title: Brain injury risk from primary blast.
abstract: BACKGROUND
  Military service members are often exposed to at least one explosive event, and many blast-exposed veterans present with symptoms of traumatic brain injury. However, there is little information on the intensity and duration of blast necessary to cause brain injury.
  
  
  METHODS
  Varying intensity shock tube blasts were focused on the head of anesthetized ferrets, whose thorax and abdomen were protected. Injury evaluations included physiologic consequences, gross necropsy, and histologic diagnosis. The resulting apnea, meningeal bleeding, and fatality were analyzed using logistic regressions to determine injury risk functions.
  
  
  RESULTS
  Increasing severity of blast exposure demonstrated increasing apnea immediately after the blast. Gross necropsy revealed hemorrhages, frequently near the brain stem, at the highest blast intensities. Apnea, bleeding, and fatality risk functions from blast exposure to the head were determined for peak overpressure and positive-phase duration. The 50% risk of apnea and moderate hemorrhage were similar, whereas the 50% risk of mild hemorrhage was independent of duration and required lower overpressures (144 kPa). Another fatality risk function was determined with existing data for scaled positive-phase durations from 1 millisecond to 20 milliseconds.
  
  
  CONCLUSIONS
  The first primary blast brain injury risk assessments for mild and moderate/severe injuries in a gyrencephalic animal model were determined. The blast level needed to cause a mild/moderate brain injury may be similar to or less than that needed for pulmonary injury. The risk functions can be used in future research for blast brain injury by providing realistic injury risks to guide the design of protection or evaluate injury.
authors: Army Research Laboratory, 328 Hopkins Rd, ATTN RDRL-SLB-W, Aberdeen Proving Ground, MD 21005, USA. kar3k@virginia.edu
authors: Karin A
authors: KA
authors: Rafaels
authors: Cameron R Dale
authors: CR
authors: Bass
authors: Matthew B
authors: MB
authors: Panzer
authors: Robert S
authors: RS
authors: Salzar
authors: William A
authors: WA
authors: Woods
authors: Sanford H
authors: SH
authors: Feldman
authors: Tim
authors: T
authors: Walilko
authors: Richard W
authors: RW
authors: Kent
authors: Bruce P
authors: BP
authors: Capehart
authors: Jonathan B
authors: JB
authors: Foster
authors: Burcu
authors: B
authors: Derkunt
authors: Amanda
authors: A
authors: Toman
mesh_terms: D000818:Animals; D001753:Blast Injuries / Q000150:complications* / Q000175:diagnosis; D001921:Brain / Q000473:pathology*; D001930:Brain Injuries / Q000175:diagnosis / Q000209:etiology*; D004195:Disease Models, Animal; D005107:Explosions; D005289:Ferrets; D008297:Male; D015599:Trauma Severity Indices