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

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.

Peri-operative management of neuromuscular blockade: A guideline from the European Society of Anaesthesiology and Intensive Care

Recent data indicated a high incidence of inappropriate management of neuromuscular block, with a high rate of residual paralysis and relaxant-associated postoperative complications. These data are alarming in that the available neuromuscular monitoring, as well as myorelaxants and their antagonists basically allow well tolerated management of neuromuscular blockade. In this first European Society of Anaesthesiology and Intensive Care (ESAIC) guideline on peri-operative management of neuromuscular block, we aim to present aggregated and evidence-based recommendations to assist clinicians provide best medical care and ensure patient safety. We identified three main clinical questions: Are myorelaxants necessary to facilitate tracheal intubation in adults? Does the intensity of neuromuscular blockade influence a patient's outcome in abdominal surgery? What are the strategies for the diagnosis and treatment of residual paralysis? On the basis of this, PICO (patient, intervention, comparator, outcome) questions were derived that guided a structured literature search. A stepwise approach was used to reduce the number of trials of the initial research ( n  = 24 000) to the finally relevant clinical studies ( n  = 88). GRADE methodology (Grading of Recommendations, Assessment, Development and Evaluation) was used for formulating the recommendations based on the findings of the included studies in conjunction with their methodological quality. A two-step Delphi process was used to determine the agreement of the panel members with the recommendations: R1 We recommend using a muscle relaxant to facilitate tracheal intubation (1A). R2 We recommend the use of muscle relaxants to reduce pharyngeal and/or laryngeal injury following endotracheal intubation (1C). R3 We recommend the use of a fast-acting muscle relaxant for rapid sequence induction intubation (RSII) such as succinylcholine 1 mg kg -1 or rocuronium 0.9 to 1.2 mg kg -1 (1B). R4 We recommend deepening neuromuscular blockade if surgical conditions need to be improved (1B). R5 There is insufficient evidence to recommend deep neuromuscular blockade in general to reduce postoperative pain or decrease the incidence of peri-operative complications. (2C). R6 We recommend the use of ulnar nerve stimulation and quantitative neuromuscular monitoring at the adductor pollicis muscle to exclude residual paralysis (1B). R7 We recommend using sugammadex to antagonise deep, moderate and shallow neuromuscular blockade induced by aminosteroidal agents (rocuronium, vecuronium) (1A). R8 We recommend advanced spontaneous recovery (i.e. TOF ratio >0.2) before starting neostigmine-based reversal and to continue quantitative monitoring of neuromuscular blockade until a TOF ratio of more than 0.9 has been attained. (1C).

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.

Guidelines on muscle relaxants and reversal in anaesthesia

OBJECTIVES

To provide an update to the 1999 French guidelines on "Muscle relaxants and reversal in anaesthesia", a consensus committee of sixteen experts was convened. A formal policy of declaration and monitoring of conflicts of interest (COI) was developed at the outset of the process and enforced throughout. The entire guidelines process was conducted independently of any industrial funding (i.e. pharmaceutical, medical devices). The authors were required to follow the rules of the Grading of Recommendations, Assessment, Development and Evaluation (GRADE®) system to assess the quality of the evidence on which the recommendations were based. The potential drawbacks of making strong recommendations based on low-quality evidence were stressed. Few of the recommendations remained ungraded.

METHODS

The panel focused on eight questions: (1) In the absence of difficult mask ventilation criteria, is it necessary to check the possibility of ventilation via a facemask before muscle relaxant injection? Is it necessary to use muscle relaxants to facilitate facemask ventilation? (2) Is the use of muscle relaxants necessary to facilitate tracheal intubation? (3) Is the use of muscle relaxants necessary to facilitate the insertion of a supraglottic device and management of related complications? (4) Is it necessary to monitor neuromuscular blockade for airway management? (5) Is the use of muscle relaxants necessary to facilitate interventional procedures, and if so, which procedures? (6) Is intraoperative monitoring of neuromuscular blockade necessary? (7) What are the strategies for preventing and treating residual neuromuscular blockade? (8) What are the indications and precautions for use of both muscle relaxants and reversal agents in special populations (e.g. electroconvulsive therapy, obese patients, children, neuromuscular diseases, renal/hepatic failure, elderly patients)? All questions were formulated using the Population, Intervention, Comparison and Outcome (PICO) model for clinical questions and evidence profiles were generated. The results of the literature analysis and the recommendations were then assessed using the GRADE® system.

RESULTS

The summaries prepared by the SFAR Guideline panel resulted in thirty-one recommendations on muscle relaxants and reversal agents in anaesthesia. Of these recommendations, eleven have a high level of evidence (GRADE 1±) while twenty have a low level of evidence (GRADE 2±). No recommendations could be provided using the GRADE® system for five of the questions, and for two of these questions expert opinions were given. After two rounds of discussion and an amendment, a strong agreement was reached for all the recommendations.

CONCLUSION

Substantial agreement exists among experts regarding many strong recommendations for the improvement of practice concerning the use of muscle relaxants and reversal agents during anaesthesia. In particular, the French Society of Anaesthesia and Intensive Care (SFAR) recommends the use of a device to monitor neuromuscular blockade throughout anaesthesia.

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.

The effects of remifentanil and esmolol on increase in intraocular pressure due to laryngoscopy and tracheal intubation: a double-blind, randomized clinical trial

PURPOSE

This study aimed to compare the effects of remifentanil and esmolol on the elevation of intraocular pressure (IOP) and hemodynamic response.

METHODS

After approval of the institutional Ethics Committee and obtaining informed consent, 60 adult patients with American Society of Anesthesiologists I-II status undergoing elective, nonophthalmic surgery were included in the study. Exclusion criteria were preexisting eye disease, neuromuscular disease, esophageal reflux, hiatus hernia, allergy to any of the study drugs, and the use of β-blockers, diuretics, or other antihypertensive agents. The patients were randomized into 2 groups by using the sealed-envelope method, as follows: group E (esmolol) and group R (remifentanil). A single intravenous dose of esmolol (0.5 mg/kg) or remifentanil (1 μg/kg) just before induction agents were given to patients in groups E and R, respectively. IOP, heart rate (HR), and mean arterial pressure (MAP) values were recorded before intubation and at 1, 3, 5, and 10 minutes after intubation.

RESULTS

The IOP decrease in group R was statistically significant compared with group E (P<0.01). HR values at 10 minutes after intubation were significantly decreased in group E compared with group R (P<0.05). There was no significant difference in MAP values between the groups.

CONCLUSIONS

It was concluded that remifentanil is more effective than esmolol in preventing IOP elevation related to laryngoscopy and tracheal intubation, while there is no significant difference between the 2 agents in terms of HR and MAP.

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.

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.

Remifentanil and etomidate for laryngeal mask airway insertion

Etomidate does not depress the upper airway reflexes, making it difficult to insert a laryngeal mask airway (LMA) when using it for anaesthesia. This study investigated the effect of adding remifentanil to etomidate for LMA insertion. Fifty adult patients, undergoing cystoscopy, were randomized to two groups. The propofol-remifentanil group (n=25) received propofol anaesthesia induction (2.5 mg/kg) and a remifentanil bolus of 0.5 microg/kg, followed by a 2-min remifentanil infusion of 0.05 microg/kg per min. The etomidate-remifentanil group (n=25) received etomidate anaesthesia induction (0.3 mg/kg) and remifentanil as described. The LMA was inserted by a blinded anaesthetist who assessed a number of parameters. Only 13 LMAs were inserted at the first attempt in the etomidate-remifentanil group compared with 23 in the propofol-remifentanil group. Gagging, chest rigidity and myoclonus occurred significantly more frequently in the etomidate-remifentanil group. We conclude that the addition of remifentanil to etomidate anaesthesia induction does not improve LMA insertion.

Comparison of two induction regimens using or not using muscle relaxant: impact on postoperative upper airway discomfort

BACKGROUND

Muscle relaxants facilitate tracheal intubation, but they are often not used for short peripheral surgical procedures. The consequences of this practice on the upper airway are still a matter of controversy. We therefore compared the incidence of post-intubation symptoms in a randomized study comparing patients intubated with or without the use of a muscle relaxant.

METHODS

A total of 300 adult patients requiring tracheal intubation for scheduled peripheral surgery were randomly assigned in a double-blind study to an anaesthetic protocol that either included or did not include a muscle relaxant (rocuronium). The primary end-point was the rate of post-intubation symptoms 2 and 24 h after extubation. The secondary end-points were the intubation conditions score (Copenhagen Consensus Conference), the rate of difficult intubations (Intubation Difficulty Scale), and the incidence of adverse haemodynamic events.

RESULTS

Post-intubation symptoms were more frequent in patients intubated without the use of a muscle relaxant, whether 2 h (57% vs 43% of patients; P < 0.05) or 24 h (38% vs 26% of patients; P < 0.05) after extubation. Intubation conditions were better when the muscle relaxant was used. In patients intubated without a muscle relaxant, difficult intubation was more common (12% vs 1%; P < 0.05), as were arterial hypotension or bradycardia requiring treatment (12% vs 3% of patients; P < 0.05).

CONCLUSIONS

The use of a muscle relaxant for tracheal intubation diminishes the incidence of adverse postoperative upper airway symptoms, results in better tracheal intubation conditions, and reduces the rate of adverse haemodynamic events.

Management of outpatient ear, nose and throat surgery

In the year under review there have been steady advances in anaesthesia. Premedication in children is best achieved with oral midazolam formulated in flavoured syrups, and the inhalational induction of anaesthesia may be accomplished using sevoflurane. Pain management of the most common surgical procedure performed in children, tonsillectomy/adenoidectomy, is still sub-optimal, but combinations of opioids and non-steroidal anti-inflammatory drugs are helpful. There are, however, some concerns regarding the possible increases in postoperative blood loss after tonsillectomy when non-steroidal anti-inflammatory drugs are used. Middle ear surgery leads to a high incidence of postoperative nausea and vomiting, and these are best managed by utilizing a total intravenous anaesthetic technique with propofol, the avoidance of nitrous oxide, and administration of dexamethasone and a 5-hydroxytryptamine receptor antagonist such as ondansetron.

Update on neuromuscular pharmacology

Since the introduction of d-tubocurarine into clinical practice, neuromuscular relaxants have been widely used in anaesthesia. Although their clinical use is easy, several points still require further attention and research. There is still a need for a drug with the clinical profile of succinylcholine but fewer unwanted side-effects. A better understanding of the effects of muscle relaxants on different muscles could help in their clinical use during the perioperative period. Much knowledge is needed about residual neuromuscular block and its detection in order to improve the quality of recovery from neuromuscular blockade. If some questions remain to be answered, several recent articles have increased our knowledge and should improve our clinical practice.

Use of remifentanil for tracheal intubation for caesarean section in a patient with suxamethonium apnoea

A parturient presented for elective caesarean section with a history of multiple spinal operations and scoliosis and a biochemical diagnosis of suxamethonium apnoea. She declined any attempt at regional anaesthesia. We describe the use of a thiopental/remifentanil technique to relax the larynx and provide rapid and excellent conditions for laryngoscopy and tracheal intubation. The parturient awoke following an uneventful caesarean section with excellent pain relief and no recall. The baby had normal Apgar scores and umbilical blood gas measurements.

Remifentanil update: clinical science and utility

The anilidopiperidine opioid remifentanil has pharmacodynamic properties similar to all opioids; however, its pharmacokinetic characteristics are unique. Favourable pharmacokinetic properties, minimally altered by extremes of age or renal or hepatic dysfunction, enable easy titration and rapid dissipation of clinical effect of this agent, even after prolonged infusion. Remifentanil is metabolised by esterases that are widespread throughout the plasma, red blood cells, and interstitial tissues, whereas other anilidopiperidine opioids (e.g. fentanyl, alfentanil and sufentanil) depend upon hepatic biotransformation and renal excretion for elimination. Consequently, remifentanil is cleared considerably more rapidly than other anilidopiperidine opioids. In addition, its pKa (the pH at which the drug is 50% ionised) is less than physiological pH; thus, remifentanil circulates primarily in the non-ionised moiety, which quickly penetrates the lipid blood-brain barrier and rapidly equilibrates across the plasma/effect site interface. By virtue of these distinctive pharmacokinetic properties, the context-sensitive half-time (i.e. the time required for the drug's plasma concentration to decrease by 50% after cessation of an infusion) of remifentanil remains consistently short (3.2 minutes), even following an infusion of long duration (> or =8 hours). Remifentanil, a clinically versatile opioid, is useful for intravenous analgesia and sedation in spontaneously breathing patients undergoing painful procedures. Profound analgesia may be achieved with minimal effect on cognitive function. Remifentanil may also provide sedation and analgesia during placement of regional anaesthetic blocks, and in conjunction with topical anaesthesia and airway nerve blocks, it may be useful for blunting reflex responses and facilitating 'awake' fibreoptic intubation. Compared with fentanyl and alfentanil in a day-surgery setting, remifentanil supplementation of general anaesthesia may improve intraoperative haemodynamic control. Both emergence time and the incidence of respiratory depression during post-anaesthetic recovery may be reduced. However, outcomes such as home discharge time, post-emergence adverse effect profile, and patient and provider satisfaction are not significantly improved, and the incidence of intraoperative hypotension and bradycardia is greater. In addition, drug acquisition costs for remifentanil are higher and clinicians may need extra time to familiarise themselves with the drug's unique pharmacokinetics.Ironically, the quick dissipation of opioid analgesic effect following remifentanil discontinuation may be a significant clinical disadvantage. Unless little or no postoperative pain is anticipated, the clinician may wish to treat prospectively using local or regional anaesthesia, non-opioid analgesics, or longer-acting opioid analgesics.

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.

Comparison of bolus remifentanil versus bolus fentanyl for induction of anesthesia and tracheal intubation in patients with cardiac disease

OBJECTIVE

Large bolus-dose remifentanil may be advantageous for use during induction of anesthesia because of its short duration of effect. Currently, there are little data on the use of large bolus-dose remifentanil because of reports of severe bradycardia and hypotension. The purpose of this study is to compare the hemodynamic effects of bolus remifentanil versus fentanyl with glycopyrrolate for induction of anesthesia in patients with heart disease.

DESIGN

A randomized, double-blinded study.

SETTING

A tertiary-care academic medical center.

PARTICIPANTS

One hundred patients for coronary artery bypass or valvular surgery.

INTERVENTION

Subjects received either (1) remifentanil, 5 microg/kg, with glycopyrrolate, 0.2 mg, or (2) fentanyl, 20 microg/kg, with 0.2 mg of glycopyrrolate, and both groups also received midazolam, 70 microg/kg, for induction of anesthesia.

MEASUREMENTS AND MAIN RESULTS

Heart rate, mean arterial pressure, systemic vascular resistance, and cardiac output were similar between the 2 groups during induction of anesthesia and tracheal intubation. The incidence of adverse events such as bradycardia (remifentanil 10%, fentanyl 10%), hypotension (remifentanil 16%, fentanyl 10%), and ischemia (remifentanil 0%, fentanyl 2%) were also similar. A greater percentage of patients in the remifentanil group lost consciousness within 1 minute of opioid administration (86% v 66%, p = 0.034).

CONCLUSION

Remifentanil with glycopyrrolate is associated with rapid and predictable clinical anesthetic effect, cardiac stability, and the ability to blunt the hemodynamic responses to tracheal intubation. Bolus remifentanil may be a feasible alternative to bolus fentanyl for induction of anesthesia in patients with heart disease because of its short duration of action and its ability to blunt the hemodynamic responses to tracheal intubation.

Tracheal intubation conditions and cardiovascular effects after modified rapid-sequence induction with sevoflurane-rapacuronium versus propofol-rapacuronium

STUDY OBJECTIVES

To compare intubation conditions and hemodynamic effects resulting from rapid-sequence induction of anesthesia with sevoflurane-rapacuronium and propofol-rapacuronium.

DESIGN

Randomized, blinded study.

SETTING

Operating suites of a large university-affiliated medical center.

PATIENTS

40 ASA physical status I and II adult patients without airway abnormalities who were scheduled for elective surgery requiring endotracheal intubation.

INTERVENTIONS

Patients were randomly allocated to receive either sevoflurane inhalational induction (Group 1) or propofol (2 mg/kg) intravenous induction (Group 2). Group 1 patients were coached on how to perform vital capacity breathing and the anesthesia machine was primed with sevoflurane 8%, N2O:O2 3.5:1.5 L/min. In both groups, when loss of consciousness was established, rapacuronium 1.5 mg/kg was administered. After 50 seconds, an anesthesiologist blinded to the study entered the room and attempted laryngoscopy and intubation.

MEASUREMENTS

Intubation conditions were graded as excellent, good, poor, or impossible according to Good Clinical Research Practice (GCRP) criteria. Arterial blood pressure and heart rate changes accompanying both induction techniques were also monitored and recorded.

MAIN RESULTS

All patients were successfully intubated within 60 seconds. Clinically acceptable intubating conditions (excellent or good scores) were obtained in 19 of 20 Group 1 patients and in 19 of 20 Group 2 patients. Moderate tachycardia was encountered in both groups and mild systolic hypotension in the Group 2 patients. There were no complications.

CONCLUSIONS

Modified rapid-sequence inhalational induction using sevoflurane and rapacuronium produced clinically acceptable intubation conditions within 60 seconds of muscle relaxant administration. The intubation conditions were similar to those produced after intravenous propofol and rapacuronium.