Does the type of anesthetic agent affect remifentanil effect-site concentration for preventing endotracheal tube-induced cough during anesthetic emergence? Comparison of propofol,sevoflurane, and desflurane

Study ObjectiveTo investigate whether the type of anesthetic agent administered affects the antitussive effect of remifentanil.DesignProspective randomized study.SettingOperating room of a university hospital.Patients78 ASA physical status 1 and 2 women, aged 20 to 65 years, who were scheduled to undergo a thyroidectomy.InterventionsPatients were randomly assigned to three groups to receive anesthesia with propofol (Group P), sevoflurane (Group S), or desflurane (Group D). The main anesthetics were titrated to maintain a target Bispectral Index for hypnosis of 40 to 60. Remifentanil was administered via effect-site target-controlled infusion (TCI). To determine the effective remifentanil effect-site concentration (Ce) to suppress coughing in each group, the up-and-down sequential allocation design was used.MeasurementsThe half maximal effective concentration (EC₅₀) values of remifentanil for preventing coughing in the groups were estimated using isotonic regression and compared among the groups.Main ResultsThe EC₅₀ of remifentanil for cough suppression in Group P [1.60 ng/mL (98.3% CI, 0.92 - 1.75 ng/mL)] was statistically lower than in Group D [1.96 ng/mL (98.3% CI, 1.81 - 2.50 ng/mL)]. The EC₅₀ in Group S was 1.75 ng/mL (98.3% CI, 1.39 - 2.13 ng/mL), which was higher than in Group P and lower than in Group D, but did not differ significantly from either group.ConclusionsRemifentanil administration for cough suppression during emergence should be customized to the anesthetic agent.     

异丙酚抑制老年患者术毕喉罩替换气管导管时机体反应的药效学

目的 探讨异丙酚抑制老年患者术毕喉罩替换气管导管时机体反应的药效学.方法 择期腹腔镜下拟行胆囊切除术的老年患者20例,ASA Ⅰ或Ⅱ级,年龄65～70岁.术毕行喉罩替换气管导管时,根据是否诱发机体反应,采用序贯法调节异丙酚血浆靶浓度,采用概率单位法得出异丙酚抑制喉罩替换气管导管时机体反应的半数有效血浆靶浓度(EC_(50))和95%有效血浆靶浓度(EC_(95))及其95%可信区间(95%CI).结果 异丙酚抑制喉罩替换气管导管时机体反应的EC_(50)(95%CI)为2.79(2.44～3.04)μg/ml;EC_(95)(95%CI)为3.61(3.27～4.78)μg/ml.结论 老年患者术毕靶控输注异丙酚血浆靶浓度3.61 μg/ml可满足喉罩平稳替换气管导管.     

The optimal dose of remifentanil for acceptable intubating conditions during propofol induction without neuromuscular blockade

Study ObjectiveTo determine the optimal remifentanil dose required to provide acceptable intubating conditions following induction of anesthesia with propofol without using neuromuscular blockade.DesignDose-response study.SettingOperating room of a university hospital.Patients50 ASA physical status 1 men, aged between 20 and 40 years, who were scheduled for general anesthesia.InterventionsIntubating conditions were evaluated according to the scoring system described by Viby-Mogensen et al. Successful intubation was defined as excellent or good.MeasurementsFor induction of anesthesia, an intravenous (IV) bolus dose of propofol 2.0 mg/kg was given over 30 seconds followed by the administration of predetermined IV remifentanil over 30 seconds; intubation was performed 90 seconds after completion of the remifentanil administration. The dose of remifentanil used for each patient was determined by the response of the previously tested patients, using the modified Dixon's up-and-down method (using 0.2 μg/kg as a step size). The first patient was tested with remifentanil 1.0 μg/kg. If intubation failed, the remifentanil dose was increased by 0.2 μg/kg; if intubation was successful, the dose was decreased by 0.2 μg/kg. Mean arterial pressure (MAP), heart rate (HR), and peripheral oxygen saturation were recorded during the study period.Main ResultsAccording to probit analysis, the effective dose of remifentanil in 50% (ED₅₀) and 95% (ED₉₅) of patients were 1.40 μg/kg and 2.40 μg/kg, respectively. Preintubation and postinduction HR and MAP values were lower than preinduction values (P < 0.001).ConclusionThe optimal bolus dose of remifentanil for acceptable intubating conditions was 2.40 μg/kg (95% confidence interval, 1.90-9.0 μg/kg) in 95% of patients during induction of anesthesia with propofol 2.0 mg/kg without neuromuscular blocking agents.     

氟比洛芬酯抑制瑞芬太尼致患者术后痛觉过敏的药效学研究

目的探讨氟比洛芬酯（凯芬）抑制瑞芬太尼致患者术后痛觉过敏反应的量效关系。方法选择我院2010年1至6月期间,择期全麻下腹部大手术患者50例,静脉注射咪达唑仑、芬太尼、丙泊酚和顺阿曲库铵麻醉诱导后,气管插管后行静脉麻醉。术中静脉输注0．25μg·kg^-1·min^-1瑞芬太尼和3～4mg·kg^-1．h^-1丙泊酚,间断静脉注射顺阿曲库铵维持麻醉。麻醉诱导后,采用序贯法静脉注射氟比洛芬酯,初始剂量为1mg／kg,相邻梯度为0．2mg／kg。采用概率单位分析法计算氟比洛芬酯抑制瑞芬太尼术后痛觉过敏的量效关系：半数有效剂量（ED50）、95％有效剂量（ED95）及其95％可信区间。结果氟比洛芬酯抑制瑞芬太尼致患者术后痛觉过敏的ED50为1．40（95％CI=I．13～1．61）mg／kg,ED95为2．21（95％CI=I．89～3．33）mg／kg。结论氟比洛芬酯抑制瑞芬太尼致术后痛觉过敏的ED50和ED95分别为1．40mg／kg和2．21mg／kg。     

The concentration of desflurane preventing spectral entropy change during surgical stimulation: A prospective randomized trial

Study objectiveTo determine the concentration of desflurane necessary to blunt changes in spectral entropy during surgical incision when two different target-controlled effect-site concentrations of remifentanil (1 and 3 ng/ml) were infused.DesignProspective, randomized controlled study.SettingOperating room of a university hospital.InterventionsForty-two patients undergoing general anesthesia for elective surgery were enrolled and randomly allocated to the R1 (1 ng/ml of remifentanil, n = 21) or R3 (3 ng/ml of remifentanil, n = 21) group. After at least a 10-min administration of target-controlled remifentanil concentration and predetermined end-tidal desflurane following endotracheal intubation, changes in spectral entropy in response to surgical incision were evaluated.MeasurementsConcentration of desflurane necessary to blunt changes in spectral entropy during surgical incision for each group was determined using Dixon's up-and-down method. Hemodynamic variables including mean arterial pressure (MAP) and heart rate (HR) were measured.Main resultsConcentration of desflurane necessary to blunt changes in spectral entropy during surgical incision in 50% of patients (EC₅₀) was 4.1% (95% CI: 3.5–4.7%) for the R1 group and 3.4% (95% CI: 3.0–3.8%) for the R3 group (P = 0.033). Additionally, the calculated EC₉₅ values using the logistic regression analysis for the R1 and R3 groups were 5.8% (95% CI: 5.0–10.8%) and 5.1% (95% CI: 4.3–10.6%), respectively. MAPs and HRs were significantly higher in the R1 than in the R3 group after surgical incision.ConclusionsDesflurane 4.1% with remifentanil 1 ng/ml and desflurane 3.4% with remifentanil 3 ng/ml significantly blunt the change in spectral entropy after surgical incision in 50% of patients.     

The effect-site concentration of remifentanil blunting cardiovascular responses to tracheal intubation and skin incision during bispectral index-guided propofol anesthesia

We sought to determine the effect-site concentration of remifentanil blunting sympathetic responses to tracheal intubation and skin incision during bispectral index (BIS)-guided propofol anesthesia. Forty-one ASA physical status I-II patients, aged 20-65 yr and undergoing major abdominal surgery, were randomly assigned to one of two groups: tracheal intubation (group TI, n = 20) or skin incision (group SI, n = 21). All patients received a target-controlled infusion of propofol of 4 microg/mL, which was then adjusted to maintain a BIS value ranging between 40 and 50. The effect-site concentration of remifentanil blocking the sympathetic responses to tracheal intubation and skin incision in 50% of cases (Ce50) was determined using an up-and-down sequential allocation method. The mean (95% confidence interval [CI]) Ce50 of remifentanil was 5.0 ng/mL for TI (95% CI, 4.7-5.4 ng/mL) and 2.1 ng/mL for SI (95% CI, 1.4-2.8 ng/mL). This study shows that effect-site concentrations of remifentanil of 5 ng/mL and 2 ng/mL are effective in blunting sympathetic responses to tracheal intubation and skin incision in 50% of patients when combined with a BIS-guided target controlled infusion of propofol.     

Effect of a remifentanil bolus dose on the cardiovascular response to emergence from anaesthesia and tracheal extubation

We have examined the effect of remifentanil on the haemodynamic response to emergence from anaesthesia and tracheal extubation in 40 ASA I-II female patients undergoing diagnostic laparoscopy, in a randomized, double-blind study. All patients received a standard general anaesthetic comprising propofol, vecuronium and 1% isoflurane with 66% nitrous oxide in oxygen. At the end of surgery, a bolus dose of remifentanil 1 microgram kg-1 (n = 20) or saline placebo (n = 20) was given and tracheal extubation was performed when standard criteria were achieved. Arterial pressure and heart rate were recorded non- invasively at 1-min intervals from the end of surgery. Remifentanil attenuated the increase in both mean arterial pressure (P < 0.001) and heart rate (P < 0.05) at extubation. Mean time to extubation was 7.2 (SEM 0.6) min and 4.0 (0.5) min in the remifentanil and saline groups, respectively (P < 0.001). There was no difference in the incidence of coughing at extubation, time to recovery from anaesthesia or time to fitness for discharge from the recovery room.      

Tracheal extubation of deeply anesthetized pediatric patients: a comparison of sevoflurane and sevoflurane in combination with low‐dose remifentanil

Purpose: We aimed to observe the emergence characteristics of children tracheally extubated in deep anesthesia with sevoflurane or sevoflurane in combination with low‐dose remifentanil. Methods: We randomly allocated 50 pediatric patients undergoing elective electronic cochlear implantation to groups either receiving sevoflurane (Group S, n = 25), or sevoflurane plus low‐dose remifentanil (Group SR, n = 25), during extubation from anesthesia. In Group S, subjects were tracheally extubated while breathing 1.3 times the minimal effective concentration of sevoflurane. In Group SR, subjects were tracheally extubated while breathing 1.0 times the minimal effective concentration of sevoflurane with 0.02–0.05 μg·kg^?1 per min remifentanil. Recovery characteristics and airway complications were noted. Results: There was no significant difference in age, weight, sex, and duration of anesthesia. The average remifentanil rate was 0.036 μg·kg^?1 per min, and compared with Group S, patients in Group SR had a lower respiratory rate (17.3 vs 20.2 per minute, P < 0.05) and a higher ETCO₂ (52.3 vs 49.4 mmHg, P < 0.05). Oral airway usage was also less frequent in Group SR (44% vs 16%, P < 0.01). Additionally, the time from extubation to spontaneous eye opening was shorter in Group SR (10.9 min vs 19.6 min, P < 0.01). Finally, six patients in Group S and five patients in Group SR had a pediatric anesthesia emergence delirium score >10. Conclusions: Low‐dose remifentanil in combination with sevoflurane provided rapid recovery and was safe for deep tracheal extubation in deep anesthesia in pediatric patients.     

不同剂量右美托咪定对舒芬太尼抑制老年患者气管插管心血管反应的半数有效剂量的影响

目的 观察复合不同剂量右美托咪定时对舒芬太尼抑制老年患者气管插管的半数有效剂量（ED50）的影响。方法 选择全身麻醉下行腹部手术的老年患者96例,ASA分级Ⅰ~Ⅱ级,将患者分为4组：对照组（C组,麻醉诱导前输注10 mL生理盐水）和右美托咪定组（D1、D2、D3组,分别于麻醉诱导前静脉泵注右美托咪啶0.1、0.3、0.5 μg/kg,泵注时间5~15 min）。所有患者均采用丙泊酚靶控浓度2.5 μg/mL及预设靶浓度的舒芬太尼全凭静脉麻醉。气管插管时采用序贯法测定舒芬太尼目标靶控浓度,记录所有患者插管前出现窦性心动过缓、低血压、呛咳的例数,并记录在PACU期间躁动、疼痛例数及术后2小时的镇静评分。结果 全麻诱导前静脉给予不同剂量右美托咪定且丙泊酚效应室浓度2.5 μg/mL下舒芬太尼抑制老年人气管插管心血管反应的EC50分别是：C组：0.246 ng/mL,D1组0.238 ng/mL,D2组0.215 ng/mL,D3组0.199 ng/mL。与C组相比,D3组气管插管前出现心动过缓的发生率较高,D2、D3组拔管期间患者躁动发生率较低,差异有统计学意义（P<0.05）。各组患者气管插管前出现低血压、呛咳的发生率及拔管期间疼痛的发生率以及术后2小时Ramsay评分差异均无统计学意义（P>0.05）。结论 随着右美托咪定的剂量增加,老年患者气管插管所需的舒芬太尼目标靶控浓度呈剂量依赖性下降,且全身麻醉诱导前静脉滴注0.3 μg/kg和0.5 μg/kg右美托咪定能够降低老年患者PACU期间的躁动发生情况。     

End-tidal sevoflurane concentration for tracheal extubation (MACEX) in adults: comparison with isoflurane

Sevoflurane has a non-pungent odour and provides smooth induction of anaesthesia. In contrast, isoflurane is irritating to the airway when used for induction, and this may also be evident during emergence from anaesthesia. We measured the end-tidal concentration of anaesthetic that prevented response to extubation in 50% of patients (MACEX) in adults receiving either sevoflurane or isoflurane. Airway complications during emergence from anaesthesia were also noted. We studied 51 adult patients, ASA 1, aged 36-59 yr. Patients received sevoflurane (n = 29) or isoflurane (n = 22) for elective intraocular surgery. The concentration at which extubation was attempted was determined by a modification of Dixon's up-and-down method. When tracheal extubation was accomplished without coughing and gross purposeful muscular movements within 1 min after extubation, it was considered a smooth tracheal extubation. Patients who developed breath-holding or laryngospasm immediately after tracheal extubation were regarded as not having been extubated smoothly. In addition, patients were observed for respiratory events during the remainder of the emergence period. MACEX values for sevoflurane and isoflurane were 1.07% and 0.83%, respectively. ED95 values of sevoflurane and isoflurane were 2.04% and 1.19%, respectively. In 12 patients in the isoflurane group, extubation was smooth but six patients had coughing episodes during the remainder of the emergence period. In contrast, one of 15 patients in the sevoflurane group in whom tracheal extubation was smooth coughed later (P = 0.035). Airway obstruction was frequent when tracheal extubation was performed at end-tidal concentrations exceeding 1 MACEX for each anaesthetic.      

Concentration of remifentanil needed for tracheal intubation with sevoflurane at 1 MAC in adult patients

BACKGROUND AND OBJECTIVE: Inhalation induction with sevoflurane provides acceptable conditions for tracheal intubation. Opioids significantly decrease the alveolar concentration needed to achieve tracheal intubation. The purpose of this study was to determine the target concentration of remifentanil providing excellent conditions for tracheal intubation with sevoflurane at 1 minimum alveolar concentration without muscle relaxant. METHODS: Twenty-four consecutive patients, aged 18-50 yr, ASA I or II, were studied. Induction of anaesthesia was performed with sevoflurane at age-adjusted minimum alveolar concentration. Remifentanil was simultaneously administered using target-controlled infusion with the Minto model. Target plasma concentration of remifentanil was selected for each patient according to an up-and-down method. RESULTS: The mean target concentration of remifentanil for successful tracheal intubation was 3.3 ng mL(-1) (95% confidence interval: 2.6-3.9 ng mL(-1)). Arterial pressure, heart rate and bispectral index did not increase after tracheal intubation in the group of patients with successful intubation. CONCLUSIONS: Remifentanil at 3.3 ng mL(-1) together with sevoflurane at 1 minimum alveolar concentration provides excellent conditions for tracheal intubation in 50% of patients.     

Pharmacokinetic-based total intravenous anaesthesia using remifentanil and propofol for surgical myocardial revascularization

BACKGROUND AND OBJECTIVE: We investigated the following aspects of pharmacokinetic-guided total intravenous anaesthesia with remifentanil and propofol in patients undergoing surgical myocardial revascularization: anaesthetic efficacy, haemodynamic effects, impact on extubation of the trachea and analgesia after operation. METHODS: Thirty-two patients undergoing on-pump coronary bypass surgery received intravenous anaesthesia with remifentanil and propofol. Both drugs were dosed and titrated based on computer-assisted pharmacokinetic models to maintain constant plasma concentrations. The propofol target plasma concentration was 1.2 microg mL(-1) throughout the procedure. A remifentanil target plasma concentration of 8 ng mL(-1) was achieved over 2 min for induction. After tracheal intubation, the opioid plasma concentration was reduced to 4 ng mL(-1), and then titrated up to 8 ng mL(-1) during surgery. Postoperative analgesia was managed with remifentanil infusion until 4 h after tracheal extubation, and a continuous infusion of tramadol was started 1 h before the remifentanil was stopped. RESULTS: After induction of anaesthesia, heart rate (-20%) and cardiac index (-6%) decreased significantly. No hypotensive episodes (mean arterial pressure < 60 mmHg) occurred. Intraoperative haemodynamics were stable. Three cases of myocardial ischaemia were detected: two by transoesophageal echocardiography and one with ST-segment monitoring. The duration of postoperative mechanical ventilation of the lungs was 95 +/- 13 min and the time to extubation was 150 +/- 18 min. Postoperative analgesia was satisfactory in all patients. CONCLUSIONS: Pharmacokinetic-based total intravenous anaesthesia with remifentanil and propofol provides adequate anaesthesia during coronary surgery with cardiopulmonary bypass and allows safe early extubation after operation.     

Effects of landiolol, a short-acting beta-1 blocker, on hemodynamic variables during emergence from anesthesia and tracheal extubation in elderly patients with and without hypertension

Purpose

Tracheal extubation and emergence procedures induce abrupt changes in hemodynamics and humoral responses. We conducted a prospective randomized study to examine the effects of the short-acting beta-1 blocker, landiolol, on hemodynamics during emergence from anesthesia in elderly patients with and without hypertension.

Methods

Thirty-one hypertensive and 32 normotensive elderly patients were randomly divided into two groups: a control (placebo group) and a landiolol infusion group. Landiolol was dissolved in 20 ml of saline and administered as an infusion at the rate of 0.125 mg·kg^?1·min^?1 for 1 min and then decreased to 0.04 mg·kg^?1·min^?1 until extubation. Control patients received an equal volume of saline. Heart rate and blood pressure were recorded every minute from immediately before the administration of landiolol up to the discontinuation of landiolol, and every 5 min from the discontinuation of landiolol to 30 min after termination of the infusion.

Results

Systolic blood pressure in the control group patients with hypertension increased during anesthesia emergence and tracheal extubation, as did the heart rate. Landiolol infusion in the elderly patients with hypertension partially prevented the increase in systolic blood pressure and completely prevented the increase in heart rate associated with emergence from anesthesia. Landiolol infusion in the elderly patients without hypertension brought about a decrease in heart rate during emergence and tracheal extubation.

Conclusion

This study indicates that the use of a landiolol infusion for preventing hemodynamic instability in elderly patients during the emergence period would be dependent on the presence or absence of hypertension in these patients.     

Effect‐site concentration of remifentanil attenuating surgical stress index responses to intubation of the trachea

Surgical Stress Index has been proposed for assessment of surgical stress and analgesia. It is a numeric index based on the normalised pulse beat interval and photoplethysmographic pulse wave amplitude. We determined the effect‐site concentration of remifentanil for attenuation of Surgical Stress Index responses to intubation of the trachea. Thirty ASA 1–2 patients received either deep or normal anaesthesia and then target‐controlled remifentanil. Burst suppression was maintained in the deep group and state entropy at 40–60 (scale 0–91) in the normal group. Mean (SD) effect‐site concentrations of remifentanil attenuating responses in 50% of patients were 2.13 (0.25) ng.ml^?1 and 3.05 (0.27) ng.ml^?1 in deep and normal groups, respectively (p = 0.034). From probit analysis, EC₅₀ and EC₉₅ of remifentanil (95% CI) were 2.34 (1.97–2.71) ng.ml^?1 and 3.19 (2.69–3.69) ng.ml^?1 in deep group and 3.17 (2.67–3.67) ng.ml^?1 and 3.79 (3.21–4.37) ng.ml^?1 in the normal group, respectively. The values from probit analysis and up‐and‐down method did not differ significantly.     

瑞芬太尼联合丙泊酚全凭静脉麻醉抑制气管拔管期副作用最低有效浓度

目的 探讨瑞芬太尼联合丙泊酚全凭静脉麻醉时,抑制患者气管拔管期循环反应的瑞芬太尼靶控输注(target controlled infusion,TCI)血浆靶浓度的半最大效应浓度(concentration for 50％ of maximal effect,EC50),以指导临床麻醉. 方法 纳入2016年6～8月于我院接受非心脏手术的全身麻醉患者30例,ASA分级Ⅰ、Ⅱ级.所有患者均在BIS监控下行瑞芬太尼联合丙泊酚全凭静脉麻醉诱导,手术结束缝皮时停用丙泊酚,并将瑞芬太尼调整至试验浓度.根据上下序贯法原则设定瑞芬太尼试验浓度,第1例患者瑞芬太尼血浆靶浓度2 μg/L,间隔浓度为0.2 μg/L.记录患者麻醉诱导前(T1),拔管期瑞芬太尼达到试验浓度时(T2),拔管即刻(T3),拔管后1 min(T4)、2 min(T5)、3 min(T6)、4 min(T7)、5 min(T8)时的MAP和HR. 结果 所有手术均在患者接受单次肌松药下成功完成,手术时间均在2h内,术中未见严重应激反应、心动过缓及低血压等不良事件发生,术后未见皮肤瘙痒、疼痛、恶心呕吐等并发症,拔管时6例患者出现呛咳.根据序贯法,瑞芬太尼抑制拔管期循环反应的EC50为1.637 μg/L,其95％CI=1.481～1.769 μg/L. 结论 瑞芬太尼联合丙泊酚全凭静脉麻醉时,抑制50％患者气管拔管期循环反应的瑞芬太尼TCI血浆靶浓度为1.637 μg/L.     

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.     

Optimal target concentration of remifentanil during cataract surgery with monitored anesthesia care

Study objectiveTo determine the effect-site target concentration (C_et) of remifentanil that provides optimal conditions for patients and operators during cataract surgery during monitored anesthesia care using a target controlled infusion (TCI) of propofol and remifentanil.DesignProspective, randomized, double-blinded study.SettingOperating room and postoperative recovery area of a university-affiliated hospital.Patients66 adult, ASA physical status I, II, and III patients undergoing cataract surgeryInterventionsGroup I received C_et of remifentanil 0.5 ng/mL; Group 2 received C_et of remifentanil one ng/mL; and Group 3 received C_et of remifentanil 1.5 ng/mL. After giving TCI propofol (C_et; one μg/mL) - remifentanil, an ophthalmologist administered topical anesthesia.Measurements and main resultsIntraoperative hemodynamics, pain scores, sedation scores, patient satisfaction scores, and operators’ satisfaction scores regarding surgical conditions were recorded. No statistical differences in heart rate or mean blood pressure were detected among the three groups during surgery. Pain scores (Group 1: 31.9 ± 17.9 vs. Group 2: 11.8 ± 7.7 and Group 3: 11.8 ± 7.7; P < 0.05) were higher and patient satisfaction scores (Group 1: 4.7 ± 0.8 vs. Group 2: 5.4 ± 0.4 and Group 3: 5.5 ± 0.4; P < 0.05) were lower in Group 1 than Groups 2 and 3. On the other hand, surgeon satisfaction was lowest in Group 3 (Group 3: 2.9 ± 1.3 vs. Group 1: 4.7 ± 0.4 and Group 2: 4.6 ± 0.7; P < 0.05) due to ocular movement.ConclusionC_et values of remifentanil and propofol of one ng/mL and one μg/mL, respectively, appear to provide optimal conditions for patients and operators during cataract surgery using monitored anesthesia care with TCI.     

雷米芬太尼靶控输注抑制全麻拔管期心血管不良反应的剂量探讨

目的探讨雷米芬太尼靶控输注(TCI)拔管期有效抑制心血管反应的半数有效血浆浓度(EC50)。方法择期全麻下行腹腔镜胆囊切除术(LC)成人患者40例,按照序贯法TCI血浆浓度分别为0.6、0.8、1.0、1.2和1.4 ng/ml的雷米芬太尼,初始靶浓度为1.0 ng/ml,若患者拔管时SBP高于基础值的20%或HR快于100次/分,或拔管时出现呛咳、躁动,则下一例患者采用高一级浓度的雷米芬太尼TCI;反之则采用低一级浓度的雷米芬太尼TCI。计算全麻拔管期有效抑制心血管反应的雷米芬太尼EC50及其95%可信区间(CI)。结果TCI雷米芬太尼抑制心血管反应的EC50为1.03 ng/ml,其95%CI为0.97~1.09 ng/ml。结论LC全麻拔管期有效抑制心血管反应的雷米芬太尼EC50为1.03 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.     

A dose–response study of remifentanil for attenuation of the hypertensive response to laryngoscopy and tracheal intubation in severely preeclamptic women undergoing caesarean delivery under general anaesthesia

BackgroundRemifentanil is known to attenuate the cardiovascular responses to tracheal intubation. We determined effective doses (ED₅₀/ED₉₅) of remifentanil to prevent the pressor response to tracheal intubation in patients with severe preeclampsia.MethodsSeventy-five women with severe preeclampsia were randomly allocated to one of five remifentanil dose groups (0.25, 0.50, 0.75, 1.0, or 1.25 μg/kg) given before induction of anaesthesia using thiopental 5 mg/kg and suxamethonium 1.5 mg/kg. Systolic arterial pressure, heart rate and plasma catecholamine concentrations were measured. Neonatal effects were assessed by Apgar scores and umbilical cord blood gas analysis. A dose was considered effective when systolic arterial pressure did not exceed 160 mmHg for more than 1 min following tracheal intubation.ResultsBaseline systolic blood pressure and heart rate did not differ among the groups. The intubation-induced increases of heart rate and blood pressure were attenuated in a dose-dependent manner by remifentanil. ED₅₀ and ED₉₅ were 0.59 (95% CI 0.47–0.70) μg/kg and 1.34 (1.04–2.19) μg/kg, respectively. Norepinephrine concentrations remained unaltered following intubation but increased significantly at delivery, with no differences between the groups. Apgar scores and umbilical arterial and venous pH and blood gas values were comparable among the groups. Two women each in the 1.0 and 1.25 μg/kg groups received ephedrine for hypotension defined as systolic arterial pressure <90 mmHg.ConclusionsThe ED₉₅ of remifentanil for attenuating the hypertensive response to tracheal intubation during induction of anaesthesia in severely preeclamptic patients undergoing caesarean delivery under general anaesthesia was 1.34 μg/kg.