Cardiac arrest remains a leading cause of death, currently affecting >250,000 Europeans outside the hospital each year. Manual cardiopulmonary resuscitation (CPR) provides between 15 to 30 % of normal blood flow to the heart and brain. For out-of-hospital cardiac arrest, the return of spontaneous circulation (ROSC) is possible only for 20-40% of patients with trained resuscitation teams. However, only 5-10% of patients will survive with good neurological status. A good quality CPR, a short time before initiation of the resuscitation and a short delay before the first defibrillation have been associated with improved neurological outcome. Unfortunately it is currently impossible to obtain reliable information on the quality of the perfusion and oxygenation of organs during CPR. The current monitoring during CPR is limited to heart rhythm analysis, pulse rate evaluation and end tidal CO2 (EtCO2). The last one is the only parameter which have been linked with probability of ROSC and its value gives no indication of the long-term prognosis nor the neurological status.