Methods For Lung Volume Reduction Research Articles

Review of lung sealant technologies for lung volume reduction in pulmonary disease.

Emphysema is an incurable and underdiagnosed disease with obstructive ventilatory impairment of lung function. Despite decades of research, medical treatments available so far did not significantly improve the survival benefits. Different bronchoscopic methods for lung volume reduction (LVR) in emphysema were used in the past 2 decades aiming to close the airways serving the hyperinflated lung regions and to allow the gas in the more distal bullas to be absorbed. Sealants and adhesives can be natural/biological, synthetic and semisynthetic. In lung surgery, lung sealants are used to treat prolonged air leak, which is the most common complication. Sealants can also be applied in bronchoscopic lung volume reduction (BLVR) as they administer into the peripheral airways where they polymerize and act as tissue glue on the surface of the lung to seal the target area to cause durable permanent absorption atelectasis. Initial studies analyzed the efficacy of bronchoscopic instillation of a fibrinogen–thrombin complex solution in advanced emphysema. Future studies will analyze the effects of adding chondroitin sulfate and poly-L-lysine to thrombin–fibrinogen complex thus promoting fibroblast attachment, proliferation and scarring, causing bronchial fibrostenosis and preventing ventilation of the affected part of the lung. Modifications of these methods were later developed, and the efficacy of BLVR with other sealants was analyzed in clinical studies. Results from current studies using this treatment method are promising showing that it is effective in improving exercise tolerance and quality of life in patients with advanced emphysema. It seems that subjective benefits in dyspnea scores and quality of life are more marked than improvements in lung function tests. The safety profile of sealant techniques in BLVR was mostly acceptable in clinical studies. The definite conclusions about the effectiveness of sealant in BLVR could be difficult because only a small population was involved in the current studies. More randomized large controlled studies are needed in establishing the definite role of biological BLVR in the bronchoscopic treatment of emphysema.

Effectiveness and efficacy of minimally invasive lung volume reduction surgery for emphysema.

Lung emphysema is a chronic, progressive and irreversible destruction of the lung tissue. Besides non-medical therapies and the well established medical treatment there are surgical and minimally invasive methods for lung volume reduction (LVR) to treat severe emphysema. This report deals with the effectiveness and cost-effectiveness of minimally invasive methods compared to other treatments for LVR in patients with lung emphysema. Furthermore, legal and ethical aspects are discussed. No clear benefit of minimally invasive methods compared to surgical methods can be demonstrated based on the identified and included evidence. In order to assess the different methods for LVR regarding their relative effectiveness and safety in patients with lung emphysema direct comparative studies are necessary.

Physiologic Basis for Improved Pulmonary Function after Lung Volume Reduction

It is not readily apparent how pulmonary function could be improved by resecting portions of the lung in patients with emphysema. In emphysema, elevation in residual volume relative to total lung capacity reduces forced expiratory volumes, increases inspiratory effort, and impairs inspiratory muscle mechanics. Lung volume reduction surgery (LVRS) better matches the size of the lungs to the size of the thorax containing them. This restores forced expiratory volumes and the mechanical advantage of the inspiratory muscles. In patients with heterogeneous emphysema, LVRS may also allow space occupied by cysts to be reclaimed by more normal lung. Newer, bronchoscopic methods for lung volume reduction seek to achieve similar ends by causing localized atelectasis, but may be hindered by the low collateral resistance of emphysematous lung. Understanding of the mechanisms of improved function after LVRS can help select patients more likely to benefit from this approach.

Design of the Endobronchial Valve for Emphysema Palliation Trial (VENT): a non-surgical method of lung volume reduction

BackgroundLung volume reduction surgery is effective at improving lung function, quality of life, and mortality in carefully selected individuals with advanced emphysema. Recently, less invasive bronchoscopic approaches have been designed to utilize these principles while avoiding the associated perioperative risks. The Endobronchial Valve for Emphysema PalliatioN Trial (VENT) posits that occlusion of a single pulmonary lobe through bronchoscopically placed Zephyr® endobronchial valves will effect significant improvements in lung function and exercise tolerance with an acceptable risk profile in advanced emphysema.MethodsThe trial design posted on Clinical trials.gov, on August 10, 2005 proposed an enrollment of 270 subjects. Inclusion criteria included: diagnosis of emphysema with forced expiratory volume in one second (FEV1) < 45% of predicted, hyperinflation (total lung capacity measured by body plethysmography > 100%; residual volume > 150% predicted), and heterogeneous emphysema defined using a quantitative chest computed tomography algorithm. Following standardized pulmonary rehabilitation, patients were randomized 2:1 to receive unilateral lobar placement of endobronchial valves plus optimal medical management or optimal medical management alone. The co-primary endpoint was the mean percent change in FEV1 and six minute walk distance at 180 days. Secondary end-points included mean percent change in St. George's Respiratory Questionnaire score and the mean absolute changes in the maximal work load measured by cycle ergometry, dyspnea (mMRC) score, and total oxygen use per day. Per patient response rates in clinically significant improvement/maintenance of FEV1 and six minute walk distance and technical success rates of valve placement were recorded. Apriori response predictors based on quantitative CT and lung physiology were defined.ConclusionIf endobronchial valves improve FEV1 and health status with an acceptable safety profile in advanced emphysema, they would offer a novel intervention for this progressive and debilitating disease.Trial RegistrationClinicalTrials.gov: NCT00129584