2. Fluid Treatment Compensatory volume of expansion (CVE) is replaced with 5mL/kg of Ringer's lactate solution before induction. The maintained dose of infusion of crystalloid during surgery is: 2~4 ml/kg/h for open procedure (maximum dose of 400ml/h), and 1~2 ml/kg/h for laparoscopic procedure (maximum dose of 200ml/h) respectively. Fluid replacement is directed by SV value. After incision (after pneumoperitoneum for laparoscopic cases) give a 200 mL Hydroxyethyl Starch 130/0.4 and Sodium Chloride bolus over <10 min. If SV increases by >10%, repeat bolus until SV increases by <10%. Record peak value achieved. Give a further colloid bolus when SV drops 10% from peak value and repeat cycle. According to the bleeding, RBC and plasma are given if necessary. SaO2≥95%, Hb > 70g/L, core body temperature> 37 ℃, HR50 /min~100/min and MAP60~100mmHg are maintained during the surgery in both groups. When SBP<90 mmHg or MAP < 60 mmHg, the two groups are given the vasoactive drug of bitartrate noradrenaline.