title: Pretreatment with normobaric and hyperbaric oxygenation worsens cerebral edema and neurologic outcomes in a murine model of surgically induced brain injury.
abstract: BACKGROUND
  Hyperbaric oxygenation is a readily available treatment modality, and its ability to improve neurological outcomes in a variety of animal models has been demonstrated. This study was designed to investigate the use of a single pretreatment regimen of either hyperbaric oxygenation or normobaric oxygenation to determine its effects in a murine model of surgically induced brain injury (SBI).
  
  
  METHODS
  Hyperbaric oxygen (2.5ATM, 1 h), normobaric oxygen (100% FIO2, 1 h) or room air (21% FIO2, 1 h) was applied on CD-1 mice immediately, or at 1, 2 or 3 h followed by SBI or sham surgical operation. Neurological assessment of the animals was done by a blinded observer at 24 and 72 h using a 21-point modified Garcia scale, wire hanging test, and beam balance test. The brain edema was evaluated using brain water content at 24 and 72 h after SBI.
  
  
  RESULTS
  There was no statistically significant difference in the mortality rate after treatment compared with the SBI group. The brain water content after SBI was significantly increased in the right (ipsilateral) frontal lobe surrounding the site of surgical resection compared with the sham group. Both hyperbaric and normobaric oxygen treatment significantly increased the brain edema and worsened the neurological outcomes using a 21-point Garcia score compared with the SBI group. The brain edema at 24 h after injury was most pronounced in the group treated with normobaric oxygenation 2 h prior to surgery. These differences disappeared at 72 h after SBI.
  
  
  CONCLUSIONS
  Immediate pretreatment with either hyperbaric (2.5ATM, 1 h) or normobaric oxygen (100% FIO2, 1 h) increased brain edema and worsened neurological function at 24 h following SBI.
authors: Department of Neurosurgery, Loma Linda University Medical Center, Loma Linda, CA 92350, USA.
authors: David
authors: D
authors: Westra
authors: Wanqiu
authors: W
authors: Chen
authors: Reiko
authors: R
authors: Tsuchiyama
authors: Austin
authors: A
authors: Colohan
authors: John H
authors: JH
authors: Zhang
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001929:Brain Edema / Q000209:etiology* / Q000473:pathology; D001930:Brain Injuries / Q000150:complications* / Q000209:etiology; D002540:Cerebral Cortex / Q000503:physiopathology; D004195:Disease Models, Animal; D007839:Functional Laterality; D006931:Hyperbaric Oxygenation / Q000009:adverse effects*; D051379:Mice; D009422:Nervous System Diseases / Q000209:etiology / Q000628:therapy*; D009460:Neurologic Examination; D019635:Neurosurgical Procedures / Q000009:adverse effects; D013997:Time Factors; D016896:Treatment Outcome