4. Cyanosis
Fourth, Cyanosis which is a bluish discoloration of the face, and soft tissues, including the lips and inner aspect of eyelids due to failure of gas exchange by the lungs leading to hypoxia and accumulation of the toxic carbon dioxide in the blood and tissues. Carbon dioxide accumulation usually changes the blood color into darker deeply brown that appears blue and thus leading to bluish discoloration known as cyanosis.
