Cyanosis

Blue or grey discolouration of skin or mucous membranes. Cyanosis may be seen peripherally at the fingertips and centrally on the lips or on the mucous membranes on and below the tongue.

Mechanism

Cyanosis is caused by a low haemoglobin oxygen saturation. Blood haemoglobin at a lower oxygen saturation is a darker red compared to highly oxygenated haemoglobin, this causes it to reflect more blue light creating a visible blue tint on skin and mucous membranes affected.

Causes

Pathological

• COPD
• Pneumonia
• Pulmonary Embolism
• Cyanotic Congenital Heart Disease
• Heart Failure: LVF, Valvular Heart Disease, Cardiogenic Shock
• Raynaud's Disease

Non-Pathological

• Hypothermia
• High Altitudes
• Tight clothes or jewelry