Abstract： Objective To study the effect of long-time carbon dioxide (CO2) pneumoperitoneum on QT dispersion (QTd) in elderly patients during Davinci robotassisted surgery.Methods Thirty elderly patients undergoing elective Davinci robot-assisted hepato-pancreato-biliary surgery with general anesthesia were enrolled in this study.Pneumoperitoneum was established at 12 mm Hg ( 1 mm Hg =0.13 3 k Pa).QTd was recorded before the induction of anesthesia; at 5,15,30,60,120,180 and 240 min after pneumoperitoneum.Results Compared with before anesthesia,mean arterial blood pressure (MAP) increased significantly at 15,30 min after pneumoperitoneum ( P＜0.05 ),and had no significant difference at 5,60,120,180,240min (P＞0.05 ).Heart rate (HR) increased significantly at 15,30 min after pneumoperitoneum (P＜0.05 ).End-tidal pressure of carbon dioxide (PETCO2) increased after pneumoperi-toneum,and had significant difference at 30,60,120,180,240 min after pneumoperitoneum (P＜0.05).In 30 patients,11 patients occurred arrhythmia including atrial extrasystole,premature ventricular beats,tachycardia.Compared with before anesthesia,QTd,corrected QTd (QTcd),QT interval,corrected QT interval (QTe) were significantly increased at 15,30,60 min after pneumoperitoneum (P＜0.05),but had on significant difference at 5,120,180,240 min after pneumoperitoneum (P＞0.05).Conclusion The effect of CO2 pneumoperitoneum on the autonomic nervous system for elderly patients might be important,as an imbalance in autonomic cardiac control might lead to serious consequences.