Doctors bring patients out of medically induced comas by gradually reducing the amount of anesthetic and other drugs in their patients' systems. Generally speaking, medically induced comas are prolonged until patients have reached a level of stability consistent with an increased chance of recovery, according to the Scientific American.
Medically induced comas are used to help patients recover from extremely serious injuries, particularly traumatic brain injuries, notes the Scientific American. To induce the coma, doctors administer a cocktail of substances, including general anesthetic drugs, to patients in carefully controlled environments. The idea behind the treatment is to curtail the body's natural triage mechanism, which would otherwise shut off blood flow to injured areas. By allowing blood to flow freely to wound sites, medically induced comas support the healing process.
To put a patient in an induced coma, medical professionals administer an anesthetic drug like propofol or pentobarbital, titrating the dose and monitoring the patient via EEG as they do so, until the patient's brainwaves show a pattern consistent with coma. Meanwhile, other drugs are sometimes also administered intravenously to help the patient recover.
Usually, doctors try to bring patients out of medically induced comas as soon as they can. If swelling is present in a head injury, a patient may be brought out of the coma as soon as the swelling has gone down. Sometimes, doctors sustain medically induced comas for weeks or months while patients stabilize. When they feel a patient is ready, doctors gradually reduce the amount of anesthetic drugs until the person regains consciousness.