MSD Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Cyanosis

By

Rebecca Dezube

, MD, MHS, Johns Hopkins University

Last full review/revision Feb 2020| Content last modified Feb 2020
Click here for the Professional Version

Cyanosis is a bluish 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.

The amount of oxygen in the blood can be estimated by pulse oximetry Arterial Blood Gas (ABG) Analysis and Pulse Oximetry Both arterial blood gas testing and pulse oximetry measure the amount of oxygen in the blood, which helps determine how well the lungs are functioning. Arterial blood gas tests are invasive... read more , in which a sensor is attached to a finger or an earlobe, or it can be measured directly by arterial blood gas analysis Arterial Blood Gas (ABG) Analysis and Pulse Oximetry Both arterial blood gas testing and pulse oximetry measure the amount of oxygen in the blood, which helps determine how well the lungs are functioning. Arterial blood gas tests are invasive... read more . Chest x-rays, echocardiography Echocardiography and Other Ultrasound Procedures Ultrasonography uses high-frequency (ultrasound) waves bounced off internal structures to produce a moving image. It uses no x-rays. Ultrasonography of the heart (echocardiography) is one of... read more Echocardiography and Other Ultrasound Procedures , cardiac catheterization Cardiac Catheterization and Coronary Angiography Cardiac catheterization and coronary angiography are minimally invasive methods of studying the heart and the blood vessels that supply the heart (coronary arteries) without doing surgery. These... read more Cardiac Catheterization and Coronary Angiography , pulmonary function tests Pulmonary Function Testing (PFT) Pulmonary function tests measure the lungs' capacity to hold air, to move air in and out, and to absorb oxygen. Pulmonary function tests are better at detecting the general type and severity... read more Pulmonary Function Testing (PFT) , and sometimes other tests may be needed to determine the cause of decreased oxygen in the blood and the resulting cyanosis.

Oxygen therapy Oxygen Therapy Oxygen is a gas that makes up about 21% of the air we breathe. The lungs take oxygen from the air and transfer it to the bloodstream (see Exchanging Oxygen and Carbon Dioxide). Oxygen is needed... 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.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Others also read
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Test your knowledge

Coughing Up Blood
Coughing up blood from the respiratory tract is called hemoptysis. Which of the following is the most likely cause of hemoptysis in adults?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
TOP