Effectiveness and sequelae of very low-dose suxamethonium for nasal intubation

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).

To Compare the Intravenous Bolus Dose of Propofol With an Equipotent Dose of Intravenous Thiopentone for the Facilitation of Laryngeal Mask Airway Insertion

Objectives Insertion of laryngeal mask airway has been facilitated by using a variety of induction agents and their combinations with minimal side effects. The current prospective study is a randomized, double-blind study conducted using induction agents, namely, propofol and its equipotent dose of thiopentone, for laryngeal mask airway insertion, and to compare their side effects in patients undergoing minor surgeries requiring general anaesthesia. Methods This prospective study was carried out at the Anaesthesiology and Critical Care Department of Gauhati Medical College and Hospital (GMCH), Assam, India. The randomized, double-blinded study comprised 80 patients aged 18 to 60 years undergoing minor surgeries (≤45 minutes) under general anaesthesia fitting into the American Society of Anesthesiologists (ASA) physical status I and II and Mallampati score (MPS) 1 and 2. The participants were randomly divided into two groups in a 1:1 ratio. Group A (n = 40) received propofol (2.5 mg/kg), while group B (n = 40) received thiopentone (5 mg/kg) injections for induction of anaesthesia. Pre-medication with midazolam (0.04 mg/kg) injection and fentanyl (1.5 mcg/kg) injection was provided to patients in both groups. Post-laryngeal mask airway insertion, parameters like conditions for insertion, time taken for laryngeal mask airway insertion, overall response, and haemodynamic parameters were recorded. The data analysis was executed using equivalence tests considering a two-sided p < 0.05 as significant. Results Group A had a higher and statistically significant ease of insertion (p = 0.029). The mean insertion time was notably different between the two groups (p < 0.001). The difference in the overall response to insertion showed no statistical significance in the two groups. Statistically, a significant difference was found in falls in heart rate and various blood pressure levels between the groups (p < 0.001). Conclusion Propofol at a rate of 2.5 mg/kg was found to be superior to thiopentone at a rate of 5 mg/kg as far as suppression of upper airway reflexes in laryngeal mask airway insertion.

The optimal dose of succinylcholine for rapid sequence induction: a systematic review and meta-analysis of randomized trials

BACKGROUND

The evidence base for the widely accepted standard regimen of succinylcholine for rapid sequence induction (1.0 mg kg- 1) remains unclear.

METHODS

We performed a systematic review and meta-analysis of randomized trials comparing any succinylcholine regimen with the standard regimen (1.0 mg kg- 1) and reporting on intubating conditions and/or apnoea times. Results were expressed as absolute risk differences (ARD) for dichotomous data and mean differences (MD) for continuous data.

RESULTS

We retrieved six trials with relevant data of 864 patients (ASA 1 or 2, aged 18-65 years, body mass index < 30 kg m- 2). Four regimens (0.3, 0.4, 0.5, 0.6 mg kg- 1) were compared with 1.0 mg kg- 1 in at least three trials each, and three (0.8, 1.5, 2 mg kg- 1) in one each. With 0.3 to 0.5 mg kg- 1, the likelihood of excellent intubating conditions was significantly decreased (ARD - 22% to - 67%). With 0.3 and 0.4 mg kg- 1, but not with 0.5, 0.6, 0.8, 1.5 and 2.0 mg kg- 1, the likelihood of unacceptable intubating conditions was significantly increased (ARD + 22% and + 32%, respectively). With 2.0 mg kg- 1, but not with 0.8 or 1.5 mg kg- 1, the likelihood of excellent intubating conditions was significantly increased (ARD + 23%). Apnoea times were significantly shorter with regimens ≤0.8 mg kg- 1 (MD - 1.0 to - 3.4 min) but were not reported with 1.5 or 2.0 mg kg- 1.

CONCLUSIONS

With succinylcholine regimens ≤0.5 mg kg- 1, excellent intubating conditions are less likely and apnoea times are shorter, compared with 1 mg kg- 1. With 0.3 and 0.4 mg kg- 1, unacceptable intubating conditions are more common. Succinylcholine 1.5 mg kg- 1 does not produce more often excellent conditions compared with 1 mg kg- 1, while 2.0 mg kg- 1 does, but the database with these regimens is weak and apnoea times remain unknown. Limited information size and strong statistical heterogeneity decrease the certainty of the evidence.

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.

A Randomized Controlled Trial to Compare Preemptive Analgesic Efficacy and Safety of Pregabalin and Gabapentin for Succinylcholine-Induced Myalgia

Background

Succinylcholine is a drug of choice for rapid induction of anesthesia but produces postoperative myalgia. Preemptive analgesia is intended to decrease perception of pain before exposure to painful stimuli. Pregabalin and gabapentin, analogs of the inhibitory neurotransmitter gamma aminobutyric acid, are effective in several models of neuropathic pain, incisional, inflammatory, and formalin-induced injury. However, the data available on their preemptive analgesic efficacy in succinylcholine myalgia are sparse. This study was designed to compare the preemptive analgesic efficacy and safety of pregabalin and gabapentin.

Materials and Methods

This randomized clinical trial included 120 surgical patients of either sex, between 18 and 70 years, and of American Society of Anesthesiologists-I/II grade. Patients were randomly allocated to control and test groups; received respective treatments 30 min before induction of anesthesia. Myalgia and pain scores were recorded using the myalgia scale and visual analog/facial rating scale at awakening at 6, 12, 18, and 24 h, respectively. Postoperative analgesic requirement over 24 h was recorded. Data were analyzed using OpenEpi (Andrew G. Dean and Kevin M. Sullivan, Atlanta, GA, USA) statistical softwares.

Results

Significantly lower pain scores were observed in the pregabalin group at 6, 12, and 24 h, and in gabapentin group at 24 h as compared to control and placebo (P < 0.05). They were however found to be equianalgesic when compared to each other (P > 0.05). Pregabalin-treated patients were more comfortable throughout with significantly less postoperative myalgia and analgesic requirement (P < 0.05).

Conclusions

Results strongly suggest the preemptive analgesic efficacy of a single oral dose of pregabalin and gabapentin over diclofenac in postoperative myalgia and pain management. However, on the basis of safety profile, pregabalin may be preferred over gabapentin in succinylcholine-induced myalgia.

Optimal dose of succinylcholine for laryngeal mask airway insertion: systematic review, meta-analysis and metaregression of randomised control trials

OBJECTIVES

To evaluate the optimal dose of succinylcholine for laryngeal mask airway (LMA) insertion and all related morbidities.

DESIGN

Systematic review, meta-analysis and metaregression of randomised controlled trials (RCTs).

DATA SOURCE AND STUDY ELIGIBILITY CRITERIA

A comprehensive search of RCTs in the PubMed, Embase, the Cochrane Library and the ClinicalTrials.gov registry up to July 2016 and articles that evaluated the use of succinylcholine chloride for LMA insertion were included in the analyses. The relative risk (RR) and the corresponding 95% CIs were determined.

INTERVENTION

Succinylcholine as the coinduction agent and the doses were divided into mini (≤0.3 mg/kg) and low (0.3-1.0 mg/kg) doses for dose-dependent effect analyses.

PRIMARY AND SECONDARY OUTCOMES

The primary outcome was the first-attempt LMA insertion failure rate. Secondary outcomes included all related adverse events.

RESULTS

Data from 10 RCTs comprising 625 participants showed that succinylcholine reduced the first-attempt LMA insertion failure rate (RR, 0.22; 95% CI 0.12 to 0.43), coughing and gagging (RR, 0.26; 95% CI 0.15 to 0.45) and laryngospasm (RR, 0.14; 95% CI 0.05 to 0.39). The use of succinylcholine did not result in a significant increase of postoperative myalgia (RR, 2.58; 95% CI 0.79 to 8.44) and did not reduce the risk of postoperative sore throat (RR, 0.76; 95% CI 0.55 to 1.03). Subgroup analysis further showed that low-dose succinylcholine reduced the LMA insertion failure rate and its related coughing and gagging when compared with mini dose.

CONCLUSION

The use of succinylcholine compared with none can facilitate LMA insertion and reduce insertion-related reflexes without significant postoperative myalgia. However, additional prospective studies with a larger sample size are required to fully evaluate the dose-dependent effect and complications of succinylcholine for LMA insertion.

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.

Intubating conditions following rapid sequence induction with three doses of succinylcholine

Background:

The aim of this prospective, randomized, double-blind study was to compare tracheal intubating conditions and the duration of apnoea following administration of 0.4, 0.6 and 1.0 mg/kg of succinylcholine during simulated rapid sequence induction of anaesthesia.

Methods:

Anaesthesia was induced with fentanyl 2 μg/kg and propofol 2 mg/kg followed by application of cricoid pressure. Patients were randomly allocated to three groups according to the dose of succinylcholine administered (0.4, 0.6 or 1.0 mg/kg). Intubating conditions were assessed at 60 s after succinylcholine administration. Time to first diaphragmatic contraction (apnoea time) and time to resumption of regular spontaneous breathing were noted.

Results:

Excellent intubating conditions were obtained in 52.4%, 95.7% and 100% of the patients after 0.4, 0.6 and 1.0 mg/kg succinylcholine, respectively; P<0.001. Acceptable intubating conditions (excellent and good grade combined) were obtained in 66.7%, 100% and 100% of the patients after 0.4, 0.6 and 1.0 mg/ kg succinylcholine, respectively; P<0.001. Apnoea time and resumption of regular spontaneous breathing were dose-dependent. Apnoea time was 3.8±1.1 min, 4.3±0.9 min and 8.2±3.4 min in groups 0.4, 0.6 and 1.0 mg/kg, respectively; P<0.001. Time to regular spontaneous breathing was 5.3±1.2 min, 5.5±1.1 min and 8.9±3.5 min in groups 0.4, 0.6 and 1.0 mg/kg, respectively; P<0.001.

Conclusion:

A dose of 0.6 mg/kg succinylcholine can be used for rapid sequence induction of anaesthesia as it provides acceptable intubating conditions with a shorter apnoea time compared with a dose of 1 mg/kg.

The optimal succinylcholine dose for intubating emergency patients: retrospective comparative study

Background

Succinylcholine remains the drug of choice for satisfactory rapid-sequence tracheal intubation. It is not clear from the literature why the 1 mg/kg dose of succinylcholine has been traditionally used. The effective dose (ED95) of succinylcholine is less than 0.3 mg/kg. The dose of 1 mg/kg represents 3.5 to 4 times the ED₉₅.

Objectives

To compare the effect of the traditionally used 1 mg/kg of succinylcholine with lower doses of 0.6 mg/kg and 0.45 mg/kg on intubation condition regarding the onset time, duration of action, duration of abdominal fasciculation, and the intubation grading.

Methods

This retrospective comparative study was carried into three groups of ASA III & IV (American Society of Anesthesiologist's Physical Status III and IV) non-prepared emergency patients who were intubated at emergency department of Hamad General Hospital, Doha, Qatar during January 1st 2007 to August 31, 2010. The Institutional Research Board (IRB) approval was obtained. This study was limited to 88 patients who received fentanyl 1µg/kg followed by etomidate 0.3 mg/kg intravenously as induction agents and succinylcholine as a muscle relaxant agent in doses of 0.45 mg/kg, 0.6 mg/kg, or 1 mg/kg.

Results

Increasing the succinylcholine dosage shortened the onset time, prolonged the duration of action, and prolonged the duration of abdominal fasciculation significantly (P<.001). Tracheal intubation was 100% successful in the three groups of patients.

Conclusion

Succinylcholine dose of 0.45 mg/kg provides an optimal intubation condition in ASA III & IV emergency non-prepared patients. Duration of action of succinylcholine is dose dependent; reducing the dose allows a more rapid return of spontaneous respiration and airway reflexes.

Is 0.6 mg/kg of succinylcholine adequate for tracheal intubation in Korean?

BACKGROUND

The usual dose of succinylcholine for tracheal intubation is 1.0 mg/kg. If the patient is not ventilated by face mask after administration of the succinylcholine (1.0 mg/kg), the patient may experience significant hemoglobin desaturation. The purpose of the present study was to evaluate an appropriate dose of succinylcholine for tracheal intubation in Korean.

METHODS

Sixty patients scheduled for elective surgery were randomly divided into three groups; group I (succinylcholine 0.3 mg/kg, n = 20), group II (succinylcholine 0.6 mg/kg, n = 20), group III (succinylcholine 1.0 mg/kg, n = 20). All patients were not premedicated. After loss of consciousness, the patients received succinylcholine 0.3, 0.6, 1.0 mg/kg, respectively. The contraction responses of the adductor pollices muscle were monitored by using TOF. Tracheal intubation was accomplished as the height of T1 was inhibited maximally. Then, intubation scores were recorded. The recovery times from neuromuscular blockade in groups II and III were also measured.

RESULTS

The acceptable conditions for tracheal intubation were 30%, 100%, and 100%, respectively in groups I, II, and III. The onset time was 80.4 +/- 15.5 sec, 69.6 +/- 13.1 sec, and 56.1 +/- 9.3 sec, respectively. The recovery time (T1 = 90%) was 446.0 +/- 86.2 sec, 694.0 +/- 84.7 sec, respectively in groups II and III. The onset time was the fastest in group III. But the recovery time in group III was slower than in group II.

CONCLUSIONS

We concluded that 0.6 mg/kg of succinylcholine is an appropriate dose for tracheal intubation in Korean except for rapid sequence intubation.

The Neuromuscular Effects and Tracheal Intubation Conditions After Small Doses of Succinylcholine

Succinylcholine 1.0 mg/kg usually produces excellent tracheal intubation conditions in 60 s. Recovery of respiratory muscle function after this dose, however, is not fast enough to forestall oxyhemoglobin desaturation when ventilation cannot be assisted. In this study, we investigated whether smaller doses of succinylcholine can produce satisfactory intubation conditions fast enough to allow rapid sequence induction with a shorter recovery time. Anesthesia was induced with fentanyl/propofol and maintained by propofol infusion and N(2)O in O(2). After the induction, 115 patients were randomly allocated to five groups according to the dose of succinylcholine (0.3 mg/kg, 0.4 mg/kg, 0.5 mg/kg, 0.6 mg/kg, or 1.0 mg/kg). Evoked adductor pollicis responses to continuous 1-Hz supramaximal ulnar nerve stimulation were recorded using acceleromyography. Tracheal intubation conditions were graded 60 s after succinylcholine administration. Onset time, maximal twitch depression, time to initial twitch detection after paralysis, and to 10%, 25%, 50%, and 90% twitch height recovery were recorded. Time to initial diaphragmatic movement as well as time to resumption of regular spontaneous respiratory movements were calculated. Onset times ranged between 82 s and 52 s, decreasing with increasing doses of succinylcholine but not differing between 0.6 and 1 mg/kg. Maximum twitch depression was similar after 0.5, 0.6, and 1 mg/kg (98.2%-100%). Recoveries of twitch height and apnea time were dose-dependent. Intubation conditions were often unacceptable after 0.3- and 0.4-mg/kg doses. Acceptable intubation conditions were achieved in all patients receiving a 0.5, 0.6, and 1 mg/kg dose of succinylcholine. Intubation conditions in patients receiving 0.6 and 1 mg/kg were identical, whereas times to T(1) = 50% and 90% and time to regular spontaneous reservoir bag movements were significantly shorter in the 0.6-mg/kg dose group (5.78, 7.25, and 4.0 min, respectively) versus patients receiving 1 mg/kg (8.55, 10.54, and 6.16 min, respectively). The use of 0.5 to 0.6 mg/kg of succinylcholine can produce acceptable intubation conditions 60 s after administration. The conditions achieved after 0.6 mg/kg are similar to those after 1.0 mg/kg. These smaller doses are associated with faster twitch recovery and shorter apnea time.

IMPLICATIONS

In normal healthy patients, succinylcholine 0.6 mg/kg produces clinical intubation conditions identical to the traditional 1.0-mg/kg dose but is associated with a shorter recovery time.

Intubation conditions and postoperative myalgia in outpatient dental surgery: a comparison of succinylcholine with mivacurium

Ninety-four patients undergoing elective outpatient third molar extraction were recruited into a double-blind, randomized, prospective trial comparing mivacurium (group M) with succinylcholine (Group S) for conditions for endotracheal intubation and the occurrence of postoperative myalgia. Anaesthesia was induced with fentanyl 1 microgram.kg-1 and propofol 2.5 micrograms.kg-1 in all patients. Group S patients were given gallamine 20 mg while group M patients were given mivacurium 0.2 mg.kg-1. Manual ventilation was commenced and anaesthesia maintained with nitrous oxide 70% and isoflurane 1 to 2% in oxygen. After two minutes, group S patients were given succinylcholine 1.5 mg.kg-1 and group M patients 0.9% saline. Nasotracheal intubation was performed 30 seconds later. Intubating conditions in group M were significantly better than those in group S (P < 0.001). The incidence of postoperative myalgia was 9.5% in group M and 26% in group S but this was not statistically significant (P = 0.09). We propose that mivacurium is a suitable neuromuscular blocker to use for endotracheal intubation in outpatient dental surgery.

Mivacurium compared with three different doses of suxamethonium for nasotracheal intubation

Suxamethonium in the doses of 1.0, 0.5 and 0.25 mg/kg was compared with mivacurium 0.15 mg/kg in 80 patients requiring nasotracheal intubation for maxillofacial surgery in a double-blind randomized controlled trial. Anaesthesia was induced with thiopentone 5 mg/kg and alfentanil 15 micrograms/kg. Patients were randomly allocated to one of the four relaxant groups. Anaesthesia was maintained with enflurane in 70% nitrous oxide and 30% oxygen and analgesia provided with intravenous pethidine 0.5 to 1.5 mg/kg and rectal indomethacin 100mg. All patients given mivacurium or suxamethonium 1 mg/kg had acceptable intubating conditions. Significantly fewer patients given suxamethonium 0.5 mg or 0.25 mg/kg had acceptable intubating conditions (90% and 70% respectively) (P = 0.003). Poor intubating conditions requiring additional relaxation were seen in two patients given suxamethonium 0.25 mg/kg and two given 0.5 mg/kg, while no patients given suxamethonium 1.0 mg/kg or mivacurium 0.15 mg/kg required additional relaxation (P = 0.004). Only four patients had postoperative myalgia, all of whom were given suxamethonium 0.5 mg/kg or more but no significant difference between groups could be demonstrated.