Hüpoksia

Hüpoksia, or hypoxia, refers to a deficiency of oxygen reaching the body's tissues. It is not the same as hypoxemia, which is low oxygen in the blood; hypoxia describes the resultant inadequate oxygen delivery at the tissue level. Hypoxia can arise from problems with atmospheric oxygen, the lungs, the blood’s capacity to carry oxygen, the blood supply to tissues, or the cells’ ability to utilize oxygen.

There are several types of hypoxia. Hypoxic (or hypoxic) hypoxia occurs when arterial oxygen is low, such as at high altitude or in lung diseases that impair gas exchange. Anemic hypoxia results from reduced oxygen-carrying capacity of the blood, as seen in anemia or carbon monoxide poisoning. Ischemic (stagnant) hypoxia is due to insufficient blood flow to tissues, seen in shock or major vascular occlusion. Histotoxic hypoxia happens when cells are unable to use oxygen, for example in certain toxin exposures like cyanide. In some cases, carbon monoxide or other toxins cause a functional form of hypoxia despite normal oxygen levels.

Physiologically, hypoxia triggers cellular and systemic responses. Cells may switch to anaerobic metabolism, and pathways regulated by hypoxia-inducible factors (HIF) can be activated, influencing erythropoiesis, angiogenesis, and metabolism. The body may respond with increased respiration and heart rate; chronic hypoxia can lead to adaptive changes such as elevated red blood cell production and new blood vessel growth.

Diagnosis typically involves arterial blood gas analysis and pulse oximetry to assess oxygen levels, along with clinical assessment and imaging as needed. Treatment targets the underlying cause and often includes supplemental oxygen, ventilatory support, and therapies addressing circulating oxygen delivery, such as transfusion for anemia or specific antidotes for toxin-related hypoxia.