Tracheal intubation without the use of muscle relaxants: remifentanil or alfentanil in combination with propofol

BACKGROUND: Alfentanil-propofol combination provides adequate conditions for tracheal intubation without neuromuscular blocking drugs in most patients. Providing an option for intense opioid effect without compromising recovery after short operations, remifentanil might offer benefits over alfentanil, especially in ambulatory surgery. In this study intubating conditions after remifentanil-propofol were compared to those after alfentanil-propofol. METHODS: In a randomized, double-blind study 60 healthy patients were assigned to one of three groups (n=20). After intravenous atropine, remifentanil 3 or 4 microg kg(-1) (Rem3 or Rem4) or alfentanil 30 microg kg(-1) (Alf30) was injected over 30 s followed by propofol 2.5 mg kg(-1). Sixty seconds after the administration of propofol, laryngoscopy and intubation were attempted. Intubating conditions were assessed as excellent, good or poor on the basis of ease of ventilation, jaw relaxation, position of the vocal cords, and patient response to intubation and slow inflation of the endotracheal tube cuff. RESULTS: Overall conditions at intubation were significantly (P<0.05) better, and the frequency of excellent conditions was significantly (P<0.05) higher in the Rem4 group compared with the Alf30 group. Intubation was judged to be impossible in 20%, 25% or 5% of the patients in the Alf30, Rem3 or Rem4 groups, respectively. No patient manifested signs of opioid-induced muscular rigidity. In terms of arterial pressures or heart rate, there were no differences between the groups. CONCLUSION: The best method was the combination of remifentanil 4 microg kg(-1) and propofol 2.5 mg kg(-1). This provided satisfactory intubating conditions in 93%, and prevented cardiovascular intubation response.     

Tracheal intubation without the use of muscle relaxants: a technique using propofol and varying doses of alfentanil.

We have noted that tracheal intubation can be accomplished in many patients after induction of anesthesia with propofol and alfentanil without the simultaneous use of muscle relaxants. This study was designed to evaluate airway and intubating conditions after administration of propofol and alfentanil in 75 ASA physical status I or II outpatients with Mallampati class I airways undergoing various surgical procedures. The patients were randomly assigned to one of five groups for induction of anesthesia. All patients received midazolam 1 mg IV before induction of anesthesia. Group I patients (n = 15) received d-tubocurarine 3 mg, thiamylal 4 mg/kg, and succinylcholine 1 mg/kg IV. Groups II-V patients (n = 15 each) received alfentanil 30, 40, 50, or 60 micrograms/kg followed by propofol 2 mg/kg IV. No muscle relaxants were given to patients in groups II-V. Airway management was performed by one of the authors who was blinded as to the dose of alfentanil administered. After loss of consciousness, patients' lungs were ventilated via face mask, and the ease of ventilation was recorded. Jaw mobility was also assessed. Ninety seconds after administration of the propofol or thiamylal, laryngoscopy was performed and exposure of the glottis and position of the vocal cords were noted. Intubation of the trachea was performed and patient response was noted. Heart rate and arterial blood pressure were also recorded before induction of anesthesia, after induction, and then again after intubation of the trachea. The lungs of all patients were easily ventilated via mask, and the jaw was judged to be relaxed in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Dose-response of remifentanil for tracheal intubation in infants

To compare the dose-response of remifentanil for tracheal intubation in infants and children, 32 healthy full-term infants and 32 children were anesthetized with 10 mug/kg glycopyrrolate and 4.0 mg/kg propofol and administered 1 of 4 doses of remifentanil (1.25, 1.50, 1.75, or 2.00 microg/kg) to facilitate tracheal intubation. We determined the effective doses of remifentanil in 50% (ED50) and 98% (ED98) of patients by using logistic regression analysis. We found that logistic regression curves were similar for infants and children (P = 0.38). ED50 and ED98 values for remifentanil were 1.70 +/- 0.1 microg/kg and 2.88 +/- 0.5 microg/kg, respectively. In a second double-blind study, 24 infants were anesthetized with propofol and randomized to receive either 3.0 microg/kg remifentanil or 2.0 mg/kg succinylcholine to facilitate tracheal intubation. The duration of apnea, tracheal intubating conditions and hemodynamic changes were determined. We found that the duration of apnea and intubating conditions after propofol/remifentanil were similar to those after propofol/succinylcholine. Bradycardia, hypotension, and chest wall rigidity did not occur. We conclude that the dose-response of remifentanil for tracheal intubation is similar in infants and children. Propofol/remifentanil provides clinically acceptable intubating conditions, stable hemodynamics, and a duration of apnea comparable to that with propofol/succinylcholine in infants.     

Propofol — not thiopental or etomidate — with remifentanil provides adequate intubating conditions in the absence of neuromuscular blockade

PURPOSE: Administration of remifentanil followed by propofol provides adequate conditions for tracheal intubation without muscle relaxants. Other hypnotic drugs have not been thoroughly investigated in this regard. Intubating conditions with remifentanil followed by propofol, thiopentone or etomidate are compared in this study. METHODS: In a randomized, double-blind study 45 healthy males were assigned to one of three groups (n = 15). After iv atropine, remifentanil 3 microg x kg(-1) were injected over 90 sec followed by propofol 2 mg x kg(-1) (Group I), thiopentone 6 mg x kg(-1) (Group II) or etomidate 0.3 mg x kg(-1) (Group III). Ninety seconds after the administration of the hypnotic agent, laryngoscopy and intubation were attempted. Intubating conditions were assessed as excellent, good or poor on the basis of ease of ventilation, jaw relaxation, position of the vocal cords, and patient response to intubation and slow inflation of the endotracheal tube cuff. RESULTS: One patient in Group I, three patients in Group II and five patients in Group III could not be intubated on the first attempt. Clinically acceptable intubating conditions were observed in 93.3%, 66.7%, 40.0% of patients in Groups I, II and III, respectively. Overall conditions at intubation were significantly (P < 0.05) better, and the frequency of excellent conditions was significantly (P < 0.05) higher in the propofol group compared with the thiopentone and etomidate groups. No patient was treated for hypotension or bradycardia. CONCLUSION: Propofol 2 mg x kg(-1) was superior to thiopentone 6 mg x kg(-1) and etomidate 0.3 mg x kg(-1) for tracheal intubation when combined with remifentanil 3 microg x kg(-1) and no muscle relaxant.     

A combination of alfentanil-lidocaine-propofol provides better intubating conditions than fentanyl-lidocaine-propofol in the absence of muscle relaxants

PURPOSE: To compare the ease of tracheal intubation without the use of muscle relaxants following an alfentanil-lidocaine-propofol sequence vs a fentanyl-lidocaine-propofol sequence. CLINICAL FEATURES: In 80 ASA I and II adult patients undergoing elective laparoscopic surgery, we compared the intubating conditions following alfentanil 20 microg x kg(-1), lidocaine 1.5 mg x kg(-1), propofol 3 mg x kg(-1) (Group I; n = 40) vs fentanyl 2 microg x kg(-1), lidocaine 1.5 mg x kg(-1), propofol 3 mg x kg(-1) (Group II; n = 40). The intubating conditions were scored by jaw relaxation, vocal cord position and response to intubation, as well as by blood pressure and heart rate changes. The intubating conditions were good or excellent in 95% of patients in Group I vs 62.5% of patients in Group II (P < 0.05). Blood pressure decreased from a preinduction value of 86 +/- 13 mmHg to 72 +/- 28 mmHg and 74 +/- 19 mmHg in Group I, and from 85 +/- 12 mmHg to 78 +/- 15 mmHg and 78 +/- 12 mmHg in Group II, one and five minutes following intubation (P < 0.05). This drop in blood pressure was not different between the two groups. CONCLUSION: An alfentanil-lidocaine-propofol sequence offers significantly better intubating conditions than a fentanyl-lidocaine-propofol sequence in healthy adult patients.     

Tracheal intubation without muscle relaxant--a technique using sevoflurane vital capacity induction and alfentanil

This randomized controlled study examined intubating conditions and haemodynamic changes following sevoflurane nitrous oxide induction in four groups: three different doses of alfentanil compared with low-dose alfentanil and suxamethonium. All patients received atropine 0.3 mg i.v. before induction of anaesthesia with vital capacity breaths of sevoflurane 8% (more than 7% in the inspiratory gas) in 60% nitrous oxide and oxygen. Patients were allocated randomly to four groups of intravenous supplements: group SA20, alfentanil 20 microg x kg(-1); group SA25, alfentanil 25 microg x kg(-1); group SA30, alfentanil 30 microg x kg(-1); group SSA, alfentanil 10 microg x kg(-1) and suxamethonium 1 mg x kg(-1). Orotracheal intubation and assessment of intubating conditions was performed by one of the investigators who was blinded to the subject's group. Intubating conditions were satisfactory or excellent in 83%, 80%, 92% and 96% of patients in groups SA20, SA25, SA30 and SSA respectively. These differences were not statistically significant. The increase in heart rate associated with laryngoscopy and tracheal intubation was effectively attenuated in all groups. Mean arterial pressure decreased significantly and similarly after induction in all groups. Two minutes after intubation the mean arterial pressure was increased significantly (P<0.05) compared to the post-induction value in group SSA. The intubating conditions obtained with sevoflurane plus alfentanil 30 microg x kg(-1) were comparable to those provided by the sevoflurane, suxamethonium and alfentanil 10 microg x kg(-1) combination.     

Tracheal intubating conditions after induction with sevoflurane 8% in children. A comparison with two intravenous techniques

We studied tracheal intubating conditions in 120 healthy children, aged 3-12 years, in a blinded, randomised clinical trial. Children were randomly allocated to one of three groups: group PS, propofol 3 mg.kg-1 and succinylcholine 1 mg.kg-1 (n = 40); group PA, propofol 3 mg.kg-1 and alfentanil 10 microg.kg-1 (n = 40); group SF, sevoflurane 8% in 60% nitrous oxide in oxygen for 3 min (n = 40). Tracheal intubating conditions were graded according to ease of laryngoscopy, position of vocal cords, coughing, jaw relaxation and movement of limbs. Overall intubating conditions were acceptable in 39 of 40 children in the propofol/succinylcholine group, 21 of 40 children in the propofol/alfentanil group and 35 of 40 children in the sevoflurane group. Children receiving propofol and succinylcholine or sevoflurane had better intubating conditions overall than those given propofol and alfentanil (p < 0.01). In conclusion, anaesthetic induction and tracheal intubation using sevoflurane 8% for 3 min is a satisfactory alternative to propofol with succinylcholine in children.     

Propofol and remifentanil for intubation without muscle relaxant: the effect of the order of injection

BACKGROUND: Common practice in intubation without muscle relaxant is to inject the opioid drug prior to the hypnotic drug. Because remifentanil reaches adequate cerebral concentration more rapidly than does propofol, we tested the hypothesis that injection of remifentanil after propofol might lead to better intubating conditions. METHODS: Thirty ASA I-II patients scheduled for elective surgery and with no anticipated difficult intubation were enrolled in the study. Five minutes after midazolam 30 microg kg(-1), patients were randomized into two groups: group PR received propofol 2.5 mg kg(-1) followed by remifentanil 1 microg kg(-1), and group RP received remifentanil 1 microg kg(-1) followed by propofol 2.5 mg kg(-1). Intubating conditions were compared using a well-validated score, and continuous arterial pressure was recorded non-invasively. RESULTS: Compared with group RP, intubating conditions were significantly better in group PR. The mean arterial pressure decrease was more pronounced in group RP. CONCLUSIONS: We therefore conclude that in premedicated healthy patients with no anticipated risk of difficult intubation, intubating and haemodynamic conditions are better when remifentanil is injected after propofol.     

Comparison of remifentanil with alfentanil or suxamethonium following propofol anaesthesia for tracheal intubation.

Sixty ASA physical status I and II, premedicated patients were administered propofol 2 mg x kg-1 and remifentanil 2 microg x kg-1 (group R), alfentanil 50 microg x kg-1 (group A) or suxamethonium 1 mg x kg-1 (group S) as a rapid bolus. One minute after study drug administration, tracheal intubation was performed. Intubation conditions were then scored. Excellent or good conditions were observed in only 35% in group R compared with groups S and A (100% and 85%, respectively; p < 0.001). The haemodynamic response to tracheal intubation was blunted in groups R and A compared with group S (p < 0.001). The mean heart rate in groups R and A was significantly lower than group S (p < 0.001). We conclude that remifentanil 2 microg x kg-1 given as a rapid bolus will not produce intubating conditions as good as those obtained with alfentanil 50 microg x kg-1 or suxamethonium 1 mg x kg-1 if administered after propofol 2 mg x kg-1.     

Tracheal intubation without muscle relaxants using propofol and varying doses of fentanyl]

This study was designed to evaluate airway and intubating conditions without muscle relaxants after administration of fentanyl and propofol in 55 patients aged 20-60 years for elective surgery. Patients were randomly assigned to one of four groups to receive fentanyl 0, 2, 3, or 4 micrograms.kg-1, respectively. Three minutes after the administration of fentanyl, propofol (2 mg.kg-1) was given for induction of anesthesia. After the loss of consciousness, laryngoscopy and tracheal intubation, supplemented with topical anesthesia of lidocaine (2 mg.kg-1), were attempted. In control group, without administration of fentanyl, all patients were judged to provide poor intubating conditions. Increasing doses of fentanyl reduced the incidences of movement and persistent coughing on laryngoscopy and intubation in a dose-related manner. However, visualization of the vocal cord was significantly. (P < 0.05) more likely to be impossible in patients in 4 micrograms.kg-1 fentanyl group (40%) compared with patients in 2 micrograms.kg-1 fentanyl group (7%). There were no significant differences among groups receiving fentanyl with respect to vocal cord position. The vocal cords were closed in 26% of patients receiving fentanyl and propofol for intubation. Tracheal intubation without muscle relaxants is not recommended because of the potential unacceptable intubating conditions.     

Propofol is superior to thiopental for intubation without muscle relaxants

PURPOSE: To compare intubating conditions and cardiovascular changes following induction of anesthesia and tracheal intubation in patients receiving either lidocaine-remifentanil-propofol or lidocaine-remifentanil-thiopental prior to induction. METHODS: In a randomized, double-blind study 76 healthy adult patients were assigned to one of two groups: lidocaine 1.5 mg.kg(-1), remifentanil 2 mug.kg(-1) and propofol 2 mg.kg(-1) (Group P) or lidocaine 1.5 mg.kg(-1), remifentanil 2 mug.kg(-1) and thiopental 5 mg.kg(-1) (Group T). Ninety seconds after the administration of the hypnotic agent, laryngoscopy and tracheal intubation were attempted. Intubating conditions were assessed as excellent, good or poor on the basis of ease of ventilation, jaw relaxation, position of the vocal cords, and patient's response to intubation and slow inflation of the tracheal cuff. The mean arterial pressure (MAP) and heart rate (HR) were measured 45 sec after hypnotic agent administration, immediately after tracheal intubation, two and five minutes after intubation. RESULTS: Excellent intubating conditions were obtained in 84% of Group P patients and 50% of Group T patients (P < 0.05). The percentage decrease from baseline MAP was significantly higher in Group P than in Group T postinduction (27.4% +/- 11.6 vs 21.8% +/- 10.0) and immediately postintubation (19.0% +/- 16.7 vs 11.2% +/- 14.9). The percentage change from baseline HR was significantly higher in Group P than in Group T postinduction (13.8% +/- 9.7 vs 0.5% +/- 12.4), immediately postintubation (8.7% +/- 13.7 vs 2.1% +/- 13.1), and two minutes postintubation (7.04% +/- 14.3 vs 3.5% +/- 14.3). CONCLUSION: Lidocaine-remifentanil-propofol is superior to lidocaine-remifentanil-thiopental for tracheal intubation without muscle relaxants. However, it induces more hypotension and bradycardia.     

The effect of topical lignocaine on intubating conditions after propofol-alfentanil induction

Background: Recent studies have found satisfactory conditions for intubation of the trachea without using muscle relaxants using an intravenous technique combining propofol and alfentanil. In this study we evaluate intubating conditions with this method and either lignocaine applied topically in the larynx and trachea or placebo.
Methods: Sixty adult patients of ASA class I were premedicated with diazepam 15–20 mg and randomly allocated to one of two groups. For induction of anaesthesia both groups were given propofol 2.5 mg/kg and alfentanil 30 μg/kg. One group received 4 ml of lignocaine 40 mg/ml (≤3 mg/kg) topically into the larynx and trachea (group L), the other group an equal amount of isotonic saline (group S) in a double-blind design. Intubation conditions were assessed as excellent, good, moderately good, poor or impossible, scored on the basis of jaw relaxation, ease of insertion of the tube and coughing on intubation.
Results: The total score for group L was significantly better than the score for group S ( P <0.0001) with significant differences with respect to ease of intubation and coughing after intubation.
Conclusions: Induction of anaesthesia with propofol 2.5 mg/kg and alfentanil 30 μg/kg combined with 4 ml of lignocaine-spray 40 mg/ml into the larynx and trachea offered consistent and satisfactory intubation conditions. We thus recommend this method for tracheal intubation, where the use of muscle relaxants is not indicated.     

静脉注射利多卡因对七氟醚复合瑞芬太尼无肌松药条件下气管插管效果的影响

目的 探讨静脉注射利多卡因对七氟醚复合瑞芬太尼无肌松药条件下气管插管效果的影响.方法气管插管全麻病人75例,年龄18～64岁,ASA分级Ⅰ或Ⅱ级.采用随机数字表法,将病人随机分为3组(n=25),A组:七氟醚+瑞芬太尼1 μg/kg;B组:七氟醚+瑞芬太尼1 μg/kg+利多卡因1 mg/kg;C组:七氟醚+瑞芬太尼2 μg/kg.吸入8%七氟醚2 min时,A组静脉注射瑞芬太尼1μg/kg,B组静脉注射瑞芬太尼1 μg/kg和利多卡因1 mg/kg,C组静脉注射瑞芬太尼2 μg/kg.瑞芬太尼注射完毕后行气管插管.从置入喉镜、声带位置、声带活动、咳嗽反射和体动反应5个方面评价气管插管条件,分为满意、良好和欠佳3个级别,记录各项满意的发生情况.于麻醉诱导前、气管插管前即刻和气管插管后即刻记录MAP和HR.结果 病人均完成气管插管.与A组相比,B组和C组咳嗽反射的满意率升高,C组气管插管前即刻和气管插管后即刻MAP、HR降低(P＜0.05),B组气管插管前即刻和气管插管后即刻MAP和HR差异无统计学意义(P＞0.05);B组咳嗽反射的满意率较C组升高(P＜0.05).气管插管期间,C组有3例发生低血压,1例心动过缓,A组和B组均未见低血压或心动过缓发生.结论 七氟醚复合瑞芬太尼用于无肌松药条件下气管插管时,静脉注射利多卡因1mg/kg不仅可优化气管插管条件,还可降低瑞芬太尼用量.

Abstract：

Objective To investigate the effect of intravenous lidocaine on the efficacy of sevoflurane combined with remifentanil for tracheal intubation without neuromuscular relaxants. Methods Seventy-five ASA Ⅰor Ⅱ patients, aged 18-64 yr, scheduled for elective surgery, needing tracheal intubation under general anesthesia, were randomly divided into 3 groups ( n = 25 each) : sevoflurane + remifentanil 1 μg/kg group (group A) ;sevoflurane + remifentanil 1 μg/kg + lidocaine 1 mg/kg group (group B); sevoflurane + remifentanil 2 μg/kg group (group C) . Two minutes after inhalation of 8% sevoflurane for anesthesia induction, remifentanil 1 μg/kg, remifentanil 1 μg/kg + lidocaine 1 mg/kg, and remifentanil 2 μg/kg were injected intravenously in groups A, B and C respectively. Tracheal intubation was performed after completion of remifentanil injection. Intubating conditions were assessed based on ease of laryngoscopy, position of vocal cords, activity of vocal cords, degree of coughing and limb movement. MAP and HR were also recorded before induction and immediately before and after intubation. Results Tracheal intubations were successful in all patients. The satisfactory rates of coughing were significantly higher in groups B and C, and MAP and HR were significantly lower immediately before and after intubation in group C than in group A ( P ＜ 0.05) . The satisfactory rate of coughing was significantly higher in group B than in group C ( P ＜ 0.05) . During intubation, 3 cases developed hypotension and 1 case bradycardia in group C. Conclusion When sevoflurane combined with remifentanil is used for tracheal intubation without neuromuscular relaxants, intravenous lidocaine 1 mg/kg can not only improve intubating conditions, but also decrease the consumption of remifentanil.     

Sevoflurane with remifentanil allows rapid tracheal intubation without neuromuscular blocking agents

PURPOSE: After inhalational induction with sevoflurane, we compared the effects of adding remifentanil 1 microg x kg(-1) or remifentanil 2 microg x kg(-1) on conditions for tracheal intubation without neuromuscular blocking agents. METHODS: Before anesthetic induction, all patients were given 0.2 mg of glycopyrrolate iv to counteract the bradycardic effects of remifentanil. Two minutes after inhalational induction with 8% sevoflurane and 50% nitrous oxide, 56 female patients with normal airways scheduled for gynecologic surgery were randomized to receive remifentanil 1 or 2 microg x kg(-1) in a double-blind fashion. One minute later, laryngoscopy was initiated for tracheal intubation. Conditions for tracheal intubation and hemodynamic response to tracheal intubation were assessed. RESULTS: Tracheal intubation was successful in all patients. The incidence of post-intubation coughing was lower in the remifentanil 2 microg x kg(-1) group compared to remifentanil 1 microg x kg(-1) group (11% vs 39%, P <0.02). Optimal intubation conditions were also higher in the remifentanil 2 microg x kg(-1) group at 89% vs 54% (P <0.01). However, the higher dose of remifentanil also resulted in a greater decrease in mean arterial pressure (P <0.05). CONCLUSIONS: The addition of remifentanil after sevoflurane induction allows for rapid tracheal intubation without neuromuscular blocking agents. The higher dose of remifentanil results in improved conditions for tracheal intubation but also caused a greater decrease in mean arterial pressure. Tracheal intubation using sevoflurane and remifentanil may be an alternative to traditional tracheal intubation with neuromuscular blocking agents.     

Remifentanil and propofol without muscle relaxants or with different doses of rocuronium for tracheal intubation in outpatient anaesthesia

BACKGROUND: The use of muscle relaxants in outpatient anaesthesia is controversial; some authors recommend an induction regimen including propofol and opioids without muscle relaxants. This study evaluated the requirements for rocuronium after remifentanil/propofol. METHODS: We examined in four groups of ASA I-II patients (n= 30 for each) the intubating conditions three minutes after induction of anaesthesia with remifentanil 0.5 microg kg(-1) min(-1), propofol 2 mg kg(-1) without muscle relaxants or with different doses of rocuronium (0.6 mg kg(-1), 0.45 mg kg(-1), 0.3 mg kg(-1)) applying the criteria proposed by the Copenhagen Consensus Conference. In the second part of the study the time course of neuromuscular block was determined by electromyography using train-of-four (TOF) stimulation. To this end, another 60 ASA I-II patients were randomly assigned to receive remifentanil 0.5 microg kg(-1) min(-1), propofol 2 mg kg(-1) and either rocuronium 0.6 mg kg(-1), 0.45 mg kg(-1), 0.3 mg kg(-1), or 0.3 mg kg(-1) followed by neostigmine 40 microg kg(-1) and atropine 20 microg kg(-1) at a T1 recovery of 10% (n=15 for each). RESULTS: Intubating conditions were good or excellent in 30 patients after rocuronium 0.6 mg kg(-1) and in 18 patients when rocuronium was omitted (P<0.01). After 0.45 mg kg(-1) and 0.3 mg kg(-1) rocuronium the numbers were 29 and 30 patients, respectively. Reducing rocuronium from 0.6 mg kg(-1) to 0.45 mg kg(-1) or 0.3 mg kg(-1) increased the onset time from 136 (35) s to 199 (34) s and 249 (52) s (mean (SD)), (P<0.01); the clinical duration decreased from 38 (10) min to 24 (8) min and 16 (5) min, respectively (P<0.01); and the duration to a TOF-ratio of 0.8 decreased from 60 (11) min to 45 (9) min and 34 (7) min (P<0.01). After rocuronium 0.3 mg kg(-1) this time interval further decreased to 22 (3) min when neostigmine was given at a T1 of 10% (P<0.01 compared with spontaneous recovery after rocuronium 0.3 mg kg(-1)). CONCLUSION: After remifentanil/propofol intubation conditions were poor in 40% of patients without muscle relaxants; adding reduced doses of rocuronium to this regimen improved the intubation conditions significantly. In addition, reducing the initial dose of rocuronium markedly shortened its time course of action.     

Dosing study of remifentanil and propofol for tracheal intubation without the use of muscle relaxants.

Sixty ASA I and II patients, premedicated with midazolam, were administered propofol 2 mg x kg-1 and remifentanil 3 microg x kg-1 (group R3), remifentanil 4 microg x kg-1 (group R4) and remifentanil 5 microg x kg-1 (group R5). Laryngoscopy and intubation were performed 1 min after the administration of the study drugs and the intubating conditions were assessed. Good to excellent conditions were observed in 12 patients in group R3 compared with 19 patients each in groups R4 and R5 (p = 0.004). Significant reductions in mean arterial pressure (MAP) and heart rate (HR) after administration of the study drug were observed in each group, p < 0.01. There was, however, no difference in mean MAP and HR between the three groups at all time points. We conclude that remifentanil 4-5 microg x kg-1 may reliably provide good to excellent conditions for tracheal intubation when administered after propofol 2 mg x kg-1.     

Small doses of remifentanil and alfetanil in continuous total intravenous anesthesia in major abdominal surgery. A double blind comparison

AIM: The purpose of this study was to test the safety and efficacy of small doses of remifentanil and alfentanil in a continuous total intravenous anesthesia technique for patients undergoing major abdominal surgery. METHODS: Sixty patients were enrolled in the study, and received in a double blind fashion either remifentanil (0.1 microg/kg/min) or alfentanil (alfentanil 0.75 microg/kg/min) in association with propofol (12 mg/kg/h at induction; 6-9 mg/kg/h for maintenance) and cisatracurium. Hemodynamic data, hypnosis monitoring data (Bispectral Index Score), ventilatory parameters and settings, drug utilisation were monitored during stress moments and during all the intraoperative period. Patients were evaluated also in the first 6 postoperative hours. RESULTS: Mean amount of propofol for induction (BIS<60) was lower in the remifentanil group than in the alfentanil group. Significantly fewer patients receiving remifentanil responded to intubation in comparison with patients receiving alfentanil in terms of non invasive blood pressure (>30 mmHg) and heart rate variations. Significantly more patients receiving alfentanil had 1 or more responses to surgery. Incidence of hypotension was significantly higher in patients receiving remifentanil. There were no differences between the 2 groups in the times for spontaneous respiration, adequate respiration, adequate responsivness (OAA/s=5) and discharge from the recovery room. Time to extubation resulted slightly shorter (p<0.05) in patients who received remifentanil. CONCLUSIONS: The use of remifentanil and alfentanil in association with propofol, in a continuous infusion total intravenous anesthesia technique, demonstrated to be safe and reliable strategies.     

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).     

Low doses of rocuronium during remifentanil-propofol-based anesthesia in children: comparison of intubating conditions

BACKGROUND : In this prospective double-blind study, intubation conditions were compared at 90 s following two different low doses of rocuronium during remifentanil and propofol anesthesia in children undergoing ambulatory procedures. METHODS : Forty-four children (ASA I-II, aged 3-12 years) undergoing day case ENT surgery were premedicated with midazolam 0.5 mg x kg(-1). Following atropine 10 microg x kg(-1), remifentanil infusion 0.5 microg x kg(-1) x min(-1) was started. After 60 s, anesthesia was induced with propofol 2.5 mg x kg(-1). Immediately after a bolus dose of propofol, the children received rocuronium doses of 0.15 mg x kg(-1) (group I, n = 22) or 0.3 mg x kg(-1) (group II, n = 22) in a randomized manner, after which an infusion of propofol 6 mg x kg(-1) h(-1) was added to the infusion of remifentanil 0.5 microg x kg(-1) min(-1) for maintenance of anesthesia. Intubating conditions were evaluated 90 s after rocuronium administration applying the Copenhagen Scoring System which included components of laryngoscopy, vocal cord movement and reaction to intubation. Hemodynamic values were recorded at predetermined time intervals. RESULTS : Excellent, good and poor intubation conditions were 18.2, 40.9 and 40.9% in group I and 40.9, 54.5 and 4.5% in group II. Clinically acceptable intubating conditions (excellent and good) were significantly higher in group II (95.5%) than in group I (59.1%) (P = 0.004). Mean values of heart rate and blood pressure did not differ significantly between groups. No children required any intervention for hemodynamic instability and/or muscle rigidity. CONCLUSIONS : The results suggest that 0.3 mg x kg(-1) of rocuronium may be a better low dose than 0.15 mg x kg(-1) of rocuronium for clinically acceptable intubating conditions in pediatric ambulatory surgery during remifentanil-propofol-based anesthesia at the doses used in the study.