Cyanosis is a bluish coloration of the skin and mucous membranes. It can affect a localized area (such as the fingers or the face) or affect the whole organism. The causes are varied and include in particular cardiac malformation, respiratory disorder or exposure to cold.

Cyanosis is the bluish coloration of the skin and mucous membranes when the blood contains a small amount of hemoglobin bound to oxygen. In other words, we speak of cyanosis when the capillary blood contains at least 5g of reduced hemoglobin (that is to say not not fixed to oxygen) per 100ml.

Remember that hemoglobin is the component of red blood cells (also called red blood cells) which carries oxygen. Its rate varies in men, women and children.

When there is little oxygen in the blood, it takes on a dark red color. And when all the vessels (of the whole body or of a region of the body) carry poorly oxygenated blood, then it gives the skin the bluish coloration characteristic of cyanosis.

Symptoms can be associated with cyanosis, depending on what is causing it. For example, breathing difficulties, chest pain, fever, heart failure or general fatigue.

Cyanosis can be limited to one part of the body, such as the lips, face, extremities (fingers and toes), legs, arms… or it can affect it entirely. We distinguish in fact:

• central cyanosis (or generalized cyanosis), which designates a decrease in the oxygenation of arterial blood;
• and peripheral cyanosis which is due to reduced blood flow. It most often affects the fingers and toes.

In all cases, cyanosis should alert and it is necessary to consult a doctor who can make a diagnosis and offer treatment.

There are many factors that cause cyanosis. These include:

• exposure to cold;
• Raynaud’s disease, ie a circulation disorder. The affected area of ​​the body turns white and cools, sometimes before turning blue;
• a local interruption of circulation, such as thrombosis (i.e. the presence of a clot – or thrombus – which forms in a blood vessel and which obstructs it);
• pulmonary disorders, such as acute respiratory failure, pulmonary embolism, edema in the lungs, hematosis disorder (refers to the gas exchange that takes place in the lungs and which allows blood rich in carbon dioxide to be transformed in oxygen-rich blood);
• a myocardial infarction;
• cardiac arrest ;
• a congenital heart or vascular malformation, this is called blue blood disease;
• severe bleeding;
• poor blood circulation;
• anemia;
• poisoning (eg cyanide);
• or some hematological diseases.

Cyanosis is a symptom that requires medical consultation. If the symptom is not managed, many complications can occur (depending on the origin of the cyanosis and its location). Let us quote for example:

• polycythemia, that is to say an abnormality in the production of red blood cells. In this case, the percentage of red blood cells relative to the total blood volume is high;
• a digital hippocratism, that is to say a deformation of the nails which become bulging (note that it is Hippocrates who defined it for the first time);
• or even discomfort or syncope.

Treatment for cyanosis depends on what is causing it. Let us quote for example:

• surgery (congenital heart defect);
• oxygenation (respiratory problems);
• taking medicines, such as diuretics (cardiac arrest);
• or the simple fact of dressing warmer (in the event of exposure to the cold or Raynaud’s disease).