Coma (cont.)

Medical Author:

Benjamin Wedro, MD, FACEP, FAAEM

Benjamin Wedro, MD, FACEP, FAAEM

Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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In this Article

• What is a "coma"?
• What is the Glasgow Coma Scale?
• What are the causes of a coma?
• Trauma
• Bleeding (Hemorrhage)
• Epidural, subdural, and subarachnoid hemorrhages
• Tumors
• Swelling
• Infection
• Lack of oxygen
• Hypoglycemic coma
• Poisons
• How is coma assessed?
• What tests are there for coma?
• What is the outcome and prognosis for a patient in a coma?
• Induced Coma
• Patient Comments: Coma - Cause
• Coma Index

The strategy to decide which tests will help provide a diagnosis will depend upon the suspected cause. Many times, the cause involves many factors and the sequence of events will require serious detective work. Blood tests, electrocardiogram and CT scan of the head are most often obtained. Further test options depend upon the patient's situation.

Depending upon the diagnosis, the evaluation may be no more than assessing blood sugar, treating hypoglycemia, and having complete resolution of the situation. On the other hand, the cause of coma may be a catastrophic brain hemorrhage without hope for significant recovery. The outlook very much depends on the cause of the coma and the ability to correct the particular situation.

There are times when a patient has brain injury or inflammation, and part of the treatment plan is to decrease intracranial pressure and rest the brain. Barbiturate medications such as Pentothal and pentobarbital can be injected similar to providing a general anesthetic. These medications can decrease the metabolic rate. Another effect is to constrict or narrow blood vessels and hopefully decreasing the volume of blood in the skull thereby decreasing pressure within it.

This technique is often used in patients with head trauma, ruptured aneurysms, and stroke. Recently, induced coma has been used as part of the Wisconsin protocol to treat rabies, an infection that invades and damages the brain. By resting the brain until the rabies virus can be cleared from the body, there is some hope that recovery is possible for rabies victims.

REFERENCES:

Huff JS, Martin ML. Altered mental status and coma. In: Wolfson AB, Hendey GW, Ling LJ, et al, eds. Harwood-Nuss' Clinical Practice of Emergency Medicine. 5th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 14.

Willoughby RE Jr, Tieves KS, Hoffman GM, Ghanayem NS, Amlie-Lefond CM, Schwabe MJ, Chusid MJ, Rupprecht CE. Survival after treatment of rabies with induction of coma. N Engl J Med. 2005 Jun 16;352(24):2508-14.