Source: University Of Pittsburgh Medical Center (<A HREF="http://www.upmc.edu/">http://www.upmc.edu/>)
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: Mon May 28 2001 - 09:59:59 MDT
Date: Posted 4/26/2001
Artificial Lung On The Horizon, Reports University Of Pittsburgh Researcher
At International Society For Heart And Lung Transplantation Meeting
VANCOUVER, BRITISH COLUMBIA, April 26 -- A University of Pittsburgh
researcher who has developed a device that functions like a temporary set of
lungs told a group of heart and lung transplant surgeons today that such
technology could have a tremendous impact for the nearly 750,000 patients
with emphysema, chest trauma or acute respiratory distress, about 150,000 of
whom die each year. 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.