The availability as well as the use of extracorporeal membrane oxygenation (ECMO) systems for severe acute respiratory or cardiocirculatory failure is steadily increasing. The decision to initiate ECMO therapy is predominantly made in emergency situations, for which the focus is on acute survival. The decisions if a patient will profit from ECMO therapy are mainly made from clinical experience and educated guess by the attending team. However, it is unknown how useful these clinical predictions are. Therefore, this observational study will compare estimated and real outcome of ECMO patients.