Which term is defined as imbalance between air and blood flow in the lungs?

• A. Pleural Space
• B. Hypercarbia
• C. Oxygen Therapy
• D. Clubbing

Answer: (A)

Ventilation-perfusion mismatch describes a mismatch between air reaching the alveoli (ventilation) and blood flowing through the surrounding capillaries (perfusion). When these aren’t aligned, some lung regions receive air but not enough blood for gas exchange, while others have blood flow but not enough air. This inefficiency is what drives gas-exchange problems and often underlies hypoxemia in lung disease. The imbalance is captured by the term ventilation-perfusion mismatch.

The other options point to different concepts: issues in the pleural space affect lung expansion rather than the balance of air and blood for gas exchange; hypercarbia means elevated carbon dioxide due to ventilation problems but isn’t the name for the airflow–blood flow mismatch itself; oxygen therapy is a treatment to raise blood oxygen; and clubbing is a sign associated with chronic hypoxemia, not the mismatch concept.