Experiment on the tangential excision of deep partial thickness burn wounds with reservation of denatured dermis and auto-skin grafting in chinese domestic pigs

Objective To explore the relationship between the bacterial quantity and the survival rate of the skin graft in the burn wound and the relationship between the thickness of the reserved denatured dermis and the survival rate of the skin graft,in order to provide some theoretical basis for clinical application.Methods In each of seven Chinese domestic pigs,seven deep second degree burns were produced on the back with spinal column with a 100 ℃ steel plate whose diameter was 5.5 cm and thickness was 2 cm.Tissue samples were harvested at 24,48,72,96,120,144 and 168 hours after burn,and analyzed for identification of bacterial strain and quantitative analysis of bacterial quantity.After the collection of tissue sample at each wound,the wound crusts were removed with a Humby knife till the appearance of the normal tissue layer.After auto-skin was transplanted(0.25 mm thick of auto-skin was obtained by using electric knife),wound was bandaged appropriately,and then the pigs were raised in separate cages.The survival rate of the skin graft was calculated 7 days after the surgery.With the same burning tool,four deep second degree burns were produced on the back of each pig to the opposite side of the spinal.All the 28 burn wounds were randomized to 7 blocks,4 burn wounds per block.By using motor dermatome,the skin at burn wounds were reserved quantitatively to the thickness of 0.83 mm,0.70 mm,0.38 mm and 0.14 mm for each of the wound per block,respectively.With surgery knife,the#shapes was scratched randomly and vertically to the wound till blood oozing from the wound surface.After 0.25 mm thick of auto-skin was transplanted on each wound,the wound was bandaged with sterile gauze pad and adhesive elastic bandage,and then the pigs were raised in separate cages.The survival rate of the skin graft was calculated 7 days after the surgery.Results At 72 hours after burn,the bacterial quantity was more than 10 5 cfu /g in 1(4.8%) out of 49 wounds,and mostly containing single bacterial type.Survival rate of skin graft was higher than 90% in 71.4% of the wounds at 72 hours.After 72 hours,the bacterial quantity was more than 10 5 cfu /g in 67.9% of the wounds,and mostly containing two or three bacterial types.Survival rate of skin graft was higher than 90% in 32.1% of wounds after 72 hours.Retained denatured dermis of different thickness,different skin graft survival rate,P 0.001,the dermal thickness of 0.14 mm,the graft survival rate was highest,followed by 0.38 mm.Conclusions For deep second degree burns,it is appropriate to remove the wound crust 3 days after burn,and the survival rate of skin graft is highest when about 0.1 mm thick of denatured dermis is reserved after removing the wound crust.