Out-of-hospital cardiac arrest (OHCA) is one of the leading causes of mortality in the industrialized world. Bystander CPR before arrival of the Emergency Medical Service (EMS) is a positive predictor of survival. During the last decade, the best form of bystander CPR has been debated. Chest Compression Only CPR (CO-CPR) has been advocated as a preferable method in situations where the bystander has no previous knowledge in CPR, both because its believed to be equally efficient but also a simplified form of CPR that could lead to a higher incidence of bystander-CPR.