Analysis of initial rhythm, witnessed status and delay to treatment among survivors of out-of-hospital cardiac arrest in Sweden

Background The characteristics of patients who survive out-of-hospital cardiac arrest (OHCA) are incompletely known. The characteristics of survivors of OHCA during a period of 16 years in Sweden are described. Methods All the patients included in the Swedish Cardiac Arrest Registry between 1992 and 2007 in whom cardiopulmonary resuscitation was attempted and who were alive after 1 month were included in the survey. Results In all, 2432 survivors were registered. Information on initial rhythm at their first ECG recording was missing in 11%. Of the remaining 2165 survivors, 80% had a shockable rhythm and 20% had a non-shockable rhythm. Only a minority with a shockable rhythm among the bystander-witnessed cases were defibrillated within 5 min after cardiac arrest. This proportion did not change during the entry period. Among survivors found in a non-shockable rhythm, the majority were bystander-witnessed cases and a few had a delay from cardiac arrest to ambulance arrival of <5 min. Of all survivors, more women (27%) than men (18%) were found in a non-shockable rhythm (p<0.0001). During the 16 years in which the register was used for this study, the proportion of survivors found in a shockable rhythm did not change significantly. The cerebral performance categories score indicated better cerebral function among patients found in a shockable rhythm than in those found in a non-shockable rhythm. Conclusion Among survivors of OHCA, a substantial proportion was found in a non-shockable rhythm and this occurred more frequently in women than in men. The proportion of survivors found in a shockable rhythm has not changed markedly over time. Survivors found in a shockable rhythm had a better cerebral performance than survivors found in a non-shockable rhythm. The proportion of survivors who were bystander-witnessed and found in a shockable rhythm and defibrillated early is still remarkably low.