Abstract: Objective To investigate the effect of different pneumoperitoneal pressures in patients with acute calculous cholecystitis (ACC) during laparoscopic cholecystectomy (LC). 
Methods A total of 60 ACC patients admitted to our hospital were selected as the research subjects, and they were divided into the observation group (n=30) and the control group (n=30) by random number table method. Both groups were treated with LC. The control group maintained conventional pneumoperitoneal pressure (12-15mmHg) during operation, while the observation group maintained low pneumoperitoneal pressure (7-8 mmHg). The perioperative indicators, postoperative pain severity, and complication rate were compared between two groups. Before operation and at 24 h after operation, the liver function and endothelial cell damage-related factors were detected and compared between two groups. 
Results The first anal exhaust time and the first time of food intake in the observation group were shorter than those in the control group (P＜0.05). The pain severity in the observation group at 1 h-24 h after operation was lower than that in the control group (P＜0.05). Alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin(TBIL), gamma-glutamyl transferase (GGT), von Willebrand factor (vWF) , thrombomodulin (TM), and endothelin-1 (ET-1) increased in the two groups at 24 h after operation, but the above indexes in the observation group were lower than those in the control group(P＜0.05). There was no significant difference in the incidence of complications between the observation group and the control group (P＞0.05). 
Conclusion Maintaining low pneumoperitoneal pressure during LC surgery is equivalent to normal pneumoperitoneal pressure in terms of operative field clarity, efficacy, and safety, and it helps to promote recovery of postoperative gastrointestinal function, reduce postoperative pain, and has a positive effect on protecting liver function and inhibiting endothelial cell damage. 

Key words: cholecystitis, acute, cholecystectomy, laparoscopic, endothelial cell damage