右美托咪定对病态肥胖患者七氟烷EC_(50)的影响

Efficacy of dexmedetomidine on sevoflurane EC_(50) for insertion of Blockbuster laryngeal mask airway in spontaneously breathing morbidly obese patients

目的计算病态肥胖患者七氟烷吸入诱导插入Blockbuster喉罩时的EC_(50)并探究右美托咪定对病态肥胖患者吸入麻醉诱导插入喉罩时七氟烷EC_(50)的影响。方法前瞻性选取2019年6月至2020年2月于首都医科大学附属北京友谊医院择期行胃减容手术的病态肥胖患者35例,按照随机数字表法将其分为右美托咪定组(D组)18例和生理盐水组(C组)17例。两组诱导前10 min以1μg/kg的负荷剂量泵注试验用药,D组为浓度为4μg/mL的右美托咪定,C组为相等容量的生理盐水,之后以0.5μg·kg^(-1)·h^(-1)持续泵注。负荷剂量泵注完成后保留患者自主呼吸,调整七氟烷浓度为5%进行吸入诱导。待患者睫毛反射消失调整七氟烷浓度,第一次的浓度为2.5%,持续吸入5 min置入喉罩,根据置入喉罩发生体动的情况按Dixon’s序贯法调整下一例患者七氟烷的吸入靶浓度,相邻浓度为增加或减少0.5%。置入喉罩后给予静脉诱导药经喉罩气管插管并进行手术。记录吸入诱导靶浓度并计算七氟烷的EC_(50),记录患者在入室静息时(T0)、吸入诱导前(T1)、睫毛反射消失时(T2)、喉罩置入前(T3)、喉罩置入后1 min(T4)的心率、平均动脉压(MAP)、潮气量(VT)、呼吸频率(RR)以及脑电双频指数(BIS)以及吸入诱导麻醉的并发症情况。结果C组患者吸入七氟烷完成置入喉罩的EC_(50)值为2.334%(95%CI:-1.333~3.507),EC_(95)值为3.266%(95%CI:2.744~55.307),D组患者吸入七氟烷完成置入喉罩的EC_(50)值为2.107%(95%CI:1.768~4.734),EC_(95)值2.826%(95%CI:2.344~15.375),D组EC_(50)较C组明显降低,差异有统计学意义(P<0.05)。D组在T1时VT为(575.00±89.66)mL,显著低于C组[(690.59±193.02)mL],D组在T1和T3时BIS值为86.22±5.47、35.71±13.07,显著低于C组(95.82±1.02、44.22±9.56),差异均有统计学意义(P<0.05)。两组并发症和血流动力学变化,差异无统计学意义(P>0.05)。结论右美托咪定可以降低自主呼吸病态肥胖患者吸入诱导Blockbuster喉罩置入时七氟烷的EC_(50),增加麻醉效能。

Objective To culculate sevoflurane EC_(50) and assess the effect of intravenous dexmedetomidine(DEX) on sevoflurane EC_(50) for Blockbuster laryngeal mask(LMA) in spontaneously breathing morbidly obese patients. Methods From June 2019 to February 2020,35 morbidly obese patients who underwent elective gastric volume reduction surgery at the Beijing FriendshipHospital,Capital Medical University were prospectively selected and divided into the dexmedetomidine group(D group) 18 cases and normal saline group(C group) 17 cases according to a random number table. The two groups were pumped with the test drug at a loading dose of 1 μg/kg 10 min before induction,group D a bolus dose of DEX 1 μg/kg was administered intravenously over 10 mins,and group C was given saline intravenously,followed by intravenous DEX infusion at a rate of 0. 5 μg·kg^(-1)·h^(-1). 5% sevoflurane was inhaled for anesthesia induction until eyelash reflex disappeared. The 2. 5% sevoflurane was initially inhaled maintaining 5 mins for anesthesia induction and then inserted LMA. End-tidal expiratory sevoflurane concentration(ETsev) was adjusted to a target value as to the modified Dixon’s up-and-down method. The next concentration of sevoflurane was increased or decreased according to the insertion of laryngeal mask. After the observation was completed,anesthetic were given intravenously and flexible bronchoscope-guided intubation was performed through the LMA. The heart rate(HR),mean arterial pressure(MAP),respiratory rate(RR),tidal volume(TV) and end-tidal carbon dioxide pressure(ETCO2) at the time of calm state(T0) before inhalation induction(T1),before LMA insertion(T2) and 1 min after LMA insertion(T3) were recorded. The ETsev concentration together with parameters and the complications related to LMA were recorded. Results EC_(50) of C group was 2. 334%(95% CI :-1. 333 ~ 3. 507) and EC_(95) was 3. 266%(95% CI : 2. 744 ~ 55. 307).EC_(50) of D group was 2. 107%(95% CI : 1. 768 ~ 4. 734) and EC_(95) was 2. 826%(95% CI : 2. 344 ~ 15. 375). The EC_(50) of group D was significantly lower than that of group C,and the difference was statistically significant(P<0.05). The VT of group D at T1 was(575. 00 ± 89. 66)mL,which was significantly lower than that of group C [(690. 59 ± 193. 02) mL],the BIS values of group D at T1 and T3 were 86. 22 ± 5. 47 and 35. 71 ± 13. 07,which were significantly lower than group C(95. 82 ± 1. 02,44. 22 ± 9. 56),the differences were statistically significant(P< 0. 05). The occurrence of adverse events were no significant between the two groups. Conclusion Intravenous dexmedetomidine can reduce sevoflurane EC_(50) for successful Blockbuster LMA insection but not influence hemodynamics and complications when sevoflurane inhalational induction is performed in spontaneous breathing morbidly obese patients.