0.99-1.00) for NIS and 1.00 (0.99-1.00) for overall survival. The length of time that EMS was on scene also had an adjusted OR of 1.00 (1.00-1.00) for both survival and NIS. Significant predictors of NIS include age, initial rhythm, witnessed, basic airway, prehospital ROSC, and therapeutic hypothermia phase. Intermittent physiologic parameters such as End Tidal CO2 measured at 30 minutes after dispatch were not predictive. Limitations include the observational study design. CONCLUSIONS: In this retrospective analysis of OHCA, a majority of survivors were NIS regardless of DOPR. Further study should examine predictors of paramedics’ decision to extend resuscitation.