A New Approach to the Vanishing Lung

 Chun K. Yip, M.D.

 (Scientific Award Lecture, CAMS 2005 Annual Meeting)

Chronic obstructive pulmonary disease (COPD) is one of the most common diseases that affect many people around the world.  It is the only major chronic disease that is still on the rise in mortality.  It has been disappointing and frustrated, for both the doctor and patients alike, in caring for patients with advanced COPD.  The relentless progression of the disease leaves the patients markedly short of breath, and debilitated.  However, with advances in medical research and technology, there are now new innovations that offer hope to these patients.  Lung volume reduction surgery (LVRS) is such a new approach.

 For years, various surgical interventions have been attempted for emphysema.  Only bullectomy was shown to be effective for giant bullous emphysema.  Lung transplant is the ultimate surgical options for any end-staged lung disease, including emphysema.  However, there is severe shortage of donor lungs.  LVRS was recently introduced as an alternative and new treatment option for severe emphysema. 

It downsizes the lung by resecting 20-30% of the most diseased part of the lung.

The exact mechanisms of how and why LVRS works are not known.  But, possibilities include:

1) It improves lung and chest wall mechanics by increasing the elastic recoil pressure of the lung, and restores the outward circumferential pull on the bronchioles, thereby improving expiratory flow.

2) It improves the mechanical function of the diaphragms and intercostal muscles, by decreasing the functional residual capacity, and returning the diaphragms to a more normally curved, and, mechanically more advantaged and lengthened configuration.

3) It restores and improves left ventricular function of the heart.

4) It causes decreased central respiratory drive.

Advances in medical technology have made LVRS possible by reducing surgical and post-operative complications.  Control of air leak is achieved by employing new surgical techniques using a surgical stapler, and buttressing the staple lines with bovine pericardium.  It is also aided by innovative post-operative management techniques, such as, avoiding positive pressure ventilation after surgery, and avoiding suction on chest tubes.

Effective post-operative pain control with epidural analgesia also contributes to the reduction in mortality and morbidity.

 Early reports suggested that LVRS in properly selected patients with severe emphysema led to improved pulmonary function, dyspnea, exercise capacity, and quality of life.

 These were confirmed by the recent federally sponsored National Emphysema Treatment Trial (NETT), which was a multi-center, randomized clinical trial comparing the risks and benefits of medical treatment with LVRS to medical treatment alone in patients with severe emphysema.  In this large 7-year study, 3,777 patients were evaluated.  1,218 patients underwent randomization.

 Results of the study also showed that, as a whole, LVRS offered no survival benefits over medical treatment alone at the 2-year mark.  But it conferred survival benefit in the subgroup of patients with upper lobe predominant emphysema and low post-rehabilitation exercise capacity.  It also demonstrated that LVRS could be performed with a relatively low perioperative mortality of 5% in appropriate candidates. 

 Additional outcomes of the trial include:

1) LVRS by median sternotomy or video-assisted thorascopic surgery (VATS) offered the best functional outcome, with sustained improvement of FEV1, 6-min walk, and gas exchange.

2) VATS approach allowed earlier recovery at a lower cost than median sternotomy.

3) Cost analysis showed that LVRS is costly relative to medical therapy, but it may be cost effective if benefits can be maintained over time.

 Less invasive alternative approaches to volume reduction are being actively investigated.

Of these, endobronchial volume reducing methods are most attractive. These include:

1) Instillation of sealants, such as fibrin glue

2) Placement of plugs endobronchially

3) Placement of one-way valves by bronchoscopy to cause collapse of emphysematous portions of lung to achieve lung volume reduction.

 Early experience of endoscopic valve in human is encouraging, and, several randomized clinical trials are ongoing.

 In conclusion, emphysema is no longer an untreatable disease.  Many therapeutic options are now available, including the new lung volume reduction surgery for selected patients.  With continued rapid advancement in medical research and technology, even more effective treatments will soon be available for this once dreadful disease.

 Dr. Yip is Clinical Professor of Medicine, Columbia University

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