Cyanosis

Cyanosis is a bluish discolouration of the skin and mucous membranes resulting from inadequate oxygenation of the blood, typically indicated by a reduced arterial oxygen saturation below 85%. It is clinically significant as it can signal underlying respiratory or cardiovascular conditions, necessitating prompt evaluation and intervention. A key association is with congenital heart defects, where oxygen-poor blood bypasses the lungs, leading to systemic hypoxia.