右美托咪定对止血带引起的血流动力学变化的影响

目的 观察右美托咪定对止血带引起的血流动力学变化的影响.方法 选择择期行下肢手术并应用止血带的患者40例,随机分为右美托咪定组（D组）和生理盐水组（N组）,每组20例.两组患者均行腰硬联合麻醉.待麻醉平面稳定后,D组静脉泵注右美托咪定0.5 μg/kg,N组静脉泵注生理盐水0.5μg/kg,均于10 min泵完,给药结束后开始上止血带驱血加压.分别记录给药前（T0）、上止血带前（T1）、松止血带前（T2）、松止血带后1 min（T3）、3 min（T4）、5 min（T5）、10 min（T6）时的平均动脉压（MAP）、心率（HR）、脉搏血氧饱和度（SpO2）.结果 与T0比较：N组的MAP在T2时上升,T2后下降,但差异均无统计学意义（P＞0.05）;D组的MAP在T2时下降但差异无统计学意义（P＞0.05）,T2后明显下降（P＜0.05）.与T2比较：N组的HR在T3明显上升（P＜0.05）;D组的HR在T3亦上升但差异无统计学意义（P＞0.05）.与N组比较,D组的MAP（P＜0.001）、HR（P＜0.01）下降,差异有统计学意义;SpO2差异无统计学意义（P＞0.05）.结论 单次静脉泵注右美托咪定0.5 μg/kg,可以加重松止血带后的血压下降,所以在腰硬联合麻醉下行下肢上止血带的手术中,不提倡使用右美托咪定.

Effects of dexmedetomidine on the tourniquet-induced haemodynamics response

Objective To observe the effects of the dexmedetomidine on the tourniquet-induced haemodynamics response. Methods Forty patients who received combined spinal-epidural anesthesia undergoing elective lower limbs operations with application of tourniquet were randomly assigned into the dexmedetomidine group （ group D） or control group （group N） （20 cases in each group）. After the level of anesthesia was stable, group D received a loading dose of dexmedetomidine （0. 5 μg/kg over 10 min）before tourniquet inflation, while group N received normal saline instead. Mean arterial pressure（ MAP ） , heart rate （ HR ） , saturation of pulse oximetry （ SpO2 ） were recorded at regular time-points immediately before dexmedetomidine （or saline）loading （TO）, before tourniquet inflation （T1）, before tourniquet deflation （ T2 ）, 1 min after tourniquet deflation （ T3 ）, 3 rain after tourniquet deflation （ T4 ） ,5 min after tourniquet deflation（ T5 ） , 10 min after tourniquet deflation（T6）. Results Compared with the TO, the MAP of group N increased at T2 point, then dropped slightly （ P 〉 0. 05 ） ; the MAP of group D significantly dropped （ P 〈 0. 05 ） after ＂1＂2 point. Compared with theT2, the HR of group N significantly increased （ P 〈 0. 05 ） at T3 point, group D also increased slightly （ P 〉 0. 05 ）. The effects of tourniquet inflation on increasing hemodynamic parameters were significantly attenuated by dexmedetomidine, and MAP （ P 〈 0. 001 ） , HR （ P 〈 0. 01 ） of group D were significantly lower than those of group N. Simultaneously, SpO2 were comparable between the two groups （ P 〉 0. 05 ）. Conclusion Single dose of dexmedetomidine （ 0. 5 μg/kg ） could exacerbate hypotension induced by tourniquet deflation, and exacerbate the intraoperative hemodynamic fluctuations. Dexmedetomidine is not advocating in operations applying tourniquet on lower limbs under combined spinal-epidural anesthesia.