Observations on pleural fluid pressures as fluid is withdrawn during thoracentesis.

In 52 patients with pleural effusions, pleural pressures were measured initially and serially as pleural fluid was withdrawn. Pleural fluid aspiration was continued until the pleural pressure fell below -20 cmH2O, or the patient developed excessive symptoms, or no more fluid could be obtained. The initial pleural pressure ranged from +8 to -21 cmH2O. The rate of pleural pressure change as fluid was withdrawn was highly variable. In 13 of 52...