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Cyanosis

By

Rebecca Dezube

, MD, MHS, Johns Hopkins University

Reviewed/Revised Nov 2023
VIEW PROFESSIONAL VERSION

Cyanosis is a bluish or grayish discoloration of the skin resulting from an inadequate amount of oxygen in the blood.

Cyanosis occurs when oxygen-depleted (deoxygenated) blood, which is bluish rather than red, circulates through the skin. Cyanosis can be caused by many types of severe lung or heart disease that cause levels of oxygen in the blood to be low. It can also result from certain blood vessel and heart malformations that allow blood to flow directly to the heart without ever flowing past the air sacs of the lung (alveoli) where oxygen is extracted from the air. This abnormal blood flow is called a shunt.

In a shunt, blood from veins in the body, which is oxygen-depleted, may flow directly into blood vessels returning blood from the lungs to the left side of the heart or directly into the left side of the heart itself. The oxygen-depleted blood then is pumped out to the body, to circulate through the skin and other tissues.

Oxygen therapy Oxygen Therapy Oxygen therapy is a treatment that delivers extra oxygen to the lungs when the level of oxygen in the blood is too low. Oxygen is a gas that makes up about 21% of the air we breathe. The lungs... read more Oxygen Therapy is often the first treatment given, in a similar fashion as for other conditions in which the level of oxygen in the blood is low. Many malformations that cause shunts can be treated with surgery or other procedures.

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