[abstract] EFFECTS OF HYPERBARlC OXYGEN ON SURVIVAL RATE OF ISLAND-FLAP FOLLOWING ISCHEMIA-REPERFUSION INJURY IN RATS.

Abstract

IN1RODUCTION: This study was to investigate whether hyperbaric oxygen (HB02) pretreatment and HBO2 after I/R increases the survival of island flap following ischemia-reperfusion (I/R) in rats. METHODS: Male Sprague-Dawley (SD) rats weighing between 250-350g were randomized into one of six groups (n=8 in each group): Control (Gl), Control + HBO2 (G2), I/R (G3), I/R + HBO2(G4), Pretreatment HBO2 + I/R (G5), Pretreatment HBO2 + I/R + HBO2 (G6). All rats were subjected to surgery of cutting left abdominal wall with 4.0 x 5.0 cm^2 for island flap with only preserved inferior epigastric vessels under anesthesia Biobrane membranes were placed between flaps and underlined recipient bed. Ischemia-reperfusion were produced with vessel clips by occlusion the inferior epigastric vessels for 10 hours. Pretreatment HBO2 was performed after 3-hr ischemia HBO2 after I/R was performed once immediately after reperfusion and once a day for 5 days. Leukocytes in flap tissues were counted under microscopy, and the overall survival rate of island flap was measured at the seventh day. RESULTS: The survival rate of flap and leukocyte counts subjected to I/R (G3) were 1.09 ± 0.62%, 367.63 ± 19.06 (mean ± SEM); 99.94 ± 0.03%, 93.38 ± 6.44 for G1; 100 ± 0.00%, 117.38 ± 2.63 for G2; 53.83 ± 3.37 %, 208.25 ± 17.89 for G4; 27.98 ±3.52 %, 177.13 ± 18.38 for G5; and 68.21 ± 3.47 %, 139.88 ± 7.95 for G6, respectively. Ischemia-reperfusion has significantly increased leukocyte counts locally in flap tissues and decreased the overall survival rate offlap compared with control (p < 0.001, ANOVA). HBO2 pretreatment and HBO2 after I/R have significantly decreased leukocyte counts in flap tissues and increased the overall survival of I/R flap (p < 0.001, ANOVA). CONCLUSIONS: HBO2 pretreatment and HBO2 after I/R can additively improve island flap survival from I/R injury in rats. The possible mechanism may be related to addictive reduce in leukocyte accumulation in injured tissues.