异丙酚麻醉下瑞芬太尼抑制不同年龄老年患者气管插管和切皮反应的半数有效血浆靶浓度

目的 确定异丙酚麻醉下瑞芬太尼抑制不同年龄老年患者气管插管和切皮反应的半数有效血浆靶浓度(EC50).方法 择期全麻老年患者116例,年龄60～79岁,体重39～82 kg,ASA Ⅰ～Ⅲ级,按年龄及刺激不同分为4组,靶控输注异丙酚,待患者意识消失时靶控输注瑞芬太尼,Ⅰ-TI组(60～69岁,n=33)和Ⅱ-TI组(70～79岁,n=31)第1例患者瑞芬太尼初始血浆靶浓度设为3.5 ng/ml,待效应室浓度与血浆靶浓度达平衡后静脉注射维库溴铵0.1 me,/kg,3 min后行气管插管.Ⅰ-SI组(60～69岁,n=26)和Ⅱ-SI组(70～79岁,n=26)第1例患者气管插管后瑞芬太尼初始血浆靶浓度设为2.5 ng/ml,待效应室浓度与血浆靶浓度达平衡后维持10 min,开始切皮,采用改良序贯法进行试验.发生心血管反应的标准:气管插管或切皮后3 min内平均动脉压或心率较气管插管或切皮前的基础值升高超过20%.计算各组EC50及其95%可信区间(CI).结果 Ⅰ-TI组和Ⅱ-TI组瑞芬太尼抑制气管插管反应的EC50及其95%CI分别为2.90(2.76～3.04)ng/ml和3.16(2.90～3.41)ng/ml,差异无统计学意义(P>0.05);Ⅰ-SI组和Ⅱ-SI组瑞芬太尼抑制切皮反应的EC50及95%CI分别为1.90(1.76～2.04)ng/ml和1.77(1.68～1.85)ng/ml,差异无统计学意义(P>0.05);与Ⅰ-TI组比较,Ⅰ-SI组EC50降低(P<0.05);与Ⅱ-TI组比较,Ⅱ-SI组EC50降低(P<0.05).结论 60～69岁患者靶控输注异丙酚至意识消失时瑞芬太尼抑制气管插管和切皮反应的EC50分别为2.90、1.90ng/ml,70～79岁患者分别为3.16、1.77 ng/ml,不随年龄增加而改变.     

复合靶控输注异丙酚时瑞芬太尼抑制重症肌无力患者气管插管反应的药效学

目的 探讨复合靶控输注异丙酚时瑞芬太尼抑制重症肌无力患者气管插管反应的药效学.方法 拟行经胸骨正中劈开胸腺切除术的重症肌无力患者45例,ASA Ⅰ或Ⅱ级,TCI异丙酚和瑞芬太尼进行麻醉诱导,异丙酚血浆靶浓度为4 μg/ml,瑞芬太尼初始效应室靶浓度(Ce)为1.8 ng/ml,依次按2.7、4.0、6.0 ng/ml梯度递增,至患者可耐受喉麻管置入声门下进行气管内表麻后,进行气管插管.采用概率单位回归分析法分别计算瑞芬太尼抑制气管插管反应的Ce50和Ce95.结果 瑞芬太尼抑制气管插管反应的Ce50为2.2 ng/ml,其95%可信区间为2.0～2.3 ng/ml;抑制气管插管反应的Ce95为3.0 ng/ml,其95%可信区间为2.8～3.5 ng/ml.结论 复合靶控输注异丙酚(血浆靶浓度为4 μg/ml)时,瑞芬太尼抑制重症肌无力患者气管插管反应的Ce50和Ce95分别为2.2、3.0 ng/ml.     

右美托咪啶复合靶控输注异丙酚时舒芬太尼抑制双腔气管插管反应的量效关系

目的 确定右美托咪啶复合靶控输注(TCI)异丙酚时舒芬太尼抑制双腔气管插管反应的效应室靶浓度(EC50和EC95).方法 单肺通气全麻胸外科手术患者30例,ASA分级Ⅰ或Ⅱ级,年龄40 ～ 64岁,体重指数＜30 kg/m2.经10 min静脉输注右美托咪啶0.6 μg/kg,随后以0.3μg·kg-1·h-1的速率维持至手术结束前30 min.TCI舒芬太尼3 min后TCI异丙酚,Ce 3 μg/ml,意识消失时静脉注射罗库溴铵0.8 mg/kg行双腔气管插管.采用序贯法进行试验,TCI舒芬太尼初始Ce 0.3 ng/ml,如果前一例患者发生气管插管反应,则下一例患者采用高一级浓度,否则采用低一级浓度,相邻靶浓度之间比率为1.1.气管插管反应的标准:气管插管后3 min内MAP波动幅度超过基础水平15％和/或HR＞90次/min.采用概率单位回归分析法计算舒芬太尼抑制双腔气管插管反应的EC50和EC95.结果 舒芬太尼抑制双腔气管插管反应的EC50为0.23 ng/ml,其95％可信区间为0.20～0.26 ng/ml;抑制双腔气管插管反应的EC95为0.26 ng/ml,其95％可信区间为0.24～0.31 ng/ml.结论 右美托咪啶复合TCI异丙酚时,舒芬太尼抑制双腔气管插管反应的EC50和EC95分别为0.23和0.26 ng/ml.     

The optimal effect-site concentration of remifentanil for lightwand tracheal intubation during propofol induction without muscle relaxation

Study Objective

To determine the most suitable effect-site concentration of remifentanil during lightwand intubation when administered with a target-controlled infusion (TCI) of propofol at 4.0 μg/mL without neuromuscular blockade.

Design

Prospective study using a modified Dixon's up-and-down method.

Setting

Operating room of an academic hospital.

Patients

28 ASA physical status 1 and 2 patients, aged 18-65 years, scheduled for minor elective surgery.

Interventions

Anesthesia was induced by TCI propofol effect-site concentration to 4.0 μg/mL, and the dose of remifentanil given to each patient was determined by the response of the previously tested patient using 0.2 ng/mL as a step size. The first patient was tested at a target effect-site concentration of 4.0 ng/mL of remifentanil. If intubation was successful, the remifentanil dose was decreased by 0.2 ng/mL; if it failed, the remifentanil dose was increased by 0.2 ng/mL. Successful intubation was defined as excellent or good intubating conditions.

Measurements and Main Results

The remifentanil effect-site concentration was measured. The optimal effect-site concentration of remifentanil for lightwand tracheal intubation during propofol induction using 2% propofol target effect-site concentration to 4 μg/mL was 2.16 ± 0.19 ng/mL. From probit analysis, the effect-site concentration of remifentanil required for successful lightwand intubation in 50% (EC50) and 95% (EC95) of adults was 2.11 ng/mL (95% CI 1.16-2.37 ng/mL) and 2.44 ng/mL (95% CI 2.20-3.79 ng/mL), respectively.

Conclusion

A remifentanil effect-site concentration of 2.16 ± 0.19 ng/mL given before a propofol effect-site concentration of 4 μg/mL allowed lightwand intubation without muscle relaxant.     

The effect of remifentanil on the bispectral index change and hemodynamic responses after orotracheal intubation

In order to examine whether changes in the bispectral index (BIS) may be an adequate monitor for the analgesic component of anesthesia, we evaluated the effect of remifentanil on the BIS change and hemodynamic responses to laryngoscopy and tracheal intubation. Fifty ASA physical status I patients were randomly assigned, in a double-blinded fashion, to one of five groups (n = 10/group) according to the remifentanil target effect compartment site concentration (0, 2, 4, 8, or 16 ng/mL). The target-controlled infusion (TCI) of remifentanil was initiated 3 min after the TCI of propofol that was maintained at the effect-site concentration of 4 microg/mL throughout the study. After the loss of consciousness and before the administration of vecuronium 0.1 mg/kg, a tourniquet was applied to one arm and inflated above the systolic blood pressure in order to detect any gross movement within the first minute after tracheal intubation, which was performed 3 min after remifentanil TCI began. A BIS value was generated every 10 s. Arterial blood pressure and heart rate (HR) were measured every minute, noninvasively. Measures of mean arterial pressure (MAP), HR, and BIS were obtained before the induction, before the start of remifentanil TCI, before laryngoscopy, and 5 min after intubation. The relationships between remifentanil effect-site concentrations and BIS change or hemodynamic responses (changes in MAP and HR) to intubation were determined by logarithmic regression. BIS values were not affected by remifentanil before laryngoscopy. During this period, MAP and HR decreased significantly (P < 0.01) in the remifentanil 8 and 16 ng/mL groups. Changes in BIS, MAP, and HR were negatively correlated with remifentanil effect-site concentration (P < 0.0001). The number of movers in the remifentanil 0-, 2-, 4-, 8-, and 16-ng/mL groups was, respectively, 10, 9, 7, 1, and 0. Hypotensive episodes (MAP < 60 mm Hg) were noted in 1, 2, and 5 patients in the remifentanil 4-, 8-, and 16-ng/mL groups, respectively. We conclude that the addition of remifentanil to propofol affects BIS only when a painful stimulus is applied. Moreover, remifentanil attenuated or abolished increases in BIS and MAP after tracheal intubation in a comparable dose-dependent fashion. IMPLICATIONS: Bispectral index change is as sensitive as hemodynamic responses after a painful stimulus for detecting deficits in the analgesic component of anesthesia. It may, therefore, be a useful monitor of the depth of anesthesia in patients who are incapable of HR and MAP responses to noxious stimuli because of medications or cardiovascular disease.     

复合异丙酚麻醉时舒芬太尼抑制强直电刺激和切皮诱发胸腹部手术患者体动反应的药效学

目的 探讨复合异丙酚麻醉时舒芬太尼抑制强直电刺激和切皮诱发胸腹部手术患者体动反应的药效学.方法 择期胸腹部手术患者50例,年龄18～57岁,ASA分级Ⅰ或Ⅱ级,体重为标准体重的80%～120%,随机分为5组(n=10):舒芬太尼效应室靶浓度0.07、0.10、0.14、0.20和0.28 ng/ml组.靶控输注异丙酚,血浆靶浓度3.0～3.2 μg/ml,患者意识消失时各组按设定的效应室靶浓度靶控输注舒芬太尼,待效应室和血浆浓度达平衡后,给予强直电刺激(频率50 Hz,强度80 mA,波宽0.25ms),观察患者反应后给肌松药,行气管插管,维持上述异丙酚和舒芬太尼的靶浓度到切皮后4 min,试验观察结束.观察强直电刺激和切皮时患者的体动反应情况.采用通过概率单位回归分析法计算舒芬太尼抑制电刺激和切皮诱发的体动反应的半数有效效应室靶浓度(EC50)和EC95及其95%可信区间.结果 复合异丙酚麻醉时舒芬太尼抑制强直电刺激诱发的体动发应的EC50和EC95及其95%可信区间分别为0.12(0.09～0.14)ng/ml和0.20(0.17～0.31)ng/ml,抑制切皮诱发的体动发应的EC50和EC95分别为0.13(0.11～0.16)ng/ml和0.21(0.17～0.29)ng/ml;复合异丙酚麻醉时舒芬太尼抑制强直电刺激和切皮诱发的体动发应的EC50和EC95的比较差异无统计学意义(P＞0.05).结论 复合异丙酚麻醉时舒芬太尼抑制强直电刺激(频率50 Hz,强度80 mA,波宽0.25 ms)诱发的体动发应的EC50和EC95分别为0.12和0.20 ng/ml,抑制切皮诱发的体动发应的EC50和EC95分别为0.13和0.21 ng/ml,且抑制两组刺激诱发的体动发应的药效学无差异,提示强直电刺激可替代切皮用于评价麻醉药的药效学.     

不同效应室靶浓度瑞芬太尼对患者异丙酚镇静效应的影响

目的 探讨不同效应室靶浓度瑞芬太尼对患者异丙酚镇静效应的影响.方法择期全麻手术患者50例,年龄20～55岁,体重48～86 kg,性别不限,ASA分级Ⅰ或Ⅱ级,BMI＜30 kg/m2,采用随机数字表法,将患者随机分为5组(n=10):R0组、R1组、R2组、R3组、R4组.麻醉诱导时R0组～R4组瑞芬太尼效应室靶浓度分别为0、2 4 6和8 ng/ml,异丙酚初始效应室靶浓度2.0 μg/ml,待效应室浓度稳定之后每隔1 min增加0.5 μg/ml,直至BIS值降至50.记录患者意识消失时的BIS值、异丙酚效应室浓度.记录BIS值降至50时的异丙酚效应室浓度、异丙酚总用量及所需时间.结果 与R0组比较,R2组～R4组意识消失时BIS值升高,异丙酚效应室浓度降低,BIS值降至50时异丙酚总用量和异丙酚效应室浓度降低,所需时间缩短(P＜0.05或0.01),R.组上述指标差异无统计学意义(P＞0.05);R2组～R4组意识消失时BIS值和异丙酚效应室浓度、BIB值降至50时异丙酚总用量和异丙酚效应室浓度以及所需时间差异无统计学意义(P＞0.05).结论 瑞芬太尼效应室靶浓度达4 ng/ml时可增强异丙酚的镇静效应,且4、6和8 ng/ml时该作用无差异.

Abstract：

Objective To investigate the effects of different target effect-site concentrations (Ces) of remifentanil on the sedative effect of propofol. Methods Fifty ASA Ⅰ or Ⅱ patients aged 20-55 yr weighing 48-86 kg with body mass index ＜ 30 kg/m2 were randomly divided into 5 groups ( n = 10 each) . Anesthesia was induced with TCI of remifentanil (Ce = 0, 2, 4, 6 and 8 ng/ml in groups R0-R4 respectively) and propofol. The initial Ce of propofol was 2.0 μg/ml in the 5 groups, and then the Ce of propofol increased by 0.5 μg/ml every 1 min until BIS value decreased to 50. BIS value and Ce of propofol were recorded as the patient lost consciousness. The effect-site concentration and consumption of propofol and the time required were recorded when BIS value decreased to 50.Results BIS value was significantly increased, while the effect-site concentration of propofol was significantly decreased as the patient lost consciousness, and the effect-site concentration and consumption of propofol were significantly decreased and the time required was shortened when BIS value decreased to 50 in R2-R4 groups compared with group R0 (P ＜ 0.05 or 0.01) . Conclusion The sedative effect of propofol can be enhanced when the Ce of remifentanil reaches 4 ng/ml, and the effects are comparable when the Ce of remifentanil reaches 4, 6 and 8 ng/ml.     

The effect of adding nitrous oxide on MAC of sevoflurane combined with two target-controlled concentrations of remifentanil in women

BACKGROUND AND OBJECTIVE: The aim of this prospective, randomized, double-blind study was to determine the effects of adding nitrous oxide on sevoflurane requirement for blunting sympathetic responses after surgical incision combined with two different target-controlled concentrations of remifentanil (1 and 3 ng mL(-1)) in female. METHODS: 102 female patients, aged 20-50 yr, ASA I, undergoing general anaesthesia for elective abdominal surgery were enrolled and randomly allocated to receive sevoflurane anaesthesia alone (Group A, n=53), or with the addition of 60% nitrous oxide (Group N, n=49). Patients of both groups were further assigned to receive a target-controlled remifentanil infusion with an effect-site concentration of either 1 ng mL(-1) (Group N1, n=27; Group A1, n=30), or 3 ng mL(-1) (Group N3, n=22; Group A3, n=23). Sympathetic responses to surgical incision were determined after a 20-min period of stable end-tidal sevoflurane and target-controlled remifentanil concentrations. Predetermined end-tidal sevoflurane concentrations and minimum alveolar concentration (MAC) for each group were determined using an up-and-down sequential allocation technique. RESULTS: The MAC of sevoflurane was 3.96% (95% confidence interval, CI95: 3.69-4.23%) in Group A1 and 1.2% (CI95: 0.9-1.3%) in Group N1 (P < 0.01), while in Groups A3 and N3 the MAC of sevoflurane was 0.36% (CI95: 0.24-0.47%) and 0.18% (CI95: 0.1-0.3%), respectively (P < 0.05). CONCLUSION: Adding 60% nitrous oxide reduces the MAC of sevoflurane by 70% when using a remifentanil concentration of 1 ng mL(-1) and 50% when using a remifentanil concentration of 3 ng mL(-1).     

依托咪酯乳剂诱导时雷米芬太尼抑制气管插管反应的效应室靶浓度

目的 测定依托咪酯乳剂诱导时雷米芬太尼抑制气管插管反应的效应室靶浓度(EC50和EC95).方法 选择23例ASAⅠ或Ⅱ级全麻择期手术患者靶控输注(TCI)雷米芬太尼,血浆浓度与效应室浓度达到平衡后静脉注射依托咪酯乳剂0.3 mg/kg,患者意识消失后静脉注射琥珀胆碱行气管插管.气管插管后2 min内最高的SBP和/或HR高出基础值15%为气管插管反应阳性.雷米芬太尼靶浓度按改良序贯法增加或减少0.5 ng/ml.用概率单位回归分析法计算出雷米芬太尼抑制气管插管反应的EC50、EC95及相应的95%可信区间(CI).结果 雷米芬太尼抑制气管插管反应的EC50为3.06 ng/ml,95%CI为2.56～3.47 ng/ml;相应的EC95为3.85 ng/ml,95%CI为3.45～6.64ng/ml.结论 复合依托咪酯0.3 mg/kg诱导时雷米芬太尼抑制气管插管反应的EC50和EC95分别为3.06 ng/ml和3.85 ng/ml.     

不同剂量右美托咪定对丙泊酚诱导效应室靶浓度的影响

目的观察不同剂量右美托咪定在全麻患者气管插管时有效性和安全性及对丙泊酚效应室靶浓度(Ce)的影响。方法 60例全麻下行择期上腹部手术患者,随机均分为四组:D1、D2、D3、C组,分别在麻醉诱导前10min静脉泵注右美托咪定0.25μg/kg(D1组)、0.5μg/kg(D2组)和1.0μg/kg(D3组)及10ml生理盐水(C组)。麻醉诱导采用靶控输注丙泊酚,以BIS为靶控目标。丙泊酚初始Ce设为1.5μg/ml,递增梯度为0.5μg/ml,同时泵注瑞芬太尼0.2μg·kg-1·min-1。BIS≤60时推注罗库溴铵0.9mg/kg,BIS≤50并维持5s行气管插管。于输注右美托咪定前(T0)、诱导前(T1)、气管插管前(T2)、气管插管后1min(T3)、3min(T4)、5min(T5)、10min(T6)时记录SBP、DBP、HR、BIS、丙泊酚Ce。结果与T0时比较,T1时D2、D3组HR减慢、D3组SBP、DBP升高(P<0.05);与T1时比较,T2时D1组和C组SBP、DBP下降,HR减慢(P<0.05);与T2时比较,T3～T5时D1组和C组SBP、DBP升高,HR增快,T3时C组BIS升高(P<0.05)。T2～T6时丙泊酚CeD1、D2、D3组明显低于C组(P<0.05)。不同剂量右美托咪定各时点对丙泊酚Ce存在明显负相关关系。结论麻醉诱导前静脉输注不同剂量右美托咪定对丙泊酚诱导效应室浓度存在负相关关系。麻醉诱导前静脉输注右美托咪定0.5μg/kg心血管反应平稳并能显著减少诱导时所需丙泊酚Ce。     

Remifentanil dose/electroencephalogram bispectral response during combined propofol/regional anesthesia

The effect of opioid administration on the bispectral index (BIS) during general anesthesia is controversial. Several investigators have reported BIS to be insensitive to opioid addition, whereas others have found a hypnotic response. We designed this study to examine the effect of remifentanil on BIS during combined regional/general propofol anesthesia under steady-state conditions. After Human Investigations Committee approval, 19 healthy ASA physical status I or II patients were enrolled in a prospective experimental design. Regional anesthesia was initiated and general anesthesia induced by using computer-assisted continuous infusion of propofol. Propofol was incrementally adjusted to a BIS of approximately 60. After 20 min at a stable propofol infusion rate, a remifentanil computer-assisted continuous infusion (effect-site target concentration of 0.5, 2.5, and then 10 ng/mL) was sequentially administered at stepped 15-min intervals. BIS decreased from 56 +/- 2 to 44 +/- 1, 95% spectral edge frequency from 17.9 +/- 0.5 Hz to 15.0 +/- 0.4 Hz, heart rate from 84 +/- 5 bpm to 62 +/- 4 bpm, and mean arterial blood pressure from 93 +/- 4 mm Hg to 69 +/- 3 mm Hg with increasing remifentanil concentration. A significant linear correlation between BIS, 95% spectral edge frequency, heart rate, and log (remifentanil effect-site) concentration was found. The change in baseline BIS was relatively modest but significant, suggesting that remifentanil has some sedative/hypnotic properties, or that it potentiates the hypnotic effect of propofol. IMPLICATIONS: This experiment identified a significant, dose-dependent decrease in bispectral index (BIS), 95% spectral edge frequency, heart rate, and mean arterial blood pressure with increasing remifentanil dose. The change in baseline BIS was relatively modest but significant, suggesting that remifentanil has some sedative/hypnotic properties, or that it potentiates the hypnotic effect of propofol.     

Reduction by Fentanyl of the Cp sub 50 Values of Propofol and Hemodynamic Responses to Various Noxious Stimuli

Background: Propofol and fentanyl infusion rates should be varied according to the patient's responsiveness to stimulation to maintain satisfactory anesthetic and operative conditions. However, somatic and autonomic responses to various noxious stimuli have not been investigated systematically for intravenous propofol and fentanyl anesthesia.

Methods: Propofol and fentanyl were administered via computer-assisted continuous infusion to provide stable concentrations and to allow equilibration between plasma-blood and effect-site concentrations. The propofol concentrations needed to suppress eye opening to verbal command and motor responses after 50-Hz electric tetanic stimulation, laryngoscopy, tracheal intubation, and skin incision in 50% or 95% of patients (Cp50 and Cp95) were determined at fentanyl concentrations of 0.0, 1.0, 2.0, 3.0, and 4.0 ng/ml in 133 patients undergoing lower abdominal surgery. The ability of propofol with fentanyl to suppress hemodynamic reactions in response to various noxious stimuli also was evaluated by measuring arterial blood pressure and heart rate before and after stimulation.

Results: The various Cp50 values for propofol alone (no fentanyl) for the various stimuli increased in the following order: Cp sub 50loss of consciousness, 4.4 micro gram/ml (range, 3.8-5.0); Cp50tetanus, 9.3 micro gram/ml (range, 8.3-10.4); Cp50laryngoscopy, 9.8 micro gram/ml (range, 8.9-10.8); Cp50skin incision, 10.0 micro gram/ml (range, 8.1-12.2); and Cp50intubation, 17.4 micro gram/ml (range, 15.1-20.1; 95% confidence interval). The reduction of Cp50loss of consciousness, with fentanyl was minimal; 11% at 1 ng/ml of fentanyl and 17% at 3 ng/ml of fentanyl. A plasma fentanyl concentration of 1 ng/ml (3 ng/ml) resulted in a 31-34% (50-55%) reduction of the propofol Cp50 s for tetanus, laryngoscopy, intubation, and skin incision. Propofol alone depresses prestimulation blood pressure but had no influence on the magnitude blood pressure or heart rate increase to stimulation. Propofol used with fentanyl attenuated the systolic blood pressure increases to various noxious stimuli in a dose-dependent fashion.     

The effect of adding two target-controlled concentrations (1-3 ng mL -1 ) of remifentanil on MAC BAR of desflurane

BACKGROUND AND OBJECTIVES: The aim of this prospective, randomized, double-blind study was to determine the effects of adding two different target-controlled concentrations of remifentanil (1 and 3 ng mL(-1)) on the desflurane requirement for blunting sympathetic responses after surgical incision (minimum anaesthetic concentration (MAC(BAR)). METHODS: 67 patients, aged 20-50 yr, ASA I, undergoing general anaesthesia for elective abdominal surgery were enrolled and randomly allocated to receive no remifentanil infusion (n = 21) or a target-controlled effect-site concentration of 1 ng mL(-1) (n = 24) or 3 ng mL(-1) remifentanil (n = 22). All patients were anaesthetized with propofol, cisatracurium and desflurane with a mixture of 60% nitrous oxide in oxygen. Sympathetic responses to surgical incision were determined after a 20-min period of stable end-tidal desflurane and target-controlled remifentanil concentrations. Predetermined end-tidal desflurane concentrations and the MAC(BAR) for each group were determined using an up-and-down sequential-allocation technique. RESULTS: The MAC(BAR) of desflurane was higher in the group receiving no remifentanil (6.25% [95% confidence interval: 5.9-6.5%]) as compared with patients of the groups receiving 1 ng mL(-1) (2.7% [2.6-2.8%]; P < 0.001) and 3 ng mL(-1) remifentanil (2% [1.9-2.2%]; P < 0.01). When considering a MAC value in this age population and the contribution of 60% nitrous oxide (0.55 MAC), the combined MAC(BAR) values, expressed as multiples of the MAC, were 1.9, 0.8 and 0.6 MAC, in the three groups, respectively. CONCLUSION: A target-controlled concentration of 1 ng mL(-1) remifentanil results in a 57% decrease in the MAC(BAR) of desflurane combined with 60% nitrous oxide. Increasing the target concentration of remifentanil to 3 ng mL(-1) produces a further 26% decrease in the MAC(BAR) values of desflurane.     

Effect-site concentration of remifentanil for laryngeal mask airway insertion during target-controlled infusion of propofol

The purpose of this study was to determine the effect-site concentration of remifentanil that would provide optimal conditions for successful laryngeal mask airway insertion during a target-controlled infusion (TCI) of propofol at 3.5 μg.ml⁻¹ without the use of neuromuscular blockade. Five minutes after propofol infusion, remifentanil was infused at a dose determined by a modified Dixon's up-and-down method. Five minutes after remifentanil infusion, the laryngeal mask was inserted. The effect-site concentration of remifentanil for successful laryngeal mask insertion in 50% of adults (EC₅₀) was 3.04 (SD 0.49) ng.ml⁻¹ during a TCI of 3.5 μg.ml⁻¹ propofol without neuromuscular blockade. From the probit analysis, the EC₅₀ and EC₉₅ of remifentanil were 2.84 ng.ml⁻¹ (95% CI 2.09–3.57 ng.ml⁻¹) and 3.79 ng.ml⁻¹ (95% CI 3.26–9.25 ng.ml⁻¹), respectively.     

Propofol and remifentanil effect-site concentrations estimated by pharmacokinetic simulation and bispectral index monitoring during craniotomy with intraoperative awakening for brain tumor resection

Different anesthetic techniques have been suggested for craniotomy with intraoperative awakening. We describe an asleep-awake-asleep technique with propofol and remifentanil infusions, with pharmacokinetic simulation to predict the effect-site concentrations and to modulate the infusion rates of both drugs, and bispectral index (BIS) monitoring. Five critical moments were defined: first loss of consciousness (LOC1), first recovery of consciousness (ROC1), final of neurologic testing (NT), second loss of consciousness (LOC2), and second recovery of consciousness (ROC2). At LOC1, predicted effect-site concentrations of propofol and remifentanil were, respectively, 3.6+/-1.2 microg/mL and 2.4+/-0.4 etag/mL. At ROC1, predicted effect-site concentrations of propofol and remifentanil were, respectively, 2.1+/-0.3 microg/mL and 1.8+/-0.3 etag/mL. At NT, predicted effect-site concentrations of propofol and remifentanil were, respectively, 0.9+/-0.3 microg/mL and 1.8+/-0.2 etag/mL. At LOC2, predicted effect-site concentrations of propofol and remifentanil were, respectively, 2.1+/-0.2 microg/mL and 2.5+/-0.2 etag/mL. At ROC2, predicted effect-site concentrations of propofol and remifentanil were, respectively, 1.2+/-0.5 microg/mL and 1.4+/-0.2 etag/mL (data are mean+/-SE). A significative correlation was found between BIS and predicted effect-site concentrations of propofol (r=0.547, P<0.001) and remifentanil (r=0.533, P<0.001). Multiple regression analysis between BIS and propofol and remifentanil predicted effect-site concentrations at the different critical steps of the procedure was done and found also significative (r=0.7341, P<0.001).     

成人与儿童丙泊酚麻醉消除切皮刺激引发躯体反应的瑞芬太尼需要量

背景在应用七氟烷麻醉中，为消除切皮刺激所引发的躯体反应，儿童需要的瑞芬太尼输注速率是成人的两倍。在全凭静脉麻醉中，关于瑞芬太尼需要量的类似数据尚无报道。方法本研究拟测定在丙泊酚麻醉期间能使50％成人（n=20，20。60岁）和儿童（n=20，3—11岁）患者对切皮刺激无躯体反应的瑞芬太尼输注速率（IR50）。每例行下腹部手术患者，在瑞芬太尼开始输注后，以血浆浓度6μg／ml的速度靶控输注丙泊酚。气管插管后，丙泊酚输注速率下调至血浆浓度3μg／ml，并持续至研究结束。瑞芬太尼输注速率根据Dixon上下调定方法确定，即每组第1名患者以0．2μg·kg^-1·min^-1速度输注，下一例患者根据前一例患者的反应作0．02μg·kg^-1·min^-1幅度调整。手术开始前，瑞芬太尼至少以恒定速率持续输注20分钟以上。手术开始后，只进行切皮操作，观察患者躯体反应，任何肉眼可见的肢体运动均视为躯体反应阳性。结果成人和儿童患者的IR50（CI95％）分别为0．08（0．06—0．12）μg·kg^-1·min^-1和0．15（0．13—0．17）μg·kg^-1·min^-1（P〈0．001）。结论本研究表明丙泊酚全凭静脉麻醉与七氟烷麻醉相似，为消除切皮刺激所引发的躯体反应，儿童所需瑞芬太尼的输注速率约是成人的两倍。     

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.     

靶控输注异丙酚复合瑞芬太尼麻醉用于重症肌无力患者胸腺切除术的效果

目的 探讨靶控输注异丙酚复合瑞芬太尼用于重症肌无力患者胸腺切除术的效果.方法 择期拟行胸腺切除术的重症肌无力患者45例,ASA分级Ⅰ或Ⅱ级,年龄16～64岁,体重45～95 kg.麻醉诱导:靶控输注异丙酚(血浆靶浓度4μg/ml)和瑞芬太尼(效应室靶浓度4 ng/ml),2%利多卡因2～3 ml行气管内表面麻醉后行气管插管,机械通气.麻醉维持:靶控输注异丙酚,血浆靶浓度3～5 μg/ml;靶控输注瑞芬太尼,效应室靶浓度3～6 ng/ml.术毕前30 min,静脉注射舒芬太尼0.15μg/kg进行镇痛.记录首次气管插管的成功情况、切皮时患者体动反应情况、苏醒时间、拔除气管导管时间、术毕拔除气管导管情况及心血管事件的发生情况.结果 所有患者均顺利完成气管插管,首次气管插管成功率100%.切皮时无一例患者发生体动反应;苏醒时间1.0～3.2 min;拔除气管导管时间2.6～7.0 min;术毕拔除气管导管率100%.麻醉诱导期间有3例患者发生心动过缓,4例患者发生低血压,对症处理后均恢复正常;术中有3例患者发生心动过缓,对症处理后恢复正常.结论 靶控输注异丙酚复合瑞芬太尼麻醉可安全有效地用于重症肌无力患者胸腺切除手术.     

Nitrous oxide prevents movement during orotracheal intubation without affecting BIS value

We sought to determine whether the addition of nitrous oxide (N(2)O) to an anesthetic with propofol and remifentanil modifies the bispectral index (BIS) during the induction of anesthesia and orotracheal intubation. Thirty ASA physical status I or II patients were randomly allocated to receive either 50% air in oxygen (control group) or 60%-70% N(2)O in oxygen (N(2)O group) that was commenced via a mask simultaneously with the induction of anesthesia. Anesthesia was performed in all the patients with IV propofol at the target effect compartment site concentration of 4 microg/mL throughout the study. A target-controlled infusion (TCI) of remifentanil was initiated 3 min after the TCI of propofol and maintained at the effect-site concentration of 4 ng/mL until the end of the study. After loss of consciousness, and before the administration of vecuronium 0.1 mg/kg, a tourniquet was applied to one arm and inflated to a value more than the systolic blood pressure. An examiner, blinded to the presence of N(2)O, sought to detect any gross movement within the first minute after tracheal intubation, which was performed 10 min after remifentanil TCI began. Inspired and expired oxygen, N(2)O, and carbon dioxide were continuously monitored. A BIS value was generated every 10 s. Arterial blood pressure and heart rate (HR) were measured noninvasively every minute. Measures of mean arterial pressure (MAP), HR, and BIS were obtained before the induction, before the start of the remifentanil TCI, before laryngoscopy, and 5 min after intubation. No significant intergroup differences were seen in BIS, HR, and MAP throughout the study. Maximum changes in BIS, HR, and MAP with intubation were significant (P < 0.01) for both groups but comparable. Six patients in the control group and none in the N(2)O group moved after intubation (P < 0.05). IMPLICATIONS: We demonstrated that 0.6 minimal alveolar concentration of nitrous oxide combined with a potent anesthetic and an opioid prevents movement after orotracheal intubation without affecting the bispectral index. This demonstrates that the bispectral index is not a useful neurophysiologic variable to monitor the level of anesthesia when nitrous oxide is added to a general anesthetic regimen using propofol and remifentanil.     

不同靶浓度舒芬太尼对腹部手术患者七氟醚MAC_(BAR)的影响

目的 评价不同靶浓度舒芬太尼对七氟醚抑制50%腹部手术患者切皮诱发应激反应的最低肺泡有效浓度(MAC_(BAR))的影响.方法 择期拟行腹部手术患者80例,年龄20～60岁,体重指数<30 kg/m~2,ASAⅠ或Ⅱ级,随机分为4组(n=20),S_0组:不使用舒芬太尼;S_(1～3)组:舒芬太尼效应室靶浓度分别为0.12、0.18和O.24 ng/ml.气管插管后吸入七氟醚,新鲜气流量10 L/min.S_0组气管插管后不给予舒芬太尼,其余组分别按设定目标靶浓度输注舒芬太尼.根据序贯法进行试验,S_(0～3)组初始呼气末七氟醚浓度分别为3.0%、1.8%、1.3%和1.1%,根据患者对切皮的反应(切皮时MAP和HR中任何一项升高幅度≥切皮前的25%为阳性反应)以1.2倍等比级增减,计算七氟醚MAC_(BAR).结果 与S_0组比较,S_1组、S_2组和S_3组七氟醚MAC_(BAR)均降低(P<0.05);与S_1组比较,S_2组和S_3组七氟醚MAC_(BAR)均降低(P<0.05);S_3组与S_2组MAC_(BAR)比较差异无统计学意义(P>0.05).结论 舒芬太尼效应室靶浓度0.12、0.18和0.24 ng/ml均可降低七氟醚MAC_(BAR),增强七氟醚抑制应激反应的效应,且呈浓度依赖性.