The investigators conduct this randomized assessor-blinded controlled trial to evaluate the effect of SVV-guided fluid therapy on postoperative morbidity and mortality in comparison with conventional fluid therapy after major abdominal surgery. Half of participants will receive GDFT perioperatively, and the others will receive conventional fluid therapy

Perioperative fluid management has been recognized as an important factor with an impact on postoperative recovery following major abdominal surgery. However, the optimal fluid management is difficult to achieve using standard parameters (e.g., heart rate [HR], blood pressure [BP], central venous pressure[CVP], or urine output) that poorly estimate preload and preload responsiveness. Goal-directed fluid therapy (GDFT) was proposed by introducing different hemodynamic variables into a dynamic perspective of individual fluid loading with or without vasoactive substances to reach predefined goal of optimal preload and/or oxygen delivery.There have been increasing numbers of studies evaluating the effect of perioperative GDFT on postoperative recovery following major abdominal surgery. However, the evidence for the beneficial effect of GDFT on postoperative recovery remains inconsistent.

Inclusion Criteria:

1. Adult patients (aged 18 to 80 years)
2. ASA I~III
3. BMI:18~30kg／m2
4. Procedures were considered major if listed for resection of gastrointestinal, gynecologic, and urologic cancer with tumor debulking, staging or reconstruction with a risk for significant surgical blood loss

Exclusion Criteria:

1. Patients under 18 years,
2. pregnant or lactating woman
3. patients with esophageal or gastric surgical history
4. co-existing congestive heart failure; chronic lung disease; or renal or hepatic dysfunction (creatinine >50 % or liver enzymes >50 % of normal values), and arrhythmias-operative down staging using chemotherapy and/or radiation therapy
5. patients undergoing emergency surgery
6. patients with co-existing congestive heart failure; chronic lung disease; or renal or hepatic dysfunction (creatinine >50 % or liver enzymes >50 % of normal values), and arrhythmias

Care providers and investigators in the operating room could not be blinded due to the presence of the cardiac index trending monitor. The postoperative assessors were blinded to the allocation.