Artificial Lung On The Horizon, Reports University Of Pittsburgh Researcher At International Society For Heart And Lung Transplantation Meeting

A potential application also exists for military personnel and civilians who may become victims of chemical warfare or terrorist attack involving toxic gases, he reported.

In an invited keynote lecture at the 21st Annual Meeting of the International Society for Heart and Lung Transplantation, Brack Hattler, M.D., Ph.D., a professor of surgery at the University of Pittsburgh School of Medicine, said laboratory and animal studies suggest the device could do an adequate job of exchanging carbon dioxide and oxygen in patients with compromised lungs, allowing the lungs to rest and heal.

"It's an alternative means of breathing," stated Dr. Hattler.

A clinical trial of the device, called the Hattler Respiratory Catheter, is expected to begin in Europe in about a year. It will be only the second time an implantable artificial lung has been tested in humans. About 10 years ago, clinical testing of another device was halted because the device's design did not allow for sufficient gas exchange. In general, progress to develop an artificial lung lags years behind that of the artificial kidney, liver and heart.

"The artificial lung especially has lingered behind progress with artificial hearts and ventricular assist devices, not because the need for lungs has not been recognized, but because we have not had a full understanding of the engineering problems and the unique material requirements until recent years," explained Dr. Hattler, who has devoted the past 14 years to the development of an artificial lung.

Together with bioengineer William J. Federspiel, Ph.D., Dr. Hattler has created an intravenous respiratory assist device that is easily inserted through a vein in the leg and positioned into the vena cava, the major vein returning blood to the heart. It consists of hollow fiber membranes that introduce oxygen into and remove carbon dioxide from the body. Key to its design, and a distinction from the device that failed, is a central balloon within the fibers that can inflate and deflate at a rate of 300 beats per minute to move the fibers and mix the blood. This allows for more efficient oxygenation of blood and removal of carbon dioxide. In essence, respiration takes place even though the lungs are severely injured and functioning poorly.

The surface area of two lungs is about the size of a tennis court. The Hattler Catheter has a surface area equivalent to an 8½ x 11 sheet of paper and can perform about 50 percent of the gas exchange requirements of an adult. Blood is exposed to a tiny amount of foreign biomaterial -- less than a half a square meter -- minimizing the likelihood that there would be an infection or clotting caused by the interaction between blood and a synthetic surface, Dr. Hattler reported.

Because the Hattler Catheter is intended to temporarily take over the function of the lungs, giving them time to heal, it could meet a dire need for patients with acute respiratory failure, such as those with emphysema, or those who have suffered trauma to the lungs. Currently, the standard of care is the use of extracorporeal membrane oxygenators, bulky and expensive units that can cause life-threatening complications and death in more than half of those who are treated with them.

The device is not envisioned to be used for prolonged support, say as a bridge to transplant, or as a total replacement of the lungs. However, findings from the clinical trial will lead to a greater understanding of what is required for the development of more long-term devices, Dr. Hattler said, enabling a jump-start for artificial lung researchers who are working to develop devices to provide long-term support for patients awaiting lung transplantation. About 25 percent of these patients die on the waiting list, in large part because no means of support currently exists. Such devices, which are about two to three years from human testing, would need to be surgically implanted.

Support for Dr. Hattler's research has been provided through grants from the U.S. Department of Defense. Work has been conducted through the University of Pittsburgh McGowan Center for Artificial Organ Development. Alung Technologies is a Pittsburgh-based company specifically created to enable the clinical phase of research.