Cyanosis is a bluish discoloration of the skin or mucous membranes caused by lack of oxygen in the blood.

Skin coloration is determined by the amount of pigment in the skin and the blood flowing through it. Blood that is saturated with oxygen is bright red. Blood that has lost its oxygen is dark bluish-red. People whose blood is deficient in oxygen tend to have a bluish discoloration to their skin called cyanosis.

Lack of oxygen (such as in suffocation or cyanotic heart disease), abnormal hemoglobin (such as methemoglobinemia) and toxins (such as cyanide) can all produce cyanosis. Most cyanosis occurs as a result of heart disease (such as congestive heart failure), lung disease, or as a terminal event such as cardiopulmonary arrest.

Mild cyanosis is difficult to detect. A person's bloodstream needs to contain a significant amount of hemoglobin without oxygen for a doctor to see cyanosis. Usually the oxygen saturation of the blood has to drop below 90% before this occurs.

Cyanosis is more obvious in the mucous membranes and nail beds, particularly in dark-skinned people. It may also appear on the feet, nose, and ears.

Many people get brief, bluish-purplish, painful color changes in their fingers (called Raynaud's syndrome) resulting from a spasm of blood vessels in the hands, often in response to the cold. Some people with Raynaud's syndrome also have a collagen-vascular disease called scleroderma.

• Brief exposure to cold air or water
• High altitudes
• Chronic obstructive pulmonary disease (COPD)
• Pneumonia, severe
• Pulmonary edema
• Congestive heart failure
• Pulmonary hypertension
• Shock
• Hyaline membrane disease associated with prematurity
• Aspiration with suffocation
• Breath-holding
• Bronchiolitis
• Congenital heart disease
• Croup
• Epiglottitis
• Asthma
• Seizures
• Drug overdoses (narcotics, benzodiazepines, sedatives)
• Drowning or near-drowning

For cyanosis caused by exposure to cold, dress warmly when going outside or stay in a well-heated room.

Call your health care provider if you have any unexplained changes in the color of your skin or mucous membranes.

Your health care provider will perform a physical examination, which includes listening to your breathing and heart sounds. In emergency situations (such as shock), the patient will be stabilized first.

Medical history questions may include:

• When did it develop?
• Did it develop suddenly?
• Has it been developing slowly?
• Are the lips blue?
• Are the nailbeds blue?
• Is the body blue all over?
• Have you had an exposure to cold?
• Have you suddenly gone to a high altitude?
• Have you inhaled anything?
• What other symptoms are also present?
• Is there difficulty breathing?
• Is there ankle, feet, and leg swelling?
• Is there a cough?
• Is there chest pain?

• Arterial blood gas analysis
• Complete blood count (CBC)
• Chest x-ray
• ECG
• Measurement of blood oxygen by pulse oximetry

Behrman RE, Kliegman RM, Jenson HB. Nelson Textbook of Pediatrics. 17th ed. Philadelphia, Pa:Saunders; 2003.

Marx JA. Rosen's Emergency Medicine:Concepts and Clinical Practice. 6th ed. Philadelphia, Pa: Elsevier Health Sciences, 2005.

Woods WA, McCulloch MA. Cardiovascular emergencies in the pediatric patient. Emerg Med Clin North Am. November 2005;23:1233-1249.