Treatment Of Ischemic Wound In Rabbit Dorsal Ear By Negative Pressure Therapy In Combination With Topical Oxygen Therapy

Chronic wounds represent a diffficult health care problem. Surgeons always cure these wounds with debridement, skin graft or flap transplantation. Chronic wounds are always the complication of another disease, or the result of serious trauma. The poor constitution of the patients is the barrier of the wound healing. The reasons and mechanism of chronic wound are so complicated that it is diffictlt to create an animal model which is similar with human chronic wound. So the ischemic wound is a good representative for a chronic one. Research the mechanism of the ischemic wound can help provide some reference related to the treatment and the mechanism of human chronic wound. The effect of the vacuum assisted closure therapy in treatment of chronic wound has been accepted by most surgeons. The reason why topical oxygen therapy was used to treat wound is based on the action mechanism of hyperbaric oxygen therapy and its shortcomings, but its mechanism is unclear so far. The objective of this experiment is to observe the effect of the treatment of ischemic wound in rabbit dorsal ear by negative pressure therapy (NPT) in combination with Topical oxygen therapy (TOT).The 56 ischemic wounds on the dorsum of rabbit eras, ligated the central neurovascular bundle and the posterior peripheral artery and vein, were divided into seven groups: group A were treated with NPT(-50mmHg) and TOT(PO2 40%±5%) at the same time for four hours every day; group B was treated with continuous NPT(-50mmHg) for four hours and an hour TOT; group C was treated with intermittent NPT(-50mmHg) for four hours and an hour TOT; group D was treated with NPT(-50mmHg) for four hours; group E were treated with NPT(-125mmHg) for four hours; group F was treated with TOT for one hour and group G was treated with conventional dressing change every other day. Take photos of the wounds at the given time point (immediately the wounds were created and the 1st,3rd,5th,7th,10th,14th,18thday after the treatment), then calculate the areas and the rate of healing with the image analysis. Tissue specimens, collected from the wound, were embedded with paraffin and studied with HE staining to observe the formation of granulation, inflammatory cell infiltration, and the edema. Furthermore, immunohistochemistry for the related antigen of Ki67 was done to estimate the proliferating cells and the Cell Apoptosis Detection Kit was used to assess the apoptosis cells. Then calculate the proliferation index and the apoptotic index. Result: the healing rates at the given time point of group A, B and C were higher than that of other groups (p<0.05). Formation of the granulation in group A, B and C was faster than that of other groups, but the cell infiltration and the edema were less serious than that of group C, D, E and F. The proliferation index of group A, B and C is larger than that of other groups, but the apoptotic index in the first three groups is less than that in other ones.The results of this experiment confirmed that NPT in combination with TOT can promote significantly healing of ischemic wound in rabbit dorsal ear.