| BackgroundWound repair is associated with the whole process of extensive deep burn treatment.Failure to close wounds of patients with large-area and deep burns in early stages due to lack of autologous skin would bring great difficulties to subsequent treatment,such as proliferation of granulation tissue and localized infection,making the survival of subsequently grafted skin more difficult.More seriously,long-term exposure of large-area wounds often leads to extremely high metabolism,sepsis,multi-organ dysfunction syndrome and other fatal complications.As a result,treatment of large area deep burn is still the major challenge clinicians are faced with nowadays.87.1% of patients with 60%-69% TBSA can survive after treatment,and only 47.8% of patients with more than 90% TBSA.How to make full use of limited skin donor sites to repair large-area and deep burn wounds and ensure survival of the grafted skin is an urgent task that needs to be tackled in rescuing severely burned patients.Traditional methods such as large sheet of skin graft,stamp-like skin graft,pulling skin graft,can improve graft survival,prognosis scar and function,but are not suitable for large area deep burn wound repair due to lack of expansion ratio.The main methods currently available for repairing large-area wounds include autologous epidermal culture and transplantation,Meek grafting,and the Chinese characteristic microskin grafting.However,culture of autologous epidermal cells in vitro needs a long time of amplification and the successful survival rate of the graft is unstable,fluctuating between 15% and 85%.Although the Meek grafting technique has improved the surgical efficiency of stamp-like skin grafting,the expansion rate is limited between 4 and 9 folds,still far from what is needed.While microskin grafting can amplify the autologous skin by 10-20 folds,the graft survival rate is largely affected by various factors such as activity of the alloskin,homogeneity and direction of microskin distribution.Therefore,it is imperative to explore a technique that can offer a more stable graft survival rate,a larger autologous skin expansion rate and a higher quality of wound healing.The present study reports our experience with mixed grafting of small auto-and cryopreserved allo-skin in repairing large-area residual wounds.Our 12-year clinical observations have demonstrated that the autologous skin expansion rate of this mixed grafting technique is as high as 9-16 folds,with the success rate of 91.8 ± 3.7%.In addition,the long-term presence of allogeneic dermal as dermal substitute attenuated scar formation.This mixed grafting technique may prove to be a liable option for the late-stage treatment of large residual wounds in severe burn patients.Part 1.Clinical trial of mixed grafting for residual wound repair in extensive burnsObjectiveThe aim of the present study is to confirm that mixed grafting of small auto-and cryopreserved allo-skin can not only remarkably increase skin expansion rate,but also resist infection effectively,and to provide a stable and reliable method to repair large–area of deep burn wounds.Methods1.Sixty-five burn patients with large residual wounds in the middle-and late-stage of treatment admitting into our burn center in the past 12 years were reviewed retrospectively.Small auto-and allo-skin mixed grafting was applied in 21 cases,routine microskin grafting in 27 cases,and Meek grafting in 17 cases.Patients’ basic data were collected,including sex,age,pre-exiting disease,burn size,burn location,and complications.Excel 2013 was used to record data.2.Before grafting,throat swabs were used to collect secretion of different parts of wounds,and submitted for detection in time to determine strains of species and positivity rate of wound bacteria.3.After grafting,wound was dressed regularly,the process of healing was observed,healing time was recorded,and healing rate was calculated.The healing rate of mixed graftin group,microskin graft group and Meek graft group were compared statistically;then,factors affecting wound healing were analyzed and the stability of survival rate of mixed-,microski-nand Meek-grafting were compared.4.Patients were followed up for 1 to 2 years and their healing quality was assessed with Vancouver Scar Scale(VSS).The healing quality btween groups was compared statistically.5.Tattoo Technology was employed to dye small allogeneic skin graft.After follow-up of 1 to 2 years,immunohistochemistry was employed to track the allogeneic dermis and their function was investigated.6.Hapiro-Wilk test,Levene test,T test,Mann-Whitney U test,Mauchly test,Mann-Whitney U,Chi square test or Fisher exact probability method,multiple linear regression and Logistic regression analysis were employed for statistic analysis.Results1.From 2002 to 2014,65 patients with severe burn were included in the study for analysis,including 47 males and 18 females,with a mean age of 35.2 ± 6.7 years,a mean burn area of 84.1 ±7.5%TBSA,and a mean residual wound area of 61.1 ± 8.1%TBSA at 20-37 days after burn injury.Of the 65 included patients,43 patients had eschar sloughing and 22 patients experienced skin grafting failure.In addition,eight patients had hypertension,four patients had diabetes,and two patients had obesity.None of the patients had other kinds of skin diseases,immunosuppression or defects and other pre-existingdiseases,no history of hormone or immunosuppressants application,etc.2.Preoperative bacterial culture in local wounds showed that the bacterial positivity rate was 94.1%,92.2% and 89.5% in mixed,microskin and Meek grafting groups,respectively.The main bacteria were Staphylococcus aureus,Acinetobacter baumannii,Streptococcus viridans,pseudomonas aeruginosa and coagulase-negative staphylococci.3.Seven to ten days after mixed grafting,autologous skin graft began to spread around.It took 14 to 20 days for autologous skin graft s next to each other to fuse into a larger unit and the epidermis of allogeniec skin graft was replaced by autologous epidermis gradually.After 3 to 4 weeks,although allogeniec dermis were still definitely visible,the boundary among allogeniec and autologous dermis became unclear gradually as time went by.Skin grafting on the residual wounds was performed at 21-59 days after burn injury.The average grafting area in Mixed-,Microskin-and Meek-grafting group was 27.0%,25.0% and 24.0% TBSA,respectively.The wound healing rate in mixed grafting group was significantly higher than that in microskin and Meek grafting groups(91.8±3.7% vs.66.5±6.9% and 75.4±5.1%;P<0.001).Multiple linear regression analysis showed that the grafting modality(mixed,microskin or Meek grafting),grafting location,pre-existing disease(diabetes and morbid obesity)were main factors affecting the wound healing rate.In the same conditions,the wound healing rate of microskin grafting and Meek grafting were 24.567% and 16.799%,which are both significantly lower than that of mixed grafting.Levene’s test showed that healing rate stability of mixed grafting was higher than that of microskin grafting(SD=3.7 vs.6.9;F=23.156 P=0.01),and there was no significant difference between mixed and Meek grafting groups(P=0.020).4.Follow-up for 1-2 years showed that the mean VSS score in mixed grafting group was lower than that in microskin grafting group,and the difference was statistically significant(n=20,4.20±1.47;n=16,6.00±2.37,P=0.008).No significantly difference was observed between mixed and Meek grafting group(n=12;4.33 ± 1.61,P=0.813).5.Allogeniec skin grafts with tattoo were continuously visible in dermis from 2 months to 2 years after operation,with collagen fibers regularly microscopically arranged.No significant inflammation was observed locally.Dermal papilla-like structure was formed,similar to autologous dermal structures nearby.ConclusionsMixed grafting of small auto-and allo-skin not only raised the graft expansion rate but also had increased survival rate and stability.Allogenic dermis,long term existence of could act as substitute for autologous dermis and improve quality of wound healing.This new technique may be proven to be effective for residual wound repair in the middle-late stages for patients with extensive deep burns.Part 2.Case report1.Survival of skin graft is critical for successful treatment in extremely extensive burnsBased on the first part,we concluded that using mixed grafting of small-size allogeneic and autologous skin could fast and effectively repair burn residual wounds at the late stage of extensive burns.Obviously,ensuring skin graft survival is critical for successful treatment.In order to improve the effect of treatment in extensive and deep burn patients,we used mixed grafting at the early stage.Results showed its survival rate was stably high,significantly improve the success rate,and reduce the cost during hospitalization.Three cases of mixed grafting in extensive deep burns in Kunshan 8.2 Explosion Accident were reported as follows.2.Three atypical cases in Kunshan 8.2 Explosion AccidentThree patients with burn size of >90%TBSA(including a full-thickness burn of >80%TBSA)were administered with anti-shock,anti-infection,nutritional support,dressing change and scab-keeping treatment during the shock phase and they got through smoothly.Then,mixed grafting was used to repair wound.Case 1: female,43 years old,dust explosion-induced 98%TBSA burn,wherein 90%TBSA full-thickness burn.After MEEK grafting at Day 6,four times of mixed grafting of autologous and cryopreserved allogenic skin were applied.About 27%TBSA residual wound was left at Day 30 and little wound at Day 65.Case 2: female,39 years old,dust explosion-induced 90%TBSA burn,wherein 82%TBSA full-thickness burn.After MEEK grafting at Day 8,four times of mixed grafting of autologous and cryopreserved allogenic skin were applied.About 20%TBSA residual wound was left at Day 30 and little wound at Day 61.Case 3: male,46 years old,dust explosion-induced 96%TBSA burn,wherein 85%TBSA full-thickness burn.After MEEK grafting at Day 7,four times of mixed grafting of autologous and cryopreserved allogenic skin were applied.About 25%TBSA residual wound was left at Day 30 and little wound at Day 67. |
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