Helping the homogeneous.

T he National Emphysema Treatment Trial (NETT) [1] helped clarify the patient selection criteria and expected risks and benefits of lung volume reduction surgery (LVRS) for patients with advanced emphysema. The NETT built on numerous earlier case series which showed that the greatest symptomatic and functional benefit accrued to patients with a predominantly upper lobe distribution of emphysema. In such patients who also had very low exercise tolerance, the surgery lowered their mortality risk over the next 5 yrs by about half. Importantly for patients in the USA, findings from the study were used to establish the criteria for Medicare coverage of the procedure. This opened the door for thousands of qualifying patients to undergo this life-enhancing and life-extending procedure. However, in the 6 yrs since, barely a trickle of emphysema patients has crawled through that door. In 2007 and 2008, only about a dozen lung volume reduction procedures per month were billed through Medicare (personal communication, J. Baldwin, Centers for Medicare and Medicaid Services). The reasons for this discrepancy are speculative, but could include concerns about the small but non-trivial operative mortality, the substantial morbidity of major surgery, the impermanence of improvement, and the difficulty predicting benefit for an individual despite propitious characteristics. Patients and their physicians have been making the intensely personal decision that the benefit of this surgery is not worth the risk. For patients whose emphysema is not in the upper lobe predominant distribution (about half of the patients enrolled in the NETT), the calculus is even less favourable. To redress this risk–benefit balance, a profusion of creative bronchoscopic approaches to the mechanical derangements of emphysema are under investigation. One method, primarily being studied for patients with diffuse, or ''homogeneous'' disease, creates holes, supported by drug-eluting stents, directly from segmental bronchi into the surrounding paren-chyma. This ''airway bypass'' allows decompression of under-ventilated space-occupying cysts and bullae. Gas trapped at a distance from the fenestrations can still find egress via the low resistance collateral channels present in emphysema. This method has shown modest benefits in pulmonary function, but has been handicapped by closure of the holes. The optimal size, number and location of the holes, as well as the safety of the procedure, remain to be determined [2]. Other methods use bronchoscopically placed one-way (expira-tory) valves to promote atelectasis of distal lung regions. These studies have also shown some modest benefits in lung function or symptoms, along …