不同剂量右美托咪定对上腹部手术患者七氟烷最低肺泡有效浓度影响

Effects of different dose of dexmedetomidine on minimum alveolar concentration of sevoflurane in patients undergoing upper abdominal surgery

目的观察静脉输注不同剂量右美托咪定对七氟烷抑制半数上腹部手术患者切皮时体动反应最低肺泡有效浓度(MAC)的影响。方法选择拟在全身麻醉下实施上腹部手术的患者,ASAⅠ或Ⅱ级,随机分为3组:D_1、D_2组在麻醉诱导前15 min分别静脉泵入右美托咪定0.4、0.8μg·kg^(-1),D0组泵入同等容量氯化钠注射液。依次静脉注射丙泊酚、芬太尼和琥珀胆碱行麻醉诱导,气管插管后机械通气,开启七氟烷挥发罐。采用up-down法确定麻醉维持期间七氟烷的呼气末浓度,当七氟烷呼气末浓度达到预设水平并维持15 min以上,且神经肌肉功能恢复后开始手术。于切皮时评估患者体动反应,以各交叉点七氟烷呼气末浓度的均数为MAC。并观察各组患者血压、心率、脑电双频指数(BIS)的变化。结果 3组患者七氟烷的MAC分别为:D_0组(1.42±0.25)%,95%CI 1.24%～1.60%;D_1组(1.06±0.25)%,95%CI0.88%～1.24%;D2组(0.82±0.19)%,95%C1 0.70%～0.93%。_D1、D_2组低于D_0组,差异有显著意义(P<0.05)。输注右美托咪定期间D_1、D_2组患者血压和心率均逐渐下降,尤以心率下降为显著,部分患者需应用阿托品干预;D_1、D_2组患者脑电双频指数(BIS)均逐渐下降,至右美托咪定泵入结束时BIS值分别降为84±3和75±4,D_1组低于D_1组(P<0.01)。结论麻醉诱导前静脉输注右美托咪定0.4、0.8μg·kg^(-1)可使上腹部手术患者七氟烷MAC分别降低25.4%和42.3%,减少七氟烷的用量。

AIM To observe the effects of different dose of dexmedetomidine on minimum alveolar concentration （MAC） of sevoflurane in patients undergoing upper abdominal surgery. METHODS Adult patients （aged from 40 to 60 years） undergoing elective upper abdominal surgery with ASA I or 11 were randomly divided into group Do, D1 and D2. Fifteen minutes before anesthesia induction, patients in the group D1 and D2 were intravenously administered with dexmedetomidine 0.4 and 0.8 μg ·kg^-1 respectively, while patients in the group Do were intravenously administered with same amount of sodium chloride injection. Inhalation of sevoflurane was started after induction of anesthesia with propofol, fentanyl and suxamethonium. The end-tidal concentration of sevoflurane during maintenance of anesthesia was determined according to up-down method. After at least 15 minutes of equilibration and full recovery from suxamethonium-induced muscle relaxation was ensured, skin incision was performed. The patient＇s somatic responses was evaluated when skin incision. MAC of sevoflurane was the mean of end-tidal concentration of sevoflurane of each crossover pair. The changes of blood pressure, heart rate and bispectral index were also observed. RESULTS The MAC of sevoflurane in the group Do, D1 and D2 was （1.42 ± 0.25） %, 95%CI 1.24% - 1.60%; （1.06 ±0.25） %, 95%CI 0.88% - 1.24%; and （0.82 ±0.19） %, 95%CI 0.70% - 0.93%, respectively. The levels of MAC in the group D2 and Do were significant lower than that in the group Do （P 〈 0.05）. Blood pressure and heart rate in the D1 group and D2 decreased gradually, but some patients need atropine to keep heart rate. Bispectral index in the group D1 and D2 decreased to 84 ± 3 and 75± 4 after dexmedetomidine was used, and the difference was significant （P 〈 0.01）. CONCLUSION Intravenous administration of dexmedetomidine 0.4 and 0.8 μg·kg^-1 before anesthesia induction could decrease the MAC of sevoflurane by 25.4% and 42.3% respectively, therefore reduce the need of sevoflurane in patients undergoing upper abdominal surgery.