目的:观察超早期（伤后6h）切痂疗法对小型猪严重烧伤后血流动力学、血液流变学及氧供氧耗的影响,并与休克期（伤后24h）切痂进行比较。方法:实验于2005-09/12在唐山工人医院烧伤研究所进行。取30只小型猪,将其背部置入80℃热水中1min,造成35%Ⅲ度烫伤（病理切片证实）。烫伤后将30只动物单纯随机分为伤后6,24h切痂组2组（n=15）,分别于伤后6,24h麻醉后一次切除全部Ⅲ度焦痂。于伤前、伤后6,8,16,24,48,72h等不同时相点检测两组猪的血流动力学、血液流变学以及氧供和氧耗等指标的变化。结果:30只猪全部进入结果分析。①伤后6,24h切痂组猪心输出量和右心房压在伤后6h分别降至伤前值的66%和68%,组间比较差异不显著（P＞0.05）。伤后6h切痂组在伤后8h即开始恢复,伤后48h已基本恢复正常。伤后24h切痂组在伤后8h时此2项指标均已降至伤前值的59%,随液体复苏右心房压缓慢升高,至切痂前（伤后24h）仍低于伤前值（P＜0.05）,伤后72h基本恢复正常;心输出量则持续下降,至伤后24h达伤前值的41%,切痂后有较大幅度回升,伤后48h基本达到伤前水平,此后继续升高,伤后72h已明显高于伤前值。②两组动物伤后低切变全血黏度和红细胞聚集指数均升高,切痂后两组各指标均逐渐降低,两指标的组间差异不显著（P＞0.05）。③两组氧供在伤后6和8h均较伤前显著下降,伤后16h时,伤后6,24h切痂组分别为（398.83±3.56）,（391.20±7.80）L/min,已恢复至伤前水平,并稳步上升。④两组氧耗各时相均较伤前有所下降,伤后6,24h切痂组分别于伤后8和16h达最低值[（138.46±1.49）,（137.09±1.67）L/min];切痂治疗后有了明显改善,逐渐恢复至伤前水平。结论:①与休克期切痂比,超早期切痂能提高心输出量、右心房压等血流动力学指标,改善机体供氧和利用氧的能力。②超早期与休克期切痂对血液流变学的影响差异并无显著性意义,说明两个时间段切痂同样安全可行。

OBJECTIVE:To investigate optimal time for early escharectomy after severe scald in minipigs. METHODS:Minipigs inflicted with 35% TBSA full thickness burn were employed in the study, and they were randomly divided into A (n = 7, with escharectomy at 6PSH), and B (n = 7, with escharectomy at 24 PSH) groups. The hemodynamics indices, hemorrheology, and the serum levels of cytokines in the two groups were determined before burns and at 6, 8, 16, 24 and 72PSH. RESULTS:The hemodynamics indices in A group obviously improved compared with those in B group. The cardiac output (CO, 2.28 +/- 0.03 L/min) and right arterial pressure (RAP, 4.54 +/- 0.04 mmHg) in A group recovered to the pre-injury levels at 48 PSH. There was no difference of the hemorrheology indices between the two groups (P > 0.05). The serum contents of cytokines in A group declined to the pre-injury level on 1 PBW, while those in B group were significantly higher than those before injury and those in A group (P < 0.05 or P > 0.01). CONCLUSION:Escharectomy during 6 PBH might be safe and feasible, thus preventing long-term complications effectively.

Aim: To investigate the effect of hemodilution therapy on hemorrheologic characteristics by using the therapy on the experimental Chinese mini pigs after severe burn, and provide a theoretical basis for clinical application of hemodilution therapy. Methods: Twenty experimental Chinese mini pigs were selected to establish the severe burn animal models, and then randomly divided into two groups: control group and experimental group. The levels of viscosity of whole blood, hematocrit(Hct), erythrocytic deformation index and erythrocytic aggregation index were measured before and 6, 8, 16, 24 and 48 hours after burn. Results: The hemorrheologic indexes such as the viscosity of whole blood, Hct and erythrocytic aggregation index in the experimental group were obviously lower than those in the control group, but the erythrocytic deformation index significantly increased. Conclusion: The application of hemodilution therapy in burn shock stage and perioperative stage can obviously relieve the concentration of blood, erythrocytic aggregation and viscosity in burn shock stage, and also promote the ability of erythrocytic deformation and improve the blood volume effectively. So it is a feasible and effective treating measure in burn shock stage and perioperative stage. It has an important significance on the early rehabilitation of burn wound with a large area and the promotion of clinical healing rate.

Aim: To investigate the feasibility of escharectomy in mini pigs within 6 hours after severe burn(super early escharectomy), so as to benefit to the early rehabilitation for severe burn wound. Methods: Chinese experimental mini pigs were selected to establish the badly burn animal models, and were randomly divided into two groups: experimental group and control group. The hemodynamics indexes[cardiac output(CO) and right atrial pressure(RAP)] and hemorheology indexes(the low shear viscosity of whole blood and the erythrocytic aggregation index) were detected before and 6, 8, 16, 24, 48 and 72 hours after burn. Results: The changes of hemodynamics: The CO and RAP of both groups dropped rapidly after burn. The CO and RAP of the experimental group began to recover at 8 hours after burn and returned to the normal level at 48 hours after burn. The CO of the control group kept dropping continuously, and then regained to the level of preinjury at 48 hours after burn, and then it still kept rising. The RAP of the control group decreased to the lowest point at 8 hours after burn, and then came to the normal level at 72 hours after burn. The changes of hemorheology: The statistical process indicated that there was no significant difference in the low shear viscosity of whole blood and the erythrocytic aggregation index between the two groups. Conclusion: The super early escharectomy will provide a more steady hemodynamics in perioperative stage and it has no harm to hemorheology. From the view of the animal experiment, the super early escharectomy is feasible. It has an important significance on the early rehabilitation of burn wound with a large area and the promotion of clinical healing rate.

Aim: To explore the practicability of repair of full skin loss of swine with composite artificial skin. Methods: Sixteen swines were grafted 3 surface of wound from full thickness skin to deep fascia on the back. The 3 surfaces were divided into compound skin grafting group and razor-thin grafts group(control Group 1) and full skin grafting group(control Group 2), respectively. The wound healing conditions were observed regularly after operation. Simultaneously, wound tissue samples were harvested for histological examination. Results: The artificial skin was composed of dermis and epidermis under light microscope. The epidermic cells proliferated, differenciated and developed into basal cell layer, prickle cell layer, granular layer and cuticula during healing. Conclusion: Composite skin, combined by epidermic cell suspension and acelluar dermal matrix, has double-deck structure of dermis and epidermis, so its histological form and ultrastructure are similar to skin. The source of skin can be increased by cultivation of epidermic cell, which can be provided for patients of large area deep burn. Tissue engineering skin equivalent has potential prospects in application of repairing skin defect.