Improved lung function after thoracocentesis in patients with paradoxical movement of a hemidiaphragm secondary to a large pleural effusion

Abstract

Previous studies have shown little or no improvement in pulmonary function and arterial blood oxygenation after therapeutic thoracocentesis. This study investigated changes in pulmonary function, arterial blood gases and dyspnoea after therapeutic thoracocentesis in patients with paradoxical movement (PM) of a hemidiaphragm due to pleural effusion. Twenty-one patients with pleural effusion and PM of a hemidiaphragm and 41 patients with pleural effusion but without paradoxical movement (NPM) were studied before and 24 h after thoracocentesis. Lung function measurements included lung mechanics, blood gas exchange and the Borg dyspnoea scale. At thoracocentesis a mean of 1,220 mL of pleural fluid was removed from the PM group and 1,110 mL from the NPM group. Post-thoracocentesis the PM group showed small but significant improvement (P < 0.05) in FEV(1) (63% vs 73%), FVC (67% vs 77%), PaO(2) (66 mm Hg vs 73 mm Hg), A-a O(2) gradient (38 mm Hg vs 30 mm Hg), and the Borg scale (5.1 vs 2.1). The NPM group showed no significant change in any parameter. Statistically significant improvement in pulmonary function following thoracocentesis was observed in patients with pleural effusion and PM of the hemidiaphragm. Patient selection may therefore explain the different outcomes of thoracocentesis reported in previous studies.