Lessons from a Valve Trial

There are several theories to explain why post-obstructive pneumonia is not frequent with endobronchial valves. One relies on the postulation that the valve blocks mainly the inspiratory flow, while allowing some expiratory flow and mucus drainage. Thus, lung segments distal to the valve are exposed to fewer particles and microorganisms, and those that do get through can still be cleared. However, when a tumour or a true foreign body is present, there is residual inspiratory flow and particulate entry in the distal segments, the expiratory clearance is impaired, and local infections are more frequent. If this is true, then valve design and correct valve placement are essential for procedure’s safety. Better understanding of these observations is important for clinical progression of BLVR. However, much more research is required if we are to understand the factors that hinder or foster pneumonias with the use of valves. An unexpected complication observed with valves and confirmed by Sterman et al. [2] is the increased risk of pneumothorax after the procedure. Pneumothoraces were observed in trials performed with other valves as well, and therefore they are unlikely to be a complication specific to the Spriation device [3] . Interestingly, when Sterman et al. [2] modified their targeting strategy to exclude treatment of the lingular segments, the post-procedure pneumothorax rate diminished. This observation suggests that the treatment strategy can improve the safety of BLVR. Bronchoscopic placement of valves for lung volume reduction is one of the many procedures now being developed to replace surgical lung volume reduction. There are at least 5 different methods of bronchoscopic lung volume reduction (BLVR), involving valves, spigots, coils, steam and biological glue [1] . All are in different stages of development and none is in current clinical practice. In this issue of Respiration , Sterman et al. [2] report results from a pilot multicenter trial with Spiration IBV unidirectional valves. The valves were used for bilateral treatment of severe heterogeneous upper-lobe predominant emphysema. The trial results suggest that bronchial valve treatment is safe, can improve quality of life in the majority of patients and has multiple mechanisms of action. Most patients with severe chronic obstructive pulmonary disease are managed in the community or in a local hospital. There is thus a large number of respiratory physicians around the world that are primarily interested to hear when, and if, any BLVR treatments are going to be available in their local hospital. So how does the trial of Sterman et al. [2] contribute to the advancement of BLVR to routine clinical practice? Safety, and in particular the risk of post-obstructive pneumonias, was the main initial concern with BLVR. Sterman et al. [2] confirm what has been known from earlier work, that a bronchial occlusion with a one-way valve is safe overall and has little influence on the risk of pneumonias [3] . Published online: January 19, 2010