Failure of oxygen to reach the brain for a variety of reasons
Asphyxiation is the term that is given to a potentially fatal condition in which oxygen is prevented from reaching the brain. If it is not treated within a few minutes, asphyxiation leads to loss of consciousness, irreversible brain damage, and, subsequently, to death.
Asphyxiation may be the result of an inability to breathe or insufficient oxygen in the inhaled air.
An inability to breathe can be due to a variety of factors. One of the most common causes is a foreign object that is lodged in the throat. Something held over the face may also block the airway, as may the person’s tongue if he or she is unconscious. A severe head injury or a drug overdose (see Drug overdose and accidental ingestion) may slow down breathing or even stop it completely. Severe damage to the wall of the chest (see Crush injuries) may prevent the lungs from inflating, particularly if one or more of the ribs has been fractured. The neck may be compressed by accidental or deliberate strangulation.
Lack of oxygen in the air can occur as a result of carbon monoxide from a car exhaust. Smoke from a fire reduces the level of oxygen in the air, or oxygen may become depleted if a person is enclosed in an airtight space.
Asphyxiation usually develops rapidly over a few minutes but can occur over several hours, depending on the cause. Most cases of asphyxiation lead to similar symptoms, including:
Eventually, loss of consciousness.
In most cases, the skin, particularly the lips, turns blue. However, when carbon monoxide poisoning is the cause, the skin may turn a bright cherry red.
Call an ambulance. Only go to the aid of a person who is being asphyxiated if you are in no danger from smoke or gases yourself. Once the person is out of danger, ask a trained first-aider to deal with any obstruction to breathing, and, if necessary, carry out emergency resuscitation until help arrives.
Once in hospital, medical treatment is directed at reversing the cause of the asphyxiation. For example, if the condition is due to a foreign body lodged in the throat, the object will be removed. If the object cannot be removed quickly, an incision may be made in the trachea (the windpipe) and a tube inserted to restore breathing until the airway can be cleared. Fractured ribs will be treated and painkillers given. Drug overdoses are treated by eliminating as much of the ingested toxic substance as possible. In some severe cases in which the underlying cause of the asphyxiation cannot be treated rapidly, mechanical ventilation (see Intensive therapy unit) may be required.
The shorter the period of oxygen deprivation, the better the prognosis. Following prolonged asphyxiation, there may be permanent brain damage.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.