Objective:To investigate the effect of ultrasound monitoring of inferior vena cava collapse index (IVC-CI) guiding fluid replacement on circulation in elderly patients during induction of general anesthesia.Methods:A total of 71 elderly patients who underwent elective surgery under general anesthesia and tracheal intubation at Hunan Provincial People′s Hospital from April 2021 to September 2022 were randomly divided into control group (35 cases) and observation group (36 cases) using a random number table method. Before anesthesia, both groups of patients underwent IVC ultrasound examination and calculated the IVC-CI value. For patients with IVC-CI≥40%, the observation group was given 8 ml/kg of crystal solution before anesthesia induction, while the control group was not treated. The incidence of hypotension, the use of vasoactive drugs, and the total infusion volume from anesthesia induction to skin incision were recorded in two groups. Mean arterial blood pressure (MBP), heart rate (HR), oxygen saturation (SpO 2), cardiac index (CI), and cardiac volume variability (SVV) before anesthesia (T 0), 5 min after induction (T 1), 1 min after tracheal intubation (T 2), 5 min after tracheal intubation (T 3), 10 min after tracheal intubation (T 4), and 1 min before skin incision (T 5) were recorded and compared between the two groups. Results:The incidence of hypotension (27.8% vs 60.0%) and utilization rate of vasoactive drugs (25.0% vs 48.6%) in the observation group were lower than those in the control group, and the total infusion volume during anesthesia induction was higher than that in the control group, with statistical significance (all P<0.05). SVV, CI and MBP at T 1, T 3, T 4 and T 5 were significantly different from those at T 0 in the control group ( F=3.85, 14.66, 3.96, all P<0.05). SVV, CI and MBP at T 1, T 3, T 4 and T 5 in the observation group were significantly different from those at T 0 ( F=3.51, 13.20, 4.35, all P<0.05). There was no significant difference in SVV, CI, MBP, HR and SpO 2 between 2 groups (all P>0.05). Conclusions:For the elderly patients with preoperative IVC-CI≥40%, pre-filling with 8ml/kg crystal solution before anesthesia induction can significantly reduce the incidence of hypotension and the utilization rate of vasoactive drugs in the elderly patients during anesthesia induction.