Benefits of Endobronchial Valve Therapy: Results of the IMPACT Study
Reason for the Study: Placement of an endobronchial valve into the breathing tube has been shown to improve lung function and shortness of breath in those with emphysema mainly in the upper parts of the lung (called heterogenous emphysema). Whether this therapy is beneficial in those with diffuse emphysema (damage throughout the upper and lower parts of the lung) is unclear.
Study: This study was conducted in Austria, Germany, and the Netherlands. All subjects had severe emphysema with lung function [how much air was exhaled in one second (FEV1)] between 15% to 45% of the predicted value. A CT scan was performed in all subjects to assess the extent of emphysema. Only those with less than 15% difference in emphysema scores between the target lobe of the lung and the same lobe on the other lung were included.
All subjects were assigned by chance to receive placement of the Zephyr endobronchial valve (EBV) in one lobe of the lung OR usual care.
The study was reported in the November 1, 2016, issue of the American Journal of Respiratory and Critical Care Medicine, volume 194, pages 1073-1082.
Results: Of the 93 subjects, 50 received usual care and 43 received endobronchial valve placement. 17 subjects who were initially assigned to have a valve placed could not participate because they were found to have collateral ventilation (See post on 12/27/15 on measuring collateral ventilation and what it means).
On average, four valves were placed in each of the 43 subjects in the EBV group. After 3 months of treatment, there was improvement of 14% in FEV1 in the EBV group, while FEV1 declined by 3% in the usual care group. This 17% difference between groups was statistically significant.
Zephyr endobronchial valve used in the study
More subjects in the EBV group improved in walking distance for 6 minutes by 26 meters or more (50% versus 14% in usual care) and for quality of life by 4 points or greater (57% versus 25% for usual care).
Adverse Events: Over the 3 months period, 44% of the EBV group and 12% in the usual care group had serious adverse events. There were 12 pneumothoraces (air in the lining around the lung) in 11 subjects in the EBV group. All of these required the subject to be treated in the hospital with a tube placed between ribs to drain the air. In five of these subjects, one or more valves had to be removed.
Zephyr endobronchial valve prevents air from entering the lung. Air can only move out of the lung, resulting in collapse of emphysema lung.
Pneumothorax in right lung. Black arrow shows collapsed lung.
Conclusions: Endobronchial valve therapy can provide meaningful improvements in lung function, exercise tolerance, and quality of life in those with diffuse emphysema without collateral ventilation. Some subjects experienced serious adverse events, mainly pneumothorax (see chest xray above and diagram on left).
My Comments: Placement of endobronchial valves for those with advanced emphysema is common and considered standard of care in in many European countries. In the United States, this procedure is investigational as it has not been approved by the Food and Drug Administration. Studies are underway in the US to further evaluate endobronchial valve therapy.
Diagram of pneumothorax in left lung