Association between interval between call for ambulance and return of spontaneous circulation and survival in out-of-hospital cardiac arrest

Abstract

To describe the association between the interval between the call for ambulance and return of spontaneous circulation (ROSC) and survival in out-of-hospital cardiac arrest. All patients suffering an out-of-hospital cardiac arrest in whom cardiopulmonary resuscitation (CPR) was started, included in the Swedish Cardiac Arrest Registry (SCAR) for whom information about the time of calling for an ambulance and the time of ROSC was available. Among 26,192 patients who were included in SCAR and were not witnessed by the ambulance crew, information about the time of call for an ambulance and the time of ROSC was available in 4847 patients (19%). There was a very strong relationship between the interval between call for an ambulance and ROSC and survival to one month. If the interval was less than or equal to 5 min, 47% survived to one month. If the interval exceeded 30 min, only 5% (n = 35) survived to one month. The vast majority of the latter survivors had a shockable rhythm either on admission of the rescue team or at some time during resuscitation. Among patients who have ROSC after an out-of-hospital cardiac arrest, there is a very strong association between the interval between the call for ambulance and ROSC and survival to one month. However, even if this delay is very long (> 30 min after calling for an ambulance), a small percentage will ultimately survive; they are mainly patients who at some time during resuscitation have a shockable rhythm. The overall percentage of patients for whom CPR continued for more than 30 min who are alive one month later can be assumed to be extremely low.