摘要:目的:探讨右美托咪啶对全麻下外科手术中肢体应用止血带辅助止血所致心血管反应的抑制作用.方法:38例患者全麻下行下肢骨科手术,随机分为右美托咪定组(DEX组,n=19)和对照组(n=19).DEX组麻醉开始前静脉输注负荷剂量右美托咪啶1 μg/kg,10 min输注完毕后以0.5 μg·kg-1·h-1持续输至术毕;对照组以相同方法输注等量生理盐水.负荷剂量输完后两组采用相同的麻醉诱导和维持方法.于患者入手术室后(T0),止血带充气前(T1),充气后10 min(T2)、20 min(T3)、30 min(T4)、40 min(T5)、50 min(T6)、60 min(T7),松开止血带后5min(T8)、10 min(T9),记录有创收缩压(ISBP)、有创舒张压(IDBP)、心率、脑电双频谱指数(BIS)值,并记录停药至自主呼吸恢复及拔管所用时间.结果:与T0比较,T1时两组血压、心率、BIS值都明显降低(P<0.05),但两组间比较差异无显著性(P>0.05);与T1比较,对照组T3~T8时ISBP、IDBP、心率增高,T7达到峰值(P<0.05或<0.01),DEX 组T1~T9时无显著变化(P>0.05).与DEX组比较,对照组T3~T8时ISBP、IDBP升高,T4~T9时心率增快(P<0.05或<0.01).两组自主呼吸恢复时间、拔管时间差异均无显著性(P>0.05).结论:右美托咪啶可有效抑制全麻下应用肢体止血带所致的心血管反应,对患者苏醒时间无影响.%Objective:To investigate the effects of dexmedetomidine on cardiovascular responses caused by application of tourniquet to the limbs and recovery time of patients under general anesthesia. Methods: Patients undergoing orthopaedic surgery of lower extremity under general anesthesia (n = 38) were randomly assigned to dexmedetomidine (group DEX,n=19) or control group (group C,n = 19). In group DEX,before induction of anesthesia, a bolus of dexmedetomidine was administered in 10 minutes,then fluid infusion was started at 0. 5 μg · kg‐1 · h‐1 until the end of the operation. Dexmedetomidine was replaced by normal saline in group C. Anesthesia induction and maintenance were started after administration of a bolus of dexmedetomidine or normal saline in respective group. In all the patients, invasive systolic blood pressure (ISBP) and invasive diastolic blood pressure (IDBP), heart rate (HR) ,bispectral index (BIS) were recorded at regular time-points after entrance into the operating room (TO) .before tourniquet inflation (Tl) ,10 (T2) ,20(T3) ,30 (T4) ,40(T5) ,50 (T6) ,60 minutes (T7) after tourniquet inflation,5(T8) and 10 minutes (T9) after tourniquet deflation. The time of withdrawal of anesthesia to the restoration of spontaneous breathing and extubation was also observed. Results: Compared with TO , ISBP, IDBP, HR and BIS values were significantly reduced (P〈0. 05 ) at Tl in both two groups,and the difference between the two groups was not significant (P>0. 05). In group C, ISBP, IDBP, HR increased from T3 to T8 compared to Tl,and reached the peak level at T7(P<0. 05 or P<0. 01 ) ,but the change was not significant from Tl to T9 in group DEX(P>0. 05). Compared with group DEX, ISBP and IDBP were increased at T3-T8 and HR increased at T4-T9 in group C (P〈0. 05 or P〈0. 01). There were no significant differences in the time of withdrawal of anesthesia to the restoration of spontaneous breathing and extubation in two groups (P>0. 05). Conclusions: Dexmedetomidine can effectively restrain cardiovascular responses caused by application of tourniquet and has no influence on recovery time of patients under general anesthesia.