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Effect of hyperbaric oxygen on neutrophil concentration and pulmonary sequestration in reperfusion injury
W A Zamboni1, H P Wong, L L Stephenson
1Microsurgery and Hyperbaric Research Laboratory, University of Nevada School of Medicine, Las Vegas, USA.
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.
Design:
Prospective randomized experimental trials.
Setting:
Laboratory.
Materials:
Male Wistar rats weighing 150 to 300 g.
Interventions:
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).
Main Outcome Measures:
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.