BMJ  2006;332:375-376 (18 February), doi:10.1136/bmj.332.7538.375

Editorial

Surgery for emphysema

New endoscopic techniques show promise

Emphysema affects 3.1 million people in the United States alone and causes severe disability and early death in up to 45% of patients.¹ Emphysematous destruction of the lung is associated with decreased elastic recoil pressure. As a result, the diseased lung requires less pressure than a normal lung to inflate and, once inflated, exerts less pressure to empty; lungs in emphysema therefore tend to remain inflated, with overexpansion of the rib cage and flattening of the diaphragm. Patients are trapped in a state of permanent hyperinflation and dyspnoea. No amount of effort can empty their lungs: the harder they strain to breathe, the more the airways collapse and obstruct the outflow of gas.

Current medical treatment with inhaled bronchodilators, glucocorticoids, mucolytics, and antioxidants may improve symptoms temporarily but does not prevent the decline in lung function. Various surgical procedures have been implemented in the past to relieve dyspnoea and improve quality of life for such patients.^w1 Early results of surgery were often encouraging, but surgery rarely achieved sustained objective functional improvement and most of those procedures were gradually abandoned.

Bullectomy is the only operation that has stood the test of time. It allows re-expansion of restricted but potentially functional adjacent lung tissue,² contributes to increased compliance and airway calibre, improves the ventilation-perfusion ratio (V/Q), and decreases the physiological dead space in the lung. Newer surgical procedures such as lung transplantation and lung volume reduction are now established procedures for selected patients, and endoscopic airway bypass and bronchoscopic lung volume reduction show promise.

International guidelines recommend lung transplantation as a viable option for a selected group of patients with end stage chronic obstructive pulmonary disease (COPD)—with forced expiratory volume (FEV₁) that is 25% lower than predicted, resting hypoxia, hypercapnia, secondary pulmonary hypertension, and a deteriorating clinical course.^w2 Transplantation can produce excellent functional results and improve quality of life.^w3 Patients with emphysema are ideal candidates for lung transplants because they experience a relatively slow functional deterioration and can tolerate a long wait for a suitable organ. They have enormous chest cavities, rarely suffer adhesions, and rarely have pulmonary hypertension. About 30% of all lung transplants are done for patients with chronic obstructive pulmonary disease,^w1 and they have better postoperative outcomes than patients with other diseases such as pulmonary fibrosis or primary pulmonary hypertension.^w3

The choice of single versus bilateral transplantation in patients with emphysema remains controversial. Younger patients and those with giant bullae or bronchiectasis should be considered for bilateral transplantation to improve lung function and increase life expectancy and to avoid potential complications associated with having one remaining diseased lung. But bilateral transplantation reduces the potential for organ sharing and diminishes the already limited pool of donor organs. Moreover, chronic rejection due to obliterative bronchiolitis affects most patients within as little as five years after surgery, limiting long term survival substantially.³

An alternative to transplantation is lung volume reduction surgery. This reduces the size of the lungs and thereby can restore the lost circumferential pull on small airways, reduce hyperinflation, and can, on average, increase FEV₁ by about 50% in most patients.^{4-8 w4} The most destroyed areas of the lung, easily identified preoperatively by high resolution computed tomography and V/Q scanning, are removed with linear staplers. This allows re-expansion and return to function of the adjacent more normal lung. But such surgery is only palliative and is associated with substantial morbidity; hence it is suitable only for selected patients needing temporary improvement in symptoms and quality of life.^4-7 Only those patients with poor exercise capacity and with emphysema localised to the upper lobe survive longer after surgery than after medical treatment.⁸

The indications for lung volume reduction surgery and transplantation overlap considerably. Younger patients with clear contraindications to lung volume reduction (such as increased pulmonary artery pressure and hypercapnia) should undergo lung transplantation, while older patients and those with contraindications to transplantation should undergo volume reduction surgery. The choice should be taken on a case by case basis, after careful discussion with the patient, keeping in mind that volume reduction surgery could also be used as a bridge to lung transplantation.

There is preliminary evidence for minimally invasive surgery such as airway bypass and bronchoscopic lung volume reduction. Both techniques aim to improve respiratory mechanics through functional exclusion of emphysematous areas of the lung without exposing patients to the risks of a conventional operation.

Airway bypass aims to improve respiratory mechanics by creating new exit pathways for the air trapped in emphysematous lungs. Under bronchoscopic guidance the surgeon punctures the wall of the segmental bronchus and inserts a stent, thereby creating an internal bronchopulmonary communication for expiration. The aim is to reduce hyperinflation, improve respiratory mechanics, and alleviate dyspnoea. The procedure has been progressively modified to improve results and prolong the period of patency of the stents. The evidence for airway bypass is at an early stage though, comprising mainly an experimental model⁹ and a study of safety and efficacy in 15 patients having lobectomy for lung cancer or lung transplantation for emphysema.¹⁰

In bronchoscopic lung reduction surgery, one-way valves are placed in the segmental bronchi supplying the most hyperinflated parts of the emphysematous lung. Deflation and sometimes atelectasis of the target area prevent air entering from the target area of the lung while allowing air and mucus to exit. Pilot studies based on small case series show a functional improvement in selected groups of patients with heterogeneous emphysema,^{11 12} and a prospective multicentre trial is comparing bronchoscopic lung volume reduction surgery with maximal medical treatment. Although the early evidence for bronchoscopic lung volume reduction is encouraging, it will take long term follow-up and randomised controlled studies to clarify the role of these interventions.

University of Rome "La Sapienza," Policlinico Umberto I, Department of Thoracic Surgery, Viale del Policlinico, Rome 00100, Italy
(sofed{at}libero.it)

Cardiothoracic Unit, Barts and the London NHS Trust, London EC1A 7BE

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References w1-w4 are on bmj.com

Competing interests: FV participated in a pilot trial on the valve described in this editorial, where valves were provided free of charge from the company (Emphasys Medical, Redwood City, CA), which had no control over the conduct of the trial or the publication of the results. GB is an associate editor at the BMJ.

References

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3. Heng D, Sharples LD, McNeil K, Stewart S, Wreighitt T, Wallwork J. Bronchiolitis obliterans syndrome: incidence, natural history, prognosis and risk factors. J Heart Lung Transplant 1998;17: 1255-63.[ISI][Medline]
4. Cooper JD, Trulock EP, Triantafillou AN, Patterson GA, Pohl MS, Deloney PA, et Al. Bilateral pneumonectomy (volume reduction) for chronic obstructive pulmonary disease. J Thorac Cardiovasc Surg 1995;109: 106-19.[Abstract/Free Full Text]
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7. Naunheim KS, Kaiser LR, Bavaria JE, Hazelrigg SR, Magee MJ, Landrenau RJ et al. Long term survival after thoracoscopic lung volume reduction: a multiistitutional study. Ann Thorac Surg 1999;68: 2026-32.[Abstract/Free Full Text]
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10. Rendina EA, De Giacomo T, Venuta F, Coloni GF, Meyers BF, Patterson GA, et al. Feasibility and safety of the airway bypass procedure for patients with emphysema. J Thorac Cardiovasc Surg 2003;125: 1294-9.[Abstract/Free Full Text]
11. Toma TP, Hopkinson NS, Hiller J, Hansell DM, Morgan C, Goldstraw PC, et al. Bronchoscopic volume reduction with valve implants in patients with severe emphysema. Lancet 2003;361: 931-3.[CrossRef][ISI][Medline]
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