2015 American Thoracic Society Annual Meeting Highlights: Approaches to Lung Volume Reduction Surgery (LVRS) for Emphysema and Heterogeneity of COPD
National Emphysema Foundation President, Laurence G. Nair also attended another session at the American Thoracic Society’s annual meeting, titled “Approaches to Lung Volume Reduction Surgery (LVRS) for Emphysema,” which highlighted the strides that lung volume reduction techniques have made since introduced about 20 years ago.
The "less is better" approach notes the "large" lungs that patients with COPD have contribute to shortness of breath in several ways. Among them is overstretching of the muscles of the chest wall and diaphragm due to oversized lungs weaken the force with which they can move air in and out of the body, increasing the work of breathing. In addition, hyper-inflated areas of lung themselves often have less functional lung tissue (referred to as bullae or blebs) and in fact, these areas can even compress neighboring normal tissue, rendering them unable to perform their duties as well. For these reasons, there is a thought that removing these overinflated, non-functional areas, which are not contributing and even are damaging to proper lung function, could be helpful. The session went on to explain that there are two ways to accomplish this. One is lung volume reduction surgery and the other is placement of one-way valves or coils into bronchial tubes that lead to these areas and essentially close them off from air so they could not inflate. These types of interventions could take place during a bronchoscopy. Bronchoscopic placement is attractive because it is a much less extensive procedure than surgical removal and when effective, and is functionally sufficient for the patient. However, who it will work on and where to place the valve or coil are topics still under discussion. It often is not successful or results in only mild improvement.
Nair reported that “a group in attendance from Columbia University, who are proponents of surgical lung reduction, brought up some interesting points.” They explained that with surgery, you can remove more damaged tissue and be more accurate as to what areas to take out. They also explained that the landmark study on LVRS was undertaken more than 20 years ago and that they feel the surgery is more refined now.” 20 years ago “the procedure was much more extensive and required a large incision. Now it can be done thorascopically (with several small incisions) so the surgery is much better tolerated than before.” The Columbia group felt surgery was the much more effective option and when successful has a track record of lasting improvement, whereas bronchoscopic lung reduction does not. Nair observed that most people in the room, though impressed by Columbia's track record, were not convinced surgery has proven to be safe enough to be thought of as the clear cut first option at this time. However, the spirited discussion is sure to spur some insightful ideas for future research in this interesting but still "not yet ready for prime time" area of treatment.
Dr. Laurence G. Nair was also in attendance at a session that highlighted the “heterogeneity” of chronic obstructive pulmonary disease (COPD). The moderators explained that it has been known for a long time that COPD patients can differ in several ways, among them, physical characteristics, pathophysiologic changes and the areas of the lung that are most diseased. The classic COPD profiles include the “blue bloaters” who are generally are more rotund, have lower oxygen in their blood, and produce abundant phlegm on a daily basis. This type of description is of someone who has "chronic bronchitis". Then there is the “pink puffer”, who generally has a normal oxygen level but is thinner and has a more hyper-inflated chest wall. They are the classic “emphysema" patient. Another type of COPD patient is more "wheezy" and has a sprirometry test that shows they are very responsive when tested for bronchodilator medication. This is very similar to those diagnosed with asthma. These types of patients are considered "overlap patients", meaning they have characteristics that “overlap” both COPD and asthma.
Data was presented from The COPD gene study, a National Institutes of Health-funded study conducted between 2008 and 2011. The study collected an array of information from about 10,000 smokers in an effort to find out why some smokers develop COPD and some do not, as well try to see if new more intricate classification schemes can be found to better identify different types of COPD. This was done by analyzing a more robust set of data including clinical variables, genetic analysis and evaluation of CT scans to view anatomic changes in each study participant. There is a "treasure trove" of data available to be mined at the genetic and cellular level to try to find new unique subtypes within the umbrella of COPD, Now scientists have the ability to identify clusters or groups with distinct profiles. Whereas, “pink puffer/blue bloater” identifiers differ by only a few basic variables, current analysis can cull through innumerable variables and find patterns that are more clinically unique, allowing for the creation of tailored or personalized therapies for individual patients. Additionally, Nair noted that this type of information could also help identify “people who more susceptible to develop rapid progression of COPD earlier than by current means. It may also allow a physician to match a given individual within a specific disease profile to the best medical treatment for them as opposed the current trial and error approach to find which medication regimen works best for someone.
Another interesting topic discussed during this session was the work done in the area of micro CT scans. A symposium lead by Dr. J.A. Hogg, a prominent pulmonary pathologist working out of Vancouver, cited findings that correlate micro CT scans with direct microscopic analysis of COPD excised lungs he did several decades ago. Dr. J.A. Hogg noted was that in the direct specimens, the loss of a part of airways called the ‘terminal bronchioles’ is the earliest finding of damage to the lungs that occurs in COPD. This finding, which can be seen on a micro CT scan occurs before evidence of COPD can be detected by traditional CT scan.” Therefore, these initial phases of COPD are "silent" and cannot be identified by today's most commonly used techniques. New technologies, such as the micro CT scan, offer the hope of finding COPD in its earliest stages. With more rapid detection of COPD, hopefully, will come earlier intervention to arrest the progression of emphysema in its tracks.