Goal-directed Fluid Therapy in Elderly Patients Undergoing Lumbar Surgery

This is a single-center, randomized controlled clinical trial. Patients aged \> 60 undergoing lumbar decompression surgery will be randomly assigned to either a GDT ( goal directed fluid therapy) group or a control group, who received conventional anesthesiologist-directed fluid therapy. Perioperative lactic acid concentrations with 7 different time point, intraoperative fluid balance and postoperative complications from admittance to 30 days after surgery were recorded. This RCT is conducted to show the evidence of benefit from GDT in terms of lactate kinetics then may reduce postoperative complications in patients undergoing spine surgery, especially in prone positions.