How can pneumonia cause cyanosis?

Pneumonia can cause cyanosis due to impaired gas exchange in the lungs, leading to decreased oxygen levels in the blood. When the alveoli become inflamed and filled with fluid or pus, oxygen cannot effectively diffuse into the bloodstream, resulting in hypoxemia. This lack of adequate oxygenation causes a bluish discoloration of the skin and mucous membranes, known as cyanosis. In severe cases, it can indicate a critical need for medical intervention.