Pleural Fluid

Transudative Effusions. Kinasewitz GT. Eur Respir J. 1997;10 :714– 718OpenUrlAbstractClinical Practice: Pleural Effusion. Light RW. N Engl J Med. 2002;346 :1971– 1977OpenUrlCrossRefPubMedChylothorax. Doerr CH, Miller DL, Ryu JH. Semin Respir Crit Care Med. 2001;22 :617– 626OpenUrlCrossRefPubMedParapneumonic Effusions and Empyema. Light RW. Proc Am Thorac Soc. 2006;3 :75– 80OpenUrlCrossRefPubMedCurrent Issues in the Diagnosis and Management of Pediatric Empyema. Lewis RA, Feigin RD. Semin Pediatr Infect Dis. 2002;13 :280– 288OpenUrlCrossRefPubMedRadiology in Pleural Disease: State of the Art. Evans AL, Gleeson FV. Respirology. 2004;9 :300– 312OpenUrlCrossRefPubMed

The pleural space is a potential space that, under normal conditions, contains a small amount of fluid that has a low protein concentration of 1 g/dL. The fluid is formed in the apical region of the parietal (chest cavity) pleura and is drained by lymphatic stomata on the parietal side of the pleura. Very little fluid moves across the visceral (lung) pleura, except in the presence of pulmonary venous hypertension.

Pleural effusions are abnormal collections of fluid in the pleural space that may develop because of transudation, when there is an imbalance between hydrostatic and oncotic pressures across intact vasculature, or because of exudation, when fluid moves across leaky blood vessels into the pleural space.

Transudative pleural effusions usually result from heart failure, hepatic cirrhosis, nephrotic syndrome, or peritoneal dialysis.

With left heart failure or mitral flow restriction, increased pulmonary venous pressure leads to fluid crossing the visceral pleura into the pleural space. Right heart failure or pulmonary arterial hypertension rarely causes excessive fluid to accumulate in the pleural space.

In cases of hepatic cirrhosis, pleural effusions most likely develop from leakage of transudative ascitic fluid into the …