Communications of the ACM
Tech for Military Vehicles May Protect Against Blast-Induced Brain Injury
Credit: MVP Parent
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. More than 250,000 warfighters were victims of such injuries during Operations Iraqi Freedom and Enduring Freedom.
Detailed Insight
Prior to 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," says Gary Fiskum, M. Jane Matjasko Professor for Research and Vice-Chair, 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 has also resulted in the development of materials and vehicle frame design that greatly reduce injury caused by under-vehicle explosions.
Fiskum and William Fourney, 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 TBI even under conditions where other vital organs remained unscathed.
"Intense acceleration can destroy synapses, damage nerve fibers, stimulate neuroinflammation, and damage the brain's blood vessels," says Fiskum. Researchers also elucidated the molecular mechanisms responsible for this specific form of TBI.
The findings are described in "Rat Model of Brain Injury Caused by Under-Vehicle Blast-Induced Hyperacceleration," published in The Journal of Trauma and Acute Care Surgery, with Julie Proctor, UMSOM Lab Manager, as primary author, and in "Neuropathology and Neurobehavioral Alterations in a Rat Model of Traumatic Brain Injury to Occupants of Vehicles Targeted by Underbody Blasts," published in Experimental Neurology, with Flaubert Tchantchou, UMSOM Research Associate as primary author, and in "Central Nervous System Changes Induced by Underbody Blast-Induced Hyperacceleration: An in Vivo Diffusion Tensor Imaging and Magnetic Resonance Spectroscopy Study," published in the Journal of Neurotrauma, with Rao Gullapalli, Professor of Diagnostic Radiology, UMSOM, as senior author.
Mitigating G-Force
Fourney, Ulrich Leiste, Assistant Research Engineer in the Clark School's Department of Aerospace Engineering, and doctoral researcher Jarrod Bonsmann 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."
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 described in "Rat Model of Brain Injury to Occupants of Vehicles Targeted by Land Mines: Mitigation by Elastomeric Frame Designs," published in the Journal of Neurotrauma.
Peter Rock, Martin Helrich Chair of the Department of Anesthesiology, notes 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 both 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.
This research is supported by the University of Maryland Strategic Partnership: MPowering the State, a collaboration between the University of Maryland, Baltimore and the University of Maryland, College Park. Initial funding was provided by a 2009 UMB-UMCP collaborative seed grant awarded to 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 described in "Aeromedical Evacuation-Relevant Hypobaria Worsens Axonal and Neurologic Injury in Rats After Underbody Blast-Induced Hyperacceleration," published in The Journal of Trauma and Acute Care Surgery.
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