PVR increases in atelectasis due to hypoxia causing which process?

PVR increases in atelectasis due to hypoxia causing which process?

• A. Hypoxic pulmonary vasoconstriction
• B. Systemic vasodilation
• C. Venous pooling
• D. Airway edema

Answer: (A)

When alveolar ventilation drops in atelectatic areas, the resulting alveolar hypoxia triggers constriction of the small pulmonary arteries supplying those units. This response, known as hypoxic pulmonary vasoconstriction, increases the resistance in the pulmonary circulation. The goal is to reduce blood flow to poorly ventilated regions and improve overall gas exchange by redirecting blood toward better-ventilated areas. This localized vasoconstriction raises pulmonary vascular resistance. The other options don’t describe this lung-specific adaptation: systemic vasodilation would not raise PVR, venous pooling relates to venous return, and airway edema affects airway caliber rather than the pulmonary arterial response to hypoxia.

When alveolar ventilation drops in atelectatic areas, the resulting alveolar hypoxia triggers constriction of the small pulmonary arteries supplying those units. This response, known as hypoxic pulmonary vasoconstriction, increases the resistance in the pulmonary circulation. The goal is to reduce blood flow to poorly ventilated regions and improve overall gas exchange by redirecting blood toward better-ventilated areas. This localized vasoconstriction raises pulmonary vascular resistance. The other options don’t describe this lung-specific adaptation: systemic vasodilation would not raise PVR, venous pooling relates to venous return, and airway edema affects airway caliber rather than the pulmonary arterial response to hypoxia.