Compare the incidence of hypotension during the propofol-induced period between the internal jugular vein variability-guided fluid infusion group and the conventional fluid infusion group through a fluid infusion experiment before anesthesia induction, so as to evaluate the feasibility of using the internal jugular vein variability under deep inspiration to guide preoperative fluid infusion.
age over 60 years； American Society of Anesthesiology (ASA) status Ⅱ-Ⅲ； Surgery with radial artery puncture； Propofol induction；
BMI≥30kg/m2； People with short necks； Previous hypotension (systolic blood pressure <90mmHg or mean arterial pressure<65mmHg)； Previous poorly controlled hypertension； Cardiac insufficiency , EF value<50%； Upper limb deep vein thrombosis； History of radiotherapy or neck surgery； Inability to maintain a supine position for necessary measurements； Mechanical ventilation status or inability to take deep breaths patients； gastrointestinal surgery； Patients allergic to propofol； Restricted fluid intake；