Patients included in the study group must have undergone therapeutic mild hypothermia (target temperature 32 to 34ºC) or controlled normothermia (target temperature 36ºC) for at least 24 hours according to the institution protocol, as long the it is in agreement with current requirements. Routine use of prehospital or in-hospital cooling during cardiopulmonary resuscitation with rapid infusion of large volumes of cold intravenous fluid is discouraged, due to lack of evidence to improve neurological outcome or mortality. Rewarming strategies (e.g. passive or active rewarming) are open depending on institutional standards. Sedation, drug-induced paralysis during mechanical ventilation, the use of cardiovascular drugs, support devices or any other intensive care therapy is left at the criteria of the treating physicians.