Role of biological protective dressing in microskin grafting in rabbit / 中华烧伤杂志

<p><b>OBJECTIVE</b>To study the effect of biological protective dressing made from porcine peritoneum in covering wounds with microskin grafts.</p><p><b>METHODS</b>Twenty New Zealand rabbits were divided into ten couples according to the random number table. Rabbits in each couple underwent surgery at the same time. A piece of full-thickness skin of 5 cm in diameter was removed symmetrically from the left and right sides of the back of each rabbit, thus forming two wounds with full-thickness skin defect. One fifth of one piece of skin of one rabbit was cut into tiny pieces of 0.2-0.5 mm in size (microskin). Then the microskin pieces were spread on the two wounds of the donor rabbit with the microskin/wound area ratio 1:10. The two wounds of each rabbit covered with microskin were divided into two groups according to the random number table. One wound was covered with biological protective dressing prepared with porcine peritoneum as experiment group, and the other was covered with the rest allograft in full size obtained from the other rabbit of each couple as control group. The general condition of wound was observed at post operation week (POW) 1-4. Wound healing rate was calculated at POW 3 and 4. Wound healing time was recorded. Specimens were harvested from wounds for histological observation at POW 1-4. Data were processed with paired t test.</p><p><b>RESULTS</b>(1) At POW 1, the biological protective dressings were found to attach firmly to the wounds in experiment group without obvious inflammatory response; the allografts survived well on the wounds in control group. At POW 2, the coverings attached well to the wounds of both groups, but became drier and darker as compared with those at POW 1. At POW 3, some wounds of the two groups healed when the coverings desiccated and separated. At POW 4, all the wounds of both groups healed without obvious difference in appearance. (2) The wound healing rates of the experiment and control groups were respectively (92.8 ± 6.2)% and (91.3 ± 7.3)% (t = 0.54, P > 0.05) at POW 3 and (98.1 ± 2.3)% and (97.0 ± 4.6)% (t = 0.38, P > 0.05) at POW 4. (3) The wound healing time was (25.0 ± 3.9) d in experiment group and (24.8 ± 2.3) d in control group. The difference between them was not statistically significant (t = 0.82, P > 0.05). (4) Histological observation showed that wounds of the two groups were all infiltrated by inflammatory cells, and new blood vessels were observed at POW 1 and 2. The survived microskin proliferated under the coverings. At POW 3 and 4, the coverings on the wounds of two groups were gradually degenerated and became necrotic and separated from the wound beds, while the wounds underneath were re-epithelialized.</p><p><b>CONCLUSIONS</b>The effect of biological protective dressing in covering wounds grafted with microskin is as good as that of the allograft, as they both help the auto-microskin proliferate and repair the wound. It could be considered to be new biological material for clinical application.</p>

Distribution and vicissitude of drug resistance of Acinetobacter baumannii in burn intensive care unit of Wuhan City Hospital No.3 in three years / 中华烧伤杂志

<p><b>OBJECTIVE</b>To study the clinical distribution characteristics and vicissitude of antibiotic resistance of Acinetobacter baumannii (AB), and to look for the risk factors of AB infection in order to provide reasonable reference for the prevention and treatment of its infection.</p><p><b>METHODS</b>Specimens of blood, venous catheters, sputum, wound exudates and pharyngeal swabs from 156 patients hospitalized in our burn ICU from January 2006 to December 2008 were collected and cultured. The clinical distribution and antibiotic resistance of AB were determined and analyzed. The risk factors related to AB infection were analyzed. Drug resistance rate data were processed with WHONET 5.3 software; the other data were processed with chi-square test and Logistic regression analysis.</p><p><b>RESULTS</b>Ninety-two strains of AB were identified during the three years from different kinds of specimens, with 41 (44.6%) from wound exudates, 14 (15.2%) from pharyngeal swabs and sputum respectively, 13 (14.1%) from blood, and 10 (10.9%) from venous catheters. AB accounted for 23.1% (30/130), 27.5% (25/91), 28.2% (37/131) respectively among the strains detected in 2006, 2007, and 2008. During the three years, except for imipenem and cefoperazone/sulbactam, the average resistance rates of AB to other ten commonly used antibiotics were all above 50.0%. Burn area (χ(2) = 24.374, P = 0.000), mechanical ventilation (χ(2) = 8.968, P = 0.003), duration of use of antibiotics (χ(2) = 3.981, P = 0.046), and deep venous catheterization (χ(2) = 9.170, P = 0.002) were the risk factors of AB infection, and the former two were independent risk factors.</p><p><b>CONCLUSIONS</b>There is a pan-drug resistance tendency of AB in our burn ICU, and the positive culture rates are increasing in recent years. Disinfection and isolation measures, appropriate use of antibiotics, avoidance of invasive performances such as deep venous catheterization and tracheostomy, or shortening their duration are important means to prevent and control infection of AB.</p>

The histological changes and the revascularization process in the grafted dermal substitutes / 中华烧伤杂志

<p><b>OBJECTIVE</b>To observe the revascularization process and histological changes in the dermal substitutes after grafting.</p><p><b>METHODS</b>Twenty-one SD rats were enrolled in the study and were randomly divided into swine acellular dermal matrix (sADM), human acellular dermal matrix (hADM), and artificial dermal equivalent (Integra) groups according to different dermal substitutes grafted underneath the skin of SD rats. The gross appearance of the grafts was observed, and the tissue biopsies were harvested at 2, 3, 4, 7, 10, 14, 21, 30, 60, 90, 120, 150, 180 post grafting day (PGD) for the observation of the revascularization process and their histological changes.</p><p><b>RESULTS</b>Gross observation: The incision in each group healed well without local swelling and inflammatory response after grafting. The grafts had a compact contact with the wounds. The texture of the grafted dermis in each group was soft and could not be felt from the surface of the body on 90 PGD. The presence of the grafts could be discerned on 180 PGD in all the groups, but some of them became smaller in size and thinner, even hard to identify in a few. Fibroblasts, neutrophils and lymphocytes migrated into the grafts from 2PGD on. New capillary sprouts from the receiving beds could be observed after 3PGD. Affluent capillary nets formed in the grafts during 30 to 60 PGD. The structure of the grafts became nearly unidentifiable from the native dermis after 150 PGDs. Absorption and degradation to various degrees occurred in some of the grafts after 180 PGD.</p><p><b>CONCLUSION</b>The revascularization of the three dermal substitutes could begin shortly after grafting. The sponge-like structure of the substitutes was advantageous for the migration of the host fibroblast into the substitute and for the secretion of the new extra-cellular matrix. The dermal substitutes could last in the wound for a long time with partial absorption and degeneration.</p>