Cyanosis refers to a blue or purple hue to the skin. It is most easily observed on the lips, tongue and fingernails. Cyanosis indicates there may be decreased oxygen in the bloodstream. It may suggest a problem with the lungs, but most often is a result of mixing blue and red blood due to defects of the heart or great vessels. Cyanosis is a finding based on observation, not a laboratory test. Cyanosis is usually caused by either serious lung or heart disease, or circulation problems.
Cases due to circulation problems are more common and often less serious. They usually affect the ends of the arms or legs or both. When cyanosis is due to heart or lung disease, it often affects the face and the arms and legs.
Cyanosis is the characteristic blue color of the skin observed when the amount of unoxygenated hemoglobin in the blood exceeds 5 grams per 100 milliters of blood (out of anywhere from 10 to 15 grams of hemoglobin per 100 milliliters). Cyanosis may be harmless - as in acrocyanosis of newborn babies - but is usually a bad sign. Cyanosis may be caused by lung problems when not enough oxygen is getting into the bloodstream, or by circulatory problems. Circulatory problems include abnormal mixing of unoxygenated blood with oxygen carrying blood. Cyanosis is usually noted first around the lips and mouth, and perhaps in the nailbeds.
Cyanosis is the physical finding of bluish discoloration of the skin and mucous membranes which result from the presence of elevated amounts of deoxygenated hemoglobin. The detection of cyanosis is subjective and cannot be considered a sensitive indicator of arterial oxygenation. A variety of factors other than the absolute amount of deoxygenated hemoglobin may influence the subjective presence of cyanosis. Unexplained cyanosis in the setting of normal arterial oxygenation should prompt further evaluation for abnormal hemoglobin, especially methemoglobin. The recreational use of nitrites has been well described, especially in the homosexual, juvenile, and other deviant populations. These patients presenting with cyanosis should be highly suspicious for methemoglobinemia.
Cyanosis can be divided into two categories, central and peripheral. The central type is seen when arterial blood is deoxygenated or an abnormal hemoglobin exists. This situation is physically manifest by skin and mucous membrane involvement. Peripheral cyanosis is due to an abnormally high amount of oxygen extraction in the periphery due to slow peripheral blood flow. All physiologic states of decreased peripheral blood flow may lead to cyanosis.
The healthcare provider can identify cyanosis by examining the person. The cause must then be found. A history and full exam will be needed first. To help figure out the cause, other tests are often ordered. A blood test called a complete blood count, or CBC, can make sure there are a normal number of blood cells. A blood test called an arterial blood gas can measure the level of oxygen in the blood. A chest x-ray can show many heart and lung disorders. A test that uses sound waves to look at the heart, called an echocardiogram, may be used. This test can show many of the congenital heart defects that may cause cyanosis and measure how well the heart is pumping blood. Other tests may be needed in some cases.
Treatment depends on the cause. Infections are often treated with antibiotics. Avoiding exposure to cold temperatures or warming the body may eliminate cyanosis related to cold temperatures. Oxygen may be needed to relieve shortness of breath. Some conditions, such as heart defects present at birth, may be treated with open heart surgery. Diuretics, or water pills, and other heart medications may be needed if heart failure is the cause. Surgery, chemotherapy, or radiation therapy may be needed for lung cancer.