Heart–Lung Interactions in Gas Exchange: From Physiology to Pathophysiology

This review outlines the physiological organization of heart-lung coupling that ensures efficient gas exchange. Subsequently, factors that compromise this efficiency are examined. The development of perturbation in lung fluid balance, originating from both capillary and alveolar sources, is discussed in detail, as it represents a frequently overlooked contributor to impaired gas exchange. Intrinsic mechanisms by which the lung resists edema formation are then presented. We provide a quantitative functional model based on physical principles to describe the diffusion-perfusion interaction in the air-blood barrier aiming to interpret several pathological conditions, including pulmonary fibrosis, lung resection, heart failure syndromes, and mechanically ventilated patients with acute hypoxemic respiratory failure (AHRF).