Assessment of intubating conditions in children after induction with propofol and varying doses of alfentanil

We have assessed tracheal intubating conditions in 60 ASA Ior II children, aged 3–12 yr, after induction of anaesthesiawith alfentanil 5, 10 or 15 µg kg^–1 followed byan induction dose of propofol. Neuro-muscular blocking agentswere not given. Three aspects of intubating conditions wereassessed on a four-point scale: ease of laryngoscopy, vocalcord position and degree of coughing on insertion of the trachealtube. The number of patients in whom each component of the assessmentwas satisfactory increased significantly as the dose of alfentanilincreased (ease of laryngoscopy P=0.003; vocal cord positionP=0.0004; degree of coughing P=0.018). Intubation was successfulin 70%, 95% and 95% of patients after alfentanil 5, 10 or 15µg kg^–1 respectively, and conditions were consideredto be excellent in 20%, 70% and 80% of patients, respectively.Side effects included pain on injection of propofol (27%), excitatorymovements (5%) and bradycardia (1.7%).     

Comparison of intubating conditions after induction with propofol and remifentanil or sufentanil

Die Anaesthesiologie - The aim of this study was to compare tracheal intubation conditions after induction of anesthesia with a bolus of propofol-sufentanil or propofol-remifentanil and a rapid...     

瑞芬太尼复合异丙酚麻醉诱导对气管插管条件及血流动力学的影响

目的对比不使用肌松剂的情况下,瑞芬太尼或芬太尼复合异丙酚麻醉诱导后对气管插管条件及血流动力学的影响。方法60名病人分为2组,诱导后2rain行气管插管术。分别记录诱导前、诱导后lmin及插管后2min的平均动脉压（MAP）和心率（Ha）。插管条件由操作者给予评分。结果两组插管成功率均为100％。瑞芬太尼组插管条件满意率80％,芬太尼73％。两组诱导后MAP和HR值较基础值均下降（P〈0．05）。插管后两组间的MAP值差异有统计学意义（P（0．05）。结论瑞芬太尼复合异丙酚麻醉诱导取得了同芬太尼复合异丙酚麻醉诱导一样良好的插管条件,在抑制插管引起的心血管反应方面瑞芬太尼组优于芬太尼组。     

Assessment of tracheal intubation in children after induction with propofol and different doses of remifentanil

Tracheal intubating conditions were assessed in 112 children after induction of anaesthesia with propofol and remifentanil 1.0, 2.0 or 3.0 micro g.kg-1. Subjects in a control group were given propofol and mivacurium 0.2 mg.kg-1. Haemodynamic and respiratory parameters were recorded. Plasma catecholamine levels were measured in a subgroup of 40 children. Intubating conditions were acceptable in 14/28 (50%), 18/26 (69%) and 22/27 (82%) in those subjects given remifentanil 1.0, 2.0 or 3.0 micro g.kg-1, respectively, and in 27/28 (96%) of the control group. Intubating conditions in subjects given remifentanil 3.0 micro g.kg-1 were better than in those given remifentanil 1.0 micro g.kg-1 (p < 0.05). There were no significant differences in intubating conditions between those given remifentanil 3.0 micro g.kg-1 and the control group. Systolic blood pressure and heart rate increased in response to tracheal intubation in subjects given remifentanil 1.0 micro g.kg-1 and in the control group (p < 0.05). Time to resumption of spontaneous respiration was prolonged in subjects given remifentanil 3.0 micro g.kg-1 (p < 0.001). In conclusion, remifentanil 2 micro g.kg-1 provides acceptable intubating conditions and haemodynamic stability without prolonging the return of spontaneous respiration.     

A comparison of intubating conditions in children following induction of anaesthesia with propofol and suxamethonium or propofol and remifentanil

Sixty ASA 1 and 2 children aged between 2 and 16 years who required tracheal intubation as part of anaesthesia for elective surgery were studied. We evaluated intubating conditions, haemodynamic responses and duration of apnoea following propofol 4 mg.kg-1 combined with either remifentanil 1.25 microg.kg-1 (group R), or suxamethonium 1 mg.kg-1 (group S). Tracheal intubation was graded as excellent, good or poor according to ease of laryngoscopy, vocal cord position, coughing, and jaw relaxation and limb movement. Thirty of group S and 28 of group R children were successfully intubated on the first attempt. Overall, intubation conditions were excellent or good in 26/30 (87%) patients in group S and 20/30 (67%) in group R (p<0.05). Mean apnoea time was 190 s in group S, and 362 s in group R (p<0.001). Heart rate increased in response to suxamethonium (p<0.01) and both systolic and diastolic blood pressure decreased in the remifentanil group (p<0.01).     

Assessment of tracheal intubating conditions in children using remifentanil and propofol without muscle relaxant

BACKGROUND: Tracheal intubation in children can be achieved by deep inhalational anaesthesia or an intravenous anaesthetic and a muscle relaxant, suxamethonium being widely used despite several side-effects. Studies have shown that oral intubation can be facilitated safely and effectively in children after induction of anaesthesia with propofol and alfentanil without a muscle relaxant. Remifentanil is a new, ultra-short acting, selective mu-receptor agonist that is 20-30 times more potent than alfentanil. This clinical study was designed to assess whether combination of propofol and remifentanil could be used without a muscle relaxant to facilitate tracheal intubation in children. METHODS: Forty children (5-10 years) admitted for adenotonsillectomy were randomly allocated to one of two groups to receive remifentanil 2 microg.kg(-1) (Gp I) or remifentanil 3 microg.kg(-1) (Gp II) before the induction of anaesthesia with i.v. propofol 3 mg.kg(-1). No neuromuscular blocking agent was administered. Intubating conditions were assessed using a four-point scoring system based on ease of laryngoscopy, jaw relaxation, position of vocal cords, degree of coughing and limb movement. Mean arterial pressure (MAP) and heart rate (HR) measured noninvasively before induction of anaesthesia to 5 min after intubation (seven time points). RESULTS: Tracheal intubation was successful in all patients without requiring neuromuscular blocking agent. Intubating conditions were clinically acceptable in 10 of 20 patients (50%) in Gp I compared with 18 of 20 patients (90%) in Gp II (P < 0.05). MAP and HR decreased in both groups after induction of anaesthesia (P < 0.01). Both HR and MAP were significantly lower in Gp II compared with Gp I after tracheal intubation (P < 0.01). No patient in the present study developed bradycardia or hypotension. CONCLUSIONS: We conclude that remifentanil (3 microg.kg(-1)), administered before propofol (3 mg.kg(-1)) provides acceptable tracheal intubating conditions in children, and completely inhibited the increase in HR and MAP associated with intubation.     

Tracheal intubating conditions using propofol and remifentanil target-controlled infusions

Using target-controlled infusions (TCI) we aimed to determine the most appropriate dose of remifentanil required for intubation, using a steady effect-site concentration of propofol and without the use of neuromuscular blocking drugs. Sixty ASA III patients presenting for elective surgery were randomly allocated to one of three groups. Anaesthesia was induced in all patients using a target-controlled infusion of propofol 6.5 microg x ml(-1). This was reduced to 3 microg x ml(-1) after 1 min. Each group received a different TCI of remifentanil, 19, 15 or 11 ng x ml(-1), which was reduced to 10, 8 or 6 ng x ml(-1), respectively, after 1 min. Laryngoscopy and intubation were attempted at 4 min. Laryngoscopy and ease of intubation were assessed using a standard scoring system. Intubation was considered satisfactory in 75% of patients in groups 1 and 2 and 35% of patients in group 3. Intubation was successful in 20/20, 19/20 and 15/20 patients in groups 1, 2 and 3, respectively. Pulse oximetry, heart rate and noninvasive arterial pressure were measured pre-induction, and at intervals until after laryngoscopy and intubation. Mean arterial pressure (MAP) and heart rate decreased following induction of anaesthesia in all groups, which was statistically significant. Following laryngoscopy, MAP and heart rate increased, but were significantly less than the corresponding baseline values.     

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.     

Muscle relaxation and increasing doses of propofol improve intubating conditions

PURPOSE: Muscle relaxants and anesthetics are usually associated during intubation. However, their relative role to facilitate the process is not clearly defined. This study was designed to determine, during intubation: i). the relative role of anesthetics and atracurium-induced neuromuscular block and; ii). the effect of different doses of propofol in the presence of complete muscle block. METHODS: Patients were randomized to four groups and received fentanyl and a standardized anesthetic procedure. Patients from groups high (H; n = 45), medium (M; n = 48) and low (L; n = 47) received 2.5 mg x kg(-1), 2.0 mg x kg(-1), and 1.5 mg x kg(-1) of propofol respectively. Atracurium (0.5 mg x kg(-1)) was then injected and tracheal intubation performed once complete block was achieved at the orbicularis oculi. Patients from group without atracurium (WA; n = 20) received propofol as in group H. Intubation was performed at the expected onset time of action of atracurium. RESULTS: Using the same dose of propofol, the incidence of good or excellent intubating conditions was 35% without atracurium and 95% with atracurium (P < 0.0001). In patients receiving atracurium, clinically acceptable intubating conditions were more frequently achieved in groups receiving the highest propofol doses (group H or M vs group L; P < 0.03). CONCLUSION: Our study confirms the interaction between anesthesia and muscle relaxation to produce adequate intubating conditions. In the conditions described, intubating conditions were more dependent on atracurium-induced neuromuscular blockade than on anesthetics, but both atracurium and propofol improved intubating conditions.     

不同剂量瑞芬太尼复合异丙酚的气管插管条件及血流动力学的变化

喉镜置入和气管插管常可引起心动过速、高血压、心律失常、血浆儿茶酚胺浓度升高及敏感患者的心肌缺血、动脉瘤破裂等，可能导致对机体的损伤。采用静脉注射阿片类药物可以抑制机体的应激反应。异丙酚是一种起效快的新型麻醉药，广泛应用于麻醉诱导和麻醉维持。瑞芬太尼具有理想的阿片类受体激动剂特性和独特的药理学特点，现已广泛应用于临床麻醉诱导和维持。异丙酚复合瑞芬太尼用于麻醉诱导，既能使麻醉达到一定深度，又能减轻气管插管的心血管反应。本研究以血压、心率及患者的反应作为观察指标，旨在观察不同剂量瑞芬太尼复合异丙酚麻醉诱导后气管插管条件及血流动力学的变化，为临床合理应用瑞芬太尼提供参考。     

Comparison of intubating conditions following propofol and succinylcholine with propofol and remifentanil 2 micrograms kg-1 or 4 micrograms kg-1

We evaluated the intubating conditions, haemodynamic responsesand duration of apnoea in 60 healthy adult patients after propofol2 mg kg^–1 combined with either a bolus of remifentanil2 µg kg^–1 or 4 µg kg^–1,or succinylcholine 1 mg kg^–1. Patients intubatedfollowing remifentanil showed dose-dependent intubating conditions,similar at 4 µg kg^–1 to the conditionsproduced with succinylcholine. Post-induction mean arterialpressure decreased from baseline values by 21% (P<0.0001),28% (P<0.0001) and 8% (P>0.05) in the remifentanil 2 µg kg^–1,remifentanil 4 µg kg^–1 and succinylcholine1 mg kg^–1 groups, respectively. The mean (SD)duration of apnoea following induction was 9.3 (2.6) minand 12.8 (2.9) min in the remifentanil 2 µg kg^–1and 4 µg kg^–1 groups, and 6.0 (0.9) minin the succinylcholine group (P<0.001 between groups). Br J Anaesth 2000; 85: 623--5     

Influence of induction technique on intubating conditions after rocuronium in adults: comparison with rapid-sequence induction using thiopentone and suxamethonium

We have assessed the effect of anaesthetic technique on intubating conditions after rocuronium 0.6 mg kg-1 in four groups (n = 25 each) of unpremedicated patients in whom anaesthesia was induced with either thiopentone 5 mg kg-1 or propofol 2.5 mg kg-1 alone, or supplemented with alfentanil 20 micrograms kg-1. Fifty control patients were anaesthetized with thiopentone followed by suxamethonium. Laryngoscopy was commenced at 45 s. Overall intubating conditions after rocuronium were similar to those after suxamethonium (good and excellent > or = 96%) only when alfentanil was part of the induction regimen. However, intubation time was similar in all five groups and averaged 55 (SD 3.2) s, and the tube could be passed through open vocal cords within 70 s. After rocuronium the response of the diaphragm to intubation was more pronounced in the two groups of patients not receiving alfentanil (P < 0.0001) and in patients anaesthetized using propofol with alfentanil (P < 0.01) than in the control group. Opioids (in doses equivalent to alfentanil 20 micrograms kg-1) constitute an integral part of an induction regimen containing rocuronium 0.6 mg kg-1, regardless of whether or not thiopentone or propofol is used, in order to achieve overall intubating conditions similar to those after suxamethonium.      

Evaluation of intubating conditions with rocuronium and either propofol or etomidate for rapid sequence induction

We have assessed the effect of two induction agents on tracheal intubating conditions after rocuronium 0.6 mgkg⁻¹ in unpremedicated patients undergoing simulated rapid sequence induction. Following pre-oxygenation, anaesthesia was induced with propofol up to 2.5 mgkg⁻¹ ( n  = 35) or etomidate 0.3 mgkg⁻¹ ( n  = 36), and further increments as required. After loss of verbal contact, cricoid pressure was applied and rocuronium was injected. Laryngoscopy was performed at 45 s and intubation attempted at 60 s after rocuronium had been given. Ninety-four per cent of patients in the propofol group had clinically acceptable (good or excellent) intubating conditions compared to only 75% in the etomidate group (p = 0.025). Owing to coughing, one patient in the etomidate group could not be intubated on the first attempt. A greater pressor response also followed intubation after induction with etomidate. We conclude that etomidate and rocuronium alone cannot be recommended for intubation at 60 s under rapid sequence induction conditions.     

Optimal remifentanil dosage for providing excellent intubating conditions when co-administered with a single standard dose of propofol

This dose–response study aimed to determine the dose of remifentanil combined with propofol 2.5 mg.kg⁻¹ which provided excellent intubation conditions in 95% of patients. Ninety premedicated female ASA 1 and 2 patients were randomly allocated to five remifentanil dose groups (1, 2, 3, 4 or 5 μg.kg⁻¹). Induction of anaesthesia was performed with a blinded dose of remifentanil infused over 60 s simultaneously co-administered with propofol 2.5 mg.kg⁻¹ infused over 45 s. Tracheal intubation was attempted 150 s after the beginning of induction. Intubating conditions were assessed with the Copenhagen score. A probit analysis was performed to calculate the intubating efficient doses (IED) of remifentanil in 95% of patients (IED₉₅). Our data revealed that the IED₉₅ of remifentanil was 4.0 (95% CI: 3.4–5.6) μg.kg⁻¹, which was associated with a maximum decrease in heart rate and mean arterial pressure of < 30%, a finding which also applied to the other groups.     

Duration of apnoea with two different intubating doses of remifentanil.

We have studied the apnoea time after induction with two successful drug intubating regimes, both containing remifentanil. Group 1 (n = 20); propofol 2 mg kg-1 and remifentanil 2 micrograms kg-1 and group 2 (n = 20); propofol 2 mg kg-1, remifentanil 1 microgram kg-1 and lignocaine 1 mg kg-1. Intubation was possible in all 40 patients, and regarded as acceptable in 90% and 85% of patients, respectively. The median time to the return of spontaneous respiration was 487 s in group 1 and 270 s in group 2 (P < 0.05). Median end-tidal CO2 concentration at the time of the first spontaneous respiration was 7.37 kPa in group 1 and 6.3 kPa in group 2 (P < 0.05). Both groups had a decrease in heart rate after induction, but this failed to reach either clinical or statistical significance, and no patient required atropine. Similarly, there was a decrease in arterial pressure after induction in both groups (P < 0.05), but this was not deemed to be clinically significant. Only two patients in each group required ephedrine 6 mg before arterial pressure was restored to within 25% of the base-line. Intubating conditions were similar in both groups, but group 2 provided a significantly shorter apnoea time.     

无肌松药条件下丙泊酚联合不同剂量雷米芬太尼用于小儿气管插管

目的观察无肌松药条件下丙泊酚联合不同剂量雷米芬太尼静脉诱导用于患儿气管插管的临床效果。方法 90例4～10岁 ASA Ⅰ级行择期整形外科手术的患儿随机均分为三组。三组在60 s 内静脉分别注射雷米芬太尼1 μg/kg(Ⅰ组)、2μg/kg(Ⅱ组)和3 μg/kg(Ⅲ组),丙泊酚4 mg/kg 在20 s 内静脉注射,40 s 后实施气管插管。根据下颌松弛度、声带位置、置入喉镜难易度、咳嗽程度和体动程度将插管条件分为满意、一般和差。结果三组均能完成气管插管。Ⅰ组、Ⅱ组和Ⅲ组插管条件满意率分别为46.7%、86.7%和90.0%。与Ⅰ组相比,Ⅱ、Ⅲ组插管满意率明显增高(P<0.05),插管时间明显缩短(P<0.01),Ⅲ组 HR 明显减慢(P<0.05)。结论在无肌松药条件下,丙泊酚4 mg/kg 联合雷米芬太尼2或3μg/kg 均可为小儿气管插管提供较好的插管条件。     

Tracheal intubation after induction of anesthesia in children with propofol — remifentanil or propofol-rocuronium

PURPOSE: To compare the intubating conditions after remifentanil-propofol with those after propofol-rocuronium combination with the aim of determining the optimal dose of remifentanil. METHODS: In a randomized, double-blind study 80 healthy children aged three to nine years were assigned to one of four groups (n=20): 2 or 4 microgxkg(-1) remifentanil (Re2 or Re4); 2 microgxkg(-1) remifentanil and 0.2 mgxkg(-1) rocuronium (Re2-Ro0.2); 0.4 mgxkg(-1) rocuronium (Ro0.4). After atropine, remifentanil was injected over 30 sec followed by 3.5 mgxkg(-1) propofol and rocuronium. After 60 sec, laryngoscopy and intubation were attempted. Intubating conditions were assessed as excellent, good or poor based on ease of ventilation, jaw relaxation, position of the vocal cords, and coughing to intubation. RESULTS: In all children intubation was successful. Overall intubating conditions were better (P < 0.01), and the frequency of excellent conditions, 85%, was higher (P < 0.01) in the Re4 group than in the Ro0.4 group. No child manifested signs of muscular rigidity. In the remifentanil groups, arterial pressure decreased 11-13% and heart rate 6-9% after anesthetic induction, and remained at that level throughout the study. CONCLUSION: The best intubating conditions were produced by the combination of 4 microgxkg(-1) remifentanil and 3.5 mgxkg(-1) propofol. It provided excellent or good intubating conditions in all children without causing undue cardiovascular depression.     

Reduction of pain during induction with target-controlled propofol and remifentanil

BACKGROUND: Pain on injection of propofol is unpleasant. We hypothesized that propofol infusion pain might be prevented by infusing remifentanil before starting the propofol infusion in a clinical setting where target-controlled infusions (TCI) of both drugs were used. A prospective, randomized, double-blind, placebo-controlled trial was performed to determine the effect-site concentration (Ce) of remifentanil to prevent the pain without producing complications. METHODS: A total of 128 patients undergoing general surgery were randomly allocated to receive normal saline (control) or remifentanil to a target Ce of 2 ng ml(-1) (R2), 4 ng ml(-1) (R4), or 6 ng ml(-1) (R6) administered via TCI. After the target Ce was achieved, the infusion of propofol was started. Remifentanil-related complications were assessed during the remifentanil infusion, and pain caused by propofol was evaluated using a four-point scale during the propofol infusion. RESULTS: The incidence of pain was significantly lower in Groups R4 and R6 than in the control and R2 groups (12/32 and 6/31 vs 26/31 and 25/32, respectively, P<0.001). Pain was less severe in Groups R4 and R6 than in the control and R2 groups (P<0.001). However, both incidence and severity of pain were not different between Groups R4 and R6. No significant complications were observed during the study. CONCLUSIONS: During induction of anaesthesia with TCI of propofol and remifentanil, a significant reduction in propofol infusion pain was achieved without significant complications by prior administration of remifentanil at a target Ce of 4 ng ml(-1).