Based on the preoperative ultrasound detection of various parametric indicators of the inferior vena cava cross-section, including the ratio of the inferior vena cava's long and short axes, cross-sectional area and circumference during two-dimensional and three-dimensional imaging, as well as the changes in respiratory variability of each parameter, we explored the predictive value of IVC ultrasound indicator parameters on hypotension after induction of general anesthesia in elderly patients undergoing elective non-cardiac surgery, screened the sensitive indicators, and calculated the cut-off values.

Inclusion Criteria:

• Elderly patients undergoing elective non-cardiac surgery under general anesthesia;
• Age 65-85 years old;
• Body mass index (BMI) 18-28 kg/m2;
• American society of anesthesiologists (ASA) class I-III.

Exclusion Criteria:

• Patient refusal or lack of cooperation;
• Inability to communicate properly;
• Severe sinus bradycardia, pacemaker implantation, atrioventricular block, and atrial fibrillation;
• Presence of severe hepatic and renal function abnormalities;
• Preoperative cardiac ultrasound suggesting LVEF <50%;
• Tricuspid valve displacement <16 mm by preoperative cardiac ultrasound;
• Chronic obstructive pulmonary disease;
• Pulmonary hypertension;
• Administration of drugs that inhibit the renin-angiotensin-aldosterone system;
• Possibility of a difficult airway.

Elderly patients undergoing elective non-cardiac surgery under general anesthesia