Background: It is well-known that cardiopulmonary resuscitation (CPR) should be attempted as early as possible after out-of-hospital cardiac arrest (OHCA). However, it has not been sufficiently investigated about the impact of time to CPR on OHCA outcome by first documented rhythm (pVT, pulseless ventricular tachycardia/VF, ventricular fibrillation; PEA, pulseless electrical activity; and asystole) in a same cohort.
Methods: We enrolled 257354 adult (≥ 18 years old) witnessed OHCA patients (median age 77 years old and 60.2% were male sex) between 2007 and 2012 from a prospective nationwide population-based cohort database in Japan. We evaluated relationships between time from collapse to first CPR by bystanders or emergency-medical-service personnel and neurologically favorable 1-month survival defined as Glasgow-Pittsburg cerebral performance category 1 or 2 both in whole population and patients who achieved return of spontaneous circulation (ROSC) by first documented rhythm. We employed logistic models for the estimation of prognoses.
Results: During the study period, the number of OHCA patients with pVT/VF, PEA, and asystole were 38661 (15.0%), 96906 (37.7%), and 121787 (47.3%), respectively. Of them, 12551 (32.5%) patients with pVT/VF, 13137 (13.6%) PEA, and 7310 (6.0%) asystole achieved ROSC. Estimated curves with their 95% confidence intervals (bands) of neurologically favorable outcome after OHCA in adults calculated from measured values (dots) were shown in the Figure by time to first CPR and first documented rhythms. Prognoses became worse as first CPR delayed irrespective of type of first documented rhythm, but were totally different by the rhythm both in total population and in patients who achieved ROSC.
Conclusions: We revealed that the OHCA outcome exceedingly differed by time to first CPR and first documented rhythm in the prospective nationwide population-based cohort database. Shortening of time to first CPR is crucial for improving the OHCA outcome.