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.
Prospective randomized experimental trials.
Male Wistar rats weighing 150 to 300 g.
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 ischemia, no HBO); and (3) ischemia (4-hour flap 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 reperfusions.
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.
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.Arch Surg. 1996;131:756-760