Citation

Rafaels KA, Bass CD, Salzar RS, Panzer MB, Woods W, Feldman SH, Cummings TJ, Capehart B. J. Neurotrauma 2011; 28(11): 2319-2328.

Affiliation

University of Virginia, Center for Applied Biomechanics, 1011 Linden Ave, Charlottesville, Virginia, United States, 22902, 434-296-7288 x122, 434-296-3453; kar3k@virginia.edu.

Copyright

(Copyright © 2011, Mary Ann Liebert Publishers)

DOI

10.1089/neu.2009.1207

PMID

21463161

Abstract

Many soldiers returning from recent conflicts in Iraq and Afghanistan have had at least one exposure to an explosive event and a significant number have symptoms consistent with traumatic brain injury. Although blast injury risk functions have been determined and validated for pulmonary injury, there is little information on the blast levels necessary to cause blast brain injury. Anesthetized, male, New Zealand White rabbits were exposed to varying levels of shock tube blast exposure focused on the head, while their thoraces were protected. The specimens were euthanized and evaluated when the blast resulted in respiratory arrest that was non-responsive to resuscitation or at four hours post-exposure. Injury was evaluated by gross examination and histological evaluation. The fatality data from brain injury was then analyzed using Fisher's exact test to determine a brain fatality risk function. Greater blast intensity was associated with post-blast apnea and the need for mechanical ventilation. Gross examination revealed multifocal subdural hemorrhages, most often near the brainstem, at more intense levels of exposures. Histological evaluation revealed subdural and subarachnoid hemorrhages in the non-responsive respiratory arrested specimens. A fatality risk function from blast exposure to the head was determined for the rabbit specimens with an LD50 at a peak overpressure of 750 kPa. Scaling techniques were used to predict injury risk at other blast overpressure/duration combinations. The fatality risk function shows that the blast level needed to cause fatality from an overpressure wave exposure to the head is greater than the peak overpressure needed to cause fatality from pulmonary injury. This risk function can be used to guide future research for blast brain injury by providing realistic fatality risk to guide the design of protection or to evaluate injury.

Language: en