Coma

What to do if someone is unresponsive

1. Call 911 or your local emergency number.
2. Check breathing. If not breathing normally, start CPR (hard, fast chest compressions in the center of the chest) and use an AED if available.
3. If breathing, place them in the recovery position (on their side, head tilted back) to keep the airway open, unless a neck injury is suspected.
4. Give naloxone for a suspected opioid overdose if it is available.
5. Do not give food or drink.
6. Tell paramedics what happened, any medicines, drugs, diabetes, seizures or recent head injury.

What a coma is

Consciousness depends on the reticular activating system in the brainstem, which keeps the brain awake, and on both cerebral hemispheres, which produce awareness. Coma results from damage or dysfunction affecting the brainstem system or both hemispheres.

Causes of coma

Coma vs related states

A medically induced coma is deliberate deep sedation used in intensive care to reduce brain activity after severe injury, control seizures, or allow ventilation. It is reversed by stopping the medicines.

How coma is assessed

Glasgow Coma Scale

The Glasgow Coma Scale (GCS) rates three responses:

• eye opening: 1 to 4
• verbal response: 1 to 5
• motor response: 1 to 6

Scores range from 3 (no response) to 15 (fully alert). A score of 8 or less indicates severe impairment and usually a need to protect the airway with a breathing tube.

Tests

• Blood tests: glucose, sodium, kidney and liver function, blood gases, toxicology, ammonia, infection markers
• CT scan of the head: for bleeding, stroke or swelling
• MRI: for detailed damage
• Lumbar puncture: for meningitis or encephalitis
• EEG: to detect seizures that may not be visible (non-convulsive status epilepticus)

Doctors also examine pupils, eye movements, breathing pattern and reflexes to locate the problem in the brain.

Treatment

1. Airway, breathing and circulation: oxygen, a breathing tube and ventilator if needed, fluids and blood pressure support.
2. Immediate treatable causes: glucose for low blood sugar, thiamine in suspected malnutrition or alcohol use, naloxone for opioids, antibiotics for suspected meningitis, seizure medicines.
3. Reducing brain pressure: positioning, medicines, and sometimes surgery to remove a blood clot or relieve swelling.
4. Supportive care in the ICU: nutrition, prevention of pressure sores, blood clots and infections, physical therapy to keep joints moving.

Outlook and recovery

Outcome depends mainly on the cause, the depth and length of the coma, and age:

• Drug and metabolic causes often have a good recovery if treated quickly.
• Traumatic brain injury generally has a better outlook than coma after cardiac arrest.
• Lack of oxygen for many minutes often causes severe, lasting damage.

Waking is usually gradual. People may be confused, agitated or have memory gaps. Many need rehabilitation for movement, speech, thinking and daily skills, sometimes for months. Some people move into a vegetative or minimally conscious state, and a small number recover further even months later, particularly after traumatic injury.

Doctors usually avoid firm predictions in the first days, especially after cardiac arrest, when cooling treatment and sedation can affect the examination. Families should ask the care team about prognosis, goals of care and the patient's known wishes.

Frequently asked questions

What is a coma?

A coma is a state of deep unconsciousness in which a person cannot be woken and does not respond to their surroundings, pain, light or sound. It is caused by severe brain injury or dysfunction, such as head trauma, stroke, lack of oxygen, overdose or infection.

Can people in a coma hear you?

People in a true coma are not thought to be aware, but some brain processing may occur, and it is hard to be certain. As they move toward consciousness, they may begin to hear. Many families talk to, read to and touch their loved one, which is safe and may be comforting.

How long can a person stay in a coma?

A coma rarely lasts more than 2 to 4 weeks. After that, people typically either regain consciousness, move into a vegetative or minimally conscious state, or die. A medically induced coma lasts as long as sedation is given.

What is the difference between a coma and brain death?

In a coma, the brain is still alive and some functions, such as brainstem reflexes and breathing, may be present; recovery is possible. Brain death is the complete and irreversible loss of all brain function, including the brainstem. It is legally recognized as death.

What is a medically induced coma?

It is a deliberate state of deep sedation created with anesthetic medicines in an intensive care unit. It reduces the brain's energy needs and pressure after severe injury, controls stubborn seizures, or allows breathing support. Doctors reverse it by stopping the medicines.