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Pulmonary vascular resistance at FRC — FRCA Primary MCQ

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HardPhysiologyPulmonary vascular resistance at FRCFRCA Primary

During ventilation with excessive PEEP, a patient’s blood pressure falls and right ventricular strain is suspected. Which lung-volume relationship explains this?

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Correct answer: D — Alveolar vessel compression at high lung volume

Pulmonary vascular resistance is lowest near FRC and rises at high lung volumes because alveolar vessels are compressed. Extra-alveolar vessels tend to be pulled open at higher lung volume, while alveolar vessels narrow. High airway pressure can increase West zone 1 conditions and right ventricular afterload. PEEP can improve oxygenation while worsening haemodynamics if excessive.

Reference: West Respiratory Physiology; Nunn's Applied Respiratory Physiology