| Background:New military revolution has being globally boomed for the past two decades. In the modern local warfare, mortality of the wounded is significantly reduced because of excellent protective devices and effective early management. However, soft tissue injury causing by explosion is still the important reason for forces attrition and combat weakening. Shock waves and heat waves produced by an explosion can cause serious damages to human tissues, for example extensive tissue defects with foreign fragments and secondary infection. As a new wound treatment technology, vacuum sealing drainage (VSD) is simple and low-price, which can effectively prevent the wound from infections and can significantly relieve the medical staff from workload. Nevertheless, there are few reports about VSD used for the treatment of explosive injury in the battlefield. In this study, the soft tissue wound models were established by simulated explosion, of which the drainage was done with vacuum-assisted closure therapy following normal debridements in a field hospital. The number of bacteria, the content of collagen and VEGF in the wounds surface were measured at 3 and 6 days postoperatively. Our hypothesis is further study the effect of VSD on soft tissue trauma caused by the explosion can help to find a scientific and effective way to management this kind of injury. Objectives:To assess the early effects of vacuum sealing drainage on the explosive wound of soft tissue, in order to find new ideas to treat battlefield injuries in the field hospital. To develop the portable vacuum sealing drainage device meanwhile.Materials and Methods:1. To develop the portable vaccum sealing drainage deviceIn order to develop portable VSD device, it is required to invent a kind of device with small volume, convenient to take, independent of electric power source, easy to operate and good at maintaining negative pressure. It was manufactured by professional factory and proved to be safe and reliable in clinical use.2. Animal groupsEight health landrace of either gender, weighted 45-55 kg, were provided by the animal experiment laboratory of Lanzhou Military Region. Sixteen explosive wound models are produced by explosion occurred on bilateral hips of all animals. After being performed debridements, one of the two wounds in one animal was randomized into the experimental group, the other would be in control group. In the experimental group, VSD treatment was applied at 3 days after wound debridements and kept for three days. In control group, the wounds were given routine dressing treatment daily.3. Wound bacterial countTissues, about 0.1 cubic centimeters per piece from 5 different positions in wound surface, were obtained at pre-operation, 3-day and 6-day post-operation. Every piece of tissue was added into physiological saline, which was 99 times of the corresponding tissues in weight. The tissue and the saline were homogenized into homogenate, which, then, was diluted by 10 times grade (10×, 100×, 1000×...). The achieved 100μL diluent was inoculated onto 10 cm blood agar plate and cultured for 24h at 37℃. Finally, the number of bacterial colonies on plates was counted.4. Masson stained histological preparationAfter 3d and 6d treatment, the pathologic specimens were drawn from the wound in the sagittal plane. The specimens were fixed with Formalin, dehydrated with Absolute Alcohol, embedded with paraffin, sliced with microtome and stained with the Masson's way. The stained slices were observed under optical microscope and pictures were taken. Masson staining of collagen in granulation tissue (green) were estimated by using Image-Pro plus6.0 software.5. VEGF Western blot analysisAfter e3d and 6d treatment, about 100mg fresh tissue was taken and cleaned for two times using pre-cooling 4℃PBS. The tissue was milled and added 0.5ml lysate, then it was put into the ice bath for 30min. Following centrifugation for 20min at 4℃, the supernatant was thought as total protein. With the BCA method to quantitate the protein samples, the proteins were transferred to PVDF membrane after 8% SDS-PAGE gel electrophoresis and closed for 2h. Then the first antibody was added and kept overnight at 4℃. The next day the second antibody was added and incubated at 37℃for 2h. The interest protein was detected using enhanced chemiluminescence. The X-ray exposure time was dependent on the experimental results. The gray level was scanned and estimated with the software of Image-Pro plus 6.0.6. Statistical analysisAll data is analyzed using statistical software SPSS 16.0. The results are mean and standard deviation ( x±SD), group comparison using paired t test. Significantly difference level was set at P < 0.05.Results:1.The portable VSD device has been used in animal experiments and clinical operation, and obtained good therapeutic effect.2. Gross observation woundThe wound surface of experimental group had huge amounts of granular granulation tissue after 3d treatment. In addition, the wound was clean, no smell, easy bleeding, no significant edema and secondary tissue necrosis. In the control group, the surface of wound was gray, where were secondary necrotic tissue, milk yellow viscous exudate, fishy smell and edema of the skin surrounding the wound. In the experimental group with 6d treatment, the granulation tissue in the wound was rich in granules, the color of which was red that means it riches in blood supply. The wound was clean, no smell, significantly than the wound edge and no tissue edema and necrosis. The surrounding skin looked normal. In contrast, the outcome of control group was different. There were huge amounts of secondary necrotic tissue, yellow viscous exudate, cracks in muscle tissue, bad wound odor and tissue edema and infection in the wound.3. Bacteriological test resultsAfter 3d and 6d treatment, the number of bacterial colonies in the experimental group was significantly less than that of the control group (p < 0.01). In experimental group, the number of bacteria after 3d treatment was 104, which did not reach the threshold value of 105 for infection. Even that level decreased after 6d treatment. However, the bacteria of more than the threshold number of bacteria 105 and 109 were found in 3d and 6d control group, respectively. The wound resulted in infection in the control group.4. Masson staining resultsAfter 3d treatment, the collagen content in wound granulation tissue was significantly difference between the experimental and control group (P < 0.01). Collagen synthesis in the experimental group was obviously higher than that in the control group. The difference was also significant in 6d treatment. As the time of treatment passed, the more collagen content of granulation tissue was found in the experimental group than the control group.5. Western blot analysisA same tendency was found in both groups, which was the amount of VEGF was accumulated and increased with the treatment continued. However, the amounts of VEGF in the experimental group were significantly higher than those of the control group at either 3d or 6d post-operation.Conclusion:With visual observation of the wound and bacteriological experiments, it confirms that using VSD in the early explosive wound can inhibit the proliferation of bacteria and reduce infection rates.Masson staining results show that the granulation tissue collagen content in the experimental group is significantly more than that in the control group, which is more and more illustrious with the treatment time going on. VEGF protein blotting experiments confirm that the VSD can promote the formation of VEGF in the wound.In summery, VSD seems an optional choice in managing the explosive wound. It values extensive application in the future. |
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