Researchers from the University of Maryland School of Medicine (UMSOM) and the University of Maryland A. James Clark School of Engineering have developed a new military vehicle shock-absorbing device that may protect warfighters against traumatic brain injury (TBI) due to exposure to blasts caused by land mines. During Operations Iraqi Freedom and Enduring Freedom, more than 250,000 warfighters were victims of such injuries.
New approach to study of blast-induced TBI
Photo courtesy of the University of Maryland BaltimoreBefore this study, most research on blast-induced TBI has focused on the effects of rapid changes in barometric pressure, also known as overpressure, on unmounted warfighters. “This is the only research to date to model the effects of under-vehicle blasts on the occupants,” explains Gary Fiskum, PhD, M. Jane Matjasko Professor for Research and vice chair, Department of Anesthesiology at UMSOM. “We have produced new and detailed insights into the causes of TBI experienced by vehicle occupants, even in the absence of significant ambient pressure changes.” The research also has resulted in the development of materials and vehicle frame design that greatly reduce injury caused by under-vehicle explosions.
Fiskum and William Fourney, PhD, associate dean of the Clark School, Keystone Professor of Aerospace and Mechanical Engineering, and director of the Dynamic Effects Laboratory, were the first to demonstrate how the enormous acceleration (G-force) that occupants of vehicles experience during under-vehicle blasts can cause mild to moderate traumatic brain injury (TBI) even under conditions in which other vital organs remained unscathed.
“Intense acceleration can destroy synapses, damage nerve fibers, stimulate neuroinflammation, and damage the brain’s blood vessels,” Fiskum says. Researchers also elucidated the molecular mechanisms responsible for this specific form of TBI.
Those findings are described in articles published in the Journal of Trauma and Acute Care Surgery, with Julie Proctor, MS, UMSOM lab manager, as primary author, and in Experimental Neurology, with Flaubert Tchantchou, PhD, UMSOM research associate, as primary author, and in the Journal of Neurotrauma, with Rao Gullapalli, PhD, professor of diagnostic radiology, UMSOM, as senior author.
Mitigating G-force experienced by vehicle occupants
Fourney, Ulrich Leiste, PhD, assistant research engineer in the Clark School’s Department of Aerospace Engineering, and doctoral researcher Jarrod Bonsmann, PhD, developed highly advanced shock-absorber designs that incorporate polyurea-coated tubes and other structures to reduce the blast acceleration experienced by vehicle occupants by up to 80 percent.
“Essentially, it spreads out the application of force,” Fourney says. “Polyurea is compressible and rebounds following compression, resulting in an excellent ability to decrease the acceleration.”
Reducing blast-induced TBI
These results were combined with those of Tchantchou, who demonstrated that mitigation of G-force by the elastic frame designs virtually eliminates the behavioral alterations in lab rats and loss of neuronal connections observed using small-scale vehicles with fixed frames, as published in the Journal of Neurotrauma.
Peter Rock, MD, MBA, Martin Helrich Chair of the Department of Anesthesiology, noted that "the research team has addressed an important clinical problem by identifying a novel mechanism to explain TBI, engineered a solution to the problem, and convincingly demonstrated improvements in morphology and behavior. This work has important implications for improving outcomes in military blast-induced TBI and might be applicable to causes of civilian TBI, such as car crashes."
Continued collaboration between the labs of Fiskum and Fourney will hopefully lead to the next generation of armor-protected military vehicles that will further protect warfighters from injury and death. An important next step will be testing a larger-scale model. “If the data holds up for those, it will hold true for full scale," Fourney says.
Project development funding
This research is supported by the University of Maryland Strategic Partnership: MPowering the State, a collaboration between the University of Maryland, Baltimore (UMB) and the University of Maryland, College Park (UMCP). Initial funding was provided by a 2009 UMB-UMCP collaborative seed grant awarded to Drs. Fiskum and Fourney. In 2013, the two were awarded a $1.5 million contract by the U.S. Department of Defense Joint Program Committee 6/Combat Casualty Care Psychological Health and Traumatic Brain Injury Program to support their research using small-scale models of under-vehicle explosions. An additional grant of $2.6 million was awarded by the U.S. Air Force, demonstrating that increasing the cabin pressure in airplanes during air-evacuation of trauma patients to a level greater than what is currently used improves outcomes following exposure of rats to TBI caused by under-vehicle explosions, as published in the Journal of Trauma and Acute Care Surgery.