RWTH Mechanical Engineers Develop a New Strategy for Cardiopulmonary Support

Custom made artificial lungs and a "seamless" exchange between a cardiopulmonary machine and a lung support system- this is the goal for three young RWTH Aachen biomedical engineers. The engineers, Jutta Arens, Peter Schlanstein, and Georg Wagner, are working on a new artificial lung under the supervision of Professor Ulrich Steinseifer of the Teaching and Research Area for Cardiovascular Engineering.

The lung can be implanted both short- and long-term. Furthermore, the parts of the lung can be cut according to the patient's needs and exchanged easily. The strategy, titled "I3-Assist: Individual, Interactive, and Integrated Cardiopulmonary Assist" won the Biomedical Engineering Award in Philadelphia.

Despite numerous studies, around 35-50% of today's patients die due to acute respiratory distress syndrome. The main causes are pulmonary inflammation, blood poisoning, inhalation of foreign substances, or multiple injuries throughout various parts of the body. In the event that standard breathing and medicine treatments are unsuccessful, an artificial lung is necessary to assume the lung's functions.

"When operating during cardiac arrest, circulation is maintained through a cardiopulmonary machine," says Arens, the project coordinator. Next, the blood is lead into a reservoir, and with the help of a pump, then directed into the membrane oxygenator. "Oxygenerator is the technical term for the artificial lung. Picture a membrane as a gas permeable barrier," explained Arens. "There, the blood is saturated with oxygen, rid of carbon dioxide, and then pumped back into the body." An oxygenator can assume the complete function of the blood gas exchange for a limited time. In extremely critical cases, the heart and lungs will have to further be supported for multiple days, if not weeks after the operation. Until now, the substitution of a second system has been necessary. The team is certain that their system can assume the function of the cardiopulmonary machine during an operation as well as the function of long term pulmonary support in an intensive care unit.

Safer, more effective, and more cost-efficient
The compact system can be transported smoothly from Aachen and positioned near a patient, meaning less tube length is needed. The longer the tube, the more blood that is required for circulation. Additionally, the contact of skin to a foreign surface leads to blood clotting. In order to prevent this, doctors administer the inhibitor, Heparin. The clotted blood can block not only the system but also vital vessels in the patient. Further possible complications include air bubbles, which can likewise lead to embolisms, i.e. blockages. Therefore the system must first be filled with a saline solution; the combination of blood and the saline solution thins the blood. In critical patients, the thinned blood has to be compensated for with blood transfusions. "Our custom-made product minimizes blood thinning and activation of blood clotting, "emphasizes Arens.

Additionally, problems with gas exchange can surface. Humans need varying amounts of oxygen, depending on temperature, anesthetization, age, and body surface. The more oxygen that is converted, the more carbon dioxide there is to remove. The pressure drop of oxygen through the membrane is high and the barrier is sufficiently gas-permeable, but longer operation times may result in complications with gas exchange. Straightaway with long-term use there is the danger of so-called plasma leaks: blood plasma leaks over the barrier. As a result, the gas transfer worsens and important organs, like kidneys, can be affected and aggravated by a large loss of fluids. In order to not place a patient further in danger, the entire device has to be exchanged. "We also reduce the risk here, because individual pieces of our modular system can be replaced during the course of use," says Wagner. Schlanstein adds, "Furthermore, it saves money and reduces a patient's trauma."

Cluster for the Development of Personalized Biomedical Technology
The strategy is ingrained in the Aachen Research-Cluster "innovating medical technology in.nrw," which is promoted by the federal state North Rhine-Westphalia for further development of personalized biomedical technology. Since the summer of 2010, 40 partners from the region have been working together on six research and developments projects, to develop innovative solutions and treatments for individual patients.

Cardiovascular treatments are important in Germany, where heart disease is the number one cause of death. The strengths of research and the economy in the Aachen region are particularly drawn upon to aid in treatment development.

Further information available under:
Innovating medical technology in.nrw

Contact:
Dipl.-Ing. Jutta Arens
Helmholtz-Institute Building
Phone: +49(0)241/80-87018
arens@hia.rwth-aachen.de