小儿食管引流型喉罩与经典喉罩插入时适宜呼气末七氟醚浓度的比较

目的比较小儿食管引流型喉罩(PLMA)与经典喉罩(CLMA)插入所需的七氟醚最低肺泡有效浓度(MAC)。方法择期全麻手术患儿54例,年龄3~9岁,ASAⅠ或Ⅱ级,随机均分为PLMA组(P组)和CLMA组(C组)。患儿吸入七氟醚行麻醉诱导,待呼气末七氟醚浓度(CETSev)达到预设值并稳定10 min后插入喉罩。七氟醚的预设值根据Dixon序贯法确定,P、C组首例患儿初始CETSev分别设为2.2%和2.0%,浓度梯度为0.2%。结果患儿插入PLMA和CLMA所需的七氟醚MAC分别为(2.21±0.11)%和(1.99±0.11)%(P<0.01),P、C组CETSev的EC95分别为2.40%(95%CI 2.28%~2.74%)和2.14%(95%CI 2.03%~2.44%)。结论 3~9岁小儿PLMA插入条件满意所需的七氟醚MAC较插入CLMA高。     

右美托咪定减少妇科腹腔镜手术七氟醚用量的临床研究

目的 观察右美托咪定(dexmedetomidine,Dex)对妇科腹腔镜手术患者七氟醚用量的节省程度. 方法 择期拟于全身麻醉下进行妇科腹腔镜手术患者40例,年龄18～59岁,BMI 18.5～24.0 kg/m2,ASA分级Ⅰ、Ⅱ级.采用随机数字表法将其分为2组(每组20例):对照组(C组)和Dex组(D组).入室后,以稳定10 min时(T0)的BP作为基础水平,麻醉诱导后采用七氟醚吸入维持,调整吸入浓度,使喉罩置入后10 min内BIS值为40～60,并维持至术毕.D组于麻醉诱导前15 min时经10 min静脉输注Dex 1.0 μg/kg后以0.4 μg·kg-1·h-1维持至术毕前约15 min,C组输注等量生理盐水.术毕即刻停用七氟醚.于切皮即刻(T1)、气腹即刻(T2)、气腹开始后10 min (T3)和术毕(T4)时记录呼气末七氟醚浓度(end-tidal concentrationof sevoflurane,CETsevo);于切皮前即刻与术毕记录七氟醚挥发罐重量,并计算单位时间七氟醚用量;记录麻醉时间、手术时间、气腹时间、苏醒时间、拔除喉罩时间、术后躁动及心血管不良事件的发生情况;术后随访,记录术中知晓的发生情况. 结果 与C组比较,D组T1～T4时CETsevo降低,七氟醚单位时间用量减少,苏醒时间、拔除喉罩时间及术后躁动发生率降低(P＜0.05或P＜0.01).两组均未见心血管不良事件和术中知晓发生.T1～T4时D组CETsevo较C组分别降低了20.6％ 、28.1％ 、26.1％和25.0％(P＜0.05),D组较C组七氟醚单位时间用量节省29.0％(P＜0.01). 结论 Dex可降低妇科腹腔镜手术患者CETsev0 20.6％～28.1％,节省七氟醚用量约29.0％,从而缩短苏醒及拔除喉罩时间,降低术后躁动的发生概率.     

序贯试验法测定小儿七氟醚诱导喉罩置入时的BIS50

目的 观察小儿七氟醚吸入诱导时.在不同的脑电双频指数(BIS)值下对应喉罩置入条件的差异,同时测定满足半数喉罩顺利置入的BIS值(BIS50).方法 30例眼科择期手术患儿,ASA Ⅰ级,采用七氟醚吸入诱导,按照序贯试验的方法设定每例患儿可进行喉罩置入的BIS值,用Dixon-Massey序贯分配试验法公式,计算喉罩置入BIS50值及其95%可信区间(CI).结果 随着BIS值升高.喉罩置入的满意率降低.小儿七氟醚吸入诱导条件下置入喉罩的BlS50为49.78(95%CI:46.85～52.89).结论 根据BIS值判定置入时机可提高喉罩置入的成功率.     

不同剂量右美托咪啶对异丙酚抑制老年患者Supreme喉罩置入反应EC50的影响

目的 评价不同剂量右美托咪啶对异丙酚抑制老年患者Supreme喉罩置入反应半数有效血浆靶浓度(EC50)的影响.方法 择期全麻膝关节手术患者,性别不限,年龄≥65岁,体重指数20～28 kg/m2,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将患者随机分为3组:小剂量右美托咪啶组(D1组)和大剂量右美托咪啶组(D2组)分别静脉输注右美托咪啶0.4和0.8 μg/kg,输注时间10 min,对照组(C组)给予等容量生理盐水,靶控输注异丙酚,C组、D1组和D2组第1例患者血浆靶浓度分别为3.5、3.0和2.6 μg/ml,待血浆靶浓度和效应室靶浓度达到平衡,BIS值50 ～ 60时,开始置入喉罩.根据是否发生喉罩置入反应确定下1例患者的异丙酚靶浓度,相邻靶浓度的比值为1.1,置入喉罩时出现体动、口角动、牙咬喉罩、呛咳、吞咽等为阳性反应.计算异丙酚抑制喉罩置入反应的EC50及其95％可信区间 (95％CI).结果 C组、D1组和D2组异丙酚抑制喉罩置入反应的EC50及其95％CI分别为3.57(2.91 ～ 3.87)、3.09 (2.66～3.53)和2.62(2.30～3.15)μg/ml.D1组和D2组EC50低于C组,D2组EC50低于D1组(P＜0.05).结论 静脉输注右美托咪啶0.4和0.8μg/kg均可降低异丙酚抑制老年患者Supreme喉罩置入反应的EC50,0.8 μg/kg效应更明显.     

小儿斜视手术七氟醚麻醉拔除喉罩的最佳脑电双频指数

目的观察小儿斜视手术七氟醚麻醉下拔除喉罩的最佳脑电双频指数(BIS)。方法择期行斜视手术患儿120例依据拔除喉罩时的BIS范围随机均分为三组:I组,75≤BIS<85;Ⅱ组,65≤BIS<75;Ⅲ组,55≤BIS<65。三组均采用七氟醚吸入全麻。记录患儿拔除时血流动力学变化、呼气末七氟醚浓度(CETSev)、PETCO2及并发症。结果Ⅲ组拔除喉罩时喉痉挛、低氧血症、咳嗽、屏气的发生率均明显低于Ⅰ、Ⅱ组(P<0.05)。结论小儿斜视手术七氟醚麻醉拔除喉罩的最佳BIS为55~65。     

小儿深麻醉喉罩拔除时安氟醚的最低肺泡有效浓度

目的　本研究旨在确定小儿喉罩平稳拔除时的安氟醚最低肺泡有效浓度。方法　选择 2 1例ASAⅠ级 ,4 - 11岁在全麻下行脐以下整形手术的病人。面罩吸入 5 %七氟醚和 6 0 %笑气诱导后置入喉罩 ,术中吸入安氟醚和 6 0 %笑气维持麻醉 ,手术结束后停止吸入笑气并维持预定的安氟醚浓度 10分钟后拔除喉罩。根据Dixon序贯法确定喉罩拔除时的安氟醚浓度 ,每 0 1%安氟醚为一个增减单位。拔除喉罩时病人没有出现咳嗽、咬牙拔管困难、体动、喉痉挛及屏气为拔管满意。结果　 5 0 %病人获得满意喉罩拔除时的呼气末安氟醚浓度(ED5 0 )为 1 0 2 % (95 %的可信区间 0 95 % - 1 11% ) ,95 %满意拔管浓度 (ED95 )为 1 14 %(95 %的可信区间 1 0 7% - 1 6 6 % )。结论　 4 - 11岁小儿喉罩满意拔除的呼气末安氟醚ED5 0和ED95分别为 1 0 2 %和 1 14 %。     

鼻咽通气道-面罩自主呼吸下丙泊酚-芬太尼-七氟醚静吸复合全麻用于小儿短小手术的效果:与喉罩自主呼吸的比较

目的 比较鼻咽通气道-面罩和喉罩自主呼吸下丙泊酚-芬太尼-七氟醚静吸复合全麻用于小儿短小手术的效果.方法 择期腹股沟斜疝高位结扎术患儿72例,采用随机数字表法,将患儿分为2组(n=36):鼻咽通气道-面罩组(M组)和喉罩组(L组).静脉注射丙泊酚1.0 mg/kg和芬太尼2.0μg/kg,保留自主呼吸,意识消失后扣上面罩,吸入2 L/min氧气和3％七氟醚,BIS值50 ～ 60时,L组置入2号喉罩,M组经左鼻腔置入鼻咽通气道并扣紧面罩,连接麻醉机行紧闭循环自主呼吸,切皮前5 min静脉注射芬太尼1 μg/kg,术中吸入七氟醚,维持BIS值40 ～ 60.于麻醉诱导前、麻醉诱导后3min、成功置入喉罩或鼻咽通气道即刻、切皮即刻、切皮后3 min、拔出喉罩或鼻咽通气道即刻测定MAP、HR、PETCO2和SpO2,记录置入喉罩或鼻咽通气道的时间和成功情况、苏醒时间、离开手术室时间及不良反应发生情况.结果 与L组比较,插管、拔管时M组MAP、HR降低,置入鼻咽通道时间较短且一次性置入成功率(100％)明显升高,患儿躁动评分及拔管后上呼吸道梗阻发生率明显降低(P＜0.05).结论 鼻咽通气道-面罩自主呼吸下丙泊酚-芬太尼-七氟醚静吸复合全麻用于小儿短小手术,易于建立人工通气道并可维持自主呼吸,对循环功能影响轻微,还可明显减少麻醉恢复期并发症的发生,其效果优于喉罩自主呼吸方式.     

不同剂量右美托咪啶对七氟醚抑制切皮诱发患者体动反应肺泡气最低有效浓度的影响

目的 探讨不同剂量右美托咪啶对七氟醚抑制切皮诱发患者体动反应肺泡气最低有效浓度(MAC)的影响.方法 择期拟在全麻下行下腹部手术患者,性别不限,年龄18～64岁,体重指数21 ～ 27 kg/m2,ASA分级Ⅰ或Ⅱ级.采用随机数字表法,将其随机分为4组:对照组(C组)和不同剂量右美托咪啶组(D1组、D2组和D3组).麻醉诱导前静脉输注右美托咪啶(生理盐水稀释至15 ml)0.2μg/kg(D1组)、0.4 μg/kg(D2组)、0.6μg/kg(D3组)或生理盐水15 ml(C组),30 min内输注完毕.4组均采用吸入七氟醚麻醉诱导,气管插管后行机械通气.采用序贯法确定麻醉维持期间呼气末七氟醚浓度.C组、D1组、D2组及D3组第1例患者呼气末七氟醚浓度分别设定为3.0％、3.0％、2.5％和2.0％,预定呼气末七氟醚浓度稳定15 min时进行切皮.评估患者切皮时体动反应,当发生体动反应时,上调一个浓度梯度,否则下调一个浓度梯度,相邻浓度比值为0.9,根据前一例患者是否发生体动反应确定下一例患者呼气末七氟醚浓度,直至每组出现第7个交叉点.以各交叉点呼气末七氟醚浓度的均数作为MAC值,并计算95％可信区间 (CI).结果 C组、D1组、D2组和D3组入选病例分别18、20、20、22例；C组、D1组、D2组和D3组七氟醚MAC值(95％CI)分别为2.5％(2.3％～2.8％)、1.5％(1.3％～1.7％)、1.3％(1.0％～1.6％)和1.1％(0.7％ ～ 1.5％).与C组比较,D1组～D3组七氟醚MAC值降低(P＜0.05)；与D1组比较,D2组和D3组七氟醚MAC值降低(P＜0.05)；D2组和D3组七氟醚MAC值差异无统计学意义(P＞0.05).结论 右美托咪啶0.2、0.4、0.6 μg/kg可明显降低七氟醚抑制手术患者切皮诱发体动反应的MAC值,且呈剂量依赖性.     

右美托咪定对七氟醚吸入诱导喉罩插入时应激反应及脑电双频指数的影响

目的 观察右美托咪定(Dex)对七氟醚吸入诱导喉罩插入时应激反应及脑电双频指数(BIS)的影响.方法 择期全麻患者60例,年龄20～60岁,ASA Ⅰ或Ⅱ级,随机均分为D1组、D2组和C组,分别于麻醉诱导前15 min静脉输注Dex 0.5、1.0 μg/kg和生理盐水,均以七氟醚复合琥珀胆碱1.0 mg/kg麻醉诱导.记录输注Dex前即刻(T0)、输注后5 min(T1)、喉罩插入前即刻(T2)、喉罩插入后1 min(T3)、3 min(T4)、5 min(T5)时的BIS、MAP、HR,并于T0、T1、T2和T5时抽取静脉血2.5 ml检测血糖(BG)和血浆皮质醇(Cor)浓度.结果 T1时D1和D2组HR、BIS和Cor较T0时降低,BG升高(P<0.05),D2组较D1组更显著(P<0.05);诱导过程中D2组心动过缓的发生率高于C组和D1组.喉罩插入后,C组MAP、HR、BIS、Cor和BG均显著升高(P<0.01);D1组Cor升高,D2组Cor降低(P<0.05),D1和D2组MAP和HR均升高(P<0.05),BIS和BG未见明显变化.除BG外,D1和D2组各指标均低于C组,D2组更显著(P<0.05).结论 Dex 0.5、1.0 μg/kg均可降低BIS,产生明显镇静效应,抑制七氟醚吸入诱导喉罩插入时的应激反应;Dex 1.0 μg/kg的作用更加理想,但要注意防止围麻醉期出现的严重心动过缓.     

喉罩通气全凭吸入七氟醚麻醉用于乳腺癌改良根治术的临床观察

目的 探讨喉罩通气全凭吸入七氟醚麻醉用于乳腺癌改良根治术的临床效果.方法 择期乳腺癌手术患者60例,随机均分为全凭吸入七氟醚组(A组)和传统静吸复合组(B组).两组术前均给予盐酸戊乙奎醚1 mg肌注,咪唑安定2 mg静注.A组给予单纯七氟醚吸入诱导,置入喉罩成功后连接麻醉机机械控制呼吸,麻醉维持采用单纯七氟醚吸入;B组给予芬太尼4μg/kg、丙泊酚1 mg/kg、顺苯磺酸阿曲库铵0.15 mg/kg静注麻醉诱导,置入喉罩成功后连接麻醉机机械控制呼吸,麻醉维持采用七氟醚持续吸入,间断注射顺苯磺酸阿曲库铵维持肌松.监测两组患者不同时点的BP、HR、SpO2等指标.记录两组患者麻醉诱导至成功置入喉罩的时间和手术结束至拔除喉罩的时间.结果 两组患者在麻醉诱导置入喉罩时的心血管反应差异无统计学意义,麻醉开始诱导至睫毛反射消失的时间差异无统计学意义,术中生命体征差异亦无统计学意义,但手术结束至拔除喉罩的时间A组明显短于B组(P＜0.05).结论 乳腺癌改良根治术采用喉罩通气全凭吸入七氟醚麻醉,麻醉诱导及苏醒迅速,能满足喉罩置入及外科手术操作的麻醉要求,并且操作方便、安全性高.     

右美托咪定对老年患者罗哌卡因胸椎旁阻滞半数有效浓度的影响

目的 评价右美托咪定(dexmedetomidine,Dex)对老年患者超声引导下胸椎旁阻滞罗哌卡因半数有效浓度(median effective concentration,EC50)的影响. 方法 选择胸腔镜下行肺叶切除术老年患者60例,年龄65 ～79岁,ASA分级Ⅱ、Ⅲ级,拟在超声引导下行胸椎旁阻滞.采用随机数字法分为两组(每组30例):对照组(C组)和Dex组(D组).C组神经阻滞用药仅为罗哌卡因;D组神经阻滞用药为罗哌卡因和0.75 μg/kg Dex的混合液.罗哌卡因初始浓度为0.5％,相邻浓度比值为1.2,若阻滞效果评定为优良,则下一例采用低一级浓度;若阻滞效果评定为差,则下一例采用高一级浓度.采用Probit概率单位回归法计算两组罗哌卡因胸椎旁阻滞的EC50及其95％置信区间(confidence interval,CI). 结果 C组超声引导下罗哌卡因的EC50为0.42％,95％C1为0.40％～0.45％;Dex组罗哌卡因的EC50为0.35％,95％CI为0.32％～0.37％. 结论 Dex可降低罗哌卡因椎旁阻滞的EC50.     

Study of the adjustment of the Ambu laryngeal mask under magnetic resonance imaging

BACKGROUND: Our aim in this study was to analyze the adjustment of the laryngeal mask, Ambu AuraOnce, in pediatric patients during magnetic resonance imaging (MRI) and to look for a correlation between clinical parameters such as the sealing pressure and the ease of introduction with radiological parameters. METHODS: One-hundred and twenty-one pediatric patients from 4 months to 17 years who required a cranial MRI for other reasons were enrolled in the study. General anesthesia was induced with sevofluorane and no relaxant was used. Insertion attempts, sealing pressure, desaturation episodes and maintenance of anesthesia were recorded. Spontaneous ventilation was maintained throughout all procedures and no episodes of desaturation below 95% were seen. Patients without cough or pharyngeal pain were discharged after 1 h. Data were classified into three groups according to the size of the used laryngeal mask (group 1 for laryngeal mask number 1(1/2); group 2 for laryngeal mask number 2, and group 3 for laryngeal mask number 2(1/2)). Sagittal MRI cuts were reviewed to calculate neck flexion, laryngeal mask position and its relationship with the trachea. RESULTS: First-attempt introduction rate of the laryngeal mask was 96%, and it was 100% after a second attempt. Sealing pressure was 22.1+/-4.15 mmHg for group 1, 22.23+/-3.94 for group 2, and 23.83+/-3.28 for group 3. The angles between the laryngeal mask and the four first cervical vertebrae were calculated (group 1, 33.65+/-8.05; group 2, 28.09+/-6.65; group 3, 25.79+/-4.26). Distances between trachea and proximal and distal cuffs were measured to evaluate proper fitting of the laryngeal mask. Anomalous placement seen on MRI, using distances from proximal and distal cuff to trachea, occurred in 23.5% in group 1, 10.9% in group 2, and 13.8% in group 3. We found no correlation between this anomalous position of the laryngeal mask and sealing pressure or ease of introduction. CONCLUSIONS: The Ambu AuraOnce can be regarded as a safe product for airway maintenance in pediatric patients. No relationship was found between radiological measurements and sealing pressures.     

右美托咪定不同途径给药对罗哌卡因腰丛-坐骨神经联合阻滞效果的影响

目的 评价右美托咪定(dexmedetomidine,Dex)不同途径给药方式对0.375％罗哌卡因腰丛挫骨神经联合阻滞(combined lumber plexus and sciatic nerve block,CLPSNB)效果的影响. 方法 90例CLPSNB患者按随机数字表法分为3组(每组30例):罗哌卡因组(R组),0.375％罗哌卡因50 ml行CLPSNB;罗哌卡因+Dex静脉注射组(D+R组),静脉输注Dex 1 μg/kg(输注时间10 min)同时0.375％罗哌卡因50 ml行CLPSNB;罗哌卡因局部麻醉药液混合Dex组(DR组),局部麻醉药Dex 1 μg/kg+0.375％罗哌卡因至50 ml行CLPSNB.R组和DR组同时静脉输注与D+R组相同容量的生理盐水.记录感觉阻滞和运动阻滞的起效时间和维持时间、术者的满意情况及副作用发生情况. 结果 3组感觉阻滞和运动阻滞的起效时间差异无统计学意义(P＞0.05);运动阻滞持续时间和首次使用镇痛药的时间DR组[(768±246) min和(1 080±300) min]、D+R组[(732±204) min和(1 050±288) min]显著长于R组[(420±126) min和(840±306) min] (P＜0.05);感觉阻滞持续时间DR组[(1008±258) min]显著长于R组[(624±216) min]、D+R组[(672±144) min](P＜0.05),而R组与D+R组比较,差异无统计学意义(P＞0.05).术者满意率DR组(100％)高于R组(85％)(P＜0.05).3组患者均未出现恶心、呕吐、低血压、呼吸抑制等副作用. 结论 Dex混合于0.375％罗哌卡因行CLPSNB麻醉效果及术者满意度佳.     

Optimal end-tidal sevoflurane concentration for the removal of the laryngeal mask airway in anesthetized adults

Sevoflurane provides smooth and rapid emergence from anesthesia and can be used when the removal of a laryngeal mask airway (LMA) is required in anesthetized patients. We sought to determine the optimal end-tidal concentrations of sevoflurane required for the removal of LMA in anesthetized adults. We studied 35 adults, aged 22-64 years old with an ASA physical status I or II, who were undergoing perineal surgery. General anesthesia was induced with thiopental, and the LMA was then inserted. Anesthesia was maintained with sevoflurane, oxygen, and air. After the surgery, the target concentration was maintained for at least 10 min, and then the LMA was removed. Each target concentration at the time of removal was predetermined by the Dixon up-down method (with 0.1% as a step size) starting at 1.7% end-tidal concentration of sevoflurane. The LMA removal was considered successful when there was no coughing, clenching of teeth, or gross purposeful movements during or within 1 min after removal and also if there was no breath holding, laryngospasm, or desaturation after removal. The end-tidal concentration of sevoflurane to achieve successful LMA removal in 50% of adults was 0.99% +/- 0.09% (mean +/- SD) and in 95% of adults was 1.18% (95% confidence limits, 1.07%-1.79%). In conclusion, we have determined that LMA removal in 50% and 95% of anesthetized adults can be safely accomplished without coughing, moving, or any other airway complications at 0.99% and 1.18% end-tidal concentrations of sevoflurane. IMPLICATIONS: Because the removal of the laryngeal mask airway (LMA) in the anesthetized state is required in some clinical situations, we sought to determine the end-tidal concentration of sevoflurane to safely remove the LMA in anesthetized adults.     

不同剂量右美托咪啶对下腹部手术患者七氟醚MACBAR的影响

目的 评价不同剂量右美托咪啶对七氟醚抑制50%下腹部手术患者切皮诱发应激反应的最低肺泡气有效浓度(MACBAR)的影响.方法 择期全麻下拟行下腹部手术患者60例,年龄25～55岁,体重45～75 kg,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将患者随机分为对照组(D0组,n=15)和不同剂量右美托咪啶组(D1～3组,n=15).D0组不使用右美托咪啶,D1-3组经10 min静脉注射右美托咪啶0.1 μg/kg负荷剂量后,分别以0.4、0.8、1.2μg·kg-1·h-1的速率静脉输注30 min后进行麻醉诱导.D0-3组第1例患者呼气末七氟醚浓度分别为3.0%、2.5%、2.0%、1.5%,以切皮时患者MAP或HR较基础值上升＜15%为抑制交感肾上腺反应有效,若抑制交感肾上腺反应有效则下一例呼气末七氟醚浓度降低一级,若无效则升高一级,相邻浓度比为0.9.计算七氟醚MACBAR及其95%可信区间(95%CI).结果 D0～3组七氟醚MACBAR及其95%CI分别为:2.85%(2.44%～3.32%)、1.9l%(1.6l%～2.26%)、1.52%(1.3l%～1.77%)、1.34%(1.15%～1.57%).与D0组比较,D1-3组七氟醚MACBAR均降低(P＜0.05);与D1组比较,D2组和D3组七氟醚MACBAR降低(P＜0.05);D2组和D3组七氟醚MACBAR比较差异无统计学意义(P＞0.05).结论 右美托咪啶0.4、0.8和1.2μg·kg-1·h-1连续输注30 min可降低七氟醚MACBAR,增强七氟醚抑制应激反应的效应,且呈剂量依赖性.

Abstract：

Objective To investigate the effects of different doses of dexmedetomidine on the minimum alveolar concentration of sevoflurane for blunting responses to skin incision ( MACBAR ) in patients undergoing lower abdominal surgery. Methods Sixty ASA Ⅰ or Ⅱ patients, aged 25-55 yr, weighing 45-75 kg, undergoing electire lower abdominal surgery under general anesthesia, were randomly divided into 4 groups ( n = 15 each): control group (Do group) and 3 dexmedetomidine groups (D1, D2 and D3 groups). The patients were unpremedicated.Dexmedetomidine was not used in group D0. A loading dose of dexmedetomidine 0.1μg/kg was injected iv over 10 min, and then dexmedetomidine was infused at a rate of 0.4, 0.8 and 1.2 μg· kg- 1 · h - 1 for 30 min in groups D1-3 respectively. Anesthesia was induced with inhalation of 8 % sevoflurane. Laryngeal mask airway was inserted when BIS value decreased to 45-55. The patients were mechanically ventilated with inhalation of sevoflurane and a mixture of 50% nitrous oxide and 50% oxygen, and the fresh gas flow was set at 1 L/min. In D0-3 groups, the initial end-tidal concentrations of sevoflurane were 3.0%, 2.5%, 2.0% and 1.5% respectively. The patients' response to skin incision was described as effective if MR or MAP increased by ＜ 15%, or ineffective (MR or MAP increased by ≥ 15%). When the response was effective, the end-tidal concentration of sevoflurane was decreased in the next patient, when ineffective, increased, and the ratio between the two successive concentrations was 0.9.The MRCBAR of sevoflurane was determined by up-and-down method, and 95% confidence interval was calculated.Results The MRCBAR (95% confidence interval) of sevoflurane was 2.85% (2.44%-3.32%), 1.91%(1.61%-2.26%), 1.52% (1.31%-1.77%), and 1.34% (1.15%-1.57%)in D0-3 groups respectively. The MRCBAR of sevoflurane was significantly lower in D1-3 groups than in D0 group, and in D2 and D3 groups than in group D1 (P ＜0.05＝. There was no significant difference in MRCBAR of sevoflurane between D2 and D3 groups (P ＞0.05) .Conclusion Continuous infusion of dexmedetomidine at 0.4, 0.8 and 1.2 μg·kg-1 ·h-1 for 30 min results in a decrease in MACBAR of sevoflurane and enhances the inhibitory effect of sevoflurane on the stress response, and in a dose-dependent manner.     

A comparison of the disposable Ambu AuraOnce Laryngeal Mask with the reusable LMA Classic laryngeal mask airway

Single-use supraglottic airway devices are now available and are intended to be comparable with the reusable LMA Classic laryngeal mask airway. We performed a randomised cross-over study comparing the Ambu AuraOnce Laryngeal Mask with the LMA Classic. Fifty patients participated in the trial. Success rates for insertion at the first attempt were similar (92% with the Ambu and 84% with the LMA Classic; p = 0.22). The volumes of air required to inflate the cuff to produce a seal were similar, but the cuff pressure was lower for the Ambu Laryngeal Mask (median (IQR [range]) 18 (10-31 [0-100] cmH(2)O) than the LMA Classic 27 (17-50 [4-90] cmH(2)O; p = 0.007). Visual analogue scores for ease of insertion were 87 (73-93 [26-97]) mm for the Ambu and 84 (60-89 [18-96]) for the LMA Classic (p = 0.017). Complications were similar in both groups. We suggest that the disposable Ambu Laryngeal Mask is an acceptable alternative to the reusable LMA Classic.     

Minimum alveolar sevoflurane concentrations required for insertion of the cuffed oropharyngeal airway and the laryngeal mask airway: a comparative study

Both the cuffed oropharyngeal airway and the laryngeal mask airway share a similar property of being less stimulating to the upper airway than the tracheal tube. This study was conducted to compare sevoflurane concentrations required for insertion of the cuffed oropharyngeal airway and the laryngeal mask airway in elderly and young adult patients. Forty-one elderly (65-90 years) and 34 young adult (18-50 years) patients, scheduled for elective surgery during spontaneous breathing anaesthesia were randomly assigned to either the cuffed oropharyngeal airway or the laryngeal mask airway group. After a predetermined end-tidal concentration of sevoflurane had been established and maintained for at least 20 min, insertion of the device was attempted without neuromuscular relaxants or other adjuvants. Each concentration at which insertion of the device was attempted was predetermined by modification of Dixon's up-and-down method with 0.5% as the step size. Sevoflurane MACCOPA [mean 1.17 (SD 0.38)%, 0.77-1.56% (95% CI)] was significantly less than MACLMA [2.00 (0.52)%, 1.45-2.55%, p < 0.05] for elderly patients. Similarly, sevoflurane MACCOPA [1.33 (0.38)%, 0.94-1.73%] was significantly less than MACLMA [2.00 (0.42)%, 1.56-2.44%, p < 0.05] for young adult patients. There were no significant differences in either MACCOPA or MACLMA between the elderly and the young adult patients. We conclude that the insertion of the cuffed oropharyngeal airway can be accomplished at a lower sevoflurane concentration, and hence, is less stimulating to the upper airway than that of the laryngeal mask airway.     

右美托咪定滴鼻用于患儿面罩吸入麻醉诱导前镇静的半数有效量

目的 测定右美托咪定(dexmedetomidine,Dex)滴鼻用于患儿面罩吸入麻醉诱导前镇静的ED50,比较幼儿、学龄前和学龄患儿ED50的差异. 方法 选择ASA分级Ⅰ、Ⅱ级接受面罩吸入麻醉诱导的患儿,按年龄分为幼儿组(1～3岁)、学龄前组(4～6岁)和学龄组(7～12岁),每组预计35例.每组均在麻醉前1h经鼻滴入Dex,起始剂量为2μg/kg,按改良序贯法进行调整,根据上一例患儿面罩吸入诱导时的镇静满意程度,下一例患儿增加或减少0.25 μg/kg.镇静效果以面罩接受程度四分法进行评估,1～2分为镇静不满意,3～4分为镇静满意.用概率单位回归分析法计算出Dex满意镇静的ED50及相应的95％置信区间(95％CI). 结果 幼儿组、学龄前组和学龄组实际所需例数分别为31、28和30.幼儿组、学龄前组和学龄组Dex滴鼻镇静的ED50和95％CI分别为1.94(1.72～2.18)、1.61(1.41～1.82) μg/kg和1.30(1.13～1.47) μg/kg,3组间比较,差异有统计学意义(P＜0.05). 结论 随着患儿年龄的增加,面罩吸入麻醉诱导前所需Dex滴鼻镇静的ED50减小.     

右美托咪啶对瑞芬太尼抑制切皮时患者体动反应半数有效效应室靶浓度的影响

目的 评价右美托咪啶对瑞芬太尼抑制切皮时患者体动反应半数有效效应室靶浓度(EC50)的影响.方法 择期拟行乳房肿瘤切除术患者40例,年龄20～50岁,体重45～58 kg,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将其随机分为瑞芬太尼组(R组)和右美托咪啶复合瑞芬太尼组(RD组),每组20例.R组和RD组切皮前分别静脉输注生理盐水和右美托咪啶1.0μg/kg,输注时间10min,同时靶控输注异丙酚,血浆靶浓度设为3.0 mg/L,13 min后开始靶控输注瑞芬太尼.采用序贯法进行试验,RD组和R组初始效应室靶浓度分别为2.5和3.0μg/L,待两药浓度均达靶浓度后切开皮肤3 cm,有体动反应,则下一例采用高一级浓度,无体动反应,则下一例患者采用低一级浓度,相邻浓度比值为1.2,发生体动反应的标准为患者出现躯干、四肢或头颈可见的运动.计算瑞芬太尼抑制患者体动反应的EC50及其95％可信区间.结果 RD组瑞芬太尼抑制切皮时体动反应的EC50为1.7 μg/L,95％可信区间为1.5～1.9 μg/L,R组瑞芬太尼抑制切皮时体动反应的EC50为2.5 μg/L,95％可信区间为2.2～2.7 μg/L,差异有统计学意义(P＜0.01).结论 靶控输注异丙酚(血浆靶浓度3.0 mg/L)下,静脉输注右美托咪啶1.0μg/kg可降低瑞芬太尼抑制切皮时患者体动反应的EC50.