Fibrothorax is a condition characterized by accumulation of fibrous tissue in the pleural cavity in reaction to undrained pleural fluid. A thick “peel” is formed on both pleural surfaces, eventually preventing complete expansion of the lung. This basic premise explains several other names by which this condition is known: trapped or encased lung, organizing empyema (or hemothorax), and constrictive pleurisy. The process of removing the fibrous peel is called decortication. Delorme used the term for the first time in 1894.1 The procedure was used primarily in the management of tuberculous pleurisy and later in the management of hemothorax.
Pathophysiology of Fibrothorax
The main causes of fibrothorax are listed in Table 132-1. The prerequisite for the formation of fibrothorax is the presence of undrained pleural effusion. The ensuing inflammatory response leads to fibrin deposition within the pleural space. This, in turn, is followed by infiltration of macrophages and fibroblasts and eventually formation of a collagen-rich “peel” that covers both the parietal and visceral pleurae and encapsulates the initial fluid collection (Fig. 132-1). At this stage, any attempts at management with thoracentesis are unsuccessful because the fluid quickly reaccumulates in the persistent cavity. Without remedial treatment, the initially thin peel continues to thicken, reaching depths of 2 cm or more.
Cross section of the lung with fibrous peel encasing the lung.
Table 132-1Causes of Fibrothorax |Favorite Table|Download (.pdf) Table 132-1Causes of Fibrothorax
Undrained pleural effusion
Recurrent effusions after open heart surgery
Unusual infections of the pleural space
Undrained pleural effusions also have a significant space-occupying effect and compress the underlying lung parenchyma. With continued organization of the fibrotic peel, the atelectatic portions of the lung become trapped. The same process occurs over the parietal pleura, both on the chest wall and on the diaphragm. The resulting physiologic changes are of the restrictive type. These effects are not always proportional to the thickness of the peel and can occur even with a limited extent of lung entrapment. Hypoxic pulmonary vasoconstriction limits blood flow and results in ventilation/perfusion mismatches. With unilateral disease, hypoxia may be absent at rest. The functional reserve is limited, however, and desaturation is seen with exercise.
The most frequent presentation is that of a patient with recurrent or persistent pleural effusion. Careful evaluation is warranted to determine whether fibrothorax is present or likely because this will influence the choice of appropriate management. Prior conditions leading to recurrent effusions and eventually an entrapped lung are often easily identified during history taking. A significant number of patients, however, may lack such a clear correlation. Depending on the underlying etiology and ...