Persistent unconsciousness or coma is quite different from recurrent or repeated attacks of sudden fainting. The coma may be preceded by stupor or may alternate with delirium. Among the common causes of coma are serious deficiencies of oxygen, sugar or vitamins; ‘excessive amounts of sedative or hypnotic or narcotic drugs. Coma occurs from intoxications associated with diabetes, uremia or liver disturbances. Heat stroke or freezing may result in long periods of unconsciousness. Damage to the circulation of the blood and excessive pressure on the brain, such as that which follows fractured skull or concussion, may be the cause of loss of consciousness that persists.
When the doctor examines a patient who has been long in coma he must find out first and as soon as possible the cause of the condition. The prompt application of treatment frequently means the difference between life and death, but proper treatment cannot be given unless the cause is known. Frequently unconscious people have been thrown into jail with a charge of drunkenness, when the cause of their stupor was not alcohol but a skull fracture. The same thing has happened to people who had had too much insulin. A person intoxicated by alcohol has the odor of alcohol on the breath; diabetic coma carries with it an odor like that of spoiled fruit and uremia gives an odor to the breath like that of urine. An exceedingly high temperature may mean heat stroke.
The doctor may measure the patient’s blood pressure as a clue to the cause of unconsciousness. An exceedingly high blood pressure may mean a stroke, or apoplexy, or uremia. An exceedingly low pressure may mean diabetes, drugs, drunkenness, or a hemorrhage.