The aim with this descriptive multicenter study is to examine the quality of the ventilation given by Emergency Medical Service (EMS) personnel during cardiopulmonary resuscitation (CPR). Primary endpoint is the ventilation quality measured as ventilation frequency, tidal volume and minute ventilation. This will primarily be studied during CPR with a 30 compression/2 ventilation ratio performed by the EMS personnel where the airway is managed with a supraglottic device but also in CPR with continuous ventilation (8-10 breaths/minute) after the airway management have been replaced with an endotracheal within the emergency room. The inclusion of patients will be performed at two sites (Uppsala; Sweden and Utrecht; Holland), all out-of-hospital cardia arrest (OHCA) patients will receive care according to current CPR guidelines using mechanical chest compressions.