ON-SCENE Initiation of Extracorporeal CardioPulmonary Resuscitation During Refractory Out-of-Hospital Cardiac Arrest

Inclusion Criteria: * \- Age between 18 and 50 years, known or as estimated at inclusion by the HEMS physician. * Witnessed arrest (last seen well \<5 min), OR signs of life (gasping, movement) * Initial rhyme is VT/VF OR Suspected of having a pulmonary embolism * Refractory cardiac arrest lasting longer than 20 minutes and shorter than 45 min If age is not exactly known at inclusion and is estimated by the HEMS physician between 18 and 50 years but finally the patient appears to be younger or older, the patient will not be excluded. Exclusion Criteria: * \- CO2 et\<1.2 kPa (10 mmHg) during CPR * No clear echographic visualisation of either the femoral artery or the femoral vein. * Expected time from collapse to arrival at an ECPR center with a direct available ECPR team is less than 30 min. The following patients will be withdrawn after initial inclusion as soon as the following information becomes available: * Known malignancy * Known intracranial haemorrhage/ischemia \<6 weeks * Care dependent for daily activities before arrest * Patients with a "do not resuscitate" order, which was not known at time of the arrest. * Refusal of deferred consent by the next of kin or by the patient himself to use the data. Deferred consent will not be asked to relatives of patients who die in scene, but are included in the study.