Medical Comas: How and When They're Used

Dr. James Bernat, a professor of neurology at Dartmouth Medical School, says that a drug-induced coma can be a helpful tool to lower intracranial pressure. He talks about how and when doctors administer the procedure.

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MICHELE NORRIS, host:

We're going to take a few minutes now to learn more about one of the treatments Ariel Sharon has had, the medically induced coma. It's also been used on the lone survivor of the Sago Mine explosion. Dr. James Bernat is a professor of neurology at Dartmouth Medical School. He says the goal of a medically induced coma is to reduce the work of brain cells and protect them from increased pressure inside the skull or after an event such as a stroke.

Dr. JAMES BERNAT (Dartmouth Medical School): The medically induced coma is intended to reduce the metabolic demand of the brain cells. When one uses a drug like pentobarbital, a barbiturate, the coma should be completely reversible, and it should induce no permanent damage itself.

NORRIS: So it's reversible, it is a temporary state. In that sense, it differs from a coma brought on by disease or trauma.

Dr. BERNAT: Right. Most comas that are the result of stroke, head trauma, cardiac arrest with lack of blood flow to the brain are a much more serious problem from which there is usually a permanent problem.

NORRIS: Is this seen as an emergency procedure, only done as a last resort?

Dr. BERNAT: It often is done as a last resort. It has certain complications and it is not uniformly effective. But it can be effective in carefully selected cases.

NORRIS: What are some of the risks and complications?

Dr. BERNAT: Well, when you use the doses of pentobarbital that are effective to induce a coma and reduction of pressure, it lowers blood pressure, and that can be a serious problem. It also can dull the heart muscle and cause heart failure, which can further impair circulation. It also renders people more susceptible to infections while receiving this medically induced coma.

NORRIS: And while patients are in this comatose state, are doctors able to monitor the patient while they're in this stage?

Dr. BERNAT: Yes, the monitoring during this is exceedingly important. One way we routinely do the monitoring is by electroencephalography, measuring brain waves. By merely looking at the brain waves, we can get a pretty good picture of how deep the coma is, even if the person is unresponsive. There's other types of monitoring. One can measure intracranial pressure directly. The other monitoring, of course, that is done in any intensive care unit would be to make sure that the person isn't suffering any side effects of this therapy.

NORRIS: I understand that this is a relatively new procedure. How common is it, and is it at all controversial?

Dr. BERNAT: I believe it is still controversial. One of our specialty societies has written an advisory paper about it warning of some of the risks. It can be very effective, so certainly when it works, it works.

NORRIS: Doctor, what would be considered a good outcome for someone who's been placed in a medically induced coma?

Dr. BERNAT: Generally, once the medications are withdrawn, the treatment itself should cause no harm. But what the problem is is why they were given that in the first place. And so it isn't that the medically induced coma causes a problem as much as it is the underlying disorder for which the pentobarbital coma was prescribed. A good outcome would be reduction of intracranial pressure to more or less normal range to allow the person to recover.

NORRIS: Dr. Bernat, thanks so much for talking to us.

Dr. BERNAT: You're welcome.

NORRIS: Dr. James Bernat teaches neurology at Dartmouth Medical School. He was talking about medically induced comas which were used on Israeli Prime Minister Ariel Sharon and Randall McCloy Jr., the lone survivor of the Sago Mine disaster in West Virginia.

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