Cyanosis

Peripheral: (Blueness of the extremties) Exposure to cold, arterial or venous obstruction, low cardiac output, venous occlusion.


Central:(Blueness of mucous membranes) Decreased arterial oxygen saturation (respiratory failure, high altitude, congenital heart disease), hemoglobin abnormalities (sulfthemoglobinemia, carboxyhemoglobinemia, methhemaoglobinemia).