One-Way Valves in Emphysema Treatment: What Should Bronchial Stenting Be Called and How Does It Really Work?

To The Editor:

As a group working for quite some time with one-way valves for emphysema treatment, we were excited to see Dr. Henry Fessler's editorial, "Collateral Ventilation, the Banc of Bronchoscopic Volume Reduction" (1). In fact, in 2004, at the 13th World Congress for Bronchology, in Barcelona, our colleague Dr. Oliveira proposed that a better designation for this treatment modality would be transbronchoscopic pulmonary emphysema treatment, or TPET, as we have been calling it (2). "TPET" acknowledges the fact that the bronchoscope is not part of the treatment per se but rather a means to deliver the treatment, and accounts for other techniques (e.g., Spiration umbrella [Spiration, Redmond, WA], Watanabe's spigot, Exhale airway bypass system [Broncus Technologies, Inc., Mountain View, CA], and Ingenito's experimental chemical atelectasis). It also avoids confusion with the lung volume reduction surgery (LVRS) procedure, and recognizes that volume reduction is not achieved in all cases (which does not mean absence of improvement in pulmonary function).

We were also inspired by Hopkinson and colleagues' article (3), which addresses many of the issues we have been facing. Of special interest are the criteria to measure improvement after TPET. Hopkinson and coworkers chose cycle endurance time as their main outcome measure, but they recognize that there is "no widely accepted definition of what constitutes a clinically significant change in endurance time at any given workload." Several possibilities could be suggested to determine improvement in patients with EBVs, but all seem to depend on arbitrary definitions of significant change.

The issue of improvement is closely related to the issue of patient selection. Currently, computed tomography (CT) scans, pulmonary scintigraphy (perfusion/ventilation), pulmonary function tests, and the 6-minute walk test (6MWT) are the choices for selecting patients for TPET. To deal with a population whose clinical status is more severe than that reported in the literature so far, we began to select patients based on the presence of dynamic hyperinflation as identified in pulmonary function tests performed before and right after the 6MWT. This has proven worthwhile: the results are impressive, especially when coupled with CT scans performed before and immediately after physical effort (unpublished data). We believe that collateral ventilation is the central issue regulating volume reduction in emphysema, and that it may explain why atelectasis is not always achieved with TPET. The significance of the completeness of lobar fissures is open to further research.

In short, after implanting valves in 20 patients, we are convinced that EBVs lessen the problem of dynamic hyperinflation.

Conflict of Interest Statement: A. M.-N. and the Medical Foundation of Rio Grande do Sul, a nonprofit research agency associated with Hospital de Cl icas de Porto Alegre, Dr. Macedo-Neto's institution, were appointed to manage a grant received from Emphasys Medical, Inc., for participation in a multicenter clinical trial. From May 2002 to May 2005, $82,000 was transferred to the Medical Foundation of Rio Grande do Sul, of which $12,000 was given to Dr. Macedo-Neto as a scholarship for participating in the clinical trial. H.G.O. and the Medical Foundation of Rio Grande do Sul, a nonprofit research agency associated with Hospital de Clinicas de Porto Alegre, Dr. Oliveira's institution, were appointed to manage a grant received from Emphasys Medical, Inc., for participation in a multicenter clinical trial. From May 2002 to May 2005, $82,000 were transferred to the Medical Foundation of Rio Grande do Sul, of which $12,000 was given to Dr. Oliveira as a scholarship for participating in the clinical trial.

AMARILIO MACEDO-NETO

HUGO G. OLIVEIRA

Hospital de Clinicas de Porto Alegre

Porto Alegre, RS-Brazil

References

1. Fessler H. Collateral ventilation, the banc of bronchoscopic volume reduction (editorial). Am J Respir Crit Care Med 2005;171:423-424.

2. Oliveira HG, Macedo-Neto A. Transbronchoscopic pulmonary emphysema treatment (TPET). J Bronchology 2005;12:271.

3. Hopkinson NS, Toma TP, Hansell DM, Goldstraw P, Moxham J, Geddes DM, Polkey MI. Effect of bronchoscopic lung volume reduction on dynamic hyperinflation and exercise in emphysema. Am J Respir Crit Care Med 2005;171:453-460.

From the Authors:

We thank Drs. Macedo-Neto and Oliveira for their interest in our paper on the effect of bronchoscopic lung volume reduction on dynamic hyperinflation in emphysema (1). Regarding nomenclature, although we don't think that it is the most important issue, our preference remains for "bronchoscopic lung volume reduction" (BLVR), which seems to be the term most established in the literature (1-6). We would suggest that the introduction of another acronym into contention at this stage is unlikely to be helpful, and we remain unconvinced that the term "transbronchoscopic" conveys any additional meaning compared with the more popular "bronchoscopic."

On the more important issue of patient selection, we would caution that although BLVR improves exercise performance by reducing dynamic hyperinflation, we did not find that the degree of dynamic hyperinflation, expressed either in relative or absolute terms, occurring in individual patients preprocedure, predicted benefit from valve placement. Issues regarding patient selection for bronchoscopic techniques will hopefully become clearer as the results from larger randomized studies become available.

Conflict of Interest Statement: Neither of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript.

NICHOLAS S. HOPKINSON

MICHAEL I. POLKEY

Royal Brompton Hospital

London, United Kingdom

References

1. Hopkinson NS, Toma TP, Hansell DM, Goldstraw P, Moxham J, Geddes DM, Polkey MI. Effect of bronchoscopic lung volume reduction on dynamic hyperinflation and exercise in emphysema. Am J Respir Crit Care Med 2005;171:453-460.

2. Ingenito EP, Reilly JJ, Mentzer SJ, Swanson SJ, Vin R, Keuhn H, Berger RL, Hoffman A. Bronchoscopic volume reduction: a safe and effective alternative to surgical therapy for emphysema. Am J Respir Crit Care Med 2001;164:295-301.

3. Ingenito EP, Berger RL, Henderson AC, Reilly JJ, Tsai L, Hoffman A. Bronchoscopic lung volume reduction using tissue engineering principles. Am J Respir Crit Care Med 2003;167:771-778.

4. Toma TP, Hopkinson NS, Hillier J, Hansell DM, Morgan C, Goldstraw PG, Polkey MI, Geddes DM. Bronchoscopic volume reduction with valve implants in patients with severe emphysema. Lancet 2003;361: 931-933.

5. Snell GI, Holsworth L, Borrill ZL, Thomson KR, Kalff V, Smith JA, Williams TJ. The potential for bronchoscopic lung volume reduction using bronchial prostheses: a pilot study. Chest 2003;124:1073-1080.

6. Venuta F, de Giacomo T, Rendina EA, Ciccone AM, Diso D, Perrone A, Parola D, Anile M, Coloni GF. Bronchoscopic lung-volume reduction with one-way valves in patients with heterogenous emphysema. Ann Thorac Surg 2005;79:411-416.

© 2006 American Thoracic Society Provided by ProQuest LLC. All Rights Reserved.