Lung Volumes and Capacities · Physiology

What happens to the physiological dead space in a patient with a pulmonary embolism?

  1. It decreases because less air is entering the lungs
  2. It increases because some alveoli are ventilated but no longer perfused
  3. It remains unchanged because it only depends on airway anatomy
  4. It becomes equal to the Tidal Volume
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Correct answer: It increases because some alveoli are ventilated but no longer perfused

Physiological dead space is the sum of anatomical dead space and alveolar dead space. In pulmonary embolism, blood flow to certain alveoli is blocked (perfusion failure), making them alveolar dead space and increasing the total physiological dead space.

Difficulty: Medium Question 37 of 40

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