1. Schematic representation of the relation between lung volume and the pulmonary vascular resistance (PVR).
Schematic representation of the relation between lung volume and the pulmonary vascular resistance (PVR). As lung volume increases from residual volume (RV) to total lung capacity (TLC), the alveolar vessels become increasingly compressed by the distending alveoli, and so their resistance increases, whereas the resistance of the extra-alveolar vessels (which become less tortuous as lung volume increases) falls. The combined effect of increasing lung volume on the pulmonary vasculature produces the typical “U shaped” curve as shown, with its nadir, or optimum, at around normal functional residual capacity (FRC).
Lara Shekerdemian, and Desmond Bohn Arch Dis Child 1999;80:
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