Perioperative Dexmedetomidine on Postoperative Delirium in Patients With Brain Tumors

In Dex group, dexmedetomidine will continue to be used during and after surgery, with a infusion of 0.4ug/kg/ h from anesthesia induction to dural closure, and then 0.08ug/kg/ h to 48 hours postoperatively.In placebo group, equivalent normal saline will be injected during operation, and the intravenous analgesia pump will not contain dexmedetomidine after operation