Therapeutical hypothermia after cardiopulmonary resuscitation: evidences and practical issues

Cardiac arrest survivors frequently suffer from ischemic brain injury associated with poor neurological outcome and death. Therapeutic hypothermia improves outcomes in comatose survivors after resuscitation from out-of-hospital cardiac arrest. Considering its formal recommendation as a therapy, post-return of spontaneous circulation after cardiac arrest, the objective of this study was to review the clinical aspects of therapeutic hypothermia. Non-systematic review of articles using the keywords "cardiac arrest, cardiopulmonary resuscitation, cooling, hypothermia, post resuscitation syndrome" in the Med-Line database was performed. References of these articles were also reviewed. Unconscious adult patients with spontaneous circulation after out-of-hospital ventricular fibrillation or pulseless ventricular tachycardia should be cooled. Moreover, for any other rhythm or in the intra-hospital scenario, such cooling may also be beneficial. There are different ways of promoting hypothermia. The cooling system should be adjusted as soon as possible to the target temperature. Mild therapeutic hypothermia should be administered under close control, using neuromuscular blocking drugs to avoid shivering. The rewarming process should be slow, and reach 36º C, usually in no less then 8 hours. When temperature increases to more than 35º C, sedation, analgesia, and paralysis could be discontinued. The expected complications of hypothermia may be pneumonia, sepsis, cardiac arrhythmias, and coagulopathy. In spite of potential complications which require rigorous control, only six patients need to be treated to save one life.