舒芬太尼复合七氟醚或丙泊酚在全麻诱导中的应用

目的 观察舒芬太尼复合七氟醚或丙泊酚在全麻诱导中的应用.方法 择期ASA I或Ⅱ级上腹部手术患者30例,随机分为七氟醚组(A组)和丙泊酚组(B组),每组15例.麻醉诱导先静脉注射舒芬太尼0.5μg/kg,1 min后,A组以肺活量法吸入8%七氟醚和8 L/min氧气,入睡后推注罗库溴铵0.6 mg/kg,维持吸入七氟醚使其呼气末浓度达6%;B组以靶控输注丙泊酚3 mg/L行麻醉诱导,入睡后推注罗库溴铵0.6 mg/kg,BIS值达50并维持5 s后行气管插管.记录患者入睡时间、BIS值达到50的时间以及不良反应.观察两组患者诱导前(T0)、达到插管条件时(T1)、气管插管时(T2)、气管插管后1 min(T3)、3 min(T4)、5 min(T5)、10 min(T6)时SBP、DBP、HR和BIS值的变化,并在各时点抽动脉血用酶联免疫法测定血浆肾上腺素(E)和去甲肾上腺素(NE)浓度.结果 A组患者诱导入睡时间、BIS值下降至50的时间均短于B组(P＜0.05),两组插管期间均无不良记忆反应.与T0时比较,两组T1时SBP、DBP明显下降(P＜0.05),B组HR明显减慢(P＜0.05).与T1时比较,两组T2～T4时SBP、DBP明显升高(P＜0.05),B组HR明显增快(P＜0.05),T5、T6时SBP、DBP和HR基本恢复到插管前水平.B组T1时SBP、DBP和HR下降幅度较A组明显(P＜0.05).两组T1～T6时BIS均小于50,组间差异无统计学意义.与T0比较,B组T3～T5时血浆E和NE浓度升高(P＜0.05).结论 舒芬太尼复合吸入七氟醚麻醉可以达到良好抑制插管应激反应的效果和足够的麻醉深度,且比复合靶控输注丙白酚麻醉诱导更为平稳和快速.     

七氟醚诱导对患儿镇静和循环的影响

目的 研究七氟醚吸入诱导对患儿循环、镇静深度的影响.方法 45例择期行腹部手术患儿随机均分为A、B、C组,分别吸入4%、6%、8%七氟醚麻醉诱导,观察体动消失时间、插管时间、诱导期不良反应和插管条件评分,记录入室时(T1)、诱导后30 s(T2)、插管前即刻(T3)、插管后即刻(T4)MAP、HR、SpO2和脑电双频指数(BIS).结果 C组体动消失时间和插管时间最快(P＜0.05),诱导后循环系统的抑制程度最大(P＜0.05),诱导中不良反应最多;插管前后A组的MAP波动最大(P＜0.05);A组插管条件评分最高.结论 七氟醚对患儿镇静程度和循环呈剂量相关性抑制,临床推荐吸入诱导浓度为6%.     

小儿七氟醚麻醉诱导方法的比较

目的 观察七氟醚诱导方法 在小儿腹腔镜短小手术中的应用效果.方法 将择期行腹腔镜腹股沟斜疝结扎术3～6岁患儿60例,随机均分为面罩肺活量吸入法诱导组(A组)与面罩潮气量吸入法诱导组(B组).记录睫毛反射消失时间、气管插管时间、血流动力学指标、拔管时间、意识恢复时间及不良反应.结果 A组睫毛反射消失时间(43.5±4.4)s,明显短于B组的(68.8±7.6)s(P<0.01);A组气管插管时间(3.5±0.7)min,明显短于B组的(6.7±1.4)min(P<0.01);两组拔管时间、意识恢复时间、不良反应的发生率差异无统计学意义.结论 两种七氟醚吸入诱导方法 均可获得良好的气管插管条件;面罩肺活量吸入诱导法起效更为迅速.     

七氟醚、异氟醚不同呼气末浓度对熵和脑电双频指数的影响

目的 观察不同呼气末浓度的七氟醚和异氟醚对熵、脑电双频指数(BIS)及血流动力学的影响.方法 40例ASA Ⅰ或Ⅱ级全麻手术患者随机均分为七氟醚组(Ⅰ组)和异氟醚组(Ⅱ组).麻醉诱导用丙泊酚1 mg/kg,1 min后吸入七氟醚或异氟醚;维持反应熵(RE)、状态熵(SE)、BIS45～55,6 min后置入喉罩.调节吸入浓度使两组患者呼气末浓度分别为0.4、0.6、0.8、1.0和1.3MAC时各维持10 min,记录RE、SE、BIS、HR和MAP.结果 两组患者不同呼气末浓度七氟醚和异氟醚RE、SE、BIS随浓度增加而逐渐下降(P<0.05),HR逐渐减慢、MAP逐渐降低(P<0.05).两组间各指标差异均无统计学意义.RE、SE、BIS间直线相关性随呼气末浓度增大相关系数有增加趋势.结论 熵和BIS均能有效监测七氟醚、异氟醚麻醉深度.     

紫绀型与非紫绀型先天性心脏病患儿七氟醚吸入诱导效果的比较

目的比较七氟醚在紫绀型与非紫绀型先天性心脏病患儿的吸入诱导效果。方法先天性心脏病紫绀型患儿20例(A组)与非紫绀型患儿23例(B组),面罩吸入6%七氟醚诱导,记录睫毛反射消失时间及脑电双频指数(BIS)值;观察RR、VT、PETCO2、SpO2及气管插管前后MAP与HR变化。结果 A组睫毛反射消失时间(77.9±34.2)s,明显长于B组的(41.0±18.0)s(P<0.01),且与PETCO2、SpO2均呈负相关关系(r=-0.669,P<0.05;r=-0.789,P<0.01);VTA组明显高于B组(P<0.05),而RR明显慢于、PETCO2及SpO2均明显低于B组(P<0.05)。两组BIS差异无统计学意义。结论七氟醚对紫绀型患儿诱导时间较长,但较非紫绀型呼吸抑制作用轻。     

BIS值监测患儿七氟醚复合氧化亚氮麻醉深度的准确性

目的 评价BIS值监测患儿七氟醚复合氧化亚氮(N2O)麻醉深度的准确性.方法 择期拟在全麻下行腹部手术患儿72例,年龄1～14岁,ASA分级Ⅰ或Ⅱ级,按年龄分层后随机分为3组(n=24):七氟醚组(S组)、七氟醚+30% N2O组(SN1组)和七氟醚+60% N2O组(SN2组).静脉注射阿托品、利多卡因、异丙酚、罗库溴铵和瑞芬太尼麻醉诱导,气管插管后行机械通气,维持PET CO2 35～45 mm Hg;吸入2.5%七氟醚维持麻醉,SN1组和SN2组分别复合吸入30%和60%N2O.手术开始时调节七氟醚吸入浓度,使七氟醚呼气末浓度(CETSev)分别达到2.5%、2.0%和1.5%,每个CETSev维持10 min视为稳态;此后调节七氟醚吸入浓度,维持BIS值40～60.于麻醉诱导前和CETSev达稳态时记录BIS值;于BIS值40～60维持20 min时记录CETSev(C50).结果 与S组比较,SN1组BIS值和C50差异无统计学意义(P＞0.05);与S组及SN1组比较,SN2组BIS值和C50降低(P＜0.05);S组、SN1组和SN2组BIS值与CETSev间的相关系数分别为-0.736、-0.817和-0.729(P＜0.01),三组相关系数比较差异无统计学意义(P＞0.05).结论 BIS值可准确地监测患儿吸人七氟醚复合N2O时的麻醉深度.     

幼儿脑电双频指数与七氟醚呼气末浓度的关系

目的 探讨幼儿患者脑电双频指数(BIS)与七氟醚呼气末浓度(CETSev)的关系.方法 择期全麻下行腹部手术的患儿120例,ASA Ⅰ或Ⅱ级,年龄1～3岁,随机均分为四组:Ⅰ组,CETSev为0.4 MAC;Ⅱ组,CETSev为0.7 MAC;Ⅲ组,CETSev为1.0 MAC;Ⅳ组,CETSev为1.3MAC.8%七氟醚面罩吸入诱导,氧流量5 L/min,待患儿意识消失后调整氧流量至2 L/min,并逐步凋节七氟醚吸入浓度,按照分组使CETSev达到并维持于相应的浓度,每一浓度均维持15 min,视为稳态CETSev.分别记录所有患儿入室(T0)、达稳态CETSev(T1)时的BIS、MAP及HR.结果 当CETSev由0.4～1.3 MAC递增时,四组患儿MAP和HR差异无统计学意义,但BIS逐渐下降(P＜0.05),BIS、MAP及HR与CETSev相关系数分别为-0.857、-0.379和0(P＜0.05).结论 无伤害性刺激时,BIS与CETScv呈一定剂量的负相关,相关性较好,BIS可用于监测七氟醚麻醉下的镇静程度.     

七氟醚、异氟醚和地氟醚对神经外科手术患者经颅电刺激运动诱发电位的影响

目的 比较七氟醚、异氟醚和地氟醚对神经外科手术患者经颅电刺激运动诱发电位(MEPs)的影响.方法 择期行神经外科手术患者60例,年龄18～64岁,ASA分级Ⅰ或Ⅱ级.随机分为3组(n=20):七氟醚组、异氟醚组和地氟醚组.监测BIS值和经颅电刺激MEPs.调节七氟醚、异氟醚和地氟醚吸入浓度,使其呼气末浓度分别达到0.50、0.75、1.00和1.30 MAC,每一浓度均维持15 min,视为稳态呼气末浓度.于给予吸入麻醉药前(基础状态)和达到各稳态呼气末浓度(T1-4)时,记录MEPs的波幅和潜伏期以及BIS值.记录MEPs波形记录失败情况.结果 与七氟醚组和异氟醚组比较,地氟醚组T1.2时波幅和BIS值降低,T1-4时潜伏期延长(P＜0.05);七氟醚组和异氟醚组各指标比较差异无统计学意义(P＞0.05).七氟醚组、异氟醚和地氟醚组基础状态、T1、T2时的记录失败率均为0;T3时记录失败率分别为0、5%和20%,三组比较差异无统计学意义(P＞0.05);T4时记录失败率分别为5%、20%和45%,与七氟醚组和异氟醚组比较,地氟醚组记录失败率升高(P＜0.05);七氟醚组和异氟醚组比较差异无统计学意义(P＞0.05).结论 地氟醚对神经外科手术患者经颅电刺激MEPs的抑制作用强于七氟醚和异氟醚.术中行MEPs监测时,七氟醚和异氟醚适宜的呼气末浓度为1.00 MAC,地氟醚为0.75～1.00 MAC.     

合并肝肺综合征的老年患者实施胆囊切除术对七氟醚吸入麻醉的药效学研究

目的 研究合并肝肺综合征(hepatopulmonary syndrome,HPS)的老年患者实施胆囊切除术期间吸入七氟醚维持麻醉的药效学变化. 方法 48例肝硬化择期行胆囊切除术的患者,性别不限,年龄60～74岁,Child-Pugh分级A级或B级,ASA分级Ⅱ或Ⅲ级,肺、肾功能检测正常.利用对比增强超声心动图检查和动脉血气分析,根据是否合并HPS将患者分为HPS组(18例)和对照组(C组,30例).入室后常规开放静脉通路,泵注右美托咪定镇静.麻醉诱导使用丙泊酚2 mg/kg、舒芬太尼2μg/kg和维库溴铵0.1 mg/kg,插管后以预设七氟醚浓度维持麻醉,采用上下交叉点法测定MAC值,术中维持BIS值在40～50,保持BP、HR平稳.记录麻醉时间,观察比较两组患者吸入七氟醚MAC值的差异,术毕停药后患者呼之睁眼时间、BIS值恢复至85的时间以及拔管时间. 结果 HPS组的MAC值为(0.88±0.07)％,而C组的MAC值为(1.13±0.09)％,两组比较,差异有统计学意义(P＜0.05).与C组比较,HPS组患者术毕停药后呼之睁眼时间[(28±9) min比(16±6) min]、BIS值恢复至85的时间[(34±9) min比(21±7) min]以及拔管时间[(38±5) min比(26±3) min]延迟,差异有统计学意义(P＜0.05). 结论 合并HPS老年患者实施胆囊切除术期间使用七氟醚吸入麻醉维持,七氟醚的MAC值显著降低,麻醉维持后苏醒时间明显延迟.     

七氟醚吸入诱导在小儿心脏手术麻醉中的应用

本文总结在大流量氧时吸入高浓度七氟醚在小儿先天性心脏病麻醉诱导中的应用。先天性心脏病患儿30例(紫绀型7例),心功能～级,平均年龄(2.5±1.3)岁,体重(11.6±3.12)kg。不给术前药,面罩吸入氧(5L/min) 8%七氟醚诱导。待疼痛反射消失后,开放静脉,停吸七氟醚,静脉给予阿托品、芬太尼、潘龙,2分钟后气管内插管。记录睫毛反射、疼痛反射消失时间、入室时、睫毛反射消失时、静脉给药前和气管插管后BP、HP、SpO2。观察诱导中患儿合作情况,有无呛咳、呕吐、呼吸抑制、喉痉挛、分泌物增多、躁动及心律失常。随机抽取7例非紫绀型小儿作为非紫绀组…     

Comparison of three techniques for induction of anaesthesia with sevoflurane in children

This study was designed to evaluate the clinical characteristics of three induction techniques using sevoflurane in children scheduled for tonsillectomy: incremental induction with sevoflurane(2,4,6,7%) in 100% O2 (group IC-O2; n=23); induction with high concentration of sevoflurane in 100% O2 (group HC-O2; n=22); and induction with high concentration of sevoflurane in a mixture of O2:N2O(50:50) (group HC-N2O; n=20). Induction was well accepted and well tolerated in most children. The addition of nitrous oxide resulted in faster loss of consciousness (P< 0.001) compared to the other induction techniques and in a tendency for reduced excitement compared with the same rapid technique without nitrous oxide (P=0.053). Time to tracheal intubation was identical in the three groups and intubation conditions were scored as good in most children. During the early induction phase, an increase in SAP and HR was observed in the three groups. Changes were maximal at two min after the beginning of induction in the three groups. SAP and HR values were back to baseline values at the time of tracheal intubation. In conclusion, the addition of nitrous oxide to a high sevoflurane concentration decreases the time to loss of eyelash reflex, tends to reduce the incidence of excitement and is not associated with an increased incidence of respiratory complications even in patients with obstructive airway.     

Rapid induction with 7% sevoflurane inhalation—not the single-breath method

The usefulness of the rapid anesthesia induction method with 7% sevoflurane, not the single-breath method, was investigated in 88 patients with ASA physical status 1. Anesthesia was induced with 3 l·min⁻¹ nitrous oxide in 3 l·min⁻¹ oxygen and sevoflurane 7% for 3 min (group A), 7% for 5 min (group B), 7% for 7 min (group C), and 5% for 7 min in conventional induction (group D). There were 22 patients in each group. Each sevoflurane concentration was given at the same time as the start of nitrous oxide inhalation except for group D. The changes in blood pressure and heart rate were the smallest in group A. The time for the loss of consciousness was shorter in groups A (47.2 s), B (44.9 s), and C (49.8 s) than in group D (73.4 s). During induction, body movements were seen in 18.2% in group A and 13.6% in the other 3 groups, but no other complications such as coughing, breath holding, or laryngospasm were seen in any group. In conclusion, the anesthesia induction method with 3 min of 7% sevoflurane inhalation was useful for rapid induction.     

Apnea during induction of anesthesia with sevoflurane is related to its mode of administration

PURPOSE: The incidence and duration of apnea during sevoflurane anesthesia have not been fully characterized. We hypothesized that sevoflurane at slowly increasing concentrations reduces incidence and shortens the duration of apnea compared to administration of a highly concentrated anesthetic mixture. METHODS: 131 women were randomly assigned to receive 35% oxygen in air and sevoflurane at: incremental concentrations of 1%, from 1% to 8% (group 1-8%, n = 42); decremental-incremental concentrations of 2%, from 8% to 4% and then from 4% to 8% (group 8-4-8%, n = 36); or fixed concentrations of 8% for induction of anesthesia (group 8%, n = 53). A blinded investigator observed whether and for how long patients stopped breathing. RESULTS: All groups reached 2.5 minimum alveolar concentration of end-tidal sevoflurane. Although apnea was observed in all groups, it was more frequent in the 8% group than in 1 to 8% (68% vs 21%, P < 0.05) or 8 to 4 to 8% groups (68% vs 20%, P < 0.05). Duration of apnea was also more pronounced in the 8% group than in 1 to 8% and 8 to 4 to 8% groups ( 58 +/- 25 s vs 32 +/- 18 sec, P < 0.05 and vs 35 +/- 16 sec, P < 0.05, respectively). CONCLUSIONS: Sevoflurane induces apnea more frequently and for longer duration at a fixed high concentration compared to incremental or decremental-incremental concentrations. Decremental-incremental concentrations offer the additional advantage of a speed of induction similar to that elicited by the 8% concentration.     

Rapid inhalation induction in children: 8% sevoflurane compared with 5% halothane

Sevoflurane has a lower blood-gas solubility and a less pungent odour than halothane; this may allow more rapid induction of anaesthesia. In a randomized, blinded study, we compared the induction characteristics of maximum initial inspired concentration of 8% sevoflurane and 5% halothane using conventional vaporizers in children aged 3 months to 3 years. There was no statistically significant difference in induction times between the two groups: mean times to loss of consciousness were 1 min 12 s (SD 18 s, range 40 s-1 min 44 s) for sevoflurane and 1 min 16 s (SD 17 s, range 50 s-1 min 52 s) for halothane, although these times were shorter than in previous studies using a gradual increase in vapour concentration. A small number of complications were noted in both groups, although none interfered with induction of anaesthesia. Struggling scores were lower in the sevoflurane group than in the halothane group (chi-square for trends = 6.34, P < 0.02). A significant number (11 of 15) of parents of children in the sevoflurane group who had previous experience of halothane induction preferred sevoflurane (chi-square for trends = 4.03, P < 0.05). We conclude that with this technique, induction was rapid with both sevoflurane and halothane. Our assessment of patient struggling and parents' perceptions suggests that induction with sevoflurane was more pleasant than with halothane.      

Effect of smoking on induction of anaesthesia with sevoflurane

Inhalational induction with sevoflurane has been shown to be a viable alternative to intravenous induction; however, studies have focused mainly on healthy patients or volunteers. Airway complications in patients with potential airway irritability have not been studied. Sixty smokers undergoing general anaesthesia were randomly assigned to one of three groups: group 1, vital capacity breathing with 8% sevoflurane; group 2, tidal breathing with 8% sevoflurane; and group 3, tidal breathing with step-up of sevoflurane (sevoflurane concentration increased by increments of 2% every 10 s until 8%). Step-up induction was significantly slower to induce loss of consciousness than a vital capacity breath or tidal breathing at 8% (p < 0.05). Step-up induction produced more complications than tidal breathing at 8% (p = 0.05). All patients had acceptable induction of anaesthesia with no patient having an oxygen saturation below 96% at any time. Blood pressure and heart rate decreased gradually over time in all groups (p < 0.001), but there were no significant differences between groups. Patient satisfaction with the techniques was high with 59 of 60 patients willing to have the same technique again. Inhalational induction with sevoflurane can be used safely as an induction technique in smokers. In common with other patient groups, use of a high initial concentration reduces induction time without causing additional airway or cardiovascular complications.     

The effects of clonidine premedication on sevoflurane requirements and anesthetic induction time.

We assessed the effects of oral clonidine preanesthetic medication (4.5 microg/kg) on the vital capacity rapid-inhalation anesthetic induction time (VCRII time) and minimum alveolar anesthetic concentration (MAC) to prevent a response to a verbal command in 50% of patients (MAC-Awake) by its hypnotic effect, and on MAC-Skin incision for the analgesic effect in patients anesthetized with sevoflurane. We studied 104 adult patients (control group: n = 52, clonidine group: n = 52) aged 30-48 yr scheduled to undergo general anesthesia. Fifty-two patients received oral clonidine 4.5 microg/kg 1.5 h before arrival in the operating room (clonidine group). The patients exhaled to residual volume and took three vital capacity breaths of 5% sevoflurane in oxygen. The VCRII time was defined as the time interval between the initiation of the VCRII and the disappearance of the response to verbal command. Anesthesia was maintained with sevoflurane in oxygen and air. The end-tidal (ET) sevoflurane concentration reached a predetermined value, then the ratio of predetermined ET to inspiratory concentration was maintained at > or =0.95 for at least 15 min before skin incision. After skin incision, the patients were observed for gross purposeful muscular movements. MAC was defined as the average of the cross-over midpoints in each cross-over. After maintaining the ET sevoflurane concentration for 15 min, patients were judged to be awake or asleep. Average times for VCRII using 5% sevoflurane were achieved in 44+/-11 s (mean +/- SD) and 27+/-6 s in the control and clonidine groups, respectively (P = 0.0001). MAC-Awake values of sevoflurane were 0.66%+/-0.03% and 0.35%+/-0.02% (P = 0.0001), and MAC-Skin incision values were 1.97%+/-0.19% and 1.29%+/-0.13% (P = 0.0001) in the control and clonidine groups, respectively. These results suggest that clonidine may have a more potent hypnotic effect than analgesic effect. IMPLICATIONS: Oral clonidine preanesthetic medication (4.5 microg/kg) significantly reduces vital capacity rapid inhalation anesthetic induction time and minimum alveolar anesthetic concentration awake for sevoflurane.     

Comparative study of inhalation induction by vital capacity breath in adults using 6% sevoflurane with oxygen or 4.5%sevoflurane in 50% nitrous oxide

OBJECTIVE: To evaluate the efficacy, side effects and hemodynamic characteristics of induction by vital capacity breath in adults using 6% sevoflurane and oxygen versus 4.5% sevoflurane and 50% nitrous oxide. PATIENTS AND METHODS: We assigned 50 ASA I-II patients aged 20 to 70 years old randomly to two groups of 25 to receive either 6% sevoflurane in oxygen or 4.5% sevoflurane in nitrous oxide. All patients were premedicated with oral bromazepam (1.5 to 3 mg). Induction was by vital capacity breath using a Mapleson A circuit (8 l. min-1) for 5 min. We recorded induction time, side effects, hemodynamic variables and patient opinion after surgery. RESULTS: Induction time was significantly faster for the sevoflurane-oxygen group (60 +/- 10 s) than for the sevoflurane-nitrous oxide group (71 +/- 8 s) (p < 0.001). Complications were minor and hemodynamic variables stable in both groups, with no statistically significant differences. The patients expressed satisfaction with both induction techniques. CONCLUSIONS: A vital capacity breath of 6% sevoflurane provided rapid induction. Induction was no more rapid when 50% nitrous oxide was added and the incidence of side effects did not decrease. Hemodynamic variables are stable during induction with sevoflurane with or without nitrous oxide, making this a well-tolerated alternative technique that is positively evaluated by patients.     

Values of the bispectral index do not parallel the hemodynamic response to the rapid increase in isoflurane concentration

PURPOSE: To investigate the changes in hemodynamic variables and bispectral index (BIS) in response to a rapid increase in isoflurane or sevoflurane concentration. METHOD: Thirty adult patients were anesthetized with either isoflurane (isoflurane group) or sevoflurane (sevoflurane group). Two minutes after induction of anesthesia with thiamylal, the inspired concentrations of isoflurane and sevoflurane were rapidly increased from 0.5 minimum alveolar anaesthetic concentration (MAC) to 3 MAC and maintained for five minutes. Heart rate (HR), mean arterial pressure (MAP), and BIS were measured every minute. RESULTS: An increase in the anesthetic concentration caused increases in HR and MAP in the isoflurane group and a decrease in MAP in the sevoflurane group. Consequently, HR and MAP in the isoflurane group were significantly higher than those in the sevoflurane group. After inhalation of high concentrations, BIS significantly and progressively decreased in both groups. CONCLUSION: BIS values decrease after a step increase in volatile agent concentration, whether or not a hyperdynamic action occurs.     

Anesthetic induction with nitrous-oxide-free sevoflurane in pediatric patients

OBJECTIVE: To evaluate the pediatric use of inhaled nitrous oxide (N2O)-free induction with sevoflurane for the purpose of protecting staff from exposure to workplace air pollution. PATIENTS AND METHODS: Prospective, randomized trial in ASA class 1-2 children in whom a tidal breathing technique was used for anesthetic induction in a variety of surgical procedures. Patients were allocated to 2 groups. The sevo-N2O group inhaled 8% sevoflurane in a 60/40% mixture of oxygen and N2O. The sevo-air group received 8% sevoflurane in a mixture of oxygen and air (inspired oxygen fraction, 40%). We recorded mean arterial pressure (MAP), heart rate, oxygen saturation by pulse oximetry (SpO2), limb response to venous puncture, alveolar concentration of sevoflurane, and incidence of adverse events. RESULTS: Twenty-two patients were assigned to each group. The vein was catheterized in all patients without a pain reflex in the limb, and there were no statistically significant differences in MAP, heart rate, SpO2, or incidence of adverse events. Mean (SD) alveolar concentration of sevoflurane, however, differed between the 2 groups: 53% (0.51%) in the sevo-N2O group and 4.91% (0.41%) in the sevo-air group (P = .028). CONCLUSIONs: N2O-free anesthetic induction by tidal breathing of 8% sevoflurane provides similar anesthetic conditions (efficacy, safety, and rapid onset) without a higher incidence of adverse events. The use of N2O can therefore be avoided.     

Clinical Characteristics of Sevoflurane in Children: A Comparison with Halothane

Background: For pediatric patients, sevoflurane may be an alternative to halothane, the anesthetic agent used most commonly for inhalational induction. The induction, maintenance, and emergence characteristics were studied in 120 unpremedicated children 1-12 yr of age randomly assigned to receive one of three anesthesia regimens: sevoflurane with oxygen (group S), sevoflurane with nitrous oxide and oxygen (group SN), or halothane with nitrous oxide and oxygen (group HN).

Methods: Anesthetic was administered (via a Mapleson D, F or Bain circuit) beginning with face mask application in incremental doses to deliver maximum inspired concentrations of 4.5% halothane or 7% sevoflurane. End-tidal concentrations of anesthetic agents and vocal cord position were noted at the time of intubation. Elapsed time intervals from face mask application to loss of the eyelash reflex, intubation, surgical incision, and discontinuation of the anesthetic were measured. Heart rate, systolic, diastolic, and mean blood pressures, and end-tidal anesthetic concentrations were measured at fixed intervals. Anesthetic MAC-hour durations were calculated. The end-tidal concentration of anesthetic was adjusted to 1 MAC (0.9% halothane, 2.5% sevoflurane) for at least the last 10 min of surgery. Intervals from discontinuation of anesthetic to hip flexion or bucking, extubation, administration of first postoperative analgesic, and attaining discharge criteria from recovery room were measured. Venous blood was sampled at anesthetic induction, at the end of anesthesia, and 1, 4, 6, 12, and 18-24 h after discontinuation of the anesthetic for determination of plasma inorganic fluoride content.

Results: Induction of anesthesia was satisfactory in groups SN and HN. Induction in group S was associated with a significantly greater incidence of excitement (35%) than in the other groups (5%), resulting in a longer time to intubation. The end-tidal minimum alveolar concentration multiple of potent inhalational anesthetic at the time of intubation was significantly greater in patients receiving halothane than in patients receiving sevoflurane. Induction time, vocal cord position at intubation, time to incision, duration of anesthesia, and MAC-hour duration were similar in the three groups. During emergence, the time to hip flexion was similar among the three groups, whereas the time to extubation, time to first analgesic, and time to attaining discharge criteria were significantly greater in group HN than in groups S and SN. Mean heart rate and systolic blood pressure decreased during induction in group HN but not in groups S and SN. The maximum serum fluoride concentration among all patients was 28 micro Meter.