Rimazolam versus sevoflurane anesthetic effects on delayed neurocognitive recovery after major abdominal surgery in the elderly: a randomized controlClinical Research Program

INTERVENTION: Group S:Sevoflurane maintenance anesthesia;Group R: Rimazolam maintenance anesthesia;Group C:None; CONDITION: Cognitive function PRIMARY OUTCOME: incidence of delayed neurocognitive recovery; SECONDARY OUTCOME: ICU admission after surgery;incidence of postoperative nausea and vomiting;Incidence of severe postoperative pain;Reoperation;Acute agitation;Length of postoperative stay in hospital;Mortality in hospital; INCLUSION CRITERIA: Study group inclusion criteria (1) ASA II to III; (2) 60 to 90 years old; (3) Undergoing major abdominal surgery (estimated operation time 2 hours or more);(4) Fluent in Chinese (speaking and reading); Inclusion criteria for the control group: (1) Age >= 60 years; (2) ASA class II or III; (3) Fluency in Chinese (speaking and reading); (4) Ability to complete neuropsychological tests independently.