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Reduced lung compliance in pulmonary fibrosis — FRCA Primary MCQ

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HardPhysiologyReduced lung compliance in pulmonary fibrosisFRCA Primary

A patient with pulmonary fibrosis has small lung volumes, high respiratory rate and reduced compliance. During ventilation, peak pressure and plateau pressure are both high with little difference between them. What is the most likely explanation?

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Correct answer: B — Reduced lung compliance

When peak and plateau pressures are both high with a small difference, the problem is reduced respiratory system compliance rather than increased airway resistance. Bronchospasm or tube obstruction would increase peak pressure disproportionately, widening the peak-plateau gap. Fibrosis makes the lung stiff, requiring higher pressure for a given tidal volume. This distinction guides ventilator adjustment.

Reference: RCoA Primary FRCA Syllabus 2026; Ganong's Review of Medical Physiology; West's Respiratory Physiology