In thoracic surgery, decortication refers to a surgical procedure done to free a fibrous capsule that has formed around the lung, secondary to an inflammatory process, such as an infection. Ordinarily there is a potential space between the lung and the inside of the chest wall, with this space “lubricated” by a thin layer of fluid. In some conditions, such as pneumonia, or after an episode of bleeding in the chest, this space can fill with fluid which can eventually solidify and form a capsule around the lung. As the capsule grows, it can entrap the lung and cause problems with breathing. In a decortication operation, the surgeon works to remove this capsule and free the lung so that it can function normally.