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

Abstract

SummaryThis 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 lg.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 (IED 95 ). Our data revealed that the IED 95 of remifentanil was 4.0 (95% CI: 3.4-5.6) lg.kg, 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. Excellent intubating conditions are important to minimise the occurrence of damage to the airway, the fourth highest cause of claims related to injuries associated with general anaesthesia [1,2]. The use of neuromuscular blocking drugs at induction of anaesthesia provides significantly better intubating conditions and less vocal cord sequelae than relaxant-free anaesthesia, and has therefore been advocated prior to tracheal intubation for elective surgery [2,3].However, patient factors may contraindicate the use of neuromuscular blocking drugs, and administration of these drugs is associated with several complications, including anaphylactic reactions, residual curarisation, and awareness during general anaesthesia [4][5][6].Significant improvements in the quality of tracheal intubation without paralysis were reported when remifentanil was co-administered with propofol 2 or 2.5 mg.kg )1 [7][8][9][10][11][12][13]. However, the optimal dose of remifentanil required for providing excellent intubating conditions when co-administered with propofol remains unknown since published results are inconsistent [7][8][9][10][11][12][13][14]. This may be related to different protocols with respect to the timing and the speed of infusion of remifentanil and propofol, and the timing and assessment of tracheal intubation.Using an optimised sequence of induction of anaesthesia and a standardised scale for the assessment of the quality of tracheal intubation we therefore conducted a dose-response study to determine the intubating efficient dosage (IED) of remifentanil co-administered with propofol 2.5 mg.kg )1 which would provide excellent intubating conditions in 95% (IED 95 ) of patients undergoing elective surgery. Methods PatientsAfter approval of the study by our institution's Ethics Committee and obtaining patients' written consent, female patients scheduled for elective gynaecological surgery requiring tracheal intubation were enrolled. Inclusion criteria were: ASA 1 and 2 physical status, age from 18 to 65 years and body mass index from 20 to 24 kg.m )2 . Patients ...

The effect of propofol/remifentanil rapid-induction technique without muscle relaxants on intraocular pressure

“…Higher doses of remifentanil (three to 5 μg/kg) provide good intubating conditions when used as a substitute for muscle relaxant [3][4][5][6], but no studies to date have examined its effect on IOP. Increases in IOP are mainly caused by increases in episcleral venous pressure (that is determined by central venous pressure), and blood volume of the eye (that is influenced by cerebral blood flow and volume), or agents that might increase extraocular muscle tone [7].…”

“…Rapid-sequence induction of anesthesia using propofol/remifentanil three to 5 μg/kg, without muscle relaxants, also controls the hemodynamic response to laryngoscopy and intubation while providing excellent intubating conditions [3][4][5][6]. However, no study to date has examined the effects of this muscle relaxant-free technique on IOP, which is important when succinylcholine is contraindicated.…”

Dose optimale de rémifentanil pour l’insertion d’un masque laryngé lors de la co-administration d’une dose standard unique de propofol

“…9 As expected, we observed a decrease in the ED 95 of remifentanil for providing excellent LMA insertion conditions compared with the IED 95 of remifentanil 4 lgÁkg -1 . 13 This decrease was due to use of a carefully standardized anesthetic induction sequence and consideration of the unique pharmacokinetic and pharmacodynamic attributes of propofol and remifentanil such that LMA insertion occurred at the time when effect-site concentration peaked for both agents. 17,18 In fact, insertion of the LMA constitutes a less noxious stimulus compared with laryngoscopy.…”

“…The range of doses of remifentanil for the insertion of the LMA was selected based on the following assumptions: the required dose of remifentanil would be less than twice the dose required to moderate hemodynamic responses to tracheal intubation and more than one-fourth of a 4 lgÁkg -1 dose determined from a recent study in a similar population, 13 and as was previously reported when using alfentanil in combination with propofol. 5 The randomization list was generated by a physician who was not involved in the enrollment of patients into the study.…”

Çocuklarda kas gevşeticisiz trakeal entübasyon

“…Kas gevşeticisiz trakeal entübasyon için remifentanil ve propofol öncelikli olarak kullanılmaktadır (6). Alternatif opioid ajanlar alfentanil, fentanil ve sulfentanil, hipnotik ajanlarsa etomidat, tiopental ve sevofuran olarak sıralanmaktadır (7,8).…”