不同剂量右美托咪定对成人喉罩置入时七氟烷最低肺泡有效浓度的影响

The Effects of Different Doses of Dexmedetomidine on the MAC of Sevoflurane in Adults with Laryngeal Mask

目的观察不同剂量右美托咪定(DEX)对成人喉罩置入时七氟烷最低肺泡有效浓度(MAC)的影响。方法选择年龄20~60岁,ASAⅠ~Ⅱ级,行择期喉罩置入全麻下腹腔镜胆囊切除术的患者75例,随机分为D_(0)组(DEX 0μg/kg),D_(1)组(DEX 0.5μg/kg)和D_(2)组(DEX 1.0μg/kg),每组各25例。三组右美托咪定于麻醉诱导前10 min泵注完毕,随后开始吸入8%七氟烷和100%氧气(6 L/min)行肺活量法诱导,待患者睫毛反射消失后调整七氟烷呼气末浓度至预设值并维持稳定15 min后置入喉罩。观察患者对置入喉罩即刻及置入喉罩后30 s内的体动反应。采用Up and Down和序贯法测定各组喉罩置入时七氟烷MAC值,相邻患者七氟烷浓度上下调节梯度值为0.2%。结果D_(0)、D_(1)和D_(2)三组喉罩置入时七氟烷MAC值分别为(2.93±0.25)%、(2.53±0.13)%和(1.93±0.21)%。静脉泵注0.5及1.0μg/kg的右美托咪定可分别使成人喉罩置入时七氟烷MAC值降低14%和34%。结论右美托咪定能有效降低成人喉罩置入时所需七氟烷MAC值。

Objective To observe the effects of different doses of dexmedetomidine(DEX)on the minimum alveolar concentration(MAC)of sevoflurane in adults with laryngeal mask.Methods Seventy-five patients of American Society of Anesthesiologists(ASA)physical statusⅠ~Ⅱgrade,age D_(2) 0~60 years,after elective laryngeal mask airway(LMA)general anesthesia for laparoscopic cholecystectomy,were randomly assigned to three groups(25 patients per group)with different dexmedetomidine infusion doses:group D_(0)(DEX 0μg/kg),group D_(1)(DEX 0.5μg/kg),and group D_(2)(DEX 1.0μg/kg).Dexmedetomidine was intravenously infused in each group according to the doses designed within 10 minutes before induction of anesthesia,respectively.A vital capacity method was applied by inhalation of 8%sevoflurane and pure oxygen(6L/min).After patient s eyelash reflection had disappeared,the end-expiratory sevoflurane concentration was adjusted to a predetermined value.A LMA was inserted when the predetermined end-expiratory sevoflurane concentration was stable for at least 15 minutes.The patient s response to LMA insertion was observed for 30 seconds.An UP and Down and a sequential methods were used to determine the MAC LMA value of sevoflurane in each group.The adjusted concentration gradient of sevoflurane was 0.2%.Results The MAC LMA value of sevoflurane in groups D_(0),D_(1) and D_(2) was(2.93±0.25)%,(2.53±0.13)%,and(1.93±0.21)%,respectively.Dexmedetomidine with doses of 0.5μg/kg an D_(1).0μg/kg was able to reduce the MAC LMA of sevoflurane by 14%and 34%,respectively.Conclusions Dexmedetomidine can effectively reduce the MAC value of sevoflurane required for laryngeal mask airway insertion in adults.