The treatment of patients with severe abdominal trauma has gained important advances in the last two decades. The contemporary injury characteristics of high-energy injuries have resulted in a large number of patients with severe multivessel injuries, and advances in prehospital care and resuscitation have made early survival of severely traumatized patients possible. However, it is recognized that although early initial surgery after injury can achieve precise injury control and repair, patients with multiple injuries may still die from intraoperative metabolic failure rather than from incomplete surgical repair. Damage control surgery (DCS) came into being, mainly to save patients with severe trauma, changing the previous strategy of performing complex and complete surgery at an early stage to a quick and simple reduced surgery, but controlling further deterioration of the injury and preserving the conditions for further treatment, so that the patient can gain time for recovery and have the opportunity to have another complete and reasonable reoperation or staged surgery. In recent years, reduction surgery aiming at damage control has gained high attention in the treatment of abdominal trauma, and there are important progresses from theory to practice, so this paper tries to make a review combining literature and own treatment experience. 1.Theoretical basis of reduction surgery in abdominal trauma Severe abdominal trauma, especially the traumatic shock caused by multiple trauma, is mainly caused by the decrease of systemic perfusion, increased vascular resistance, reduced oxygen transport efficiency and stress, and often combined with serious abdominal infection, large vessel injury and abdominal wall defect, etc. Patients often have severe acidemia, hypothermia and coagulation dysfunction, and then carry out complex surgery. Surgery with large trauma can only aggravate the physiological disorders of the organism and increase the difficulty of resuscitation, but visceral bleeding and abdominal infection have to be dealt with immediately, otherwise these injuries are more heavily contaminated and shocked. Therefore, damage control surgery aimed at rapid and effective hemostasis, control of abdominal infection, and temporary abdominal closure is the key to correct the above pathophysiological disorders. This concept has been widely applied in trauma management with satisfactory results and is now increasingly used in the daily treatment of more serious trauma, but many theoretical issues remain to be resolved. The pathophysiological changes after abdominal trauma will not be discussed any further, and damage control should be understood as the control of the damage of the surgery itself rather than the control of the lesion damage, which should belong to the scope of macroscopic minimally invasive surgery, while the latest progress is to further explore the theoretical basis of damage control from the perspective of molecular immune mechanism. The immune response of the body after severe trauma can be divided into inflammatory response syndrome (SIRS) and compensatory anti-inflammatory response syndrome (CARS), which develop in parallel and complement each other, while the initiating mechanisms of immune deterioration after severe trauma are unknown so far, such as ischemia-reperfusion injury, endotoxin, heat shock proteins from inactivated tissues, and complement, etc. However, it is clear that surgical trauma affects the immune system through humoral immunity and cellular immunity constitutes an additional blow to the body’s immune system. A decrease in HLA-DR expression can be seen after elective abdominal surgery, and the degree of surgical trauma is positively correlated with the increase in serum IL-6 levels. Since we cannot block the immune dampening effect of severe trauma, can we work to mitigate the additional blow to the body’s immunity from surgery? Damage control, originally intended to rapidly correct coagulation disorders, hypothermia and acidosis, has been further developed as “damage control orthopedics (DCO)” or “damage control orthopedic surgery (DCO)”. It has been further developed as “damage control orthopedics (DCO)” or “damage control orthopedic surgery (DCOS)”, or even “immune control”, i.e., not only to block the aforementioned deterioration of endostasis, but also to reduce the excessive immune response of the body, but also to The timing of later definitive surgery should also take into account the changes in the immune status of the body. There are few similar studies, but one retrospective study showed that the systemic immune response in the 3-d postoperative period in severely traumatized patients treated according to the DCOS concept was significantly lower than in patients in the conventional definitive surgery group, although the degree of trauma was significantly higher in the former group than in the latter. Surgery performed during immune overload is more likely to result in postoperative multiorgan dysfunction than surgery performed during endostasis, and therefore definitive surgery should be performed when the immune response returns to normal. Performing surgery when the immune response is dysregulated may lead to further amplification of the systemic inflammatory response and/or compensatory anti-inflammatory response, with a subsequent increase in the probability of infection. A prospective study comparing the timing of definitive surgery after DCOS in severely traumatized patients showed that the incidence of organ dysfunction was significantly higher in patients undergoing early reoperation after initial surgery (2-4 d postoperatively) than in patients undergoing late reoperation (6 d postoperatively), and serum IL-6 levels were also significantly higher in the latter group. Due to the lack of randomized controlled studies, DCOS can only be based on the observation of the aforementioned immunological indicators. In conclusion, reduction surgery aimed at damage control is not only to rapidly correct the pathophysiological disorder of severe abdominal trauma, but also to avoid excessive blow to the immune system of the body by surgery; again the timing of definitive surgery should not only depend on the stability of homeostasis in the body, but also to assess the regression of the overactive immune response. 2.The implementation plan of reduction surgery in case of abdominal trauma The treatment of severe abdominal trauma requires close cooperation and mutual collaboration among multiple disciplines to complete. Most patients can be treated by conventional surgery, and only when the physiological potential of a few patients is close to the limit, damage control surgery must be used. The indications for DCS are not yet standardized, and we are on high alert for high-energy abdominal, multisite trauma or with major vascular injury, usually pre-judged within 10 min of the start of surgery, and Asensio’s principles for DCS selection can be used as a reference. dcs usually consists of an initial brief dissection (reduction surgery), ICU resuscitation, and later definitive surgery, and may sometimes require the addition of “unplanned reoperations”. Reduction surgery in case of abdominal trauma is reflected as simple and rapid control of the injury, more effective than definitive surgery in reducing the pathophysiological changes of the body and creating conditions for the next definitive surgery. (1), hemostasis The primary task of reduction surgery is to control fatal bleeding. The obvious local active bleeding should be sutured, and those who cannot be ligated or sutured, immediately use the caulking method to stop bleeding, and cannot wait until all other methods of hemostasis are tried and ineffective before considering caulking, let alone blind clamping when probing is unclear, so as not to accidentally injure important tissues. 1) Treatment of injured vessels Complex revascularization techniques should be avoided as much as possible, and simple lateral repair, ligation or temporary intracavitary shunts are generally used, and if necessary, the abdomen can be quickly closed after direct gauze filling, and vascular intervention can be contacted to stop bleeding. However, for pelvic retroperitoneal hemorrhage, interventional treatment has limited effect, when retroperitoneal exploration can be opened and unilateral or bilateral internal iliac veins can be directly ligated and then filled. Hepatic artery, mesenteric vessels, inferior vena cava and iliac vein can be ligated, and even portal vein and superior mesenteric vein can be considered for ligation, but they will cause severe intestinal stasis, and temporary venous diversion can be considered for establishment. 2) Curettage Curettage has been used for almost all intra-abdominal organs and retroperitoneal tissue bleeding, including arteriovenous bleeding and traumatic bleeding, with the advantages of short time, easy operation and precise hemostatic effect. It is particularly suitable for bleeding with limited conditions at the time of initial surgery, pathophysiologic impairment of the patient, or uncontrollable bleeding. If solid organ bleeding is still suspected after the initial procedure, or in patients with complex hepatic trauma whose condition is unstable and cannot be explored in detail, radiological interventions can be combined to achieve optimal results, and some authors even advocate interventional hepatic artery embolization immediately after tamponade. Peritoneal tamponade requires a close combination of delicate intraoperative manipulation, close postoperative observation, and exact repair at the time of reoperation to achieve optimal results. Perihepatic gauze tamponade, moreover, is an essential damage control technique in the management of traumatic hepatic hemorrhage. A recent retrospective study found that postoperative adequate peritoneal tamponade in patients with hepatic rupture resulted in significantly fewer transfusions and a significantly lower mortality rate than in patients in the no or inadequate tamponade group. Gauze tamponade can be removed after 24-48h postoperatively, and in our experience up to 7d. Negative pressure assisted tamponade is the most effective, i.e. double cannula with negative pressure continuous flushing in the middle, which not only can ensure close fitting of tamponade gauze to tissues; but also can play the role of drainage and reduce the possibility of infection as much as possible; at the same time, iodophor flushing is used later to further reduce the incidence of infection, prolong the tamponade time and ensure the tamponade effect. In the specific operation, we should pay attention to: (1), the pressure vector generated by the caulking should be used to close the traumatic tissue wound and fix the traumatic organ; (2), it is better to caulk on the basis of repair for large vessel injury; (3), in the case of suspicious effect of caulking, we can continue to stay in the operating room after operation, and enter the abdomen again after 30 min to remove the caulking and deal with the missed bleeding point. For patients with hemodynamic instability after pelvic fracture, retroperitoneal gauze tamponade can be used as a means of resuscitation, and it has been reported to adopt a median incision in the lower abdomen without entering the free abdominal cavity and tamponade directly in the anterior sacral space; the effectiveness of this method needs further in-depth study. (2), control of infection After hemorrhage control, the gastrointestinal tract is quickly explored and the infection is controlled by simple suturing or direct clamping of the broken organ site. Small gastrointestinal perforations can be closed with a single continuous suture. Complex intestinal injuries or colonic breakage should avoid one-stage resection anastomosis and be left in the abdominal cavity after direct closure, because abdominal infection depends mainly on whether the intestine is perforated or not, independent of the perforation site. Multiple injuries can be considered for resection when the length of intestinal segment injury is >50%. We treated a patient with severe multiple injuries, duodenal penetration injury, and inferior vena cava rupture, who underwent “duodenal repair, inferior vena cava rupture repair, and jejunostomy” in an outside emergency hospital. The patient was transferred to our hospital for “unplanned reoperation (abscess drainage, abdominal gauze tamponade to stop bleeding, jejunostomy, temporary laparotomy)”, and “removal of gauze tamponade” was performed 7 d after the reoperation, and the patient’s condition was quickly controlled, and enteral nutrition was satisfactorily restored, pending later definitive surgery. More than 80% of pancreatic trauma with simple external drainage with or without pancreatic tail resection can achieve satisfactory results, and complex pancreatic head resection or even GI reconstruction surgery is strongly avoided, supplemented by tamponade if necessary. (3), temporary abdominal closure (temporary abdominal closure, TAC): mainly for the prevention and treatment of inter-abdominal compartment syndrome (ACS), while facilitating rapid access to the abdomen when reoperation for severe abdominal trauma or abdominal infection. ACS caused by the rush to close the abdomen under great incisional tension has brought about serious complications such as necrotizing fasciitis, intestinal fistula, multiple organ dysfunction, and high mortality, while the special advantages of temporary abdominal closure are avoiding bowel exposure, reducing visceral adhesions, and preventing peritoneal retraction. The fastest progress is the invention of various covering materials, which should meet the following requirements: good airtightness, exact drainage effect, strong resistance to infection, good biocompatibility, little damage to the intestinal canal and fascia, high cost effectiveness, easy intraoperative operation, and easy postoperative management, etc. The recent emergence of biomaterials is worth looking forward to. At present, we still use the most polypropylene mesh, which is also supplemented with negative pressure suction, with good results and few complications, and at the same time, we can promote the postponed closure of the abdominal cavity after the second-stage implant. At present, the temporary abdominal closure technique is more and more widely used, especially the negative pressure assisted closure has saved many patients with severe abdominal trauma, but there is still a big controversy about its late abdominal wall reconstruction, especially the pointers of delayed closure, timing selection, how to reduce the incidence of postoperative incisional hernia and abdominal wall compliance maintenance. 3. Resuscitation after reduction surgery and definitive surgery Once the abdominal cavity is temporarily closed, ICU resuscitation is started immediately with the aim of maintaining stable endostasis and correcting metabolic failure within 36-48h. The previous resuscitation especially emphasized acid correction and heat preservation, and relatively neglected the timely correction of coagulation disorders, but the recent concept of “damage control resuscitation” clearly emphasized the need to correct coagulation disorders from the early stage of trauma treatment. Definitive surgery is usually performed 24-48 h after the initial operation, with the main purpose of removing the occlusion, implementing vascular and digestive tract reconstruction, and closely exploring to avoid missing the injury. In patients with severe abdominal wall defects and intestinal edema who are still unable to close the abdominal cavity, temporary abdominal closure may continue to be performed, and as the patient’s pathophysiological condition gradually improves, the abdominal cavity may be closed by gradually drawing together the abdominal wall incision, second-stage suturing, and skin grafting until normal closure. Finally, given the pathophysiological and immunological characteristics of severe abdominal trauma, reduction surgery aimed at damage control has a high rate of complications and mortality, including incisional infection (50-100%), abdominal infection (25-8%), intestinal fistula (5-25%), and abdominal hypertension (20%). 4.Summary In conclusion, the reduction of surgery in the treatment of severe abdominal trauma is not equal to giving up the rescue, but holding the concept of damage control, reducing the extra blow brought to the patient by various treatment measures, and creating good conditions for the follow-up treatment, requiring not “successful surgery”, but “successful treatment”. Success”. Therefore, it is necessary to limit the extra blows caused by various treatment measures to what the patient can bear at that time, especially to avoid the extra blows caused by the complications of treatment measures.