title: Effect of hyperbaric oxygen on neutrophil concentration and pulmonary sequestration in reperfusion injury.
abstract: OBJECTIVE
  To evaluate the effect of hyperbaric oxygen (HBO) on muscle flap arterial neutrophil concentration and pulmonary neutrophil sequestration following ischemia-reperfusion injury in a rat gracilis muscle microcirculation model.
  
  
  METHODS
  Prospective randomized experimental trials.
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  Male Wistar rats weighing 150 to 300 g.
  
  
  METHODS
  Gracilis muscle flaps were raised on isolated vascular pedicles. Three groups were evaluated: (1) sham (flap raised, 4-hour observation, no ischemia, no HBO), (2) ischemia control (4-hour flap is ischemia, no HBO); and (3) ischemia (4-hour flap is ischemia) plus HBO (last 90 minutes of ischemia, 100% oxygen, 2.5 atm absolute).
  
  
  METHODS
  Flap pedicle arterial leukocyte and neutrophil concentrations were assessed at 5 and 90 minutes of reperfusion in the 3 groups. Pulmonary neutrophil sequestration was measured in a blinded fashion, using histologic examination and myeloperoxidase assay in the 3 groups at 5 and 90 minutes of reperfusion.
  
  
  RESULTS
  Ischemia produced an increase in pedicle arterial leukocyte and neutrophil concentrations in blood flowing to the gracilis muscle flap; administration of HBO significantly reduced concentration to sham levels (P < .05). There were no significant differences in pulmonary neutrophil sequestration among the experimental groups.
  
  
  CONCLUSIONS
  In this rat gracilis muscle microcirculation model, the increase in pedicle arterial leukocyte and neutrophil concentrations following ischemia-reperfusion injury was significantly reduced to sham levels by HBO treatment. This observed reduction was not attributable to HBO-induced pulmonary sequestration, which did not significantly change with HBO administration. Further investigation is required to elucidate the mechanisms of action of HBO in ameliorating ischemia-reperfusion injury in this model.
authors.affiliation: Microsurgery and Hyperbaric Research Laboratory, University of Nevada School of Medicine, Las Vegas, USA.
authors.forename: W A
authors.initials: WA
authors.lastname: Zamboni
authors.forename: H P
authors.initials: HP
authors.lastname: Wong
authors.forename: L L
authors.initials: LL
authors.lastname: Stephenson
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D006931:Hyperbaric Oxygenation; D007511:Ischemia / Q000503:physiopathology*; D007958:Leukocyte Count; D008168:Lung / Q000276:immunology* / Q000503:physiopathology; D008297:Male; D008833:Microcirculation; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000276:immunology / Q000503:physiopathology; D009504:Neutrophils; D011446:Prospective Studies; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000503:physiopathology* / Q000628:therapy*