Mesothelioma Update

By Mark Block, MD; and Alice M. Boylan, MD

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Pleurodesis

Pleurodesis generates intrapleural inflammation that causes pleural symphysis and obliteration of the pleural space, preventing reaccumulation of a symptomatic pleural effusion. Talc is the most effective agent for this task, and is equally effective when administered as an aerosol during thoracoscopy or as a slurry via an existing chest tube. For pleurodesis to be effective, the affected lung must be able to expand to fill the pleural space. This may not occur if tumor deposits on the visceral pleura create a “trapped” lung. Pleurodesis is ineffective in this setting because the visceral and parietal surfaces need to be in contact for pleural symphysis to occur.
If the diagnosis of mesothelioma has been confirmed and no additional biopsies are anticipated, then simple chest tube drainage and instillation of talc slurry is appropriate. Prior to chest tube placement, however, a large-volume thoracentesis should be performed. If the postthoracentesis chest radiograph demonstrates failure of the lung to expand (trapped lung), and the patient experiences minimal improvement in dyspnea, chest tube placement and pleurodesis are unlikely to be of benefit. A chest tube may evacuate the effusion, but the lung will not expand and the patient will be left with a tube draining a persistent space. In this setting, the chest tube acts as a foreign body; the longer it remains in the pleural space, the greater the risk of contamination and subsequent empyema. Placement of a Pleurx pleural catheter (Denver Biomedical; Golden, CO) is an option for these patients. With this system, an indwelling pleural catheter is placed during an outpatient procedure. Patients access the catheter at home at regular intervals to drain accumulated pleural fluid. This provides symptomatic relief without the need for prolonged hospitalization, and over a period of weeks to months, it may produce pleural symphysis.¹⁴ If the lung does expand with a large-volume thoracentesis and the patient experiences symptomatic improvement, chest tube placement is indicated. Care should be taken to avoid injury to the underlying lung and to place the tube in a dependent portion of the effusion. Larger-caliber catheters are most effective because the talc slurry can become viscous. Once talc has been instilled, daily chest radiographs should be obtained to insure that loculated collections do not form. If they do, prompt identification and catheter drainage is essential for optimal results.

If the diagnosis of mesothelioma is suspected but not confirmed, thoracoscopy should be performed. Multiple biopsy specimens can be taken and the underlying lung can be assessed intraoperatively for its ability to expand once the effusion has been drained. If the lung is not trapped, talc is insufflated at the completion of the procedure. Intraoperative talc insufflation has a success rate of better than 95% in this setting.¹⁵ As with pleurodesis performed with the chest tube already in place, vigilance against accumulation of loculated effusions in the postoperative period insures optimal results.

A particularly troublesome situation that should be avoided is any instrumentation of the pleural space that causes injury to the lung parenchyma in the setting of a trapped lung. Because the lung is unable to expand, pleural symphysis cannot occur and air leaks persist. Prolonged chest tube drainage because of the persistent air leak increases the risk of infection and empyema formation in the residual pleural space. If this situation is encountered, the chest tube usually can be removed safely, even in the presence of a sizable air leak. Early chest tube removal minimizes the risk of empyema.

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