INDICATIONS/CONTRAINDICATIONS

Indications

Pleurectomy and decortication (P/D) originally pioneered as a therapy for mycobacterial tuberculosis empyema, has evolved to become an increasingly valuable surgical treatment for malignant pleural mesothelioma (MPM) and remains integral to the management of infectious empyema. The extent of P/D varies according to the burden of pleural disease, the extent of underlying lung entrapment, and whether the underlying disease is benign or malignant. P/D for MPM represents the most complete and extensive form of P/D and will be used to illustrate the fundamental approach, essential surgical techniques, perioperative considerations, and the common pitfalls and complications of the procedure.

The operative goal in both malignant and benign pleural diseases is to free the lung from its constrictive pleural process, fully re-expand the lung, and return the patient to normal respiratory function. In malignant cases, the additional need for removal of all macroscopic and microscopic tumors requires a more extensive and complete P/D, often with reconstruction of thoracic anatomy. Elements of this extensive form of P/D can often be excluded in benign cases because the volume of affected pleura and lung is often less, and complete removal of all areas of disease is not essential for an adequate therapeutic result.

Pleural effusion complicated by fibrothorax, resulting from chronic effusions or infectious empyema, is the most common benign indication for P/D. The potential space between the visceral and parietal pleura accumulates fluid secondary to an imbalance in the rate of production or reabsorption of pleural fluid. Infections of the lung, congestive heart failure, undrained hemothorax, or sympathetic effusions related to intra-abdominal pathology or postsurgical fluid, are the most common causes of pleural effusions.

Fibrin deposition within the pleural fluid and the formation of a dense fibrous pleural peel encases the lung in a collapsed and “entrapped” position, creating a larger potential space between the parietal and visceral pleura. Drainage alone will not correct this space problem. Reinflation of the lung with obliteration of the space is necessary for control of the effusion, pleurodesis of the pleural space, and for providing healthy vascularized tissue capable of transporting antibiotics and immune cells to the affected area.

P/D for malignant disease has been described for both primary and secondary malignancies of the pleura. Patients with malignant pleural metastases with diffuse pleural carcinomatosis, malignant effusions, or malignant lung entrapment, are generally not considered candidates for P/D because the overall prognosis is limited, the morbidity of the operation significant, and the results poor. Recovery from thoracotomy alone may require 3 months and if suspected survival is less than 12 months, the recovery time represents a significant morbidity compared to the overall palliative effect. However, in cases where long-term survival can be accomplished with control of metastatic disease, P/D has been well described. Metastatic thymoma to the pleura and diaphragm is amenable to P/D with disease control and long-term survival accomplished in many cases.

Recently, P/D has become increasingly common in the treatment of MPM. MPM is a rare but lethal primary pleural malignancy characterized by a diffuse pattern of pleural growth. MPM has an incidence of approximately one case per 100,000 in the United States, totaling nearly 2,000 to 3,000 cases per year. The primary causative risk factor for the development of MPM is asbestos exposure. The relationship between asbestos exposure and MPM was first described in the United States by Selikoff et al. in 1964. It is now commonplace for thoracic surgeons to inquire about asbestos exposure in patients found to have lung or pleural abnormalities. In addition to asbestos mining, an exposure history occurs most frequently in shipyard workers, construction and demolition professionals, plumbers, boiler repair servicepersons, and manufacturing workers in industries producing heat-resistant products. Another significant exposure risk occurs in family members who have had contact with contaminated work clothes.

In MPM, the disseminated involvement of the visceral and parietal pleura overlying the lung, pericardium, and diaphragm, makes complete macroscopic and microscopic resection challenging. Invasion into the chest wall is also common. The role of surgical resection, either with extrapleural pneumonectomy (EPP) or P/D remains controversial. However, to date, the best survival rates have been reported for patients who have undergone surgical resection within a multimodality setting in expert centers. Individual medical or surgical treatments, such as systemic chemotherapy, nonsurgical cytoreduction with radiation therapy, and palliative management of effusions without resection for curative intent have been shown to offer little survival benefit or durable control of the disease. A combined multimodality approach, with maximal surgical cytoreduction of tumor, systemic chemotherapy, radiation, and palliation of pleural space complications, offers the best chance for survival and the most durable long-term results.

Pleurectomy refers to the removal of the pleura, and decortication derives from the Latin term for removing the “cortex,” or rind, surrounding the lung. The goal of P/D in MPM is complete macroscopic removal of all tumors without removal of the underlying lung. To achieve maximum cytoreduction, P/D involves resection of the parietal pleura, visceral pleura, the pericardium, and in many instances, the diaphragm. In benign infectious cases, the visceral pleura may be separable form the fibrin peel and true visceral pleurectomy unnecessary, thus only the performance of a decortication needed. In malignant cases, tumor infiltration of both parietal and visceral pleura requires both P/D. Extended resection of the diaphragm and pericardium must be reconstructed to maintain normal thoracic and cardiac physiology.

In the treatment of MPM, the well-known complications of EPP and the high operative mortality reported have led many surgeons to offer similar cytoreduction with P/D, a less morbid operation with decreased respiratory perturbation. In addition, refinements in patient selection and perioperative care substantially decreased mortality rates. Most modern series have reported mortality rates of less than 4% with P/D and to date, there is no evidence showing superior survival benefits of EPP over P/D. Indications supporting P/D over EPP can be related to patient characteristics or tumor characteristics. In patients whom cardiovascular or respiratory reserve cannot tolerate pneumonectomy, P/D is clearly indicated. In early stage disease confined to the parietal pleura or confined to parietal and visceral pleura without involvement of underlying lung parenchyma, P/D provides surgical clearance of disease without the additional morbidity or mortality associated with pneumonectomy.

Contraindications

In cases of benign fibrothorax with lung entrapment, there are few absolute contraindications. However, in patients unfit for major surgery, or who have significant underlying lung or bronchial disease that will not permit reexpansion of the lung, other interventions should be considered. In the most high-risk patients, or those who have poorly controlled or ongoing pulmonary infections, chest tube thoracostomy or open-window drainage may provide adequate control of the infectious process without exposing the patient to undue surgical risk. If the duration or extent of the pleural process is less chronic or complex, a minimally invasive, or VATS approach, may be attempted, and the degree of pleural resection and decortication considerably less.

In malignant cases, patients with substantial tumor burden, and especially those with confluent sheets of tumor involving the entire lung, with obliteration of the pleural space, P/D is unfeasible. In addition, patients with multiple areas of chest wall invasion are not suitable for resection because multiple chest wall resections are not practical. Severe cardiorespiratory comorbidities and poor performance status are relative contraindications and must be addressed on an individual basis.

PREOPERATIVE PLANNING

All patients with confirmed MPM must have thorough imaging of the chest and upper abdomen with computed tomography (CT). If chest wall or neurovascular invasion is suspected an MRI should be obtained to confirm invasion and plan appropriate vascular or neurosurgical aspects of the operation. PET/CT scanning has greatly enhanced the ability to stage MPM patients and provide important prognostic information. Standardized uptake values (SUV) of greater than or equal to 10 have been correlated with a significantly shorter survival time and a 3.3 times greater risk of dying compared to SUV levels below 10. This suggests that PET may help to stratify patients for different treatments according to their metabolic activity. In addition, PET/CT can also be used to predict the presence of mediastinal “N2” lymphatic spread, which is considered a relative contraindication to resection in some centers. Preoperative mediastinoscopy is a safe and appropriate method for confirming the presence of tumor in the mediastinal nodes and can aid in patient selection. However, while mediastinoscopy is more accurate than CT scanning, up to 25% of patients with MPM will have lymphadenopathy in areas inaccessible to conventional mediastinoscopy, such as the peridiaphragmatic and internal mammary regions. In addition, while N2 disease does impart a worse prognosis, lymph node involvement should not be used as an absolute criteria denying surgical resection as most lymph node stations can be surgically cleared or treated with radiation therapy.

Preoperative pulmonary function tests (PFTs), ventilation/perfusion (V/Q) scans, and cardiac evaluation must be performed. PFTs must include forced expiratory volume in 1 second (FEV1) and diffusion capacity (DLCO). The disease process itself may impair the patient’s ability to comply with and perform adequately on PFTs. V/Q scans are helpful in cases where PFT results are questionable and provide a more accurate assessment of lung function. The perfusion data from the V/Q scan allows the most accurate calculation of the postoperative predicted values for the FEV1 and DLCO. Patients with postoperative predicted values of greater than 40% are considered acceptable for either EPP or P/D and those with values below 40% are candidates for P/D only. Cardiac evaluation should demonstrate an ejection fraction of greater than 45% without reversible ischemia; however, poor cardiac function is one determinant in favor of P/D.

In benign cases, radiographic tests such as standard chest x-rays and CT scans are adequate for the diagnosis of fibrothorax. Imaging that reveals a loculated collection, extensive pleural thickening, air–fluid levels within the effusion, or failed re-expansion of the lung after drainage, suggest entrapment of the lung and fibrothorax. Contrast-enhanced scans are the most sensitive test for identifying significant pleural thickening and enhancement of the pleura suggests active infection. Pleural fluid analysis revealing low glucose and pH, elevated LDH, and significant polymorphonuclear cells indicate a complicated effusion requiring immediate drainage. Chest tube thoracostomy with fibrinolytic therapy may be attempted. However, definitive management usually requires surgical P/D to adequately drain the entire effusion, re-expand the lung, and provide apposition of the lung to the chest wall, essential aspects of successful treatment.

SURGERY

Positioning

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