Unexpandable lung.

Unexpandable lung is a mechanical complication by which the lung does not expand to the chest wall, impeding a normal apposition between the two pleural layers. The main mechanism involved is the restriction of the visceral pleura due to the formation of a fibrous layer along this pleural membrane. This happens because of the presence of an active pleural disease (lung entrapment), which can be resolved if proper therapeutic measures are taken, or a remote disease (trapped lung), in which an irreversible fibrous pleural layer has been formed. The clinical suspicion arises with the presence of post-thoracocentesis hydropneumothorax or a pleural effusion that cannot be drained due to the appearance of thoracic pain. The diagnosis is based on the analysis of the pleural liquid, the determination of pleural pressures as we drain the effusion and on air-contrast chest CT. As both represent the continuity of one same process, the results will depend on the time at which these procedures are done. If, when given a lung that is becoming entrapped, the necessary therapeutic measures are not taken, the final result will be a trapped lung. In this instance, most patients are asymptomatic or have mild exertional dyspnea and therefore they do not require treatment. Nevertheless, in cases of incapacitating dyspnea, it may be necessary to use pleural decortication in order to resolve the symptoms.