| Objective: The purpose of the present study was to determine the effects of hyperbaric oxygen (HBO) on survival of a full thickness and big proportion and superlength random flap and on angiogenesis of subdermal vessels of the flaps in the rabbit and to understand its effects on the whole survival of skin flaps thoroughly so as to provide the rationale for its clinical use.Methods: 1.The design of the groups: All the rabbits were divided into two groups randomly:group A is control group , random flap alone ,group B is flap plus HBO 2.The design of the random flap: All animals were anesthetized with inject 5% sodium pentobarbital (10mg/kg) into the vein . The flap was sharply incised and elevated between dartos and subdermal vascular network, then sutured to its bed . 3. The HBO group started to accept hyperbaric oxygen treatment after flap transplantation immediately, twice a day from post-operation to the third day, then reduced to one time per day to the seventh day, seven days altogether. 4. On postoperative day 3 and day 7, the survival area of flaps was measured with planimetry. And a sample were harvested from each flap for pathological check and immunohistochemical test.Flap survival was studied, histologic studies were performed and blood vessel density were mersured. The data from the experiment were analyzed statistically.Results: 1.Gross observation: Scabs appeared on the middle and distal parts of the skin flap of the both groups. The necrosis region of the control group was larger than that of the trial group. The survival area of the skin flap in the trial group[ (78.31±1. 02) %]is larger than that of the control group [ (61. 74±3. 77) %]. There was significant difference between the two goups(P=0.0037<0.01).2.Histological observations: In both groups, full lamina necrosis appeared on the distal part of the skin flap. Cell nucleuses condensed or diminished with atrophy.Survival skin flaps showed a certain extent of edema, and the epidermises were thin.In the trial group, large area of granulation tissue and a great quantity of blood vessels formed, these phenomena were rare in the control group.3.Mean flap blood vessel density : Mean flap blood vessel density in middle segment of HBO group was 2. 92±0. 82/MM2 and that in control was 2. 33±0. 72/MM2. There was significant difference between the two groups.(P<0.01)4.masculine cell expression of VEGF in flap tissue: masculine cell expression of VEGF in HBO group was 5. 73±1. 63/MM2 and that in control was 4.84±1.12/MM2. There was significant difference between the two groups.( P<0. 01)5.masculine cell expression of HIF in flap tissue: masculine cell expression of HIF in HBO group was 4. 61±0. 83/MM2 and that in control was 5. 38 + 1. 24/MM2. There was significant difference between the two groups.( P<0. 01)Conclusions:These results support the notion that HBO rescues tissue at risk of hypoxic damage by inducing angiogenesis and can improve the ratio of the longth and width of the flaps .HBO holds promise as a method of improving the survival of the ischemic random skin flaps. It makes HBO therapy simple and practical and will bepromising future in the tissue transplantation. The higher survival length of the flap might owe to the mechanism that HBO perhaps helps the flap tissue to produce more VEGF and less HIF in the flap. All these changes improve the local angiogenesis and microcirculation, promote wound healing and increase the survival length of the flap in the experiment group.
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