Measuring Collateral Ventilation for Bronchoscopic Volume Reduction

Dear Dr. Mahler:

I read your post on December 11, 2015, about the need to measure collateral ventilation to know who might benefit from placing valves into the airways to collapse parts of emphysema lung. My pulmonary doctor has mentioned a study/program in Boston that I am considering.  I have “advanced emphysema” and am limited in doing anything more than daily activities.  I struggle with yard work, raking, and even walking our dog. I would like to know more about how is collateral ventilation measured?  Is this complicated?

Many thanks.

Albert in Saco, ME

Dear Albert:

Your question is quite important. Studies have shown that the valves are effective in collapsing lung that is not working only if there is no collateral ventilation present. Please review information about collateral ventilation on my December 11 post.

To answer your question, there are several ways to measure whether someone has collateral ventilation. If a valve is placed in a lobe in the lung with collateral ventilation, the lobe will not collapse and therefore will not help you breathe easier. In the article by Kloosters and colleagues published in the New England Journal of Medicine, the authors used a method called the Chartis System. This system was developed by Pulmonx, a company who makes the Zephyr valves used in the study.

Here is a brief summary. I will try to make this complicated process as simple as possible.

First, you are given medication to make you sleepy and temporarily forgetful

Bronchoscopy used to measure collateral ventilation

Diagram of scope passed thru mouth into the lungs (called bronchoscopy)

(called conscious sedation). Then, a bronchoscope is passed through your nose or mouth into the breathing tubes (airways). A plastic tube is then passed through the scope, and a balloon at the end of the plastic tube is inflated to block flow or air to the “target’ lobe.

The tip of the plastic tube extends beyond the balloon and can measure any air flow to determine whether collateral ventilation is present or not (see figure below).

System used to measure collateral ventilation

Scope on right with plastic tube and balloon inflated that blocks flow of air into the lobe.

You can find more information on the website:    https://pulmonx.com/ous/products/chartis-system/

Placement of valves into emphysema lobes has been approved in most counties in western Europe and is a common treatment for advanced emphysema in Europe. However, in the US, the Food and Drug Administration has not approved this procedure at the present time. So, you will need to go to a medical center doing a study on placement of valves for emphysema. Beth Isreal-Deaconess Medical Center in Boston is the nearest center to Saco, Maine, doing this research procedure. Certainly, your pulmonary physician can refer you for evaluation if you are interested.

Best wishes,

Donald A. Mahler, M.D.

Valves for Emphysema

New Study on Endobronchial Valves as Treatment for Emphysema

The results of a new study evaluating placement of valves inside the lung – called bronchoscopic lung volume reduction – was published in the December 10, 2015, issue of the New England Journal of Medicine.

Diagram of scope passed thru mouth into the lungs (called bronchoscopy)

Diagram of scope passed thru mouth into the lungs (called bronchoscopy)

Background: With bronchoscopic lung volume reduction, valves are placed into the breathing tubes to block the flow of air out of the specific area of the lung. This collapses part of the “bad” lung which is not functioning and allows the “good lung” to expand.  This allows the diaphragm (the main breathing muscle) to work more effectively. Ideally, this will improve lung function and make it easier to breathe.  A diagram of how bronchoscopy is done is shown on the left below; a view of one of the valves used in the study is shown on the right below.

Zephyr valve used in the study

Zephyr valve used in the study

 

 

 

Zephyr valve prevents air from entering the lung. Air can only move out of the lung,  resulting in collapse of emphysema lung.

Zephyr valve prevents air from entering the lung. Air can only move out of the lung, resulting in collapse of emphysema lung.

 

 

 

 

 

 

 

 

Unfortunately, this procedure does not work for everyone who has emphysema. Researchers around the world are trying to find out the best candidates for this treatment. One reason that bronchoscopic lung volume reduction may not work is if someone has a hole or defect in the fissure that separates lobes in the lung. A brief anatomy lesson will help to explain this concern. There are 3 lobes or discrete parts in the right lung and 2 lobes or discrete parts in the left lung. In the figure below, fissures are shown by black curves.

Diagram showing 3 lobes in the right Lung and 2 lobes in the Left Lung. The black curves are fissures which separate the lobes. If there is a defect in a fissure, putting in a valve into one breathing tube will not collapse the desired part of the lung.

Diagram showing 3 lobes in the right Lung and 2 lobes in the Left Lung. The black curves are fissures which separate the lobes. If there is a defect or hole in a fissure, putting in a valve into one breathing tube will not collapse the desired part of the lung.

 

In some individuals, small openings or pores allow air to flow across the fissure from one lobe to another. This flow is called collateral ventilation.  However, this is not beneficial if the goal is to collapse a part of “bad” lung. The collateral ventilation allows air to bypass the lung blocked by the valves, just like a bypass road allows you to drive around or bypass a city.

Study: Klooster and colleagues at the University Medical Center in Groningen, Netherlands, were able to measure whether someone had collateral ventilation or not. In those who did not have collateral ventilation, 34 patients received endobronchial valves and 34 patients were the control group and treated with standard medical therapy.

Findings at 6 months: There were significant increases in breathing tests [by 140 ml in how much air can be exhaled in one second (FEV1) and by 347 ml in vital capacity (FVC)] and in the distance walked in 6 minutes (by 74 meters) in the valve group compared with the control group.  There were 23 serious adverse events in the valve group and 5 in the control group. One person who received valves died. Some individuals required removal of the valves (15%) or replacement of the valves (12%).

My Comment: These findings make sense. If you are going to have valves placed inside of your breathing tubes to collapse areas damaged by emphysema, the treatment team should make sure that you do not have collateral ventilation. This should lead to better overall benefits of bronchoscopic lung volume reduction.

Although the authors had patients report on their quality of life, I am disappointed that the researchers did not have the participants rate their shortness of breath with a valid questionnaire. Those with emphysema are bothered most by their breathing difficulty, and being able to breathe easier is one of the key goals of treatment.

Like another study that I summarized in September 2015 under COPD News, there are risks with the procedure and you need to weigh possible benefits and possible risks. Certainly, you should discuss these with you doctor and the specialists who perform this procedure.