Eighty patients undergoing elective lumbar spine surgery were randomized to receive either fluid maintenance (n=40) or fluid loading (n=40). Both groups received intravenous fluids at 2 ml/kg/h until surgical incision, while the fluid loading group received an additional 5 ml/kg over 10 minutes after anesthesia induction. The primary outcome was the incidence of hypotension before surgical incision. Secondary outcomes included changes in mean blood pressure (mBP), heart rate (HR), pleth variability index (PVi), stroke volume variation (sVV), pulse pressure variation (PPV), stroke volume index (SVI), cardiac index (CI), and postoperative complications up to postoperative day 2. Outcomes were assessed at multiple time points until surgical incision. Overall, fluid loading significantly reduced the incidence of hypotension (p=0.014) and was particularly effective in patients with a baseline PVi >16. Other hemodynamic parameters, such as PVi, sVV, and PPV, were significantly improved immediately after fluid loading. However, no significant differences were found in postoperative complications or hospital length of stay between the two groups. The findings suggest that intravenous fluid loading is beneficial in preventing hypotension in patients positioned prone for surgery, particularly for those with a high baseline PVi.