Esketamine Combined With Pregabalin on CPSP in Spinal Patients.

"* Drug: Pregabalin~* 150mg (2hrs) pre operatively and 75mg twice daily post operatively for 7 days(POD1-7), followed by dose reduction to 75mg once daily for 7 days(POD8-14)~* Drug: S-ketamine infusion~* 0.5 mg/kg bolus after induction of anesthesia +0.12 mg/kg/h continuous intravenous infusion for 48 h"

"* Drug: Placebo capsules~* Two placebo capsules (2hrs) preoperatively and twice daily post operatively for 7days, followed by dose reduction to single capsule once daily for 7days~* Drug: Normal saline~* 0.9% saline bolus after induction of anesthesia + intravenous infusion for 48 hours"