Effect of TEE-guided Non-fluid Limited Combined With Dobutamine on Hepatic Venous Blood Flow Spectrum

In the dobutamine group, 3\~6μg/kg/min dobutamine will be injected intravenously after anesthesia induction until hemostasis is completed. The dose of dobutamine will be increased if the operating field grade exceeds Grade II. Monitoring LVEDV and SV with TEE to ensure preload: after admission, the patient will be given 3-4 mL /kg/h equilibrium fluid as background infusion. LVEDV and SV will be monitored using TEE every 30 minutes after anesthesia induction. If LVEDV\<75mL or SV\<45mL, 200mL colloidal fluid will be given within 5min.

In the control group, 3mL/h normal saline will be injected intravenously after anesthesia induction until hemostasis is completed. According to the currently commonly used principle of LCVP, the fluid will be limited to 3-4 ml /kg/h after anesthesia induction. If the operating field grade exceeds Grade II, nitroglycerin will be injected intravenously for remedial purposes at a rate of 0.3-0.8μg/kg/min.