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

Remifentanil for tracheal intubation without neuromuscular blocking drugs in adult patients: a systematic review and meta-analysis

There is increasing interest in the use of short-acting opioids such as remifentanil to facilitate tracheal intubation. The aim of this systematic review was to determine the efficacy and safety of remifentanil for tracheal intubation compared with neuromuscular blocking drugs in adult patients. We conducted a systematic search for randomised controlled trials evaluating remifentanil for tracheal intubation. Primary outcomes included tracheal intubation conditions and adverse events. Twenty-one studies evaluating 1945 participants were included in the analysis. Use of remifentanil (1.5-4.0 μg.kg-1) showed no evidence of a difference in tracheal intubation success rate compared with neuromuscular blocking drugs (risk ratio (95%CI) 0.97 (0.94-1.01); six studies; 1232 participants; I2 28%; p = 0.16; moderate-certainty evidence). Compared with neuromuscular blocking drugs, the use of remifentanil (2.0-4.0 μg.kg-1) makes little to no difference in terms of producing excellent tracheal intubation conditions (risk ratio (95%CI) 1.16 (0.72-1.87); two studies; 121 participants; I2 31%, p = 0.54; moderate-certainty of evidence). There was no evidence of an effect between remifentanil (2.0-4.0 μg.kg-1) and neuromuscular blocking drugs for bradycardia (risk ratio (95%CI) 0.44 (0.01-13.90); two studies; 997 participants; I2 81%; p = 0.64) and hypotension (risk ratio (95%CI) 1.05 (0.44-2.49); three studies; 1071 participants; I2 92%; p = 0.92). However, the evidence for these two outcomes was judged to be of very low-certainty. We conclude that remifentanil may be used as an alternative drug for tracheal intubation in cases where neuromuscular blocking drugs are best avoided, but more studies are required to evaluate the haemodynamic adverse events of remifentanil at different doses.

Relationship between ANI and qNOX and between MAC and qCON during outpatient laparoscopic cholecystectomy using remifentanil and desflurane without muscle relaxants: a prospective observational preliminary study

This study was designed to investigate qCON and qNOX variations during outpatient laparoscopic cholecystectomy using remifentanil and desflurane without muscle relaxants and compare these indices with ANI and MAC. Adult patients undergoing outpatient laparoscopic cholecystectomy were included in this prospective observational study. Maintenance of anesthesia was performed using remifentanil targeted to ANI 50-80 and desflurane targeted to MAC 0.8-1.2 without muscle relaxants. The ANI, qCON and qNOX and desflurane MAC values were collected at different time-points and analyzed using repeated measures ANOVA. The relationship between ANI and qNOX and between qCON and MAC were analyzed by linear regression. The ANI was comprised between 50 and 80 during maintenance of anesthesia. Higher values of qNOX and qCON were observed at induction and extubation than during all other time-points where they were comprised between 40 and 60. A poor but significant negative linear relationship (r² = 0.07, p < 0.001) was observed between ANI and qNOX. There also was a negative linear relationship between qCON and MAC (r² = 0.48, p < 0.001) and between qNOX and remifentanil infusion rate (r² = 0.13, p < 0.001). The linear mixed-effect regression correlation (r²) was 0.65 for ANI-qNOX and 0.96 for qCON-MAC. The qCON and qNOX monitoring seems informative during general anesthesia using desflurane and remifentanil without muscle relaxants in patients undergoing ambulatory laparoscopic cholecystectomy. While qCON correlated with MAC, the correlation of overall qCON and ANI was poor but significant. Additionally, the qNOX weakly correlated with the remifentanil infusion rate. This observational study suggests that the proposed ranges of 40-60 for both indexes may correspond to adequate levels of hypnosis and analgesia during general anesthesia, although this should be confirmed by further research.

A blinded randomized study comparing intubating conditions after either rocuronium 0.6 mg·kg-1 or remifentanil 2 µg·kg-1 in elderly patients

BACKGROUND

To facilitate tracheal intubation, either a neuromuscular blocking agent or a bolus dose of remifentanil can be administered. We hypothesized that rocuronium 0.6 mg·kg^-1 provided a larger proportion of excellent intubating conditions compared to remifentanil 2 µg·kg^-1 in patients above 80 years.

METHODS

A total of 78 patients were randomized to either rocuronium 0.6 mg·kg^-1 or remifentanil 2 µg·kg^-1 . General anaesthesia was initiated with fentanyl and propofol. Two minutes after the administration of either rocuronium or remifentanil, tracheal intubating conditions were evaluated using the Fuchs-Buder scale by a blinded investigator, and our primary outcome was the proportion of patients presenting intubating conditions deemed as excellent. Further outcomes included the Intubating Difficulty Scale (IDS), hoarseness or sore throat 24 h postoperatively, and intervention against hypotension.

RESULTS

No difference in the occurrence of excellent intubating conditions was found comparing the rocuronium group with the remifentanil group; 10 (28%) versus 15 (39%) (p = .29), respectively, relative risk = 0.72. Interventions against hypotension were used in 24 (67%) versus 28 (74%) (p = .51), respectively. Hoarseness and sore throat 24 h postoperatively were found in 37% versus 35% p = .86, and 14% versus 5% p = .20, respectively. The IDS score was 2 versus 2 p = .48.

CONCLUSION

No difference in intubating conditions was found 2 min after the administration of either rocuronium 0.6 mg·kg^-1 or remifentanil 2 µg·kg^-1 in patients aged above 80 years. Intubation conditions were less than optimal in a large proportion of this patient population.

CLINICAL TRIALS REGISTRATION

NCT04287426.

Perioperative Opioid Administration

Opioids form an important component of general anesthesia and perioperative analgesia. Discharge opioid prescriptions are identified as a contributor for persistent opioid use and diversion. In parallel, there is increased enthusiasm to advocate opioid-free strategies, which include a combination of known analgesics and adjuvants, many of which are in the form of continuous infusions. This article critically reviews perioperative opioid use, especially in view of opioid-sparing versus opioid-free strategies. The data indicate that opioid-free strategies, however noble in their cause, do not fully acknowledge the limitations and gaps within the existing evidence and clinical practice considerations. Moreover, they do not allow analgesic titration based on patient needs; are unclear about optimal components and their role in different surgical settings and perioperative phases; and do not serve to decrease the risk of persistent opioid use, thereby distracting us from optimizing pain and minimizing realistic long-term harms.

Assessment of remifentanil for rapid sequence induction and intubation in patients at risk of pulmonary aspiration of gastric contents compared to rapid-onset paralytic agents: study protocol for a non-inferiority simple blind randomized controlled trial (the REMICRUSH study)

Background

Rapid-onset paralytic agents are recommended to achieve muscle relaxation and facilitate tracheal intubation during rapid sequence induction in patients at risk of pulmonary aspiration of gastric contents. However, opioids are frequently used in this setting. The study’s objective is to demonstrate the non-inferiority of remifentanil compared to rapid-onset paralytic agents, in association with an hypnotic drug, for tracheal intubation in patients undergoing  procedure under general anesthesia and at risk of pulmonary aspiration of gastric contents.

Methods

The REMICRUSH (Remifentanil for Rapid Sequence Induction of Anaesthesia) study is a multicenter, single-blinded, non-inferiority randomized controlled trial comparing remifentanil (3 to 4 μg/kg) with rapid-onset paralytic agents (succinylcholine or rocuronium 1 mg/kg) for rapid sequence induction in 1150 adult surgical patients requiring tracheal intubation during general anesthesia. Enrolment started in October 2019 in 15 French anesthesia units. The expected date of the final follow-up is October 2021. The primary outcome is the proportion of successful tracheal intubation without major complications. A non-inferiority margin of 7% was chosen. Analyses of the intent-to-treat and per-protocol populations are planned.

Discussion

The REMICRUSH trial protocol has been approved by the ethics committee of The Comité de Protection des Personnes Sud-Ouest et Outre-Mer II and will be carried out according to the principles of the Declaration of Helsinki and the Good Clinical Practice guidelines. The results of this study will be disseminated through presentations at scientific conferences and publications in peer-reviewed journals. The REMICRUSH trial is the first randomized controlled trial powered to investigate whether remifentanil with hypnotics is non-inferior to rapid-onset paralytic agents with hypnotic in rapid sequence induction of anesthesia for full stomach patients considering successful tracheal intubation without major complication.

Trial registration

ClinicalTrials.gov NCT03960801. Registered on May 23, 2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05192-x.

Comparison of intubating conditions after induction with propofol and remifentanil or sufentanil : Randomized controlled REMIDENT trial for surgical tooth extraction

PURPOSE

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 induction technique.

MATERIAL AND METHODS

A total of 70 patients (American Society of Anesthesiologists (ASA) classification I‑II) undergoing outpatient surgery under general anesthesia with intubation for tooth extraction were randomly assigned to two groups in this double-blind study. Patients received either a bolus of remifentanil (3 μg/kg) or sufentanil (0.3 μg/kg) together with 2.5 mg/kg propofol for intubation. The primary outcome was the percentage of excellent intubation conditions and the secondary outcomes were the percentage of patients with a decrease of over 20% in mean arterial pressure (MAP) or heart rate (HR), time to achieve spontaneous respiration, time between the end of surgery and extubation and time to achieve an Aldrete score of 10. VAS pain score was >3 or having laryngeal pain 15 min after arriving in the postanesthesia care unit (PACU) were also analyzed.

RESULTS

Intubating conditions (perfect + good conditions) were significantly better with remifentanil than with sufentanil (88.5% vs. 68.6%; p = 0.01). When using remifentanil, the hemodynamic conditions were good. Using remifentanil did not significantly increase the pain score or the laryngeal pain in the recovery room. This was confirmed by no significant differences between the groups for morphine consumption. Remifentanil significantly decreased the time to achieve an Aldrete score of 10.

CONCLUSION

When intubation without muscle relaxants is required, intubating conditions are much better when a remifentanil bolus is used compared to a sufentanil bolus. The remifentanil/propofol rapid induction technique is a valuable technique to quickly intubate and achieve good conditions.

High-flow Nasal Cannulae Versus Non-invasive Ventilation for Preoxygenation of Obese Patients: The PREOPTIPOP Randomized Trial

BACKGROUND

In obese patients, preoxygenation with non-invasive ventilation (NIV) was reported to improve outcomes compared with facemask. In this setting, high-flow nasal cannulae (HFNC) used before and during intubation has never been studied against NIV.

METHODS

The PREOPTIPOP study is a randomised, single-centre, open-labelled, controlled trial including obese patients requiring intubation before scheduled surgery. Patients were randomised to receive preoxygenation by HFNC or NIV. HFNC was maintained throughout intubation whereas NIV was removed when apnea occurred to perform laryngoscopy. The study was designed to assess the superiority of HNFC. The primary outcome was the lowest level of end-tidal oxygen concentration (EtO2) within 2 min after intubation. Secondary outcomes included drop in pulse oximetry and complications related to intubation.

MAIN FINDINGS

A total of 100 patients were randomised. The intent-to-treat analysis found median [IQR] lowest EtO2 of 76% [66-82] for HFNC and 88% [82-90] for NIV (mean difference - 12·1 [- 15·1 to - 8·5], p < 0·0001). Mild desaturation below 95% was more frequent with HFNC (30%) than with NIV (12%) (relative risk 2·5, IC 95% [1·1 to 5·9], p = 0·03) and median lowest SpO2 during intubation was 98% [93-99] in HFNC vs. 99% [97-100] in NIV (p = 0·03). Severe and moderate complications were not different but patients reported more discomfort with NIV (28%) vs. HFNC (4%), p = 0·001.

INTERPRETATION

Compared with NIV, preoxygenation with HFNC in obese patients provided lower EtO2 after intubation and a higher rate of desaturation < 95%.

FUNDING

Institutional funding, additional grant from Fisher & Paykel.

TRIAL REGISTRATION

Clinical trial Submission: April 10, 2017. Registry name: Preoxygenation Optimization in Obese Patients: High-flow Nasal Cannulae Oxygen Versus Non-invasive Ventilation: A Single-centre Randomised Controlled Study. The PREOPTIPOP Study. Clinicaltrials.gov identifier: NCT03106441 N°ID RCB: 2017-A00305-48. Institutional review Board: CPP Nord-Ouest I, registration number 019/2017. URL registry:https://clinicaltrials.gov/ct2/show/NCT03106441.

Pre-administration of remifentanil in target-controlled propofol and remifentanil anesthesia prolongs anesthesia induction in neurosurgical patients: A double-blind randomized controlled trial

BACKGROUND

Pre- and co-administration of remifentanil in target-controlled propofol and remifentanil anesthesia are the most common methods in clinical practice. However, anesthesia induction time by timing remifentanil administration was not identified. Therefore, we investigated the induction time of anesthesia based on type of remifentanil administration in target-controlled anesthesia.

METHODS

A total of 60 patients were randomly assigned to 1 of 2 groups: Pre-administered with remifentanil before propofol infusion (Group R, n = 30) and co-administered with remifentanil with propofol (Group N, n = 30). The primary outcome was total induction time based on the order of remifentanil administration. Secondary outcomes were from start of the propofol infusion time to loss of consciousness (LOC), rocuronium onset time, time to Bispectral index (BIS) 60, and hemodynamic variables.

RESULTS

The mean ± SD of total induction time was 180.5 ± 49.0 s in Group N and 246.3 ± 64.7 s in Group R (mean difference: 65.8 seconds; 95% CI: 35.0-96.5 s, P < .01). Time to BIS 60 and rocuronium onset time were longer in the Group R (P < .01 and P < .01, respectively). The Δheart rate and Δcardiac output values were lower in the Group R (P = .02 and P = .04, respectively). Injection pain was reported by 11 of 28 (39%) in the Group N and in 2 of 28 (7%) in the Group R (difference in proportion: 32%, 95% CI: 10-51%, P = .01).

CONCLUSION

Pre-administration of remifentanil in target-controlled propofol and remifentanil anesthesia prolongs total induction time about 35% compared to co-administration of remifentanil and propofol by decreased CO.

Induction of anaesthesia with remifentanil after bolus midazolam administration in Landrace/Large White swine

OBJECTIVE

To investigate an alternative combination for anaesthesia induction in swine.

STUDY DESIGN

Randomized, 'blinded' experimental study.

ANIMALS

Forty-five Landrace/Large White swine weighing 20.0±1.5 kg.

METHODS

Pulse oximetry, heart rate (HR) and blood pressure were measured after premedication with ketamine, midazolam and atropine as well as after intubation following induction with a fixed dose of 0.2 mg kg^-1 midazolam combined with 1, 2, 3, 4 or 5 μg kg^-1 remifentanil (groups R1, R2, R3, R4 and R5, respectively). Intubation was evaluated using a numerical scoring system assessing jaw relaxation, resistance to the laryngoscope, vocal cord position, vocal cord movement and response to intubation. The time required to intubate and necessity for an additional midazolam dose were recorded. Baseline and post-intubation variables were compared with paired t tests, whereas for differences between the remifentanil groups the Spearman's rank correlation coefficient was estimated. Multivariate regression analysis was performed to disentangle the effect of remifentanil dose and the additional midazolam.

RESULTS

Higher dose of remifentanil was associated with better vocal cord position (p<0.001), better response to intubation (p<0.001), shorter time required for intubation (p=0.030) and less frequent necessity for additional administration of midazolam (p=0.004). In total, 39.5% of the animals required additional midazolam. In groups R1, R4 and R5, there were decreases in HRs (p=0.009, p=0.008 and p=0.032, respectively) between baseline and post-intubation phase; in groups R3 and R4, there were decreases in systolic blood pressure (p=0.040 and p=0.019, respectively). In the multivariate analysis, remifentanil dose was not associated with the observed changes in haemodynamic variables. One animal developed apnoea and four electrocardiographic anomalies; all resolved without pharmaceutical interventions.

CONCLUSIONS AND CLINICAL RELEVANCE

A combination of 0.2 mg kg^-1 midazolam with 4 or 5 μg kg^-1 remifentanil may provide an alternative method of anaesthesia induction for swine.

Avoidance versus use of neuromuscular blocking agents for improving conditions during tracheal intubation or direct laryngoscopy in adults and adolescents

BACKGROUND

Tracheal intubation during induction of general anaesthesia is a vital procedure performed to secure a patient's airway. Several studies have identified difficult tracheal intubation (DTI) or failed tracheal intubation as one of the major contributors to anaesthesia-related mortality and morbidity. Use of neuromuscular blocking agents (NMBA) to facilitate tracheal intubation is a widely accepted practice. However, because of adverse effects, NMBA may be undesirable. Cohort studies have indicated that avoiding NMBA is an independent risk factor for difficult and failed tracheal intubation. However, no systematic review of randomized trials has evaluated conditions for tracheal intubation, possible adverse effects, and postoperative discomfort.

OBJECTIVES

To evaluate the effects of avoiding neuromuscular blocking agents (NMBA) versus using NMBA on difficult tracheal intubation (DTI) for adults and adolescents allocated to tracheal intubation with direct laryngoscopy. To look at various outcomes, conduct subgroup and sensitivity analyses, examine the role of bias, and apply trial sequential analysis (TSA) to examine the level of available evidence for this intervention.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, BIOSIS, International Web of Science, LILACS, advanced Google, CINAHL, and the following trial registries: Current Controlled Trials; ClinicalTrials.gov; and www.centerwatch.com, up to January 2017. We checked the reference lists of included trials and reviews to look for unidentified trials.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that compared the effects of avoiding versus using NMBA in participants 14 years of age or older.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently. We conducted random-effects and fixed-effect meta-analyses and calculated risk ratios (RRs) and their 95% confidence intervals (CIs). We used published data and data obtained by contacting trial authors. To minimize the risk of systematic error, we assessed the risk of bias of included trials. To reduce the risk of random errors caused by sparse data and repetitive updating of cumulative meta-analyses, we applied TSA.

MAIN RESULTS

We identified 34 RCTs with 3565 participants that met our inclusion criteria. All trials reported on conditions for tracheal intubation; seven trials with 846 participants described 'events of upper airway discomfort or injury', and 13 trials with 1308 participants reported on direct laryngoscopy. All trials used a parallel design. We identified 18 dose-finding studies that included more interventions or control groups or both. All trials except three included only American Society of Anesthesiologists (ASA) class I and II participants, 25 trials excluded participants with anticipated DTI, and obesity or overweight was an excluding factor in 13 studies. Eighteen trials used suxamethonium, and 18 trials used non-depolarizing NMBA.Trials with an overall low risk of bias reported significantly increased risk of DTI with no use of NMBA (random-effects model) (RR 13.27, 95% CI 8.19 to 21.49; P < 0.00001; 508 participants; four trials; number needed to treat for an additional harmful outcome (NNTH) = 1.9, I² = 0%, D² = 0%, GRADE = moderate). The TSA-adjusted CI for the RR was 1.85 to 95.04. Inclusion of all trials resulted in confirmation of results and of significantly increased risk of DTI when an NMBA was avoided (random-effects model) (RR 5.00, 95% CI 3.49 to 7.15; P < 0.00001; 3565 participants; 34 trials; NNTH = 6.3, I² = 70%, D² = 82%, GRADE = low). Again the cumulative z-curve crossed the TSA monitoring boundary, demonstrating harmful effects of avoiding NMBA on the proportion of DTI with minimal risk of random error. We categorized only one trial reporting on upper airway discomfort or injury as having overall low risk of bias. Inclusion of all trials revealed significant risk of upper airway discomfort or injury when an NMBA was avoided (random-effects model) (RR 1.37, 95% CI 1.09 to 1.74; P = 0.008; 846 participants; seven trials; NNTH = 9.1, I² = 13%, GRADE = moderate). The TSA-adjusted CI for the RR was 1.00 to 1.85. None of these trials reported mortality. In terms of our secondary outcome 'difficult laryngoscopy', we categorized only one trial as having overall low risk of bias. All trials avoiding NMBA were significantly associated with difficult laryngoscopy (random-effects model) (RR 2.54, 95% CI 1.53 to 4.21; P = 0.0003; 1308 participants; 13 trials; NNTH = 25.6, I² = 0%, D²= 0%, GRADE = low); however, TSA showed that only 6% of the information size required to detect or reject a 20% relative risk reduction (RRR) was accrued, and the trial sequential monitoring boundary was not crossed.

AUTHORS' CONCLUSIONS

This review supports that use of an NMBA may create the best conditions for tracheal intubation and may reduce the risk of upper airway discomfort or injury following tracheal intubation. Study results were characterized by indirectness, heterogeneity, and high or uncertain risk of bias concerning our primary outcome describing difficult tracheal intubation. Therefore, we categorized the GRADE classification of quality of evidence as moderate to low. In light of defined outcomes of individual included trials, our primary outcomes may not reflect a situation that many clinicians consider to be an actual difficult tracheal intubation by which the patient's life or health may be threatened.

Prediction of hemodynamic reactivity using dynamic variations of Analgesia/Nociception Index (∆ANI)

The Analgesia/Nociception Index (ANI), a 0-100 non-invasive index calculated from heart rate variability, reflects the analgesia/nociception balance during general anesthesia. We hypothesized that dynamic variations of ANI (∆ANI) would provide better performance than static values to predict hemodynamic reactivity during desflurane/remifentanil general anesthesia. One hundred and twenty-eight patients undergoing ear-nose-throat or lower limb orthopedic surgery were analyzed in this prospective observational study. The ANI, heart rate and systolic blood pressure were recorded before induction, at skin incision, during procedure and at emergence from general anesthesia. Changes in these variables were recorded after 1 min for ANI (ANI_1min) and 5 min for heart rate and systolic blood pressure. The dynamic variation of ANI at the different time points was defined as: ∆ANI = (ANI_1min - ANI)/([ANI + ANI_1min]/2). Receiver-operating characteristic (ROC) curves were built to evaluate the performance of ANI, ANI1 min and ∆ANI to predict hemodynamic reactivity (increase by more than 20 % in heart rate and/or systolic blood pressure within 5 min). For the prediction of hemodynamic reactivity, better performance was observed with ∆ANI (area under ROC curve (AUC ROC) = 0.90) in comparison to ANI (ROC AUC = 0.50) and ANI_1min (ROC AUC = 0.77). A ∆ANI threshold of -19 % predicts hemodynamic reactivity with 85 % [95 % CI 77-91] sensitivity and 85 % [95 % CI 81-89] specificity. Dynamic variations of ANI provide better performance than static values to predict hemodynamic reactivity during desflurane/remifentanil general anesthesia. These findings may be of interest for the individual adaptation of remifentanil doses guided by ∆ANI during general anesthesia, although this remains to be demonstrated.

Endotracheal intubation without muscle relaxants in children using remifentanil and propofol: Comparative study

Introduction:

Endotracheal intubation is essential during general anesthesia and muscle relaxant drugs provide ideal conditions for this purpose. The objective of this study was to evaluate the intubating condition of remifentanil combined with propofol without muscle relaxant.

Materials and Methods:

In this prospective randomized study, 60 children aged 3-12 years, American Society of Anesthesiologists physical status I and II were included. All the children were premedicated with 0.05 mg/kg midazolam and 1.5 mg/kg lidocaine 5 min before the induction of anesthesia with 3 mg/kg propofol. Then, they were allocated randomly to receive either 2 μg/kg remifentanil (group R) or 1.5 mg/kg succinylcholine (group S). Tracheal intubation was attempted 90 s after the administration of propofol. The quality of intubation was assessed by using Copenhagen score based on jaw relaxation, ease of laryngoscopy, position of vocal cord, coughing and limb movement. Heart rate and blood pressure were recorded before and after induction, and 1, 3, 5 min after intubation.

Results:

There was no significant difference in intubating condition between the two groups (P = 0.11). Intubation condition was excellent in 26 of 30 (86.7%) patients in the group R compared with 30 (100%) patients in the group S. We observed significant difference in heart rate and systolic blood pressure over time between two groups (P = 0.02, P = 0.03 respectively). After intubation, we had higher heart rate and systolic blood pressure with a significant difference in group S compared with group R (P = 0.006, P = 0.018). None of the children had a chest rigidity, laryngospasm, and hypoxia.

Conclusions:

In premedicated children, propofol-remifentanil combination provides adequate conditions for tracheal intubation that is comparable with succinylcholine. Hemodynamic response to laryngoscopy and tracheal intubation was controlled better in group R.

Infraorbital and infratrochlear nerve blocks combined with general anaesthesia for outpatient rhinoseptoplasty: A prospective randomised, double-blind, placebo-controlled study

INTRODUCTION

We conducted a study to determine the efficacy of bilateral extraoral infraorbital and infratrochlear nerve blocks during outpatient rhinoseptoplasty under general anaesthesia.

PATIENTS AND METHODS

In this prospective, double-blind, randomised, controlled trial, 40 adult patients undergoing outpatient rhinoseptoplasty under general anaesthesia were assigned to receive bilateral infraorbital and infratrochlear nerve blocks with either 10mL of 0.25% levobupivacaine (Group LB) or isotonic saline (control group). Patients in Group LB received 0.1mL/kg of isotonic saline as a placebo and patients in the control group received 0.1mL/kg of morphine. The primary endpoint was total perioperative morphine consumption (intraoperative and in the post-anaesthesia care unit). The secondary endpoints were pain scores, time spent in the post-anaesthesia care unit and the outpatient ward, block-related complications and patient satisfaction.

RESULTS

The total dose of perioperative morphine was lower in Group LB than in the control group (2.5±2.8mg versus 9.5±3.5mg, respectively, P<0.001). The mean±SD or median [IQR] times spent in the post-anaesthesia care unit (60±10min and 78±33min, respectively, P<0.03) and in the outpatient ward (210 [178-223] min versus 275 [250-300] min, respectively, P<0.001) were lower in Group LB than in the control group. There were no differences between groups for other endpoints.

CONCLUSION

Bilateral extraoral infraorbital and infratrochlear nerve blocks performed with 0.25% levobupivacaine during general anaesthesia combining remifentanil and desflurane reduce the perioperative dose of morphine and the time spent in the post-anaesthesia care unit and the outpatient ward in adult patients undergoing outpatient rhinoseptoplasty.

Dose of rocuronium for rapid tracheal intubation following remifentanil 2 μg kg-1 and propofol 2 mg kg-1

CONTEXT

Full relaxation is not mandatory for successful tracheal intubation.

OBJECTIVE

We tried to find the dose of rocuronium that gave acceptable intubation conditions in a rapid sequence intubation with remifentanil and propofol.

DESIGN

A dose-finding study of rocuronium using a modified Dixon's up-and-down method.

SETTING

A single tertiary care teaching hospital.

PARTICIPANTS

Patients undergoing elective surgery under general anaesthesia.

INTERVENTIONS

After premedication with midazolam and glycopyrrolate, anaesthesia was induced using remifentanil 2 μg kg and propofol 2 mg kg, and a predetermined dose of rocuronium was administered. The dose of rocuronium was determined by a modified Dixon's up-and-down method starting from 0.8 mg kg with an interval of 0.1 or 0.05 mg kg. Intubation was performed 60 s after the start of the rocuronium injection. Intubation conditions were graded as excellent, good or poor. Excellent or good were regarded as clinically acceptable.

MAIN OUTCOME MEASURE

A dose of rocuronium needed for acceptable intubation condition in 50% of patients (ED50) during rapid tracheal intubation after induction of anaesthesia with remifentanil and propofol.

RESULTS

Twenty-eight patients were enrolled to obtain six crossovers. The ED50 of rocuronium was 0.20 mg kg (95% confidence interval, CI 0.17 to 0.23 mg kg) by a modified Dixon's up-and-down method.

CONCLUSION

After induction of anaesthesia with remifentanil 2 μg kg and propofol 2 mg kg, the ED50 of rocuronium for acceptable intubation condition was 0.20 mg kg (95% CI, 0.17 to 0.23 mg kg) for rapid sequence intubation. Thus, we recommend that the intubation dose should be 0.8 mg kg.

TRIAL REGISTRATION

Clinical trial registration KCT0000094.

Intubating conditions and side effects of propofol, remifentanil and sevoflurane compared with propofol, remifentanil and rocuronium: a randomised, prospective, clinical trial

BACKGROUND

Tracheal intubation without muscle relaxants is usually performed with remifentanil and propofol or sevoflurane. Remifentanil 1.0 to 4.0 μg·kg(-1) and propofol 2.0-3.0 mg·kg(-1) or sevoflurane up to 8.0 Vol% provide acceptable, i.e. excellent or good intubating conditions. We hypothesized that sevoflurane 1.0 MAC would provide acceptable intubating conditions when combined with propofol and remifentanil.

METHODS

Eighty-three patients to be intubated were randomised to two groups. The SEVO group received propofol 1.5 mg kg(-1), remifentanil 0.30 μg kg min(-1) and sevoflurane 1.0 MAC; the MR group received the same doses of propofol and remifentanil plus rocuronium 0.45 mg kg(-1). We evaluated intubation and extubation conditions, mean arterial pressure (MAP), heart rate (HR) and bispectral index (BIS). The vocal cords were examined for injury by videolaryngoscopy before and 24 hours after surgery.

RESULTS

ACCEPTABLE INTUBATING CONDITIONS WERE SEEN MORE FREQUENTLY WITH ROCURONIUM THAN WITH SEVOFLURANE: 97% versus 82%; p = 0.03; the subscore for vocal cords was comparable: 100% versus 98%. MAP before intubation decreased significantly compared with the MAP at baseline to the same extent in both groups; ephedrine IV was given in 15 (SEVO) versus 16 (MR) patients; p = 0.93. BIS at tracheal intubation was 27 (13-65) in the SEVO group, 29 (14-62) in the MR group; p = 0.07. Vocal cord injuries (oedema, haematoma) were similar: 4 patients in each group.

CONCLUSIONS

Overall intubating conditions were better when rocuronium was used; the subscore for vocal cords was comparable. The incidence of side effects was the same in the two groups.

TRIAL REGISTRATION

ClinicalTrials.Gov: NCT 01591031.

Remifentanil dose for laryngeal mask airway insertion with a single standard dose of propofol during emergency airway management in elderly patients

BACKGROUND

This study determined the dose of remifentanil to use during insertion of a Classic™ laryngeal mask airway (LMA, The Laryngeal Mask Co., Nicosia, Cyprus) in elderly patients during emergency airway management when combined with a single dose of propofol.

METHODS

Patients aged 65-80 years were enrolled. Anesthesia was induced with propofol 1 mg/kg, and then a blinded dose of remifentanil was infused over 30 s after confirming the patient's loss of consciousness. The dose of remifentanil was determined using Dixon's up-and-down method, starting at 0.5 µg/kg (a step size of 0.1 µg/kg). Insertion of the LMA was attempted 60 s after loss of consciousness.

RESULTS

In total, 23 patients were recruited and the mean age ± standard deviation was 72 ± 3 years. The effective dose for successful LMA insertion in 50% of the patients (ED50) was 0.20 ± 0.05 µg/kg. No patient needed more than 0.3 µg/kg.

CONCLUSIONS

Remifentanil 0.20 ± 0.05 µg/kg with propofol 1 mg/kg resulted in excellent LMA insertion in 50% of elderly patients without significant hemodynamic changes during emergency airway management.

Real-time Detection of Gastric Insufflation Related to Facemask Pressure–controlled Ventilation Using Ultrasonography of the Antrum and Epigastric Auscultation in Nonparalyzed Patients

Background:

The authors sought to determine the level of inspiratory pressure minimizing the risk of gastric insufflation while providing adequate pulmonary ventilation. The primary endpoint was the increase in incidence of gastric insufflation detected by ultrasonography of the antrum while inspiratory pressure for facemask pressure-controlled ventilation increased from 10 to 25 cm H2O.

Methods:

In this prospective, randomized, double-blind study, patients were allocated to one of the four groups (P10, P15, P20, and P25) defined by the inspiratory pressure applied during controlled-pressure ventilation: 10, 15, 20, and 25 cm H2O. Anesthesia was induced using propofol and remifentanil; no neuromuscular-blocking agent was administered. Once loss of eyelash reflex occurred, facemask ventilation was started for a 2-min period while gastric insufflation was detected by auscultation and by real-time ultrasonography of the antrum. The cross-sectional antral area was measured using ultrasonography before and after facemask ventilation. Respiratory parameters were recorded.

Results:

Sixty-seven patients were analyzed. The authors registered statistically significant increases in incidences of gastric insufflation with inspiratory pressure, from 0% (group P10) to 41% (group P25) according to auscultation, and from 19 to 59% according to ultrasonography. In groups P20 and P25, detection of gastric insufflation by ultrasonography was associated with a statistically significant increase in the antral area. Lung ventilation was insufficient for group P10.

Conclusion:

Inspiratory pressure of 15 cm H2O allowed for reduced occurrence of gastric insufflation with proper lung ventilation during induction of anesthesia with remifentanil and propofol in nonparalyzed and nonobese patients. (Anesthesiology 2014; 120:326-34)

Prediction of immediate postoperative pain using the analgesia/nociception index: a prospective observational study

BACKGROUND

The analgesia/nociception index (ANI) is derived from heart rate variability, ranging from 0 (maximal nociception) to 100 (maximal analgesia), to reflect the analgesia/nociception balance during general anaesthesia. This should be correlated with immediate postoperative pain in the post-anaesthesia care unit (PACU). The aim of this study was to evaluate the performance of ANI measured at arousal from general anaesthesia to predict immediate postoperative pain on arrival in PACU.

METHODS

Two hundred patients undergoing ear, nose, and throat or lower limb orthopaedic surgery with general anaesthesia using an inhalational agent and remifentanil were included in this prospective observational study. The ANI was measured immediately before tracheal extubation and pain intensity was assessed within 10 min of arrival in PACU using a 0-10 numerical rating scale (NRS). The relationship between ANI and NRS was assessed using linear regression. A receiver-operating characteristic (ROC) curve was used to evaluate the performance of ANI to predict NRS>3.

RESULTS

A negative linear relationship was observed between ANI immediately before extubation and NRS on arrival in PACU. Using a threshold of <50, the sensitivity and specificity of ANI to discriminate between patients with NRS≤3 and NRS>3 were both 86% with 92% negative predictive value, corresponding to an area under the ROC curve of 0.89.

CONCLUSIONS

The measurement of ANI immediately before extubation after inhalation-remifentanil anaesthesia was significantly associated with pain intensity on arrival in PACU. The performance of ANI for the prediction of immediate postoperative pain is good and may assist physicians in optimizing acute pain management.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT01796249.

Optimal remifentanil dosage for intubation without muscle relaxants in elderly patients

BACKGROUND

Remifentanil used in combination with propofol provides adequate conditions for tracheal intubation without muscle relaxants. Delivery of the optimal dose is important to prevent poor intubation conditions and drug-related complications. No previous study has investigated the use of a remifentanil-propofol combination in elderly patients.

OBJECTIVE

The aim of the present study was to determine the dose of remifentanil necessary for rapid tracheal intubation without the use of muscle relaxants in elderly patients.

METHODS

A total of 24 patients >65 years of age with American Society of Anesthesiologists status I-II who were scheduled to undergo elective surgery under general anaesthesia were enrolled. After premedication with glycopyrrolate and midazolam, anaesthesia was induced with 1 mg/kg propofol, and a blinded dose of remifentanil was then infused over 30 s after confirming the patient's loss of consciousness. The remifentanil dose was determined using Dixon's up-and-down method, starting at 2 µg/kg. Intubation was performed 60 s after the loss of consciousness. Intubation conditions were assessed with the Stockholm score and an assessment of excellent or good condition was regarded as being clinically acceptable. The effective dose needed for acceptable intubation conditions in 50 % of the subjects (ED(50)) was determined by Dixon's up-and-down method, and the ED(50) and the effective dose needed for acceptable intubation conditions in 95 % of the subjects (ED(95)) with 95 % confidence intervals (CIs) were determined by probit analysis.

RESULTS

In total, 24 patients were recruited and the median age (interquartile range) was 70 (66-74) years. The ED(50) of remifentanil for tracheal intubation was 1.15 (standard deviation 0.13) µg/kg. The ED(50) and ED(95) of remifentanil obtained from the probit analyses were 1.16 (95 % CI 1.01, 1.29) µg/kg and 1.39 (95 % CI 1.27, 2.13) µg/kg, respectively. Blood pressure and heart rate decreased significantly after propofol and remifentanil administration, but were within 30 % of baseline values.

CONCLUSIONS

Combined with 1 mg/kg propofol, 1.39 (95 % CI 1.27, 2.13) µg/kg remifentanil resulted in acceptable intubation conditions within 60 s in 95 % of elderly patients without major complications.

Prospective observational study of the non-invasive assessment of immediate postoperative pain using the analgesia/nociception index (ANI)

BACKGROUND

The analgesia/nociception index (ANI), a 0-100 non-invasive index calculated from heart rate variability, reflects the analgesia/nociception balance during general anaesthesia. The aim of this study was to evaluate the ANI in the assessment of immediate postoperative pain in adult patients undergoing general anaesthesia.

METHODS

Two-hundred patients undergoing scheduled surgery or endoscopy with general anaesthesia were included in this prospective observational study. Pain intensity was assessed using a 0-10 numerical rating scale (NRS) after arousal from general anaesthesia. Receiver-operating characteristic (ROC) curves were built to assess the performance of ANI to detect patients with NRS>3 and NRS ≥ 7 on arrival in the postoperative care unit.

RESULTS

A negative linear relationship was observed between ANI and NRS (ANI=-5.2 × NRS+77.9, r(2)=0.41, P<0.05). At the threshold of 57, the sensitivity and specificity of ANI to detect patients with NRS>3 were 78 and 80%, respectively, with a negative predictive value of 88%, corresponding to an area under the ROC curve (AUC) of 0.86. At the threshold of 48, the sensitivity and specificity of ANI to detect NRS ≥ 7 were 92 and 82%, respectively, with a negative predictive value of 99%, corresponding to a ROC curve AUC of 0.91.

CONCLUSIONS

A measurement of ANI during the immediate postoperative period is significantly correlated with pain intensity. The measurement of ANI appears to be a simple and non-invasive method to assess immediate postoperative analgesia.

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

STUDY OBJECTIVE

To determine the optimal remifentanil dose required to provide acceptable intubating conditions following induction of anesthesia with propofol without using neuromuscular blockade.

DESIGN

Dose-response study.

SETTING

Operating room of a university hospital.

PATIENTS

50 ASA physical status 1 men, aged between 20 and 40 years, who were scheduled for general anesthesia.

INTERVENTIONS

Intubating conditions were evaluated according to the scoring system described by Viby-Mogensen et al. Successful intubation was defined as excellent or good.

MEASUREMENTS

For 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 RESULTS

According to probit analysis, the effective dose of remifentanil in 50% (ED(50)) and 95% (ED(95)) 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).

CONCLUSION

The 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.

The EC(50) of remifentanil to minimize the cardiovascular changes during head holder pinning in neurosurgery

BACKGROUND

During neuroanesthesia, head holder pinning commonly results in sympathetic stimulation manifested by hemodynamic changes, such as increased heart rate and arterial blood pressure. Remifentanil has been used successfully to control acute autonomic responses during neurosurgical procedures. The objective of this study was to determine effect-site concentration of remifentanil for suppressing the hemodynamic response to head holder pinning with the probability of 50% (EC(50)).

METHODS

Forty-one ASA physical status I or II patients, between the ages of 20-70, who were scheduled for neurosurgery were recruited into this study. After arrival in the operating room, standard monitoring was applied throughout the study, which included a bispectral index monitor. Both propofol and remifentanil were administered by Target-control infusion device. The Dixon "up-and-down" sequential allocation method was used to determine the EC(50) of remifentanil.

RESULTS

The EC(50) of remifentanil was 2.19 ± 0.76 ng/ml by the turning point estimate (TPE). In probit analysis, EC(50) was 2.42 ng/ml (95% CI : -0.62-4.66) and EC(95) was 5.70 ng/ml (95% CI : 4.02-67.53). The EC(50) estimator comes from isotonic regression is 2.90 ng/ml (95% CI : 1.78-3.65). The EC(95) estimator comes from isotonic regression is 4.28 ng/ml (95% CI : 3.85-4.41).

CONCLUSIONS

This study showed that EC(50) of remifentanil was 2.19 ± 0.76 ng/ml by TPE. EC(50) was 2.42 ng/ml (95% CI -0.62-4.66) in probit analysis, as back up analysis. The EC(50) estimator comes from isotonic regression is 2.90 ng/ml (95% CI : 1.78-3.65).

Remifentanil as single agent to facilitate awake fibreoptic intubation in the absence of premedication

Remifentanil is increasingly being used as the primary agent to provide sedation during awake fibreoptic nasal intubation. In this observational study, we aimed to determine the optimal effect site concentration of remifentanil, using a target controlled infusion based on the Minto pharmacological model, to provide optimal safe intubation conditions without the use of other sedatives/premedication and/or spray-as-you-go local anaesthesia. Twenty patients with anticipated difficult airway participated in the study. Good intubating conditions were achieved in all patients with mean (SD) effect site concentration of 6.3 (3.87) ng.ml(-1) of remifentanil recorded at nasal endoscopy and 8.06 (3.52) ng.ml(-1) during tracheal intubation. No serious adverse event occurred during any of these procedures. These preliminary findings suggest that this is a feasible and safe technique for awake fibreoptic nasal intubation.

Optimal effect-site concentration of remifentanil for preventing development of hypertension during tracheal intubation with inhaled desflurane induction

BACKGROUND

The aim of the present study was to determine the effect-site concentration of remifentanil needed to prevent haemodynamic instability during tracheal intubation with inhaled desflurane induction.

METHODS

One hundred American Society of Anesthesiologists I and II female patients were randomized to receive an effect-site concentration of remifentanil of 0, 1, 2, 3, or 4 ng/ml. Induction of anaesthesia was started with intravenous injection of propofol 2 mg/kg. Ninety seconds after the completion of propofol injection, rocuronium (0.8 mg/kg) and remifentanil were administered simultaneously with 3% desflurane inhalation. Tracheal intubation was attempted 150 sec after the commencement of remifentanil administration.

RESULTS

A probit model of remifentanil concentration was predictive of successful intubation without development of hypertension (P for goodness-of-fit = 0.419). The effect-site concentration of remifentanil needed to achieve successful intubation without development of hypertension in 95% of the patients was 3.3 ng/ml (95% confidence interval, 2.6-4.8 ng/ml).

CONCLUSIONS

The effect-site concentration of remifentanil of 3.3 ng/ml is effective in blunting the haemodynamic response in 95% of the patients when 2.0 mg/kg of propofol induction was followed by 3% desflurane inhalation.

Refined induction of anesthesia with remifentanil after bolus propofol administration in Landrace/Large White swine

The authors report a prospective randomized blind study in which they used a refined anesthetic technique in male Landrace/Large White swine (n = 125 pigs, 19 ± 2 kg, 10-15 weeks old). The animals were first premedicated with ketamine, midazolam and atropine and then given a dose of 1, 2, 3, 4 or 5 μg remifentanil per kg body weight (dose amounts were randomly assigned) after a bolus dose of propofol. The authors assessed the intubation conditions (e.g., jaw relaxation and other parameters) 20 min after premedication and then 5 min after anesthesia induction. All animals that received each of the different remifentanil dose amounts were successfully intubated in less than 30 s. No animal developed apnea during intubation or experienced substantial reductions in heart rate or blood pressure (> 25%) between the two time points (20 min after premedication and 5 min after anesthesia induction). Overall intubation conditions were significantly better in animals that received 5 μg remifentanil per kg body weight than in animals that received other dose amounts (P < 0.001). The average time to intubation was significantly shorter for animals that received 5 μg remifentanil per kg body weight than for animals that received any of the other dose amounts (P < 0.001). The authors concluded that for this study, 5 μg remifentanil per kg body weight resulted in excellent intubating conditions in this swine breed.