Re-expansion pulmonary edema

Last revised by Liz Silverstone on 15 Jun 2023

Re-expansion pulmonary edema is an uncommon but important cause of non-cardiogenic pulmonary edema.

Pulmonary edema occurs in the setting of rapid re-expansion of a collapsed lung, presenting as acute dyspnea. The onset can be delayed by up to 24 hours. It occurs following ~1% of pneumothorax re-expansions or thoracentesis procedures and mortality has been reported at 20% 7. Re-expansion pulmonary edema has also been reported following non-pulmonary procedures, such as hepatic cyst drainage with consequent re-expansion of atelectatic lung 1

The exact underlying mechanism is unknown but is thought to be a form of permeability edema 4 related to endothelial changes occurring when the lung has been collapsed for 3 or more days. Hydrostatic edema may be a contributing factor in some cases 5. High negative intra-pleural pressure may be a risk factor.

Bilateral pulmonary edema can occur and is likely due to a combination of reperfusion injury and inflammatory response. In this scenario, the mortality rate can be as high as 40% 4.

Rapid lung re-expansion in the following settings 2:

  • rapid drainage of large pneumothoraces/pleural fluid collections

  • patients in whom the lung has been collapsed for over 7 days

  • alveolar (air-space) opacity

  • usually unilateral in those portions of the lung that were previously collapsed

  • rarely edema can develop in the contralateral lung

  • the clinical setting is critical to making the diagnosis

  • edema may persist for several days and up to one week

Re-expansion edema appears as regions of ground glass opacification. It may be peripheral in distribution and associated with smooth interstitial thickening 3 however the distribution varies and dependent opacity along fissures and interlobular septa can occur.

Pre-procedure checks will identify patients at risk and rapid re-expansion should be prevented by the use of clamps or taps.

Measured aspiration limited to 1-1.5L/hour is safer than an underwater seal for large sub-acute pneumothoraces.

If respiratory distress occurs during drainage of a large pleural effusion, consider reintroducing the pleural fluid into the thoracic cavity. A report of two cases indicates rapid resolution of symptoms 6.

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Cases and figures

  •  Case 1: post pleural tap
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  • Case 2: on left
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  • Case 3
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  • Case 4: in right lower lobe
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  • Case 5
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  • Case 6: pneumothorax and re-expansion PO
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