New NC State computer models are contributing to more successful vascular surgery, guiding the development of novel drug inhalation therapies, and providing data for stricter federal air pollution standards. Two such models have been created by interdisciplinary research teams headed by Dr. Clement Kleinstreuer, a professor of mechanical and aerospace engineering (MAE).

With funding from the National Institutes of Health through Duke University, one team has developed and used a blood flow model to create optimal designs for synthetic blood vessels called grafts. Grafts are used in femoral bypass surgeries as “detours” around a blockage in the patient’s blood vessel, in kidney dialysis, and in other peripheral vascular surgeries.

The newly designed, three-dimensional graft ends provide optimal matching at the attachment to patients’ own blood vessels, smoothly directing blood into the junction area. The results can be dramatic. “With the new graft end, the likelihood of a second surgery within two to three years is significantly reduced from its current rate of 33 percent,” says Kleinstreuer. “To go back on the operating table after two to three years is not only traumatic but expensive.” Team members include Dr. P.W. Longest and doctoral student Zhonghua Li of NC State’s MAE department, Dr. Joseph P. Archie of Wake Medical Center, Dr. George A. Truskey of Duke University’s Biomedical Engineering Department, and Dr. Mark L. Farber of the UNC School of Medicine.

 A more elaborate blood flow model has provided specifications to help surgeons optimize placement of stents, grafts, and other implants to avoid leaks and potential rupture of diseased arteries. “With optimal design, excessive blood vessel wall stresses are mitigated or avoided,” Kleinstreuer explained.

Yet another Kleinstreuer team, including Dr. Zhe Zhang, MAE graduate students Huawei Shi and Burton Kennedy, and U.S. Environmental Protection Agency (EPA) collaborator Dr. C.S. Kim, has developed a computer model of the upper respiratory system. The team has recently employed the model to track the way inhaled droplets and vapor of a highly toxic military jet fuel are deposited in the lungs. That work, funded by the EPA, the U.S. Air Force, and the National Science Foundation, has provided federal toxicologists with evidence of adverse impacts, especially on children. It may also provide justification for more stringent air pollution standards proposed for 2005.

Perhaps even more dramatic, the lung aerosol transport model and its “controlled air particle stream methodology” may be applicable to development of inhaled medication, possibly replacing repeated injections of drugs such as insulin for diabetics, or chemotherapy for lung cancer patients.

“With these technologies, we are not only helping to people live longer lives, but also improving their quality of life,” Kleinstreuer said. “And that translates into lower costs for society.”