RT Journal Article SR Electronic T1 Mechanisms controlling the volume of pleural fluid and extravascular lung water JF European Respiratory Review JO EUROPEAN RESPIRATORY REVIEW FD European Respiratory Society SP 244 OP 252 DO 10.1183/09059180.00002709 VO 18 IS 114 A1 G. Miserocchi YR 2009 UL http://err.ersjournals.com/content/18/114/244.abstract AB Pleural and interstitial lung fluid volumes are strictly controlled and maintained at the minimum thanks to the ability of lymphatics to match the increase in filtration rate. In the pleural cavity, fluid accumulation is easily accommodated by retraction of lung and chest wall (high compliance of the pleural space); the increase of lymph flow per unit increase in pleural fluid volume is high due to the great extension of the parietal lymphatic. However, for the lung interstitium, the increase in lymph flow to match increased filtration does not need to be so great. In fact, increased filtration only causes a minor increase in extravascular water volume (<10%) due to a marked increase in interstitial pulmonary pressure (low compliance of the extracellular matrix) which, in turn, buffers further filtration. Accordingly, a less extended lymphatic network is needed. The efficiency of lymphatic control is achieved through a high lymphatic conductance in the pleural fluid and through a low interstitial compliance for the lung interstitium. Fluid volume in both compartments is so strictly controlled that it is difficult to detect initial deviations from the physiological state; thus, a great physiological advantage turns to be a disadvantage on a clinical basis as it prevents an early diagnosis of developing disease.