Large soft tissue injuries are relatively common in clinical practice. Every year, more and more patients suffer from severe trauma due to high incidence and sudden accidents, which can easily lead to undesirable consequences such as trauma necrosis, tissue liquefaction and infection if not treated properly. The key to treatment is timely and thorough debridement to eliminate the dead space and drain the accumulated blood and fluid in the wound. The traditional treatment method is to place drainage strips in the wound after thorough debridement, and to change the medication and anti-infection treatment regularly after surgery, but the common clinical drainage methods have certain limitations and passivity, which easily lead to incomplete drainage and accumulation of blood and fluid, which not only increase the risk of infection, but also aggravate the pain of patients and the workload of medical staff, and easily lead to cross-infection and nosocomial infection. The use of continuous closed negative pressure drainage to treat large soft tissue injuries can drain the necrotic and liquefied tissue from the trauma surface in time and provide a good environment for the growth of traumatic granulation tissue. At the same time, the incidence of systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS) is greatly reduced, and the speed of wound healing is significantly improved as well as the complications are reduced because the toxins from the decomposition products of trauma are avoided. The treatment of 63 patients with large soft tissue injuries admitted to our hospital from September 2009 to January 2012 is reported below. 1, clinical data 1.1 general data 63 cases of male 48 cases, female 15 cases, age 17 ~ 65 years old, the average 31.7 years old. There were 22 cases of soft tissue avulsion injury of the lower leg, 9 cases of soft tissue contusion of the thigh with subcutaneous fat liquefaction, 17 cases of open fracture of the tibiofibula with bone exposed skin defect, 7 cases of skin decortication injury, 6 cases of skin necrosis after trauma of the lower limb, and 2 cases of skin contusion of the lower leg with osteofascial compartment syndrome. The injury area was 8.0cm×9.0cm~40.0cm×70.0cm. 1.2 Materials and methods 1.2.1 Materials ①Clear suture pack. ② medical foam (VSD material): polyethylene alcohol hydration seaweed salt foam (commonly known as “artificial skin”) produced by Wuhan Visdi Medical Technology Co. The package is 10cm×15cm×1cm, which can be appropriately trimmed according to the size and shape of the trauma, and contains a multi-lateral hole rigid silicone plastic drainage tube inside. ③Semi-permeable adhesive film: produced by the British S&N company, transparent film with unidirectional breathable function, it is easy to paste, non-allergenic, breathable and moisture permeable performance. ④Tee joint. ⑤ Negative pressure source: VSD special suction machine or the central negative pressure device at the head of the bed. 1.2.2 Method For patients with soft tissue avulsion injury, first clear the wound, then trim and thin the avulsed skin and plant it back, and cover the surface with VSD material for negative pressure closed drainage; for patients with open fractures, make simple fixation of the fracture in emergency, try to use soft tissue to cover the bone, thin and perforate the skin of the dehiscence, plant it back on the trauma, and evenly pressurize the negative pressure closed drainage; for those with skin contusion defect, after thorough clearing, take VSD material of similar size to the trauma, cover the trauma with VSD, make full and complete contact with the trauma, and intermittently suture the edges of VSD to the skin for fixation purposes. The skin sebum at the edge of the VSD is removed with 75% alcohol, wiped with dry gauze, and the entire trauma is closed with a bio-permeable film, which should cover more than 3 cm of the trauma edge to avoid air leakage. The drainage tube was led out from under the film next to the trauma and connected to the negative pressure source. The trauma then contracted and the VSD collapsed significantly together with the film, indicating a good seal and satisfactory negative pressure effect. After the trauma is closed, no special treatment is needed. The negative pressure indicator on the drainage bottle should be observed frequently, and the negative pressure is generally controlled between -0.017~-0.080MPa. If the collapsed VSD pops back up to its original state or if secretions accumulate under the film, suggesting the disappearance of negative pressure, the seal needs to be checked and later closed with bio-permeable film paste, or the negative pressure drainage bottle needs to be replaced. The film was removed 7 to 10 days after drainage and the VSD was removed to observe the wound. For skin avulsion wound with in situ skin grafting, continue to change the dressing and remove the wound 2 weeks after surgery. For skin contusion defects, if there is little secretion and fresh granulation, autologous skin grafting or flap transfer can be performed to close the wound. On the contrary, multiple VSD drainage is required. 2, results 63 patients applied 1 to 2 times of continuous negative pressure closed drainage, the course of treatment 7-10 days. In 22 cases of calf skin avulsion injury, the drainage device was removed and the dressing was changed 7 days after surgery, and the wound was removed 2 weeks after surgery, and all the skin grafts were viable; 16 cases of calf skin defects caused by subcutaneous fat liquefaction and skin decortication in the thigh and 6 cases of skin necrosis after trauma, the drainage device was removed 7 days after surgery, and the traumatic granulation was fresh, and autologous skin grafts were performed; 17 cases of skin defects with bone exposure underwent flap transfer, and the wounds healed well. The wound healed well. In 2 cases of osteofascial compartment syndrome of the lower leg, the swelling of the lower leg subsided 5 days after surgery, and after removal of the drainage device, the wound was directly sutured without muscle necrosis. In all cases, there were no systemic and local complications. 3. Discussion In the treatment of patients with large soft tissue injuries, the negative pressure closed drainage technique can achieve rapid closure of the trauma surface and win valuable time for the treatment of other more serious injuries, which is conducive to the comprehensive treatment of severe trauma. After treatment with negative pressure closed drainage technology, the trauma surface can be reduced by about 20%, the dead cavity is completely eliminated, the trauma surface granulation tissue is flat, fresh and capillary-rich; the bacterial culture of infected trauma surface is negative; the total hospitalization days are significantly shortened, the number of dressing changes, antibiotic dosage and cost are greatly reduced, and the course of disease can be shortened by 1M3~1/2. In addition, no dressing change is needed for 7~10 days, which reduces the pain caused by repeated dressing changes and the medical treatment. This reduces the pain caused by repeated dressing changes and reduces the workload of medical personnel. For patients with soft tissue stains or defective wounds that are impossible to close in the initial treatment, or when necrotic demarcation cannot be determined and thorough debridement is difficult, covering the wounds with negative pressure closed drainage technique is an excellent method. The application of negative pressure closed drainage to cover the wound can prevent recontamination and also fully drain the secretions, exudate and necrotic tissue fragments in the wound, which facilitates infection control and tissue edema reduction, and avoids the possibility of secondary infection and surgical failure of skin grafting and tissue flap transfer repair after forcible one-stage closure of the wound. The present data confirm the actual clinical effect of continuous negative pressure closed drainage technique, which is worthy of wide application. Issues to be noted when using negative pressure closed drainage: ① Necrotic tissues and foreign bodies should be removed as thoroughly as possible from the trauma. ② Trim the polymer foam under aseptic conditions according to the size and shape of the trauma, and make sure that the foam can fully touch the whole trauma after being placed in the trauma, and multiple pieces of material can be used when the trauma is large, but the foam should fully touch the trauma. All lateral holes and tips of the drainage tube should be fully embedded in the foam; the distance between the drainage tube and the edge of the foam material should not exceed 2 mm. If the foam used is large, two or more drainage tubes should be placed, but the excess drainage tube should be trimmed and cut according to the size of the trauma. ④ The trauma closure should be tight. The polyurethane film used for sealing is a kind of biotransparent film, which has good adhesion and can ensure the evaporation of the skin (sweat hole), and will not cause skin allergic reaction even if used continuously for more than 2 weeks. Closure of the wound is an important step, which is related to the maintenance of negative pressure and therefore requires careful and patient handling. The “mesenteric method” is used when applying the dressing, using a film of sufficient length to wrap the drainage tube first and then apply it around the wound. (5) The area of injury in emergency surgery is large, so the visible bleeding must be ligated, and the negative pressure must not be too large, otherwise it can lead to more blood and plasma loss, hypoproteinemia, and affect wound healing. (6) A reliable sign of effective negative pressure is the obvious contraction of the foam material to harden (which can be touched by film observation). It must be noted that once the negative pressure disappears, the closure should be checked immediately for tightness and compensated if necessary, otherwise the wound is in a closed and non-negative pressure environment, which may quickly worsen the infection. (7) Once the wound is clean, second-stage suturing, free skin grafting or tissue flap transplantation can be performed. If the wound is large or the infection is severe, a second negative pressure closure may be performed after 7 days of the first negative pressure closure. Usually, the area of foam material used in the second closure can be 2/3 to 3/4 of the first, which is more conducive to the growth of granulation and filling of the dead cavity.