A medically induced coma requires an extreme type of general anesthesia that essentially deactivates the brain, which prevents the patient from being revived or reacting on her own. During an induced coma, cardiac rhythm, blood pressure and breathing are maintained mechanically or with the use of drugs.

A patient can be placed in an induced coma with the administration of barbiturate drugs or by lowering the body temperature to around 91 degrees. The purpose of an induced coma is to allow the brain to rest after an injury, such as one that caused the brain to be deprived of oxygen; a blood clot; a blow to the head that caused pressure in the brain to increase; or a chemical imbalance in the nerve cells of the brain resulting from a drug overdose. Doctors can bring the patient out of the coma by discontinuing the treatment.

Often, a patient lapses into a coma independently after a severe accident because the brain is damaged so badly. As with induced comas, in some cases of natural comas, it’s in the patient’s best interest to remain unconscious because the brain must use a lot of energy responding to sense impressions, conscious thoughts and muscle movement when awake.