Neurological outcomes in patients transported to hospital without a prehospital return of spontaneous circulation after cardiac arrest

INTRODUCTION As emergency medical services (EMS) personnel in Japan are not allowed to perform termination of resuscitation in the field, most patients experiencing an out-of-hospital cardiac arrest (OHCA) are transported to hospitals without a prehospital return of spontaneous circulation (ROSC). As the crucial prehospital factors for outcomes are not clear in patients who had an OHCA without a prehospital ROSC, we aimed to determine the prehospital factors associated with 1-month favorable neurological outcomes (Cerebral Performance Category scale 1 or 2 (CPC 1-2)). METHODS We analyzed the data of 398,121 adult OHCA patients without a prehospital ROSC from a prospectively recorded nationwide Utstein-style Japanese database from 2007 to 2010. The primary endpoint was 1-month CPC 1-2. RESULTS The rate of 1-month CPC 1-2 was 0.49%. Multivariate logistic regression analysis indicated that the independent variables associated with CPC 1-2 were the following nine prehospital factors: (1) initial non-asystole rhythm (ventricular fibrillation (VF): adjusted odds ratio (aOR), 9.37; 95% confidence interval (CI), 7.71 to 11.4; pulseless ventricular tachycardia (VT): aOR, 8.50; 95% CI, 5.36 to 12.9; pulseless electrical activity (PEA): aOR, 2.75; 95% CI, 2.40 to 3.15), (2) age <65 years (aOR, 3.90; 95% CI, 3.28 to 4.67), (3) arrest witnessed by EMS personnel (aOR, 2.82; 95% CI, 2.48 to 3.19), (4) call-to-hospital arrival time <24 minutes (aOR, 2.58; 95% CI, 2.22 to 3.01), (5) arrest witnessed by any layperson, (6) physician-staffed ambulance, (7) call-to-response time <5 minutes, (8) prehospital shock delivery, and (9) presumed cardiac cause. When four crucial key factors (with an aOR >2.0 in the regression model: initial non-asystole rhythm, age <65 years, EMS-witnessed arrest, and call-to-hospital arrival time <24 minutes) were present, the rates of 1-month CPC 1-2 and 1-month survival were 16.1% and 23.2% in initial VF, 8.3% and 16.7% in pulseless VT, and 3.8% and 9.4% in PEA, respectively. CONCLUSIONS In OHCA patients transported to hospitals without a prehospital ROSC, nine prehospital factors were significantly associated with 1-month CPC 1-2. Of those, four are crucial key factors: initial non-asystole rhythm, age <65 years, EMS-witnessed arrest, and call-to-hospital arrival time <24 minutes.