Why does a pulmonary embolism, which obstructs blood flow to portions of the lung, lead to hypoxemia, characterized by a lower-than-normal arterial oxygen partial pressure?

💡 Explanation

A pulmonary embolism disrupts blood flow, creating areas of lung that are ventilated but not perfused. Because of this ventilation-perfusion mismatch, oxygen cannot effectively diffuse into the blood, therefore hypoxemia occurs rather than normal oxygenation. Capillary recruitment and blood pH effects are less direct.

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