While most comas are an inadvertent lapse into prolonged unconsciousness, medically induced comas are essentially the opposite. Rather than being in a coma because of an injury, the patient is put into a drug-induced coma to prevent further damage. Here’s a look at why a medically induced coma might be necessary.
How does a medically induced coma work?
Medically induced comas are kind of like a mixture between a normal coma and the anesthetic state necessary for most surgeries. A doctor or anesthesiologist administers a controlled amount of a sedative or anesthetic to induce a coma-like state of unconsciousness. Anesthetics (Propofol or thiopental), barbiturates (pentobarbital), or benzodiazepines are medications that are typically used for this procedure.
A medical team provides constant monitoring of the patient while under the effects of the medicine, particularly since medically induced comas are virtually only used when a patient is already in critical care. It differs from sedation in that, when simply sedated, the patient may still have some consciousness about them, with a tendency to lapse into sleep. A medically induced coma, however, ensures that the patient is in a “deep state of unconsciousness,” according to the American Society of Anesthesiologists. A medically induced coma may last a little as twelve hours or -- in one case -- as long as six months.
Why is a medically induced coma necessary?
The point of a medically induced coma is to prevent the patient from incurring further brain damage. For example, when a traumatic brain injury occurs, it can cause bleeding in and swelling of the brain. This can cause the brain to shift a little bit, putting pressure on the brainstem that turns off certain reflexes controlled by this region (pupil dilation, blinking, some jaw reflexes, and breathing patterns, among other things). Swelling can cause significant damage as well -- there is only a finite amount of space the brain can swell into, as it is surrounded by barriers of fluid, tissue, and, of course, the bone-hard skull. The more it swells, the more pressure gets put on not only the injured parts of the brain, but also the brain stem. Furthermore, this swelling can inhibit blood flow. When the brain fails to receive an adequate supply of blood, it also fails to receive an adequate supply of oxygen, and cells begin to die.
A medically induced coma is usually reserved as a last resort when other treatments are ineffective. In a state of unconsciousness, the brain lapses into less activity and can actually get some rest and begin to recover on its own.
Another reason for a medically induced coma can be in the case of an extremely long seizure. Although seizures are extremely complicated and come in many different forms, essentially it is a malfunction of a group of brain cells. While seizures generally last under ten minutes, they can continue for much longer than that -- or occur off and on for several days. Turning off the brain this way can help the brain stop and give it some time to heal.
With certain infections, particularly those that can enter the nervous system causing encephalitis or meningitis, a medically induced coma can slow the body down while other options are explored. Certain heart surgeries also make use of the medically induced coma, although in this case it is brought on by an extremely cold environment, resulting in hypothermia and slowing down blood flow. This is a relatively new procedure.