Influence of lung volume, fluid and capillary recruitment during positional changes and exercise on thoracic impedance in heart failure

Highlights • Intrathoracic impedance increased with lung volume during slow vital capacity maneuvers. • Positional changes (upright to supine) resulted in increased impedance, while pulmonary blood volume increased, and an index of extravascular lung water and lung volume decreased. • During exercise, lung volume and pulmonary blood volume increased, and an index of extravascular lung water decreased. However, impedance was not altered significantly.