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Cyanosis

Cyanosis

Definition

Cyanosis is a physical sign causing bluish discoloration of the skin and mucous membranes. Cyanosis is caused by a lack of oxygen in the blood. Cyanosis is associated with cold temperatures, heart failure, lung diseases, and smothering. It is seen in infants at birth as a result of heart defects, respiratory distress syndrome, or lung and breathing problems.

Description

Blood contains a red pigment (hemoglobin) in its red blood cells. Hemoglobin picks up oxygen from the lungs, then circulates it through arteries and releases it to cells through tiny capillaries. After giving up its oxygen, blood circulates back to the lungs through capillaries and veins. Hemoglobin, as well as blood, is bright red when it contains oxygen, but appears dark or "bluish" after it gives up oxygen.

The blue discoloration of cyanosis is seen most readily in the beds of the fingernails and toenails, and on the lips and tongue. It often appears transiently as a result of slowed blood flow through the skin due to the cold. As such, it is not a serious symptom. However, in other cases cyanosis is a serious symptom of underlying disease.

Causes and symptoms

The blue color of the skin and mucous membranes is caused by a lack of oxygen in the blood. Low blood oxygen may be caused by poor blood circulation, or heart or breathing problems. It can also be caused by being in a low-oxygen environment or by carbon monoxide poisoning. More rarely, cyanosis can be present at birth as a sign of congenital heart disease, in which some of the blood is not pumped to the lungs where oxygen would make the blood a bright red color. Instead, the blood goes to the rest of the body and remains unoxygenated. Cyanosis also may be caused by poisoning from chemicals, drugs, or contaminated food and water.

Other signs of low blood oxygen may accompany cyanosis, including feeling lightheaded or fainting.

Treatment

Treatment of the underlying disease can restore proper color to the skin.

KEY TERMS

Hemoglobin A colored substance (pigment) in the blood that carries oxygen to tissues and gives blood its red color.

Respiratory distress syndrome Also known as hyaline membrane disease, this is a condition of premature infants in which the lungs are imperfectly expanded due to a lack of a substance on the lungs that reduces tension.

Prognosis

If the underlying condition (such as heart or lung disease) can be properly treated, the skin will return to its normal shade.

Resources

BOOKS

Carolson, Karen J., Stephanie A. Eisenstat, and Terra Ziporyn. The Harvard Guide to Women's Health. Cambridge, MA: Harvard University Press, 1996.

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"Cyanosis." Gale Encyclopedia of Medicine, 3rd ed.. . Encyclopedia.com. 15 Oct. 2017 <http://www.encyclopedia.com>.

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cyanosis

cyanosis this, like any word with the prefix cyan, derives from the Greek for dark blue. It refers to a blue tinge seen on the surface of the whole or part of the body, due to lack of oxygen in the blood. The apparent colour of the skin depends on the state of oxygenation of the blood in the microscopic vessels below the surface. Blood in the arteries is normally bright red, the colour of red blood cells when the haemoglobin they contain is carrying its full quota of oxygen. In conditions of hypoxia due to altitude, lung disease, heart defects, or heart failure, the blood leaves the lungs without being fully oxygenated, and the arterial blood is less red. The degree of desaturation of haemoglobin at which such ‘central cyanosis’ is detectable varies between observers as well as between patients. Detection also depends on the superficial blood vessels being well-filled; if they are largely ‘shut down’ the skin is simply pale whatever the colour of the blood. Undoubtedly, however, if blueness is evident, there is significant hypoxia.

When arterial oxygen saturation is normal, the extent to which the blood becomes desaturated as it flows through the skin depends on the rate of blood flow. If blood flow is sluggish, a larger fraction of the oxygen is removed than if it is florid. Thus when cheeks are flushed, increased blood flow brings bright red blood near the surface; the oxygen supply is far in excess of need, with very little being removed. But when hands and feet are cold, the reflex constriction of blood vessels — to conserve heat as part of body temperature regulation — reduces the flow, so a higher proportion of the oxygen is removed to supply the skin tissue, and the blood becomes bluer before it moves on. Hence we can become ‘blue with cold’ — but only superficially. The arterial blood itself remains bright red, if everything else is normal. For similar reasons of diminished blood flow, cyanosis is seen locally in a part of the body — say a leg or a big toe — when the circulation in that part is compromised by arterial disease.

Sheila Jennett


See also breathing; haemoglobin; hypoxia; lungs; oxygen.

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"cyanosis." The Oxford Companion to the Body. . Encyclopedia.com. 15 Oct. 2017 <http://www.encyclopedia.com>.

"cyanosis." The Oxford Companion to the Body. . Encyclopedia.com. (October 15, 2017). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/cyanosis

"cyanosis." The Oxford Companion to the Body. . Retrieved October 15, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/cyanosis

cyanosis

cyanosis (sī´ənō´sĬs), bluish coloration of the skin, mucous membranes, and nailbeds, resulting from a lack of oxygenated hemoglobin in the blood. It is a symptom of many disorders, including various pulmonary and heart diseases and many congenital heart defects (see blue baby). Cyanosis that is caused by slowed circulation through peripheral blood vessels results in a bluish tinge only on the cool portions of the body (fingertips, nose, ears). In such cases the capillary blood gives up more than normal amounts of oxygen. Although this type of cyanosis can be caused by reduced cardiac output (e.g., in congestive heart failure), the most common causes are nervous tension and exposure to cold. Another type of cyanosis results from poisoning, either by nitrates in contaminated food or water or by certain chemicals and drugs.

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"cyanosis." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 15 Oct. 2017 <http://www.encyclopedia.com>.

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"cyanosis." The Columbia Encyclopedia, 6th ed.. . Retrieved October 15, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/cyanosis

cyanosis

cyanosis (sy-ă-noh-sis) n. a bluish discoloration of the skin and mucous membranes resulting from an inadequate amount of oxygen in arterial blood (central c.), due to reduced oxygenation of blood in the pulmonary circulation, or in venous blood (peripheral c.), due to excessive extraction of oxygen in the tissues. Cyanosis is associated with heart failure, lung diseases, the breathing of oxygen-deficient atmospheres, and asphyxia. Cyanosis is also seen in blue babies, because of congenital heart defects.
cyanotic adj.

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"cyanosis." A Dictionary of Nursing. . Encyclopedia.com. 15 Oct. 2017 <http://www.encyclopedia.com>.

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"cyanosis." A Dictionary of Nursing. . Retrieved October 15, 2017 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/cyanosis

cyanosis

cy·a·no·sis / ˌsīəˈnōsəs/ • n. Med. a bluish discoloration of the skin resulting from poor circulation or inadequate oxygenation of the blood. DERIVATIVES: cy·a·not·ic / ˌsīəˈnätik/ adj.

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"cyanosis." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 15 Oct. 2017 <http://www.encyclopedia.com>.

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"cyanosis." The Oxford Pocket Dictionary of Current English. . Retrieved October 15, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/cyanosis