Cyanosis refers to a bluish-purple color of the skin. It is most easily seen where the skin is thin, such as the lips, mouth, earlobes and fingernails.

Cyanosis means there may be decreased oxygen in the bloodstream. It may suggest a problem with the lungs or heart. Cyanosis is a finding based on what is seen, not by a laboratory test.

Types of Cyanosis

“Acrocyanosis” refers to cyanosis found in the arms and legs, particularly the palms of the hands and the soles of the feet. It can also be seen on the skin around the lips. Acrocyanosis is often normal in babies, as long as no cyanosis is present in the central part of the body. Children may have acrocyanosis when they are cold (such as swimming in cold water) but it should go away once they are warmed up.

“Central cyanosis” refers to cyanosis found on “central” parts of the body, including the mouth, head and torso. Central cyanosis is never normal in the newborn period and is almost always linked to a lower amount of oxygen in the blood. It could be due to a problem of the heart, lungs or blood.

Causes of Cyanosis

Central cyanosis occurs because blood changes color based on the presence (or absence) of oxygen. Red blood is oxygen rich, but blood with less oxygen turns blue or purple. Red blood flowing through the tiny vessels in the skin produces a healthy red-pink color. Blue blood is oxygen poor and causes a bluish-purple tint to the skin.

Conditions That Cause Cyanosis

Cyanosis is usually caused by abnormalities of the heart, the lungs or the blood. Under normal conditions, after receiving oxygen from the lungs, red (oxygen rich) blood is delivered from the heart to the rest of the body. When it returns to the heart, the blue (oxygen poor) blood is directed to the lungs to collect more oxygen.

Abnormalities in the lungs can prevent oxygen from entering the blood, which can lead to cyanosis. Some examples of lung abnormalities that can lead to cyanosis include:

• Events that limit the amount of oxygen you can breathe in (smoke inhalation from house fires, carbon monoxide poisoning)
• A blockage in the airway that limits the amount of oxygen getting into your lungs (choking on an object, croup)
• Primary lung disease (asthma, pneumonia, bronchiolitis)
• Congenital heart abnormalities can cause some blue (oxygen poor) blood to bypass the lungs altogether and never collect enough oxygen (see below). Problems in the blood can decrease its ability to absorb oxygen. All of these problems cause blue (oxygen poor) blood to get pumped to the body.

Questions and Answers

What is normal blood circulation?

Blue blood (oxygen poor) returns to the right side of the heart and is pumped to the lungs where it receives oxygen and turns red. The red blood (oxygen rich) then goes to the left side of the heart and is pumped to the body. As blood circulates through the body, organs take oxygen away and make it turn blue. The blue blood then returns to the right side of the heart and back to the lungs to receive oxygen and become red again.

What is cyanotic heart disease?

The term cyanotic heart disease refers to a group of congenital (present at birth) heart defects that cause cyanosis in infants and children.

Does all congenital heart disease cause cyanosis in children?

Not all heart or lung disease is linked with cyanosis. Not having cyanosis may be reassuring, but it does not exclude the possibility of a heart defect.

Cyanosis in congenital heart defects results when blue blood (oxygen poor) does not reach the lungs to make red blood, or when red blood (oxygen rich) is mixed with blue blood before it returns to the body. This can be the result of many reasons and is specific to the type of congenital heart defect. Some examples are:

• Transposition of the great arteries (TGA): Cyanosis occurs because the aorta (the big blood vessel that carries red blood to the body) and the pulmonary artery (big blood vessel that carries blue blood to the lungs) are coming from the wrong ventricles. In transposition of the great arteries, blue blood returns normally to the right side of the heart; however, it is pumped back to the body via the aorta. On the opposite side, red blood returns normally to the left side of the heart; however, it is pumped back to the lungs via the pulmonary artery. This abnormal route of blood results in blue blood being pumped back to the body without ever going to the lungs to get oxygen and turn red, resulting in cyanosis.
• Tetralogy of Fallot (TOF): Cyanosis occurs in TOF when there is a major obstruction on the right side of the heart that prevents blue blood (oxygen poor) from getting into the lungs via the pulmonary artery. Because of the obstruction, blue blood is diverted across a hole in the bottom (ventricular) chambers of the heart, known as a ventricular septal defect, or VSD, and travels out of the heart to the rest of the body, causing cyanosis.
• Total anomalous pulmonary venous return (TAPVR): Cyanosis occurs because red blood (oxygen rich) returning from the lungs takes an abnormal (or anomalous) course back to the heart. Instead of returning to the left side of the heart and being pumped directly to the body, it returns to the right side of the heart first. The red blood then mixes with blue blood resulting in a purple mix of blood (mix of oxygen poor and rich). Blood then passes through a hole in the top chambers, known as an atrial septal defect (ASD), and then to the left side of the heart. The purple mixed blood results in cyanosis.
• Truncus arteriosus: Cyanosis occurs because there is a common great artery “trunk” consisting of the aorta and pulmonary artery. There is a hole in the bottom chambers, known as a ventricular septal defect (VSD), and blue blood mixes with red blood to make a purple mix of blood (oxygen poor and rich) before it is pumped out to the rest of the body.
• Hypoplastic left heart syndrome (HLHS): Cyanosis occurs in HLHS because red (oxygen rich) blood does not flow immediately to the body from the left side of the heart because it is extremely small (hypoplastic). Instead, red blood returning from the lungs on the left side mixes with blue blood on the right side via a hole in the top chambers known as an atrial septal defect (ASD). The blood is then pumped to the lungs via the pulmonary artery. A connecting vessel that is present in the baby from fetal life, known as a patent ductus arteriosus, or PDA, directs blood into the aorta and out to the body.

How can I tell if my child has cyanosis?

Parents can usually recognize cyanosis, but it is not always easy, even for doctors. This is especially true in children with darker skin.

The best way to look for cyanosis is to look at the nail beds, lips and tongue, and to compare them to someone with the same color skin. A parent or sibling serve as a good comparison.

What do I do if I think my child has cyanosis?

First, do not panic. Second, examine your child. Cyanosis found only on the hands, the feet and the area around the lips is known as acrocyanosis and is a normal finding in babies.

Cyanosis on the lips, tongue, head or torso is central cyanosis, and should be promptly evaluated by a doctor.

How is cyanosis diagnosed?

It depends. First, your doctor will gather more historical information, examine your child and get an oxygen saturation measurement. This latter test is painless, does not involve needles, and is a special lighted “bandage” probe placed on a finger or toe for a few minutes while the oxygen level is measured. This test will definitively determine if the level of oxygen is normal or low.

Depending on the findings, your doctor may be able to provide reassurance, or they may decide that further evaluation is necessary.

Your doctor may also decide that a consultation with a specialist is needed. They may request the services of a heart or lung specialist, the emergency room, or doctors specialized in intensive care.

How is cyanosis treated?

Most cyanosis in children is a result of “acrocyanosis” and does not need treatment. If there is a primary lung or heart issue, the underlying condition causing the cyanosis will be treated either medically or surgically.