Respiratory Mechanics and Gas Exchange · USMLE Step 1

Which statement best describes the concept of ventilation–perfusion (V/Q) mismatch?

  1. Regions where ventilation and perfusion are both zero
  2. Uniform ventilation and perfusion throughout the lung
  3. Mismatch of ventilation and perfusion in lung regions
  4. Equal global reduction in ventilation and perfusion
Show answer and explanation

Correct answer: Mismatch of ventilation and perfusion in lung regions

V/Q mismatch arises when some lung regions receive differing levels of ventilation and perfusion, impairing efficient gas exchange.

Difficulty: Medium Question 10 of 20

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