Signs of Life as a Predictor of Survival in Patients With Out-of-Hospital Cardiac Arrest and Long Low-Flow Times

Introduction: Long low-flow times in patients with out-of-hospital cardiac arrest (OHCA) are associated with poor outcome. Signs of life during cardiopulmonary resuscitation (CPR) is a simple method to evaluate in the field, but little is known about its impact on survival in patients with long low-flow times. Hypothesis: Thirty-day survival in OHCA patients with long prehospital low-flow times is higher in patients with signs of life during CPR than in patients with no signs of life during CPR. Methods: Observational, retrospective, single center study of OHCA patients referred to a tertiary cardiac arrest center in the Central Demark Region from 2015-2018. Risk factors were assessed by univariate logistic regression. Comparisons were made by Kaplan-Meier survival curves and log-rank test. Results: In a cohort of 807 patients with OHCA, 30-day survival was seen in 364 (45%). Among patients discharged from hospital, favorable neurological outcome with CPC 1-2 was observed in 93%. Signs of life during CPR was present in 315 (39%) patients. Risk of 30-day mortality was significantly reduced in patients presenting signs of life during CPR (RR 0.25, 95% CI [0.20-0.30]). Poor survival was seen in patients with low-flow times exceeding 30 minutes compared to patients with shorter low-flow times, (11% versus 66%, p < 0.001). In patients with low-flow times > 30 min, the survival rate increased to 33 % in the presence of signs of life during CPR compared to only 3% in patients without signs of life during CPR, p < 0.001. Conclusions: In OHCA patients, low-flow times > 30 minutes were highly associated with poor survival, however signs of life during CPR predicts higher survival both in the overall population and in patients with long low-flow times. Thus, resuscitation efforts may not be futile in patients with long low-flow times presenting signs of life during CPR.