Endobronchial valves in a highly parsed emphysema population

Lung volume reduction surgery is a thoracic surgical procedure whereby the hyperexpanded lungs of patients with severe emphysema are reduced in size by surgical excision of, ideally, the areas that are most severely destroyed. This operation, usually done bilaterally and almost always by video-assisted thoracoscopy, substantially improves pulmonary function, dyspnoea, and quality of life in appropriately selected patients. Several clinical series show about a 50% mean improvement in forced expiratory volume in 1 s (FEV1), and increased survival has been shown in one subgroup of patients. Lung volume reduction surgery is among the most carefully studied operations in medicine, having been subjected to many randomised controlled trials, all of which established its eff ectiveness. However, as with all operations, lung volume reduction surgery engenders some risk. To receive the benefi ts, even appropriate candidates for lung volume reduction surgery must accept a 3–4% risk of perioperative death, a 1–2 week hospitalisation, and a several week period of recovery. Thus, there has been an eff ort to try to reduce the risk of lung volume reduction surgery and achieve the same physiological benefi ts by less invasive approaches. The best studied non-surgical approach to lung volume reduction is bronchoscopic placement of oneway endobronchial valves (bronchoscopic lung volume reduction) designed to shut down air infl ow to a segment or lobe, thereby allowing that region to collapse. Randomised studies with these valves, however, have shown very disappointing mean group improvements in various measures of lung function. These studies showed statistically, but not clinically, signifi cant changes when all patients were analysed. Post-hoc analyses have suggested, not surprisingly, that those with markedly heterogeneous disease and complete interlobar fi ssures (which do not allow collateral ventilation across them) improve more with valves than do other patients. In The Lancet, Claire Davey and colleagues compare bronchoscopic lung volume reduction with sham bronchoscopy in a randomised trial comprising 50 patients with heterogeneous emphysema and intact interlobar fi ssures. The authors show convincingly that prospective selection of patients with heterogeneous disease and minimal collateral ventilation yields substantially greater improvements than treatment of those without these characteristics. Although the results are not quite as impressive as in the post-hoc analysis of Sciurba and colleagues’ study, the present trial does show a median 8·77% (IQR 2·27–35·85) improvement in FEV1 after unilateral valve placement, as well as signifi cant improvements in exercise capacity (the higher mean improvement in FEV1 of 24·8% is skewed by a few high-responding outliers). Extrapolation, however unscientifi c, to expect a nearly doubled eff ect if bronchoscopic lung volume reduction is done bilaterally might achieve results that are perhaps half of what can be achieved by surgery (18% improvement in FEV1 with valves vs 30–50% with surgery). We declare no competing interests.