Quality and efficiency of bystander CPR. Belgian Cerebral Resuscitation Study Group.

Incorrectly performed bystander CPR might compromise survival of the cardiac arrest patient. We therefore evaluated the outcome in 3306 out-of-hospital primary cardiac arrests of which 885 received bystander CPR. bystanders performed CPR correctly in 52%, incorrectly in 11%, 31% performed only external chest compressions (ECC) and 6% only mouth-to-mouth ventilation (MMV). The initial ECG in cases without bystander CPR was ventricular fibrillation in 28% (95% confidence interval: 27-30%); 45% (41-50%) and 39% (29-48%), respectively when bystander CPR was performed correctly or incorrectly; 43% (37-49%) when only ECC was applied and 22% (11-33%) when only MMV was practiced. Long term survival, defined as being awake 14 days after CPR, was 16% (13-19%) in patients with correct bystander CPR; 10% (7-14%) and 2% (0-9%), respectively when only ECC or only MMV was performed; 7% (6-8%) when no bystander was involved; 4% (0-8%) when bystander CPR was performed incorrectly. Bystander CPR might have a beneficial effect on survival by maintaining the heart in ventricular fibrillation by ECC. A negative effect of badly performed bystander CPR was not observed compared to cases which had not received bystander CPR.