Experimental Study On The Effects Of Delaying On The Ischemia-reperfusion Of The Expanded Skin Flap

Objective To study the effects of delaying on the ischemia-reperfusion of the expanded skin flap,analyze the difference between 1-delaying and 2-delaying on the expanded skin flap.Methods Tissue expanders were implanted subcutaneously on the back of 4 mini pigs.There were 4 groups:①injected to 150%,no intervention;②injected to 150%,1-delaying:③injected to 150%,2-delaying;and④normal skin, control group。The differences in light microscope,electron microscope, MVD,MDA content,MPO content and flap survival were observed at different times.Results The HE dyeing showed:The vascular numbers of Group②and③increased after the surgery,reaching the peak at 10 days and keeping stable after 21 days.MVD test showed:There were significant difference between Group①/④,Group②/④and Group③/④(P=0.000).No significant differences had been found between Group①/③(P=1.505) and Group①/②(P=0.114).There were difference between Group②/③(P=0.026).MDA test showed:There were significant difference between Group①/④,Group②/④and Group③/④(P=0.000).There were difference between Group①/③(P=0.033).No significant differences have been found between Group①/②(P=0.132) and Group②/③(P=0.525).The MDA content decreased after delaying and the peak focuses at 24 hours,showing that the first 24 hours after the transplantation of the expanded flap are the key period for the intervention of I/R.But there were no difference between 1-delaying and 2-delaying.MPO test showed:There were significant difference between Group①/④,Group②/④and Group③/④(P=0.000).No significant differences have been found between Group②/③(P=0.677),Group①/②(P=0.609) and Group①/③(P=0.354).The MPO content decreased after delaying and the peak focuses at 24 hours.But there were no difference between 1-delaying and 2-delaying. The flap survival in Group①was 98%,and in Group②and③were 100%。Conclusion Expansion could increase the MVD and survival of the expanded flap.The process of expansion was not noly a process of ischemia-reperfusion, but also a process of ischemia-preconditioning.The first 24 hours after the transplantation of the expanded flap are the key period for the intervention of ischemia-reperfusion.Delaying could increase the flap survival,but colud not increase the MVD.Both of 1-delaying and 2-delaying could not add the injury of the expanded flap.