From Our ArchivesMedical Author: Zab Mohsenifar, MD
Medical Editor: Leslie J. Schoenfield, MD, PhD
Emphysema is a crippling disease that affects almost 2 million people in the USA. Smoking is the principal cause of emphysema. Genetic (inherited through genes) forms of emphysema, however, also exist. These genetic forms are caused by certain biochemical (enzyme) deficiencies in the lungs. The main symptom in patients with emphysema is shortness of breath at rest and even more so during exercise. The traditional medical treatment of emphysema includes drugs that widen or open the air passages (bronchodilator drugs), oxygen, exercise programs (regimens), and steroids when the disease worsens (exacerbates). I should point out, however, that oxygen therapy is the only treatment that has been associated with an actual improvement (increase) in the duration of life (survival) for certain patients with emphysema.
Emphysema is generally a diffuse disease of the lungs. Diffuse means that the disease is spread throughout and involves the entire lungs. Some parts of the lungs, however, may be involved more than other parts. For example, emphysema involves predominantly the upper parts (lobes) of the lungs in smokers and the lower lobes in people with the enzyme deficiencies. Conceivably, therefore, surgical removal (resection) of the diseased parts of lung can result in expansion of the healthy areas of lung. Expansion of the remaining lung would be expected to occur to make up (compensate) for the surgical loss of lung volume or just to fill the void. This expansion of lung tissue is the main principle and the rationale behind Lung Volume Reduction Surgery.
Numerous studies since the 1950s have suggested that surgical resection of the diseased portion of the lungs (lung volume reduction surgery) may benefit patients with emphysema. In the past, one of the biggest problems with this surgery has been that air can leak from the sutured (sewn closed) surface of the remaining lung. You see, the air can leak because the diseased (emphysematous) lung tissue may not heal well enough to hold the sutures properly. Moreover, continuous air leaks can create additional problems, such as infection in the lungs. With the development of new techniques for effectively closing off the remaining lung surface, however, this issue of air leakage has been somewhat resolved.
Nevertheless, important questions regarding lung volume reduction surgery still remain. These questions include:
- How effective is lung volume reduction surgery?
- Which patients might be expected to benefit from this operation?
- How long will the benefits of the operation last?
To answer these and other questions, the NIH (National Institutes of Health) and CMMS Center for Medicare and Medicaid Services) in 1996 organized a randomized clinical trial for the treatment of emphysema. In randomized trials, patients are assigned to one treatment or another simply by chance. This study is still ongoing. Patients at 17 participating major medical centers in the USA are randomly assigned to receive either maximal medical therapy or the lung volume reduction surgery. So far, close to 1100 patients with emphysema have entered the study.
Of course, we are anxiously awaiting the final results of this study. Recently, however, the investigators learned and revealed that the surgery indeed might harm certain patients, for example, those who had emphysema that was extremely severe and vastly diffuse (throughout the lungs). Thus, these particular patients did not benefit from the surgery and actually did not do well clinically after the surgery. (Emphysema was considered extremely severe if the result of a lung function test called the forced vital capacity (FEV1) was less than 20% of the predicted normal value.)
The study will continue for an additional 2 years, at which time the final data will be analyzed in detail. Already, it is very clear that some patients with emphysema can benefit substantially from lung volume reduction surgery. The questions remain, however. Just which patients will benefit and how long will the benefit last? We hope that the final results of this randomized clinical trial will largely provide the answers to these questions.