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EDITORIAL |
Spain
INTRODUCTION
The role of surgery in pulmonary tuberculosis (TB) has changed from collapse therapy. Before chemotherapy, pulmonary resection for TB had a prohibitive operative mortality rate of 20–40%. The efficacy of modern antimycobacterial chemotherapy drastically reduced the indications for pulmonary resection to the treatment of complications of TB or sequelae such as tracheal or bronchial stenosis, aspergillomas growing on cavitated lesions, bronchiectasis, destroyed lungs, massive hemoptysis, bronchopleural fistulas, empyema, and also to rule out lung cancer in patients with pulmonary masses. Currently, the prevalence of TB remains high in many areas of the world. Resistance to antituberculous drugs has been noticed since the drugs were first introduced. During the 1980s, the epidemic of AIDS, changes in immigration patterns throughout the world, intravenous drug abuse, delay in diagnosis, insufficient health care infrastructures, and inappropriate treatments led to an increased incidence of resistance to chemotherapy, thereby allowing the emergence of multidrug-resistant tuberculosis (MDR-TB) as the most frequent indication for surgery in patients with localized TB lesions and a sufficient expected cardiovascular function after resection.1
MULTIDRUG-RESISTANT TUBERCULOSIS
MDR-TB is caused by Mycobacterium tuberculosis strains that are resistant to at least rifampin and isoniazid. Mutations can produce bacilli resistant to any of the currently used drugs against TB. Drug resistance may be primary or secondary. Primary resistance occurs in individuals with no history of previous treatment; these patients are initially infected with resistant organisms. Secondary resistance presents during therapy for TB, either because the patient was treated with an inappropriate regimen or because they were not compliant with the prescribed treatment. The prevalence of MDR-TB among patients with TB in the United States has increased from 2% to 9% in the past 3 decades.2 Results of medical therapy alone for MDR-TB are not satisfactory, and in 40% of cases there is treatment failure leading to a dismal prognosis with a mortality rate of 50%.1,3–5 Because of these high failure and mortality rates, surgical resection has been advocated to supplement medical therapy.1–2
SURGERY FOR MULTIDRUG-RESISTANT TUBERCULOSIS
Patients with MDR-TB usually present with either thick-walled cavitary lesions or with a destroyed lobe or lung that contains a substantial amount of bacilli, making it difficult for the penetration of antibiotics. Surgical removal of these bacterial foci is essential for cure. In patients with MDR-TB, destruction of the left lung requiring pneumonectomy occurs more frequently than that of the right lung.6–7 Timing of surgery in MDR-TB patients is very important for the success of radical resection. Attempts should be made preoperatively to produce a sterile sputum smear and culture.8–9 However, in approximately half of the patients with MDR-TB, this is not possible even with an adequate antibiotic regime.10 Some authors recommend surgical resection after 6 to 8 months of multiple drug treatment.10 Others advocate surgery after only a 3-month regime of chemotherapy.11 In general, surgery is indicated when the mycobacterial count in sputum reaches its expected nadir.
When surgical resection is indicated, oral intake should be supplemented with parenteral nutrition, because few patients requiring surgery have a normal body weight. Accurate assessment of operative risk and cardiorespiratory residual function is essential. The principle of mycobacterial surgery is to remove all gross disease, and this necessitates resection of all cavities as well as the destroyed lung tissue. The general thoracic surgeon should bear in mind the impact of technical difficulties and a high complication rate. Lobectomy or pneumonectomy has to be considered a high-risk procedure and technically cumbersome because of heavy intrathoracic adhesions and areas of chronic sepsis. Very often, resections have to be performed extrapleurally because of obliteration of the pleural space.10,12 Destruction of the left lung is found in 60–70% of patients referred for pneumonectomy.10–11 This may be related to anatomic factors such as smaller caliber of the left main bronchus, limited space surrounded by the aortic arch and enlarged lymph nodes, and the angle of its origin from the trachea, which results in bronchial compression, thus inducing retention of secretions and infection.13
Muscle flap reinforcement of the bronchial stump after surgery is advocated by the majority of authors to prevent postoperative development of bronchopleural fistula, especially in patients with positive sputum at the time of operation.10 The latissimus dorsi is most frequently utilized. However, Naidoo and Reddi14 performed bronchial stump reinforcement in only 2 patients and had no cases of fistula in their series. This fact, as commented by the authors, indicates that stump reinforcement still remains a matter of controversy. No differences in bronchial stump disruption have been reported between staple and suture closure.15 The most important factor in avoiding bronchial fistula is the correct placement of the resection line which has to fall on healthy tissue and as close as possible to the carina. Also, the endoscopic finding of tuberculous bronchitis may predispose to the development of bronchopleural fistula.16 In the series of Naidoo and Reddi,14 no case of bronchopleural fistula was observed after interrupted resorbable bronchial suture placement. Major complications have been described, ranging from 20% to 46%.6,8,11,13 Operative mortality has been reported to be in the range of 3% to 7.6%.7,16 Although their series was short, excellent results with no mortality was reported by Naidoo and Reddi.14
Postoperative individualized chemotherapy is essential to ensure long-term cure in patients with MDR-TB, even after removal of the largest lesions. This is because of a high prevalence of positive smear in the resected lung in patients with MDR-TB presenting with fibrocavitary lesions who had a preoperative negative smear.17 In most cases, postoperative antibiotic therapy is recommended for approximately 2 years after achieving a sterile sputum smear and culture. In patients with MDR-TB who are good surgical candidates, clinical and bacteriologic responses after surgery are gratifying, and cure can be obtained in more than 90% of cases if postoperative antibiotics are continued for the appropriate period of time.8,17
Given the increasing epidemic of MDR-TB, it is likely that lung resection in the 21st century will play an important role as an adjunct to chemotherapy in patients who have amenable lesions and who are treated with medical regimens deemed unlikely to effect permanent control of their MDR-TB. The recent contribution of Naidoo and Reddi14 is a good example of how an aggressive treatment can be instrumental in achieving excellent results in such a complex group of patients. However, the real answer to the problem of MDR-TB lies in prevention.
REFERENCES
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