Mechanics of the canine diaphragm in pleural effusion

摘要

pleural effusion is a common complicating feature of many diseases of the lung and pleura, and its occurrence is frequently associated with dyspnea. In an attempt to identify the mecha-nism(s) that underlie this symptom, pulmonary function studies have been performed in patients before and shortly after the removal of pleural liquid, and these studies have shown that the increase in lung volume after thoracocentesis is substantially smaller than the volume of liquid withdrawn (3, 9, 15). Brown et al. (3), for example, reported in nine patients with large pleural effusions that the withdrawal of a mean liquid volume of 1.11 liters was associated with a mean increase in functional residual capacity (FRC) of only 0.32 liter. Similarly, in nine patients studied by Estenne et al. (9), FRC increased 0.46 liter following the removal of 1.82 liters of liquid. This difference in volume implies that pleural effusion causes not only a partial deflation of the lung but also an expansion of the chest wall.