Medically Induced Coma
What exactly is a medically induced coma? Strictly speaking, coma is a state of prolonged unconsciousness that may last for several weeks or longer. The brain continues to function, but the patient is unresponsive to external stimuli. Most comas are caused by severe illness or serious injures, such as head trauma, stroke, or drug overdose.9 But in some cases patients are temporarily placed in a comatose state with sedative medications administered by health care professionals. This procedure is known as medically induced coma. The goal is to protect the brain from further injury and to give it time to heal itself. However, because there are potential complications, it is only done in the most critical situations.
- Medically induced comas are performed by a physician in a hospital setting. Unlike a natural coma, it is reversible.
- A barbiturate or other sedative is administered in order to induce and maintain the patient’s comatose state.
- Medically induced coma is done only as a last resort to prevent further injury and to save the patient’s life.
- There are possible complications that can occur, and these complications must be weighed against the potential benefits.
Why Is It Done?
The brain is fueled by oxygen and glucose, which are channeled to it by the bloodstream. When it needs more “fuel,” it opens capillaries to draw in nutrients and keep operating. But too much blood pours into the brain after a serious injury. The brain works harder to deal with the trauma, bringing in more nutrients and swelling to accommodate them. Because it is surrounded by the skull, the brain has little room to expand. If the pressure is not relieved, the patient will die in a few days. There are few options available to physicians in treating severe head injuries. Medically induced coma is tried if all other efforts fail. When a patient is in a comatose state the brain expends less energy and blood flow is consequently reduced, which minimizes swelling.1
While the patient is in a medically induced coma, the brain continues to work at a minimal level. Basic functions like respiration, circulation, and digestion continue. There may be reflexive movements of the limbs and responses to touch or pain.
How Is It Done?
Medically induced coma takes placed only in the intensive care unit (ICU) of the hospital where the necessary personnel and monitoring technology are available. A sedative medication is given to the patient by an infusion pump that administers precisely measured doses of the drug.8 Some of the drugs employed to induce a coma include the following:
- Propofol. Propofol is a general anesthetic that is preferred for its short-acting properties. Its sedative effects are almost immediate, but they only last for a few minutes after intravenous infusion ends. This allows healthcare personnel to conduct clinical neurological assessments as they monitor the patient during the coma. Some studies suggest that propofol may have protective effects on the brain and results in better and quicker recovery compared to morphine sedation.3-6
- Barbiturates. Barbiturates such as pentobarbital and thiopental have been the traditional drugs of choice for medically induced comas.
- Benzodiazepines. Midazolam is a benzodiazepine that has been used for medically induced comas lasting longer than 72 hours.
- Opioids. Opioids such as morphine and fentanyl have also been used to induce comas.
Monitoring the comatose patient is vitally important. Brain waves are measured by electroencephalography (EEG) to determine how deep the coma is. Intracranial pressure is measured by inserting a fiberoptic tube into the patient’s head to monitor blood flow. Often the Glasgow Scale is used to measure the degree of coma. The patient is assigned a numerical scored based on how well he responds to external stimuli. Vital signs are carefully monitored to ensure that blood pressure, pulse, and oxygen are maintained at normal levels.1,3,8
How Long Does Medically Induced Coma Last?
The length of medically induced coma varies depending on the situation and how long it takes to achieve the desired outcome. It may be only 12 hours, or it can last for several weeks; in one case, the patient was kept in a coma for 6 months.1 A good patient outcome is considered to be a reduction of intracranial pressure to more or less normal levels.7
What Are the Risks?
Medically induced coma is relatively safe. It is completely reversible, lasting only as long as the patient receives sedation. Most people come out of it with no complications. However, all medical procedures have associated risks. The chief risk of medically induced coma has to do with patient outcomes. Medically induced coma only prevents further injury to the brain; it cannot address the damage which is already done. Thought the patient’s life is saved, they could end up in a vegetative state—not from the coma, but because the damage which had already occurred was too severe.1
Other possible complications are associated with the use of pentobarbital. At the doses needed to induce a coma, pentobarbital lowers blood pressure to critical levels. It dulls the heart muscle, which can lead to heart failure and impairs circulation. It also renders the patient more susceptible to infection.7
Why This Article?
This article discusses medically induced coma, which is a procedure used in a hospital setting to treat severe brain trauma. Coma can result from abusing alcohol or drugs.
- Connolly, C. (2006). Slowing Down the Brain is Still Fraught with Risk. The Washington Post.
- South Carolina Department of Disabilities and Special Needs. Head injury: a family guide.
- Skoglund, K., Enblad, P., Marklund, N. (2009). Effects of the neurological wake-up test on intracranial pressure and cerebral perfusion pressure in brain-injured patients. Neurocrit Care, 11(2), 135.
- Rossaint, J., Rossaint, R., Weis, J., Fries, M., Rex, S., Coburn, M. (2009). Propofol: neuroprotection in an in vitro model of traumatic brain injury. Crit Care, 13(2), R61.
- Kelly, D. F., Goodale, D. B., Williams, J., Herr, D. L., Chappell, E. T., Rosner, M. J., et al. (1999). Propofol in the treatment of moderate and severe head injury: a randomized, prospective double-blinded pilot trial. J. Neurosurg., 90(6), 1042.
- McKeage, K., Perry, C. M. (2003). Propofol: a review of its use in intensive care sedation of adults. CNS Drugs, 17(4), 235-72.
- NPR. (2006). Medical Comas: How and When They’re Used. All Things Considered.
- Lallanilla, M. (2013). What Is a Medically Induced Coma? Live Science.
- Mayo Clinic. (2018). Coma.