Cyanosis is a bluish coloration of the skin and mucous membranes. Occurs cyanosis at reduced blood levels of oxygen, because the hemoglobin, which is not linked with oxygen (reduced hemoglobin), has a dark color. Shining through through the skin, dark blood gives them a bluish tinge, especially in areas where the skin is thinner (lips, cheeks, ears, and others). The degree of cyanosis may be different: from grayish-blue to blue-black skin tone.
Most often, cyanosis is connected with blood circulation, when the slowing down of blood flow and venous congestion promote greater uptake of oxygen and accumulation in the blood of the reduced hemoglobin. In these cases, cyanosis is more pronounced in the parts of the body remote from the heart (see Acrocyanosis).
In addition, cyanosis appears in some diseases of the lungs (pneumonia, pleurisy, the pneumothorax) and if the blood circulation in a small circle (narrowing of the pulmonary arteries, pulmonary edema). In such cases, discoloration of skin and mucous membranes evenly (diffuse cyanosis).
Expressed cyanosis observed in the number of congenital heart defects, when part of venous blood, bypassing the light that enters the blood system.
Bluish coloration of the skin appears in the administration of aniline, nitrobenzene, bertoletti salt, because under the influence of these poisons the blood haemoglobin turns into methemoglobin, which also has a dark color. Suddenly appearing cyanosis may be a sign of acute circulatory disorders requiring emergency treatment (see Circulation insufficiency).

cyanosisCyanosis (from the Greek. kyaneos - dark blue) - bluish coloration of the skin and mucous membranes. Pathological symptom observed in various diseases, accompanied by disorder of blood circulation and breathing. Color of skin, very reminiscent of cyanosis, also occurs when methemoglobinemia and sulfhemoglobinemia.
The degree of cyanosis different from grey or slightly bluish tint to the temporary stiff lips and limbs during exercise or in the cold. In some cases, cyanosis becomes resistant, covers almost the entire body expressed dark and even the blue-black color. The main cause of cyanosis, and circulatory disorders is the accumulation of peripheral blood (capillaries) reduced Hb above 5 g%, which is more likely to occur in patients with Hb high and a large number of red blood cells. For example, if 8 g% total Hb and saturation of blood with oxygen up to 50% cyanosis does not occur, as the number of the reduced Hb in the blood is less than 5 g per cent. Possible cyanosis due to intensive use tissues of oxygen from capillary blood flow. This contributes to the expansion of capillaries in combination with a slow flow with sufficient voltage stress of oxygen in the blood. Finally, for the emergence of cyanosis is of great importance absorption blood oxygen in the lungs. The latter depends on violations of pulmonary ventilation and diffusion.
All of these points, contributing to the accumulation of the reduced ERY, in clinical practice combine to give different levels of cyanosis. As a rule, long lasting insufficient oxygen saturation increases the number of erythrocytes and NI (secondary polycythemia), which in turn strengthens cyanosis. When the effect of these factors is the so-called Central cyanosis. Peripheral cyanosis due to increased uptake tissues of oxygen from flowing in them capillary blood. This is combined with a slowing of blood flow in capillaries as a result of increased venous pressure.
Cyanosis easier to see where the skin is thinner. When Ophthalmoscope study well defined cyanosis in the fundus; engorged blood vessels become dark purple tint (cyanosis retinae).
Cyanotic shade cheeks and cheekbones characteristic of the mitral valve of the heart. A more pronounced cyanosis in combination with symptomatic of drum sticks observed in patients with congenital pulmonary artery stenosis (blue disease). In these patients, cyanosis cover the entire surface of the body. But more often cyanosis, there has only limited areas of the body, in particular on the limbs. At the Central cyanosis skin feels warm, and when the peripheral is cold because of the stagnation and slow the blood flow. With attentive studying of cyanotic site it is possible in some cases to see extended to small blood vessels (better detected by the method), in others - all-skin-blue-violet color (mainly Central cyanosis).
When the temperature of the skin to 15 - 10to Hb giving oxygen to a small extent and the skin becomes red, despite the presence of the conditions for the emergence of cyanosis. When the shock of the skin gray-blue, leaden tint due to poor filling with blood capillaries. Color of skin, reminding cyanosis may be caused by the introduction of aniline derivatives, nitrites, nitrates, sulfa drugs, etc.