Abstract: Abstract: Objective　To investigate the effect of different intraoperative fluid therapy on postoperative delirium (POD) in patients undergoing spinal surgery. Methods　A total of 195 patients of middle- and elderly-aged (≥ 50 years old) scheduled for elective spinal surgery were included and randomly divided into two groups by using a random number table: restrictive fluid therapy group (group RF, n=97) and goal-directed fluid therapy group (group GDT, n=98). In group RF , a bolus of lactated Ringer's solution was firstly administered at 5 mL/kg during the induction of anesthesia, then at 5 mL/(kg×h) until the end of surgery. For patients in the GDT group, in addition to the initial administration of lactated Ringer's solution at 5 mL/kg, the following fluid therapy was adjusted by using CNAP noninvasive blood pressure monitoring system to maintain 9%≤PPV≤13%. The volume of fluid infusion, blood transfusion volume and urine volume, blood loss, as well as the usage of vasoactive agents were all recorded during the entire operation. The mean arterial pressure (MAP), heart rate (HR), cardiac index (CI) and regional cerebral oxygenation index (rSO2) were recorded at different time points, including before anesthesia induction (T0), 5 minutes after anesthesia induction (T1), when the operation began (T2), and at different time points (30 minutes, 60 minutes, 90 minutes and 120 minutes) during operation (T3-T6), at the end of operation (T7), at 5 minutes after operation (T8). Arterial blood samples were collected to test lactic (LAC) value at T2 and T7. The Visual Analogue pain score (VAS ) and the Method-Chinese revision(CAM-CR) score were recorded three days after the operation. Results　Compared with group RF, MAP and rSO2 were increased at T5-T8 in group GDT, while CI and HR were increased at T6-T8 in group GDT (P＜0.05). Meanwhile, compared with group RF, less usage of ephedrine [(1.5± 0.5) mg vs. (4.7 ± 5.8) mg, t=3.309, P＜0.05], more intraoperative fluid infusion volume [(1826.1 ± 608.5) mL vs. (1345.4 ± 548.7) mL, t=5.791, P＜0.05] and more intraoperative urine volume [(470.9 ± 296.8) mL vs. (380.8 ± 228.1) mL, t=2.326, P＜0.05] were observed in the group GDT. POD incidence rate was lower in group GDT than that in group RF (4.1% vs. 12.4%, χ2=4.448, P＜0.05). Conclusion　The goal-directed fluid therapy can stabilize the perioperative hemodynamics, improve tissue perfusion and reduce the incidence of POD following spinal surgery.

Key words: fluid therapy;delirium;postoperative complications;restrictive fluid therapy, goal-directed fluid therapy, spinal surgery