Why does alveolar dead space ventilation increase during pulmonary embolism, even when total ventilation remains constant?

💡 Explanation

During a pulmonary embolism, blood flow to affected alveoli is obstructed, increasing the ventilation-perfusion ratio in those areas. This creates alveolar dead space because ventilation is wasted on areas without perfusion; therefore, dead space ventilation rises, rather than efficient gas exchange occurring due to the imbalance between ventilation and perfusion.

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