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 who have a large quantity of blood deficient in oxygen tend to take on a bluish discoloration 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 as in cardiopulmonary arrest.

Mild cyanosis is difficult to detect. There needs to be more than 5 grams of deoxygenated hemoglobin in a person's bloodstream 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 for dark-skinned people. It can also appear on the feet, nose, and ears.

Many people get brief bluish-purplish painful color changes in their fingers -- this is called Raynaud's Syndrome which results from 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

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

• time pattern
  • When did it develop?
  • Did it develop suddenly?
  • Has it been developing slowly?
• quality
  • Are the lips blue?
  • Are the nailbeds blue?
  • Is the body blue all over?
• aggravating factors
  • Have you had an exposure to cold?
  • Have you suddenly gone to a high altitude?
  • Have you inhaled anything?
• other
  • 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