Therapeutic hypothermia is also known as controlled or protective hypothermia. This intentionally decreased body temperature of a person is performed in acute conditions in unconscious people with careful monitoring of their vital functions.
The principle of the method is lowering the temperature of the patient's body below body 32-34°C (89-93°F). The desired effect can be achieved by intravenous administration of cold infusions; or by administration of cold solutions into the patient's stomach or urinary bladder. The second option is the usage of external cooling systems of varying complexity (bags with ice or packs of cooling gel, special cooling blankets, etc.). The hypothermia is usually maintained up to 24 hours, which is followed by cautious gradual warming to normal temperature.
The main goal of hypothermia is to decrease the body's metabolism and the need of oxygen and nutrients. During hypothermia, brain has only minimal metabolic activity this significantly decreases brain damage in situations when the brain lacks oxygen. For example, a man can be successfully resuscitated from icy water (typically a person, who accidentally fell through thin ice) even after dozens of minutes. Therapeutic hypothermia is therefore carried out in conditions where there was a significantly decreased cerebral blood flow (most usually after periods of cardiac arrest due to dangerous arrhythmias such as the ventricular fibrillation) and its objective is to minimize brain damage from lack of oxygen.
Hypothermia can cause a number of complications such as a significant drop in blood pressure, bradycardia and occurrence of heart rhythm disorders. This is the reason, why the hypothermic patient must be continuously monitored.
Hypothermia can not prevent the brain damage, which has already taken place, but it may reduce its size and improve the prognosis of the patient.