The Association Between Duration of Resuscitation and Favorable Outcome After Out-of-Hospital Cardiac Arrest: Implications for Prolonging or Terminating Resuscitation
Background—Little evidence guides the appropriate duration of resuscitation in out-of-hospital cardiac arrest (OHCA), and case features justifying longer or shorter durations are ill-defined. We estimated the impact of resuscitation duration on the probability of favorable functional outcome in OHCA using a large, multi-center cohort.
Methods—Secondary analysis of a North American, single blind, multi-center, cluster-randomized clinical trial (ROC-PRIMED) of consecutive adults with non-traumatic, EMS-treated, OHCA. Primary exposure was duration of resuscitation in minutes (onset of professional resuscitation to return of spontaneous circulation [ROSC] or termination of resuscitation). Primary outcome was survival to hospital discharge with favorable outcome (modified Rankin scale [mRS] 0-3). Subjects were additionally classified as survival with unfavorable outcome (mRS 4-5), ROSC without survival (mRS 6), or without ROSC. Subject accrual was plotted as a function of resuscitation duration, and the dynamic probability of favorable outcome at discharge was estimated for the whole cohort and subgroups. Adjusted logistic regression models tested the association between resuscitation duration and survival with favorable outcome.
Results—The primary cohort included 11,368 subjects (median age 69 years [IQR: 56-81 years]; 7,121 men [62.6%]). Of these, 4,023 (35.4%) achieved ROSC, 1,232 (10.8%) survived to hospital discharge, and 905 (8.0%) had mRS 0-3 at discharge. Distribution of CPR duration differed by outcome (p<0.00001). For CPR duration up to 37.0 minutes (95%CI 34.9-40.9 minutes), 99% with eventual mRS 0-3 at discharge achieved ROSC. Dynamic probability of mRS 0-3 at discharge declined over elapsed resuscitation duration, but subjects with initial shockable cardiac rhythm, witnessed cardiac arrest, and bystander CPR were more likely to survive with favorable outcome after prolonged efforts (30-40 minutes). Adjusting for prehospital (OR 0.93; 95%CI 0.92-0.95) and inpatient (OR 0.97; 95%CI 0.95-0.99) covariates, resuscitation duration was associated with survival to discharge with mRS 0-3.
Conclusions—Shorter resuscitation duration was associated with likelihood of favorable outcome at hospital discharge. Subjects with favorable case features were more likely to survive prolonged resuscitation up to 47 minutes.
- Received May 3, 2016.
- Revision received September 22, 2016.
- Accepted October 3, 2016.