Spotlight on Research

Over the past 30 years in Sweden, the ambulance response time in out-of-hospital cardiac arrest (OHCA) has doubled—yet counter-intuitively, the chances of surviving an OHCA have also substantially increased.

A study team accessed data from the Swedish Registry of Cardiopulmonary Resuscitation (CPR) to determine the effect of ambulance response time on 30-day survival after OHCA. Over 20 000 cases of OHCA between 2008 and 2017 were included. The study used a model that was adjusted for age, sex, calendar year, and place of collapse, and analysed data for four groups of emergency medical service (EMS) response times: 0–6 minutes, 7–9 minutes, 10–15 minutes, and >15 minutes. A decrease in survival was seen with increasing EMS response time regardless of the initial heart rhythm. This remained true regardless of whether or not CPR was performed before EMS arrival for the time intervals up to 15 minutes. For those in a shockable rhythm, the adjusted survival dropped from 44 to 25% when the EMS response time increased from 0–6 minutes to 10–15 minutes.