Research Of Full-Thickness Chest Wall Defects In Dogs Treated By Vacuum Sealing Drainage For Its Safety And Wound Healing

In the modern warfare, the Incidence rate of Chest wall defects caused by Blast injury is high, and the treatment of the defects is difficult, the chest wall with Large area soft tissue defect is more difficult to repair. In the old days, the first aid to these defects always in the way of packing or covering gauze to the defects. Then the Closed thoracic drainage is used to reexpanse the lung. All of these operations are complicated and needed specialized physician. Vacuum sealing drainage (VSD) is a Simple and efficient way in healing the wound. After packing or covering Polyvinyl alcohol of alginate foam to the wound and packing a layer of Biological membrane to the surface of foam and wound, the Drainage tubes from the foam are connected to the Negative pressure aspirator and the treatment begin. In recent years, the application of vacuum sealing drainage(VSD) on the chest wall defects in clinic has increased and gain a good result. If this technique can put in use in the battlefield., the treatment efficiency could be higher and the mortality could be lower. For the reason that The application of VSD needed a good environment in operation room and the effect of Negative pressure to the heart and lung is indefinite, the direct use of VSD on chest wall is not popular. At present, Closed thoracic drainage is still the main method in curing the pneumothorax. In the first aid, the most important thing is turning the Open pneumothorax to the Closed pneumothorax and then exhausting the gas. At the same time, Close the wound and accelerate the wound healing. VSD is a technical can do all these things. The purpose of this research is to certify the safety of the application of vacuum sealing drainage(VSD) on the chest wall defects and try to find out The most suitable Negative pressure for wound healing. Look forward a simple and effective treatment for the first aid in the battlefield.[Objective]Certify the safety of the application of vacuum sealing drainage(VSD) on the chest wall defects and try to find out The most suitable Negative pressure for wound healing.[Methods]3cm×4cm chest wall defected were randomly divided into5groups. All the defects were connected to the disposable-VSD devices. Gas was pumped out of pleural cavity by VSD with the help of vacuum gauge.24hours later, CT scan were applied to check the pneumothorax existed. The groups were divided by different negative pressure:60kpa,40kpa,20kpa, lOkpa, Okpa. In each group, the drainage of the wound and time of pleura closing were measured at1st,3rd and5th day after surgery. At5th day, tissues were drawn to observe by HE and immunohistology staining. At the same time, blood pressure and Blood gas analysis of all the dogs are examined. CT scan on the dog’s chest were carried before the operation and After the open window thoracostomy and24hours after the application of the VSD device. During the process of the surgical operation and the application of the VSD device, the impedance value of Electrical Impedance Tomography are took down.[Results]The blood pressure of the dogs decreased after the surgery, then rose again after the application of the VSD device. When the blood pressure became stable, the Blood gas analysis became normal.the pneumothorax was disappeared under the effect of subatmospheric pressure, but the atelectasis was still existence from the outcome of the CT scan. The outcome of the24hours CT scan reveal that lung recruit completely. With the occurrence of pneumothorax, the impedance value of the whole thoracic cavity gradually become larger until it get a maximum value. When we applicate the VSD to the chest wall, the value gradually become smaller until it drop to a minimum and stable value. The drainage of subatmospheric pressure60kpa (77.6±6.62ml) and40kpa (77.8±4.97ml) group were more than others at the first day, and the closing time of pleura of60kpa (3.2±1.30days) and40kpa (3.6±0.55days) group were faster. However, blood gas analysis manifested type I respiratory failure in group60kpa. HE staining showed there was granulation tissue and immunohistology staining showed CD34positive. No difference existed between group60kpa and40kpa, but neovascularization in the two groups is much more than that in the other three groups.[Conclusion]This research certify the safety of the application of vacuum sealing drainage(VSD) on the chest wall defects. Furthermore, we find that the VSD can cure the pneumothorax safely and help the lung recruitment maneuver. VSD can promote the wound drainage and promote the close of the pleura. increase the growth of Granulation tissue and blood vessel. Especially, the40kpa group can achieve the best result and be safer.It can not achieve better treatment effect when the subatmospheric pressure get larger. And the larger subatmospheric pressure could do harm to the breath..VSD could be a simple and effective treatment for the first aid of repair the chest wall defects in the battlefield.