COPD: How long before the implantable lung is here?

Extracorporeal membrane oxygenation (ECMO) is often a last resort treatment for patients with acute respiratory failure. The method uses an external pump to circulate blood through an artificial lung back into the bloodstream. However, the use of ECMO for long-term support is not possible for patients with chronic respiratory failure. So far, a lung transplant is the only option in this case, but matching donor organs are in short supply.

In this MEDICA-tradefair.com interview, Prof. Rolf Rossaint explains how an implantable lung support system could function as a replacement, the foundation of which is currently being laid.

Prof. Rossaint, what is the goal of the priority program "Towards an Implantable Lung"?

Prof. Rolf Rossaint: A growing number of people suffer from chronic obstructive pulmonary disease (COPD). COPD is the fourth leading cause of death worldwide and is projected to become the third leading cause in just a few short years. Patients with an advanced stage of the disease frequently need some form of lung support. That is why we are working towards the creation of an implantable artificial lung, resembling modern artificial heart implants.

Modern artificial lung systems have major limitations - how are you planning to address these drawbacks?

Rossaint: In today's artificial lung systems, the blood encounters very large artificial surface areas, which is not so much the case with artificial hearts, for example. The blood passes membranes that facilitate the extracorporeal gas exchange. Activation of the coagulation system occurs on these surfaces, leading to complications from bleeding and development of blood clots in patients after a short time. This induces thromboses, which clog the oxygenator. A long-term application thus results in poor biocompatibility.

Our program studies various areas to find opportunities for improvement. We address questions such as "How can you implant this type of system? What strategies can prevent coagulation? Can we treat the oxygenator surface area, can patients take certain medications, or can the entire system be lined with endothelial cells to inhibit activation of coagulation? And what about the body’s immune response? Does a large artificial surface trigger a generalized inflammatory response or can this be prevented?"

Thanks to the coronavirus pandemic, we have all learned more about the life-support system called ECMO that can rescue patients in the intensive care unit. How does it compare to the support system you are developing?

Rossaint: ECMO systems are large, inpatient devices that are currently used primarily for COVID-19 patients with acute respiratory failure. However, you might consider smaller devices if you are only looking to take over portions of the gas exchange. Patients in this setting often have a condition where the lungs cannot remove enough of the carbon dioxide (CO2) that builds up in the blood. In cases like this where you only need to remove extra CO2, it only takes a smaller device. These types might even be implantable.

This means they do not necessarily have to look like modern cardiac support devices.

Rossaint: No, you could miniaturize them. Of course, we are also exploring ways to achieve this goal. There are a variety of technical options, which is why medical science collaborates with experts in the basic sciences, including engineering sciences, physics, mathematics, and computer science in all subprojects of our program.

When do you expect initial findings of your research?

Rossaint: The program has been funded for six years, and I expect we will create some basic requirements for the system’s structure within this timeframe. That being said, it will then be another ten to twelve years before we will have an implantable device that is suitable for long-term use.

How important are such mechanical replacement systems compared to actual donor organs?

Rossaint: They are very important in my view. We know there is a shortage of donor lungs, and it will stay that way for a long time to come, judging by today's needs. Given how often COPD is a cause of death today, we could significantly reduce the suffering of many patients with late-stage COPD and help maintain their quality of life.

Dialysis has only been around for 50 years and is now a standard treatment all around the world. Artificial heart and mechanical support systems have not achieved this scale until 20 or 30 years ago. I think we will experience a similar trajectory once we have an artificial lung: we will see a widespread use because there will be a widespread demand that is nearly unfathomable.