| Aim:To design and manufacture a infusion pump prototype machine and a microprocessor infusion pump. To verify the effects of continuous constant pressure skin expansion. Methods : A pig model was made with HY — I tpye constant pressure pump and white young domestic pigs. A variety of tissue responses to coutinuous tissue expansion was investigated with auto-image analysis, pathology, transmission electron microscopy, biochemical determination, immunohis-tochemistry and molecule biology techniques. Results:HY—I type constant pressure infusion pump accords with the standards of animal experiments. The surgical procedures of implanting skin expanders with perpendicular short incisions to the expansive borders are suitable to continuous fast tissue expansion and water infusing expansion had been completed for six days under the filling pressure of 5.3kPa,with a coustant in-line pressure and no circulation disturbance. Tissue morphologic changes of coutinuous tissue expansion(CTE) are similar to those of intermittent tissue expansion (ITE),in which the epidermal layer was thickened,the dermal layer became thinner and elastic and reticular fibers proliferated greatly,and thinner tibric capsules aera found in CTE. Expanding stimulation not only increased cell proliferation and apoptosis,but also enhanced collagen protein synthesis and catabolism,but the final results are that The thickness of the epidermal layer,the density of fibroblasts and capillary and the total collagen protein were all increased, which means that expansion could iuduce skin growth. The comparative analysis showed that CTE was more effective in inducing skin growth. Measuring results indicated that CTE gained the same amout of local additional skin as ITE,with the same expanders and the same amount of water iu-fusion,but the true gain of skin area produced by CTE was less than that of ITE. The immediate natural strechback rates of expanded compound skin tissue... |
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