If the unconscious person is suspected of having ingested something toxic, the doctor may pump the stomach to identify its contents and prevent more of the substance from being absorbed. Blood, fluids, and drugs may be administered to keep the heart beating and the blood pressure normal. In the deepest stages of a coma, the brain may be so damaged that it can't carry out essential body functions, such as breathing. A respirator, a machine that helps the lungs to function, may be necessary. The likelihood of recovery from a deep coma that lasts more than a few hours is difficult to predict.
Recovery is more likely with some causes than with others.
Full recovery after the heart has stopped or the person is deprived of oxygen rarely occurs if the coma lasts as long as a month. For those who remain in a deep coma longer than a few weeks, the family needs to decide whether they want doctors to continue using a respirator, feeding tube, and drugs. Occasionally, after a brain injury, lack of oxygen, or a severe brain-damaging illness, a person with severe brain damage may enter a vegetative state. A person in this state has relatively normal sleeping and waking patterns, breathes and swallows spontaneously, and may even show a startle reaction to loud noises but has temporarily or permanently lost all capacity for conscious thought and behavior. Most people in a vegetative state have prominent abnormal reflexes, including stiffening or jerking of the arms and legs.