Trapped Lung

A 46-year-old woman with end-stage liver disease that was complicated by recurrent hepatic hydrothorax requiring multiple thoracenteses presented with breathlessness. Chest examination found no breath sounds on the right side. Radiography of the chest revealed a hydropneumothorax (Panel A; the arrows indicate pneumothorax, and the asterisk hydrothorax). The hydrothorax was drained with the use of a pigtail catheter, with persistent pneumothorax (Panel B, arrows). A computed tomographic scan of the chest showed trapped lung (pneumothorax ex vacuo) with thickened visceral pleura and no evidence of endobronchial obstruction (Panel C).

Trapped Lung

  • Also known as unexpandable/unexpanded lung
  • There is non-expandable lung post fluid removal, often thoracocentesis.
  • Due to pleural space inflammation from remote disease resulting in the development of a mature, fibrous membrane that impedes re-expansion
  • This negatively pressured space is filled with fluid. Drainage of this space will unavoidably cause pneumothorax (post-thoracocentesis pneumothorax) from parenchymal-pleural fistulae
  • Radiographic features
    – Thickened visceral pleura
    – Lobar collapse
    – Basal pneumothorax

Difference to lung entrapment

  • Due to ACTIVE pleural disease causing unexpandable lung, will result in mediastinal shift
  • Lung entrapment may occur in the context of pleural effusion secondary to a neoplasm, rheumatoid arthritis, uremia, infection etc

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Reference:

Jeffrey Albores, M.D., and Tisha Wang, M.D. Trapped Lung. N Engl J Med 2015; 372:e25

http://radiopaedia.org/articles/trapped-lung

Pereyra MF, et al. Pulmón no expansible. Arch Bronconeumol.
2013;49:63–9

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