Normal volume and cellular contents of pleural fluid

The pleural space in healthy humans was thought to contain a few milliliters of fluid, based on extrapolation from animal studies. However, because of the obvious technical difficulties in atraumatically retrieving such a small volume of fluid, the exact volume and cellular content of human pleural fluid has not been known. Development of a minimally invasive pleural lavage technique has allowed, for the first time, the measurement of volume and cellular content of the pleural fluid in healthy humans.