Q: What's the difference between a trapped and an entrapped lung?
Answer: Both trapped and entrapped lungs refer to the condition where lungs do not expand after drainage of the pleural cavity. It can be occupied by effusion, air, or mass. By definition trapped lung refers only to the pleural causes and entrapped lung refers to both pleural and non-pleural causes. Pleural causes are mostly due to adherence to the chest wall due to inflammation. Examples of non-pleural causes are endobronchial obstruction or any interstitial disease.
Most patients/ with a trapped lung usually have a transudative effusion. An entrapped lung mostly results in an exudative effusion.
References:1. John T. Huggins,Fabien Maldonado,Amit Chopra,Najib Rahman,Richard Light, Unexpandable lung from pleural disease : Respirology Volume23, Issue2 February 2018 Pages 160-167 https://doi.org/10.1111/resp.13199