Protective effect of dexmedetomidine combined with epidural block on postoperative analgesia and early cognitive impairment in elderly patients after radical resection of colorectal cancer: a randomized controlled trial

Interventions: Dexmedetomidine group:Patients were injected with 0.6 µg/kg/h dexmedetomidine by intravenous injection after anesthesia induction to 30 min before the end of the surgery.;Epidural blockade group:The epidural blockade was conducted by epidural injection of 2% lidocaine;Combined group:Patients were treated with both dexmedetomidine and epidural blockade as described above;Control group:Patients were injected with 0.6 µg/kg/h of normal saline Primary outcome(s): MMSE scores at different time points after surgery;Ramsay scores at different time points after surgery;VAS scores at different time points after surgery;PCIA pressing times Study Design: Randomized parallel controlled trial