Anoxia, << an OK see uh, >> is the lack of a normal supply of oxygen to body tissues, or the inability of the tissues to use the oxygen. It is also called hypoxia.
Anoxic anoxia occurs when blood flowing through the lungs does not pick up enough oxygen. This can happen when there is a reduced amount of oxygen in the air, such as at altitudes above 10,000 feet (3,000 meters). The blood also can fail to pick up sufficient oxygen because of defects in the lungs or because of obstruction of the air passages involved in breathing. Rapid, deep breathing is a common symptom of anoxic anoxia. The condition is often accompanied by cyanosis, a bluish coloration of the skin. Severe cases may lead to loss of consciousness and even death.
Anemic anoxia occurs when the blood cannot carry its normal load of oxygen. This happens when the blood has insufficient amounts of hemoglobin (the substance that transports oxygen in the blood), or when the hemoglobin is altered by carbon monoxide or other poisons.
Stagnant anoxia develops when the blood flows so slowly that it loses most of its oxygen before completing its course through a tissue. Part of the tissue thus receives little or no oxygen. An example of stagnant anoxia occurs during cold temperatures when blood vessels under the fingernails and in the lips constrict, causing cyanosis in those body parts.
Histotoxic anoxia is caused by poisons that make the tissues incapable of using the oxygen supplied. Cyanide is such a poison.
See also Altitude sickness ; Oxygen .
