Factors modifying the effect of bystander cardiopulmonary resuscitation onsurvival in out-of-hospital cardiac arrest patients in Sweden

Aim To describe possible factors modifying the effect of bystander cardiopu lmonary resuscitation on survival among patients suffering an out-of-hospit al cardiac arrest. Patients A national survey in Sweden among patients suffering out-of-hospit al cardiac arrest and in whom resuscitative efforts were attempted. Sixty p er cent of ambulance organizations were included. Design Prospective evaluation. Survival was defined as survival 1 month aft er cardiac arrest. Results In all, 14 065 reports were included in the evaluation. Of these. r esuscitation efforts were attempted in 10 966 cases, of which 1089 were wit nessed by ambulance crews. The report deals with the remaining 9877 patient s: of whom bystander cardiopulmonary resuscitation was attempted in 36%. Su rvival to 1 month was 8.2% among patients who received bystander cardiopulm onary resuscitation vs 2.5% among patients who did not receive it (odds rat io 3.5, 95% confidence interval 2.9-4.3). The effect of bystander cardiopul monary resuscitation on survival was related to: (1) the interval between c ollapse and the start of bystander cardiopulmonary resuscitation (effect mo re marked in patients who experienced a short delay); (2) the quality of by stander cardiopulmonary resuscitation (effect more marked if both chest com pressions and ventilation were performed than if either of them was perform ed alone); (3) the category of bystander (effect more marked if bystander c ardiopulmonary resuscitation was performed by a non-layperson); (4) interva l between collapse and arrival of the ambulance (effect more marked if this interval was prolonged); (5) age (effect more marked in bystander cardiopu lmonary resuscitation among the elderly); and (6) the location of the arres t (effect more marked if the arrest took place outside the home). Conclusion The effect of bystander cardiopulmonary resuscitation on surviva l after an out-of-hospital cardiac arrest can be modified by various factor s. Factors that were associated with the effect of bystander cardiopulmonar y resuscitation were the interval between the collapse and the start of bys tander cardiopulmonary resuscitation, the quality of bystander cardiopulmon ary resuscitation, whether or not the bystander was a layperson, the interv al between collapse and the arrival of the ambulance, age and the place of arrest. (C) 2001 The European Society of Cardiology.