The human body takes part in coordinating the physiological processes to maintain its internal temperature. When the temperature of the body becomes abnormally low, the body experiences a condition called hypothermia. Sometimes, forcing the body to become colder can be life-saving. Controlled hypothermia is an artificially induced hypothermia with the goal of slowing down the metabolic rate of a person’s body.
Controlled hypothermia is usually used in medical operations such as open-heart surgery to minimize the metabolic demands of the heart, brain, and other vital organs, giving them less risk to damages. When a patient is induced with controlled hypothermia, a medication is given to so that the patient does not shiver. The patient’s body is then cooled between 25 to 32°C. The heart is turned off and replaced with heart-lung pump that temporarily circulates the patient’s blood. The heart is further chilled to a temperature below 15°C throughout the surgery. At this very low temperature, the heart can survive without the supply of blood during the surgery.
Some emergency doctors use controlled hypothermia to minimize damages to the heart in cardiac arrest victims. The physician induces coma and decreases the body temperature of a patient to about 91°F. This causes metabolic rate to slow down requiring organs to use less blood to function, thus allowing the heart to work less than normal.
OpenStax Anatomy and Physiology