132: Fibrothorax and Decortication

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.

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.

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 the degree of parenchymal involvement, symptoms may vary. Exertional dyspnea is the most common symptom, usually reported as progressive over a long period of time. Chest discomfort and nonproductive cough are also seen. The most common signs are limited respiratory movement of the affected hemithorax, decreased breath sounds on auscultation, and dullness to percussion.

Imaging techniques are of paramount importance. Standard chest radiographs (Fig. 132-2) demonstrate obliteration of the costophrenic angle and thickened pleural surfaces, initially seen over the diaphragmatic surface and the lateral chest wall, progressing superiorly and eventually obliterating the pleural space. The intercostal spaces may be narrowed, and the overall size of the hemithorax may be reduced. Pleural calcifications, when present, can help determine the thickness of the parietal peel.

CT scanning is essential in the evaluation of fibrothorax (Fig. 132-3). In addition to the information regarding the extent of the fibrotic process, the thickness of the peel, the presence of loculations, and potential differentiation from neoplastic pleural disorders (i.e., mesothelioma) are revealed. CT scanning provides useful information about the status of the underlying lung parenchyma. Tuberculous lesions, bronchiectasis, and underlying lung malignancies can be identified. In addition, a reasonable estimation of the effectiveness of the decortication can be made based on the extent of diseased lung parenchyma, which usually limits the postoperative expansion.

Pulmonary function studies should be obtained not so much for diagnostic purposes but primarily to quantify the degree of pulmonary impairment and serve as a measure of postoperative improvement. Perfusion scanning offers little additional information and is not performed routinely.

The best management for fibrothorax is prevention. Early and aggressive treatment of persistent pleural effusions, hemothorax, and empyema can avoid the development of the restrictive fibrous peel.^2,3 In the first several weeks, drainage usually is feasible either with tube thoracostomy or with thoracoscopic techniques and achieves excellent results. When treatment is delayed or unsuccessful, however, management decisions become more complicated. Both the need for a decortication and the optimal timing for the operation have to be determined. The decision to proceed with a decortication depends on several factors. The extent of the disease has to be such that it causes significant symptomatology and objective physiologic pulmonary impairment. Patients requiring decortication are those with at least 50% compression of the lung (especially with apical involvement), those with unsuccessful attempts at aspiration, and those with lack of improvement after 6 weeks of conservative management. The nature of the underlying disease is also important. In cases of empyema, failure of initial drainage usually is considered an indication for decortication; the goals of the operation in this setting are not only alleviation of lung constriction but also elimination of the infected pleural space by reexpansion of the lung. In the case of hemothorax, control of coagulation disorders must be addressed before extensive surgery. If the initial intervention has been tube thoracostomy, an early decision, within several days, should be made regarding the necessity of more aggressive surgical evacuation. In patients with tuberculosis, decortication is performed after completion of antituberculous chemotherapy and when there is considerable pleural involvement that does not change despite thoracentesis.

Table 132-2 shows conditions in which decortication is contraindicated. These include patients with significant ipsilateral bronchial obstruction, primary or metastatic pleural malignancy, uncontrolled infection, contralateral disease, and operative risk when it is prohibitively high.

Conventional Approach

In the majority of patients for whom decortication is performed via a thoracotomy, the classic operative technique suggested by Williams⁴ and Samson⁵ is still used and will be described briefly in the following text. The basic tenets of the operation include complete pleurolysis, establishment of a decortication plane between the fibrous peel and the visceral pleura, and decortication of all pleural surfaces, including the diaphragm.

After induction of general anesthesia, flexible bronchoscopy is performed to rule out the presence of endobronchial obstruction. The use of a double-lumen endotracheal tube is preferred because frequent ventilatory changes (i.e., intermittent inflation of the affected lung) may be used during the procedure. Although a posterolateral thoracotomy traditionally has been preferred, a muscle-sparing thoracotomy still can be used without impairment in visualization. The chest is entered through the sixth interspace to provide better exposure of the lower lobe and the diaphragm, where the peel is usually thicker and the adhesions denser. Unless the chest is severely contracted and the ribs tightly apposed, rib resection usually is not required. One or two ribs may be shingled posteriorly to facilitate exposure, however.

Before inserting the chest retractor, the pleural space is bluntly developed for a distance of a few centimeters, sometimes in an extrapleural plane as necessary (Fig. 132-4). The need for complete extrapleural dissection is controversial. Most surgeons advocate this maneuver to ensure complete chest wall expansion. The counterargument is that extrapleural dissection may lead to significant bleeding and also can be extremely tedious at the apex of the lung and over the mediastinum. Regardless of whether the parietal pleura is left in place, complete lysis of all pleural adhesions is required. Any loculated spaces are drained and the contents are sent for culture. Concern about contamination of the remainder of the pleural cavity by drainage of such spaces is not justified; the immediate priority in treatment of pleural infections is lung reexpansion and that should be accomplished as completely as possible.

When the visceral peel is encountered, it is incised in layers until the underlying visceral pleura is identified (Fig. 132-5). The most favorable location to initiate the dissection is usually the lateral surface of the lung, away from the diaphragm, where the fibrous peel is usually thicker. The peel then is dissected bluntly off the pleura; we prefer to use a peanut dissector or the tip of a metal sucker for this purpose. The lung usually is kept inflated at this stage to facilitate separation of the peel (Fig. 132-6). As the decortication progresses; however, the inflated lung impairs visualization, and the final stages usually are performed with the lung collapsed. Minor air leaks from the raw surface of the pulmonary parenchyma are unavoidable but heal quickly if the lung is fully reexpanded. Depending on the degree of inflammation and the presence or absence of parenchymal disease, complete decortication may be impossible in certain areas without significant parenchymal injury. In these cases, it is better to leave some layers of the peel behind than to create a severe and difficult-to-manage air leak. In addition, the remaining peel can be incised in several locations, akin to relaxing incisions, thereby allowing some reexpansion of the underlying lung (Fig. 132-7).

After the decortication is complete, hemostasis is obtained, and the pleural cavity is irrigated and drained widely. We prefer to use three chest tubes. Two straight tubes are laid posteriorly in the costovertebral recess and anteriorly to the hilum, respectively, and directed toward the apex. The third (right-angle) tube is placed between the diaphragm and the lung base and directed posteriorly toward the posterior costophrenic recess.

Thoracoscopic (i.e., video-assisted thoracic surgery) drainage of a hemothorax or early-stage empyema has been established as the surgical approach of choice over the last decade.^2,6,7 Its use in cases of organized empyema, as well as other causes of fibrothorax, is not as widely accepted. Cheng et al.⁸ reported a small series of decortications for chronic empyema, primarily in patients deemed unfit for thoracotomy. Nine of ten patients had resolution of the empyema. Kim et al.⁹ reported on 70 patients who underwent thoracoscopic decortication for empyema with the use of an endoscopic shaver system. Decortication was successful in 65 of the 70 patients. Waller and Rengarajan¹⁰ performed thoracoscopic decortication in 36 patients with organized empyema Fifteen patients required conversion to thoracotomy for incomplete lung expansion, leaving 21 of the 36 patients (58%) with a successful outcome. This report describes in relative detail the technique for formal thoracoscopic decortication.

In our experience, video-assisted thoracic surgical decortication is almost always feasible in patients with fibrothorax not associated with long-standing empyema. A typical example is that of persistent pleural effusion after open heart surgery. These patients present with chronic effusions despite multiple thoracenteses. Another common population consists of trauma patients with hemothorax who have been treated inadequately by tube thoracostomy. Contrary to the cases of organized empyemas, access to the pleural space in these patients is easily obtained thoracoscopically. The lower lobes and varying parts of the upper lobes usually are encased with moderate-thickness fibrous peel and do not expand with lung inflation. The peel is incised with endoscopic scissors. Once an edge is bluntly developed and lifted with a grasper, an endoscopic peanut dissector or the tip of a metal sucker is used to separate the peel from the lung parenchyma (Fig. 132-8). Traction is applied on the peel either directly or, because of limited space, by rolling it on the grasper (Fig. 132-9). Usually it is incised and removed in several pieces, always leaving a small edge so that further dissection is facilitated. The dissection is initiated usually on the convex lateral surface of the lower lobe and extended radially to all directions. Thoracoscopy allows for improved visualization of the lung base and the diaphragm, where the peel is also separated in the same fashion. The pleural space is drained with two chest tubes, usually through the existing ports.

All tubes are maintained on suction to facilitate drainage of the pleural space and lung expansion. Reexpansion of the lung and obliteration of the pleural space can be enhanced by the use of elective positive-pressure ventilation in the immediate postoperative period. Before the chest tube is removed, or if the findings on chest x-ray are of concern, a CT scan may be obtained to identify the presence of any undrained collections. If found, a decision regarding chest tube manipulation or additional percutaneous drainage is needed, particularly in cases of empyema. Instillation of fibrinolytic agents may be an additional option, although data for their use in the postoperative setting are lacking. Occasionally, patients may be discharged with one or more chest tubes if there is a persistent air leak or continued drainage.

In the recent era, operative mortality for decortication ranges between 0% and 5%, determined primarily by the underlying medical comorbidities. The most common complications are hemorrhage, prolonged air leaks, persistent empyema, and wound infections. Generally, these complications can be minimized with meticulous operative technique, which involves careful dissection and avoidance of parenchymal injuries, and achieves complete lung reexpansion, probably the most important step in controlling the pleural space. In a recent study by Melloni et al,¹¹ extended duration of symptoms (>60 days) and prolonged conservative management (>30 days) were associated with increased morbidity. The best functional results are achieved in cases where the underlying lung parenchyma is free of any significant disease. In these cases, significant improvements are seen both in vital capacity and in forced expiratory volume in 1 second, as well as in lung perfusion, usually becoming apparent early in the postoperative period and extending up to 3 years after the decortication. The degree of lung reexpansion on chest x-ray correlates well with functional outcomes. Although it is thought that pleural disease of shorter duration usually leads to better results, occasional favorable outcomes have been reported in patients with long-standing tuberculous pleuritic disease.

Failure to achieve a satisfactory outcome is usually due to one of the three factors: underlying parenchymal disease, incomplete operation, or development of postoperative complications. Occasionally, in the presence of a severely affected lung, parenchymal resection may be required because decortication alone will not achieve the desired reexpansion. Concomitant resections not only increase the potential for postoperative complications but also create new space problems, which often require even more extensive surgery (e.g., muscle flaps or thoracoplasty). Careful patient selection and decision making are required in such cases. The attention to meticulous technique that achieves complete lung expansion and avoids significant parenchymal, diaphragmatic, or phrenic nerve injuries cannot be overemphasized.

The primary cause of fibrothorax is undrained pleural fluid. Exertional dyspnea and chest discomfort are the most common symptoms. Early and aggressive treatment of undrained pleural collections can minimize the risk of developing a restrictive peel. Removal of the peel and complete reexpansion of the lung are keys to the success of decortication.

A lesson from clinical experience with tuberculous empyema is that the underlying entrapped lung will gradually expand and minimize the residual space; a routine observation in pediatric patients with common bacterial empyemas. This process of gradual adaptation, however, can require months to years. Furthermore, it is unclear if the gradual expansion of the underlying lung is associated with an increase in lung function.