Objective To observe the efficacy and safety of dexmedetomidine (DEX) and sufentanil on postoperative analgesia in patients with mitral stenosis undergoing valve replacement.Methods Forty cases of heart valve replacement surgery patients aged 45 y-70 y with American Society of Anesthesiologists (ASA) class Ⅱ-Ⅲ were randomly divided into sufentanil group (SF group) and sufentanil combined with DEX group (SD group).SF group was treated with sufentanil(0.09 μg·kg-1·h-1) by patientcontrolled intravenous analgesia,while SD group was treated with sufentanil(0.09μg· kg-1·h-1)and DEX(0.08 μg· kg-1·h-1).The visual analog scale (VAS),Ramsay-score,mean radial artery pressure (MAP),finger pulse oxygen saturation (SpO2) and the rate of adverse reaction of patients after operation(respiratory depression,nausea,vomiting,etc.) between the two groups were compared at the time 12(T1),24(T2),36(T3),48 h(T4) following operation.Results ① VAS:The VAS of SD group [(2.4±0.6),(2.8±0.7),(2.3±0.6),(2.0±0.4)] was significantly lower than that of SF group [(4.0±1.0),(4.3±1.1),(3.7±0.7),(3.5±0.5)] at T1,T2,T3,T4,(P<0.05).② Ramsay-score:At T1,T2,T3,T4,the Ramsay-score of SD group [(3.3±0.5),(3.0±0.4),(3.5±0.6),(3.2±0.7)] was significantly higher than SF group [(1.2±0.6),(1.4±0.4),(1.2±0.5),(1.1±0.6)] (P<0.05).③ MAP:Compared with the MAP at T0 (83±12) mmHg (1 mmHg=0.133 kPa),at T1,T2,T3,T4 [(99±11),(99±12),(96±13),(93±13) mmHg] was increased in SF group (P<0.05).The MAP at T1,T2,T3,T4 [(86±10),(86±10),(84±11),(83±10) mmHg] was not significantly different with that at T0(82±13) mmHg in SD group (P>0.05).There was no significant difference between SD group and SF group at T0 in MAP (P>0.05).At T1,T2,T3,T4,the MAP of SD group was more stable than that of SF group (P<0.05).④ There was no significant difference between SD group and SF group at T0,T1,T2,T3,T4 in SpO2.⑤ The rate of adverse reaction:at T1,T2,T3,T4,the rate of nausea and vomiting in SD group (10%,5%) was obviously lower than that of SF goup(25%,15%)(P<0.05).There was no respiratory inhibition in both groups.Conclusions Combination of sufentanil and DEX in patients with mitral stenosis underwent valve replacement can enhance the effect of sufentanil on analgesia.This treatment provides satisfactory sedation and being low in adverse reaction. Key words: Postoperative analgesia; Dexmedetomidine; Sufentanil; Mitral valve replacement