Hypoxia is a medical condition characterized by an inadequate oxygen supply to body tissues. It typically manifests as a bluish discoloration of the skin and mucosae, especially in fair-skinned individuals, when hemoglobin (Hb) saturation drops below 75%.

Types of Hypoxia

There are four primary types of hypoxia, each resulting from a different cause:

1. Anemic hypoxia: This type occurs due to insufficient oxygen delivery caused by a lack of red blood cells (RBCs) or RBCs with abnormal or insufficient Hb.

2. Ischemic hypoxia: Caused by impaired or obstructed blood circulation, leading to stagnant blood flow.

3. Histotoxic hypoxia: This occurs when body cells cannot utilize the available oxygen, often due to the presence of metabolic poisons like cyanide.

4. Hypoxemic hypoxia: Characterized by reduced arterial pO₂, it can result from abnormal ventilation-perfusion coupling, pulmonary diseases affecting ventilation, or breathing air with low oxygen content.

Carbon Monoxide Poisoning

A specific type of hypoxemic hypoxia, carbon monoxide poisoning, is a leading cause of death from fires. Carbon monoxide (CO), an odorless, colorless gas, binds to Hb more than 200 times more strongly than oxygen, significantly reducing Hb's oxygen-carrying ability. Even trace amounts of CO can cause severe hypoxia. Treatment for CO poisoning involves using 100% oxygen at normal atmospheric pressure or oxygen hyperbaric chambers, which supply the patient with higher-than-normal oxygen levels, effectively displacing the CO from the Hb. This method provides a life-saving solution to an otherwise lethal problem.