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Coma

Definition

A coma is a state of deep unconsciousness that a person cannot be woken from. A person in a coma cannot react to events in the environment.

Causes

Information about your environment is normally passed from the brainstem into the rest of the brain. This feedback allows a person to be aware of and react to the environment. A coma is caused by a breakdown in this system.
Brainstem and Cerebrum
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The system may be interrupted by:

Risk Factors

Risk factors for coma include:
Brain injury is more common in men. Age groups that are more likely to experience brain injury include 5 years or younger, 15-24 years old, and 75 years or older. Risk factors for brain injury include:

Symptoms

Symptoms of a coma include the following:

Diagnosis

Since the patient cannot speak, information will need to be gathered from other sources, including friends, family members, and people who witnessed an accident if one occurred. This is important to help with diagnosis. The doctor will also need to know about the person’s medical history and any drug or alcohol use. It is important to provide honest information in order to help with treatment.
The doctor will test reflexes, listen to breathing, and examine the eyes. A physical exam will also be done including tests of the nervous system.
The patient's bodily fluids will be tested. This can be done with:
Images may be taken of the patient's bodily structures. This can be done with:
The patient's brain activity may be tested. This can be done with:
Clinical findings of comatose patients can be rated according to the Glasgow Coma Scale (GCS). This scale assesses three different functions: eye opening, motor response, and verbal response. Scores can range from 15 to 3. A lower score indicates less responsiveness. Scores are interpreted as follows:

Treatment

A coma is a medical emergency. Any unconscious person should be taken to the emergency room right away.

Emergency Treatment

Doctors will work quickly to determine the cause of the coma. Further treatment will depend on the cause of the coma. Supportive care may include:
  • Monitoring of vital signs
  • Oxygen therapy
  • Delivering fluids directly into the blood through an IV
  • Ventilator to help support breathing
If a specific cause of the coma is suspected, supportive care may also include:
  • Glucose delivered through IV—in case low blood sugar is causing the coma
  • Naloxone—if a narcotics overdose is suspected
  • Thiamine (vitamin B1) may be given with glucose if alcoholism or malnutrition is suspected
In some cases, surgery may correct the cause of a coma.

Ongoing Treatment

If the coma persists after emergency care, ongoing care may be needed. After the person is stabilized, treatment will focus on providing nutrition and preventing infections. The care staff will also work to prevent bedsores .

Prevention

The following can help decrease your risk of coma:

RESOURCES

Brain Injury Association of America http://www.biausa.org

National Institute of Neurological Disorders and Stroke http://www.ninds.nih.gov

CANADIAN RESOURCES

Brain Injury Association of Canada http://biac-aclc.ca

Ontario Brain Injury Association http://www.obia.ca

References

Coma. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated December 9, 2013. Accessed November 18, 2014.

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