Cyanosis: blue coloring of the skin

Cyanosis is the blue coloring of the skin. We know cyanosis and peripheral cyanosis. Both have to do with blood supply. Cyanosis is not always serious: in most cases it occurs on the fingernails as a result of cold. But sometimes there is suffocation and the skin turns blue. When is cyanosis dangerous and when does it occur?

Cyanosis and peripheral cyanosis

Cyanosis is also called cyanosis: it is the blue coloring of the skin and mucous membranes as a result of reduced blood supply. With peripheral cyanosis, only the fingers, toes, lips and nose are discolored blue.
Normally the skin and mucous membranes are pink because they have good blood circulation. Blood contains hemoglobin, a substance that gives the blood its red color. When oxygen saturation in the blood falls below 85 percent, the reduced hemoglobin has increased to such an extent that skin and mucous membranes reflect blue to blue-gray light instead of pink.


Cyanosis is mainly noticeable on the nails, lips, ears, feet and hands. It is often more difficult to detect in people with dark skin or thick skin. It is therefore important to be able to see in daylight. The skin and mucous membranes are blue to blue-gray in color. It is best to compare the skin color of the patient’s palms, for example, with your own hands. However, the mucous membranes are not always discolored blue, sometimes only the skin is discolored blue. With peripheral cyanosis, only the lips, nose, fingers and toes are discolored. The nose, toes and fingers also feel very cold. In addition, cyanosis can occur very locally, such as with Raynoud’s phenomenon. Only the nails and fingers are discolored blue. In children, blue discoloration on the fingers or hand is often seen as a result of playing with an elastic band or string that is tied tightly around the finger. Make it clear to children that they should not do this.

Cause: heart problems

In newborns, blue discoloration may occur due to cardiac shunts. This is the direct flow of blood from one half of the heart to the other half. This affects the pressure in the heart and results in reduced oxygen saturation in the blood. This is manifested by a blue discoloration of the skin and mucous membranes. This is not always immediately visible in newborn babies. In these cases, the baby’s health can suddenly deteriorate rapidly at a later date. Other heart problems such as a narrowed pulmonary artery or problems with the vascular system can also cause cyanosis. The problem can also lie with the lungs, when the gas exchange system does not work properly. Pneumonia may be suspected.
A local bruise is not the same as cyanosis. A bruise is caused by contusion or damage to the blood vessels, causing subcutaneous bleeding. A bruise appears. This has nothing to do with reduced oxygen saturation in the blood. Anemia often results in pale skin and not blue skin. However, the lips may turn blue and the fingers and toes may feel cold.

Oxygen deficiency and suffocation

With cyanosis there does not always have to be a lack of oxygen. Especially when the blood supply is cut off locally. With central cyanosis, which means that the problem lies in the heart or blood vessels, there is often a shortage of oxygen. Doctors must then quickly switch to administering oxygen. In case of asphyxiation, a blue discoloration also occurs. In case of oxygen deficiency, in addition to cyanosis, accelerated breathing and heart rate also occur. Consciousness is reduced and the patient becomes confused, dazed and later in a coma. Cyanosis can also occur as a result of asthma, which causes reduced oxygen levels. Some asthma patients regularly develop a blue color. Asthma patients can be helped with medication, which is administered with a puffer. Cyanosis can also occur as a result of carbon monoxide poisoning. This is because carbon monoxide easily attaches to hemoglobin and displaces oxygen.

Blue skin turns black

If the oxygen deficiency continues for a very long time, the tissue will die as a result. The skin then no longer turns blue but black. This can occur with a bacterial infection, in which the blood vessels become blocked by blood clots. The tissue may also have no blood supply for some reason, causing it to die. Bacteria can then penetrate the tissue and cause an infection. This is also called gangrene or gangrene.

In the mountains

People who live in the high mountains know the phenomenon of cyanosis all too well. In the mountains the air is much thinner and contains less oxygen. As a result, the number of blood cells increases and the skin turns blue.

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