Experimental: GDFT group

Patients in GDFT group will receive GDFT protocol, Stroke volume variation (SVV)≤12% and cardiac index (CI)≥2.5L/min/m2 are the goals of fluid therapy, while the mean arterial pressure (MAP) are kept between 65 and 90 mmHg. 5mL/kg of crystalloids will be infused during induction period, followed by an infusion rate of 2 mL/kg/h to supplement the physiological requirements. If SVV\>12% for more than 5 min, a 250 mL bolus of colloid is given. Another 250 ml bolus of colloid is administrated if SVV was still more than 12% or SV decreased over 10%. If the CI\<2.5 L/min/m2, inotropes are used to achieve this minimum CI, serving as a safety parameter to prevent the patient from being exposure to a low cardiac output state. If SVV and CI reached the s target range but MAP could not maintain the expected level, vasopressors were started. Assess the patients every 5min intraoperatively to ensure that all parameters adhere to the target range according to the study algorithm.

No_intervention: conventional fluid therapy group

Patients in conventional fluid therapy group, fluid management will be carried out according to the clinical practice routine, maintaining MAP≥65mmHg and urine output ≥0.5ml/kg/h, intraoperatively. When the anesthesiologist empirically determines that the fluid infusion is sufficient but MAP does not maintain the expected level, vasopressor or inotropic drugs are given to maintain the blood pressure.