asphyxia(redirected from asphyxiant)
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asphyxia(ăsfĭk`sēə), deficiency of oxygen and excess of carbon dioxide in the blood and body tissues. Asphyxia, often referred to as suffocation, usually results from an interruption of breathing due to mechanical blockage of the breathing passages, paralysis of the respiratory muscles following electric shock, inundation of the lungs as may occur with pneumonia or drowning, or substitution of carbon monoxide for oxygen in the red blood cells. Symptoms of asphyxia vary but may include light-headedness, nausea, and gasping, followed by unconsciousness and death. An area quickly affected is the cerebral cortex, the brain center for speech and other conscious behavior; it can be irreparably damaged by as little as five minutes of oxygen deprivation. Damage to the medulla may result in interference with the heartbeat or other involuntary processes. Artificial respirationartificial respiration,
any measure that causes air to flow in and out of a person's lungs when natural breathing is inadequate or ceases, as in respiratory paralysis, drowning, electric shock, choking, gas or smoke inhalation, or poisoning.
..... Click the link for more information. is the most practical first-aid procedure for asphyxia. Trained personnel can provide oxygen and employ techniques to maintain the heart rate and respiration (see resuscitatorresuscitator
, device used to revive a person whose normal breathing has been disrupted. Several types are in wide use. The automatic tank resuscitator consists of a face mask that fits tightly over the nose and mouth and is connected by a tube to one or more tanks of gas.
..... Click the link for more information. ).
a pathological condition arising as the result of disturbances in breathing and characterized by an acute lack of oxygen and an excess of carbon dioxide in the blood and tissues. Asphyxia can arise as a consequence of a mechanical impediment to the intake of air into the respiratory tract owing to a constriction of the tract from without (for example, suffocation), the development of swelling, the accumulation of liquid (in cases of aspiration of vomitus), the contraction of the respiratory tract as a result of edema of the larynx (diphtheritic croup), or a spasm of the muscles of the larynx (for example, in the case of tetanus). Paralysis of the respiratory musculature or of the respiratory center (for instance, in the case of botulism) can also cause asphyxia.
Asphyxia of a fetus or infant can arise through the cessation or decrease in delivery of oxygen to the fetus, the accumulation of carbon dioxide and the acidic products of metabolism in the organism, and more often as a result of a disturbance in the uteroplacental or umbilical circulation, or an illness of the mother or fetus. In the case of asphyxia of a fetus, measures are taken to improve the circulation in the fetus and to hasten childbirth. Asphyxia of the fetus and infant is the most common cause of stillbirth and of infant mortality, and also of disorders that appear in the child’s later development.
In cases of asphyxia, a quickening and deepening of the breathing (inspiratory shortwindedness, that is, shortwind-edness with difficulty in inhalation), caused by the lack of oxygen in the organism, is observed. Further changes in the breathing are marked by an excess of carbon dioxide in the blood and tissues. Inspiratory shortwindedness is replaced by expiratory shortwindedness (that is, shortwindedness with difficulty in exhalation), which is followed by the cessation of breathing. The skin takes on a bluish color, and dizziness, loss of consciousness, and contraction followed by dilation of the pupils of the eye appear. In the final stage, involuntary urination, defecation, secretion of sperm, and disappearance of reflexes can appear. Disturbances of the heartbeat, acidosis connected with the accumulation of acidic products in the organism, and so on are observed. The clinical course of asphyxia can take different forms depending on the cause of the disease. However, in all cases death occurs five to six minutes after the cessation of breathing and circulation as a result of the destruction of the nerve cells of the central nervous system (the centers of respiration and circulation), which are most sensitive to oxygen deprivation.
Treatment consists of the elimination of the causes of asphyxia, that is, the restoration of the passageways of the respiratory musculature. When the heart stops, artificial respiration and heart massage are performed. In the case of infant asphyxia, treatment is similar to that of asphyxia brought about by other causes. When possible, however, placental circulation is not stopped (that is, the umbilical cord is not tied off) either until expulsion of the placenta or until the infant emerges from the state of asphyxia. At the same time, measures are taken to combat the disturbance of the acid-base equilibrium (acidosis) in the blood of the fetus or of the infant.
Many changes in the internal organs and in the blood are discovered during autopsy following death from asphyxia; among them are pinpoint hemorrhaging in the mucous and serous membranes, acute emphysema and edema of the lungs, and the accumulation of stagnant dark blood in the abdominal organs, in the vessels of the brain, and in the right half of the heart, and such. The observation of these changes is very important in the performance of the postmortem diagnosis, which has great significance since asphyxia, as shown through forensic medicine, is one of the most frequent causes of death. The forensic medical definition of asphyxia is broad and includes toxic asphyxia caused by the effects of poisonous substances on the various physiological mechanisms that take part in the respiratory process.
REFERENCESRukovodstvo po patologicheskoi fiziologii, vol. 3. Edited by A. A. Bogomolets. Moscow-Leningrad, 1936. Page 273.
Smol’ianinov, V. M., K. I. Tatishchev, and V. F. Chervakov. Sudebnaia meditsina, 3rd ed. Moscow, 1963.
Osnovy reanimatologii. Moscow, 1966.
V. A. FROLOV