Pleural Effusion Caused by Trapped Lung

Jay T. Heidecker, MD, Marc A. Judson, MD


South Med J. 2003;96(5) 

In This Article


Trapped lung occurs when a fibroelastic peel is created that covers the visceral pleura on part or all of a lung lobe. It does not allow the lobe to expand to the chest wall. Negative pressure between the chest wall and the nonexpanding lung is created and fluid migrates into the pleural space in response to the negative pressure. This is an end-stage complication of various inflammatory processes. Simple thoracentesis is not successful as the negative pressure gradient remains and the effusion re-accumulates. Pleurodesis is seldom successful because complete apposition of pleural surfaces cannot be achieved before pleurodesis. Causes of trapped lung include empyema, malignancy, postcardiac and pericardial surgery, rheumatoid arthritis, uremic pericarditis, hemothorax, tuberculosis, and histoplasmosis.[4] To our knowledge, there has been only one previous reported patient with a trapped lung from sarcoidosis,[3] and that patient's pleural effusion resolved with corticosteroids. Specific causes of trapped lung that may be prevented include early evacuation of persistent pleural effusion after cardiac surgery[5] and complete evacuation of hemothorax in trauma patients.[6] The standard treatment is decortication of the inflammatory fibrous bands. The placement of small-bore indwelling drainage catheters in patients with advanced malignant pleural effusion with trapped lung can alleviate dyspnea.[7]

Our patient required decortication of her trapped right lung. Although the patient's right lower and middle lung lobes did not completely reexpand, the patient noted marked improvement in her dyspnea. We suspect that decortication was not able to remove all the fibrosis responsible for lung entrapment. Trapped lung should be considered as a cause of pleural effusion in sarcoidosis patients with extensive pulmonary parenchymal disease and pleural effusions that fail to respond to corticosteroids and thoracentesis.


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