A Correlation Study of Internal Jugular Vein Variability Under Deep Inhalation and Propofol-induced Hypotension

Inclusion Criteria: * age over 60 years * American Society of Anesthesiology (ASA) status Ⅱ-Ⅲ * Surgery with radial artery puncture * Propofol induction Exclusion Criteria: * 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.