Cyanosis classification

Cyanosis is defined as bluish discoloration of the skin and or mucous membrane resulting from insufficient oxygenation of the blood and the presence of at least 5g/dl unsaturated hemoglobin in tissue. Anemia may lead to hypoxia but is not the cause of cyanosis. Right to left shunt in congenital heart disease causes central cyanosis. Secondary erythrocytosis (increased red blood cell mass due to hypoxia) and polycythemia (neoplastic proliferation of reb blood cell) are different conditions and need different evaluation. Cyanosis may be classified into central cyanosis and peripheral cyanosis.

• Cyanosis may be classified into two groups:^[1]

• Peripheral cyanosis affecting hands and feet
• Central cyanosis affecting mucous membrane, lips, tongue and sublingual tissue