What is ACS? ACS (Abdominal Cavity Syndrome) is a syndrome in which increased intra-abdominal pressure from any cause is accompanied by new dysfunctions or aggravation of existing dysfunctions in multiple organ systems such as cardiovascular, pulmonary, renal, cranio-cerebral and digestive systems. Due to the lack of awareness among pediatric patients, the case fatality rate is as high as 40%~60%, and in some primary hospitals, the case fatality rate is even as high as 90%. ACS is not uncommon in pediatrics, and the persistent elevation of intra-abdominal pressure can lead to severe abdominal distension, impaired ventilation, refractory hypercapnia, renal insufficiency, and ultimately multiorgan insufficiency or even failure. ACS is an independent risk factor for death, and is receiving increasing attention in critically ill patients. In order to strengthen the awareness, the international standard of ACS in children has been stipulated Internationally, in order to strengthen the attention of pediatricians to ACS WSACS guidelines in 2013 defined ACS in children as persistent IAP>10mmHg with new organ dysfunction or aggravation of pre-existing organ impairment due to increased intra-abdominal pressure.WSACS guidelines standardized the definition of ACS in children for the first time. The WSACS guideline defines ACS for the first time in children in order to differentiate it from the criteria for adults and to increase the importance of ACS for pediatricians. What is the treatment for ACS? Effective abdominal decompression is the mainstay of treatment for ACS and is effective in reversing organ dysfunction, so definitive and effective abdominal decompression should be given as soon as ACS is diagnosed. Commonly used decompression therapies are: abdominal puncture and drainage and cesarean section for decompression. According to the cause of intra-abdominal hypertension, reasonable measures should be selected. Caesarean section decompression and drainage is the most reliable method of decompression for ACS caused by large amount of intra-abdominal fluid or necrotic infection. However, whether to close the peritoneal cavity at the end of the operation, or to temporarily close the peritoneal cavity or to make a partial opening, a rational choice should be made according to the situation. Factors that militate against closure of the peritoneal cavity are severe edema of the bowel wall, subjective sensation of excessive tightness of closure, planning of reoperation, blockage of hemostasis, and pulmonary or hemodynamic deterioration in the patient as the peritoneal cavity is closed. Temporary closure of the peritoneal cavity reduces comorbidities such as enterocutaneous fistulae; do not force closure of large abdominal wall defects; place a polytetrafluoroethylene patch suture over the defect. For patients who do not have surgical conditions, it is feasible to drain fluids by abdominal puncture and/or indwelling catheter drainage, and closely observe changes in intra-abdominal pressure. Ischemia/reperfusion injury is an important part of the development of ACS. Clinical trials have shown that Octreotide can inhibit neutrophil exudation and improve reperfusion-mediated oxidative damage, thus playing a role in the treatment of ACS. To improve the prevention of ACS in children, measurement of intra-abdominal pressure is an important and easy way to diagnose ACS at an early stage once ACS is suspected. Enhanced prevention of ACS is important because of the high mortality rate that remains after decompression therapy.