oksygenasjon

Okysgenasjon, or oxygenation, is the physiological process by which oxygen moves from the lungs into the blood and from there to body tissues. It encompasses airway ventilation, alveolar gas exchange, transport of oxygen by blood, and the extraction of oxygen by cells. The main measurable parameters are arterial oxygen partial pressure (PaO2), oxygen saturation (SaO2), and arterial oxygen content (CaO2). The relationship between PaO2 and SaO2 is described by the oxygen-hemoglobin dissociation curve.

Mechanism and measurement: Oxygen diffuses from the air in the alveoli into capillary blood driven by a partial pressure gradient. Most oxygen is bound to hemoglobin in red blood cells; a small fraction remains dissolved in plasma and contributes to PaO2. CaO2 is approximated by the formula CaO2 ≈ (Hb × 1.34 × SaO2) + (0.003 × PaO2). Oxygen delivery to tissues also depends on cardiac output and hemoglobin concentration, while tissue extraction lowers venous oxygen content.

Clinical relevance: Adequate oxygenation is essential for cellular respiration. Hypoxemia (low PaO2) or hypoxia (insufficient oxygen delivery to tissues) can result from factors such as low inspired oxygen (e.g., high altitude), ventilation-perfusion mismatch, diffusion impairment, intrapulmonary shunt, anemia, or circulatory failure. Assessment typically uses arterial blood gas analysis and pulse oximetry.

Management implications: When oxygenation is inadequate, interventions aim to improve alveolar oxygen uptake and delivery. These include supplemental oxygen, noninvasive or invasive ventilation to support ventilation, and, in severe cases, advanced support such as extracorporeal membrane oxygenation (ECMO).