AnaesthesiaVolume 79, Issue 4 p. 344-348 Editorial Residual neuromuscular block: time to consign it to history G. Rodney, Corresponding Author G. Rodney Consultant [email protected] grantrod0606 Department of Anaesthetics, Ninewells Hospital, Dundee, UK Correspondence to: G. Rodney Email: [email protected]Search for more papers by this authorP. K. B. C. Raju, P. K. B. C. Raju Consultant Anaespk Department of Anaesthetics, Ninewells Hospital, Dundee, UKSearch for more papers by this authorS. J. Brull, S. J. Brull Professor Emeritus, Consultant Mayo Clinic College of Medicine and Science, Jacksonville, FL, USA Mayo Clinic Florida, Jacksonville, FL, USASearch for more papers by this author G. Rodney, Corresponding Author G. Rodney Consultant [email protected] grantrod0606 Department of Anaesthetics, Ninewells Hospital, Dundee, UK Correspondence to: G. Rodney Email: [email protected]Search for more papers by this authorP. K. B. C. Raju, P. K. B. C. Raju Consultant Anaespk Department of Anaesthetics, Ninewells Hospital, Dundee, UKSearch for more papers by this authorS. J. Brull, S. J. Brull Professor Emeritus, Consultant Mayo Clinic College of Medicine and Science, Jacksonville, FL, USA Mayo Clinic Florida, Jacksonville, FL, USASearch for more papers by this author First published: 29 January 2024 https://doi.org/10.1111/anae.16238Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat References 1Klein AA, Meek T, Allcock E, et al. Recommendations for standards of monitoring during anaesthesia and recovery 2021: guideline from the Association of Anaesthetists. Anaesthesia 2021; 76: 1212–1223. 10.1111/anae.15501 CASPubMedWeb of Science®Google Scholar 2Thilen SR, Weigel WA, Todd MM, et al. 2023 American Society of Anesthesiologists Practice Guidelines for Monitoring and Antagonism of Neuromuscular Blockade: a report by the American Society of Anesthesiologists Task Force on Neuromuscular Blockade. Anesthesiology 2023; 138: 13–41. 10.1097/ALN.0000000000004379 PubMedWeb of Science®Google Scholar 3Fuchs-Buder T, Romero CS, Lewald H, et al. Peri-operative management of neuromuscular blockade: a guideline from the European Society of Anaesthesiology and Intensive Care. European Journal of Anaesthesiology 2023; 40: 82–94. 10.1097/EJA.0000000000001769 PubMedWeb of Science®Google Scholar 4Naguib M, Brull SJ, Hunter JM, Kopman AF, Fülesdi B, Johnson KB, Arkes HR. Anesthesiologists' overconfidence in their perceived knowledge of neuromuscular monitoring and its relevance to all aspects of medical practice: an international survey. Anesthesia and Analgesia 2019; 128: 1118–1126. 10.1213/ANE.0000000000003714 PubMedWeb of Science®Google Scholar 5Carvalho H, Verdonck M, Cools W, Geerts L, Forget P, Poelaert J. Forty years of neuromuscular monitoring and postoperative residual curarisation: a meta-analysis and evaluation of confidence in network meta-analysis. British Journal of Anaesthesia 2020; 125: 466–482. 10.1016/j.bja.2020.05.063 PubMedWeb of Science®Google Scholar 6Klucka J, Kosinova M, Krikava I, Stoudek R, Toukalkova M, Stourac P. Residual neuromuscular block in paediatric anaesthesia. British Journal of Anaesthesia 2019; 122: e1–e2. 10.1016/j.bja.2018.10.001 CASPubMedWeb of Science®Google Scholar 7Kotake Y, Ochiai R, Suzuki T, et al. Reversal with sugammadex in the absence of monitoring did not preclude residual neuromuscular block. Anesthesia and Analgesia 2013; 117: 345–351. 10.1213/ANE.0b013e3182999672 PubMedWeb of Science®Google Scholar 8Hunter JM, Naguib M. Sugammadex-induced bradycardia and asystole: how great is the risk? British Journal of Anaesthesia 2018; 121: 8–12. 10.1016/j.bja.2018.03.003 CASPubMedWeb of Science®Google Scholar 9Orihara M, Takazawa T, Horiuchi T, et al. Comparison of incidence of anaphylaxis between sugammadex and neostigmine: a retrospective multicentre observational study. British Journal of Anaesthesia 2020; 124: 154–163. 10.1016/j.bja.2019.10.016 PubMedWeb of Science®Google Scholar 10Savic L, Savic S, Hopkins PM. Anaphylaxis to sugammadex: should we be concerned by the Japanese experience? British Journal of Anaesthesia 2020; 124: 370–372. 10.1016/j.bja.2020.01.003 Web of Science®Google Scholar 11Thomsen JLD, Marty AP, Wakatsuki S, Macario A, Tanaka P, Gätke MR, Østergaard D. 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Anesthesia and Analgesia 2018; 127: 71–80. 10.1213/ANE.0000000000002670 PubMedWeb of Science®Google Scholar 15Weigel WA, Williams BL, Hanson NA, et al. Quantitative neuromuscular monitoring in clinical practice: a professional practice change initiative. Anesthesiology 2022; 136: 901–915. 10.1097/ALN.0000000000004174 PubMedWeb of Science®Google Scholar 16Edwards LA, Ly N, Shinefeld J, Morewood G. Universal quantitative neuromuscular blockade monitoring at an academic medical center - a multimodal analysis of the potential impact on clinical outcomes and total cost of care. Perioperative Care and Operating Room Management 2021; 24: 100184. 10.1016/j.pcorm.2021.100184 Google Scholar 17Bowdle TA, Haththotuwegama KJ, Jelacic S, Nguyen ST, Togashi K, Michaelsen KE. A dose-finding study of sugammadex for reversal of rocuronium in cardiac surgery patients and postoperative monitoring for recurrent paralysis. 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Learning objectivesBy reading this article you should be able to:•Explain the definitions of depth of neuromuscular block using post-tetanic count, train-of-four count and train-of-four ratio.•Discuss the pharmacological variability of neuromuscular blocking and reversal drugs.•Detail the consequences of residual block and its prevention.•Describe the differences between acceleromyography and electromyography and their clinical use.Key points•Recent guidelines address monitoring of neuromuscular blocking drugs and antagonists.•Residual neuromuscular block is common, unrecognised and causes harm to patients.•Recovery from neuromuscular block requires a calibrated train-of-four ratio ≥0.9.•Quantitative monitoring is essential to optimise surgical conditions and avoid residual neuromuscular block.•Antagonism is more predictable with sugammadex than with neostigmine, but cannot guarantee recovery without quantitative monitoring. By reading this article you should be able to:•Explain the definitions of depth of neuromuscular block using post-tetanic count, train-of-four count and train-of-four ratio.•Discuss the pharmacological variability of neuromuscular blocking and reversal drugs.•Detail the consequences of residual block and its prevention.•Describe the differences between acceleromyography and electromyography and their clinical use. •Recent guidelines address monitoring of neuromuscular blocking drugs and antagonists.•Residual neuromuscular block is common, unrecognised and causes harm to patients.•Recovery from neuromuscular block requires a calibrated train-of-four ratio ≥0.9.•Quantitative monitoring is essential to optimise surgical conditions and avoid residual neuromuscular block.•Antagonism is more predictable with sugammadex than with neostigmine, but cannot guarantee recovery without quantitative monitoring. Monitoring and reversal of neuromuscular block have been reviewed extensively, including in this journal.1Hunter J.M. Reversal of neuromuscular block.BJA Educ. 2020; 20: 259-265Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar,2McGrath C.D. Hunter J.M. Monitoring of neuromuscular block.CEACCP. 2006; 6: 7-12Google Scholar Issues with management of neuromuscular block (NMB) and residual block persist, despite the introduction of the intermediate duration neuromuscular blocking drugs (NMBDs) in the 1980s, the reversal agent sugammadex in 2008, and availability of an increasing array of quantitative neuromuscular monitors for clinical practice. The most recent guidance from the Association of Anaesthetists (AoA), the American Society of Anesthesiologists (ASA) and the European Society of Anaesthesiology and Intensive Care (ESAIC) are reviewed, as will key aspects of neuromuscular physiology and pharmacology pertinent to clinical practice. A clinical practice strategy is described that uses quantitative neuromuscular monitoring for all patients receiving neuromuscular blocking drugs and offers guidance for neuromuscular block antagonism. The information is primarily intended to guide perioperative care of adult patients, but the principles are equally applicable to paediatric patients and critical care. Decades of evidence, expert opinion and editorial reviews have culminated in the publication of three landmark papers from the AoA, the ASA and the ESAIC.3Raval A.D. Uyei J. Karabis A. Bash L.D. Brull S.J. Incidence of residual neuromuscular blockade and use of neuromuscular blocking agents with or without antagonists: a systematic review and meta-analysis of randomized controlled trials.J Clin Anesth. 2020; 64109818Crossref PubMed Scopus (24) Google Scholar, 4Naguib M. Brull S.J. Kopman A. colleagues Consensus statement on perioperative use of neuromuscular monitoring.Anesth Analg. 2018; 127: 71-80Crossref PubMed Scopus (171) Google Scholar, 5Blobner M. Hollmann M.W. Luedi M.M. Johnson K.B. Pro-con debate: do we need quantitative neuromuscular monitoring in the era of sugammadex?.Anesth Analg. 2022; 135: 39-48Crossref PubMed Scopus (8) Google Scholar, 6Klein A.A. Meek T. Allcock E. et al.Recommendations for standards of monitoring during anaesthesia and recovery 2021: guideline from the Association of Anaesthetists.Anaesthesia. 2021; 76: 1212-1223Crossref PubMed Scopus (113) Google Scholar, 7Thilen S.R. Weigel W.A. Todd M.M. et al.American Society of Anesthesiologists practice guidelines for monitoring and antagonism of neuromuscular blockade: a report by the American Society of Anesthesiologists Task Force on neuromuscular blockade.Anesthesiology. 2023; 138: 13-41Crossref PubMed Scopus (42) Google Scholar, 8Fuchs-Buder T. Romero C.S. Lewald H. et al.Peri-operative management of neuromuscular blockade: a guideline from the European society of Anaesthesiology and intensive care.Eur J Anaesthesiol. 2023; 40: 82-94Crossref PubMed Scopus (32) Google Scholar The standout theme of these publications is the need for quantitative neuromuscular monitoring when patients receive neuromuscular blocking drugs. The 6th edition (2021) of the AoA's monitoring standards is a consensus document stating: "quantitative neuromuscular monitoring should be used whenever neuromuscular blocking drugs are given, throughout all phases of anaesthesia from before initiation of neuromuscular block until recovery of the train-of-four (TOF) ratio to >0.9 has been confirmed."6Klein A.A. Meek T. Allcock E. et al.Recommendations for standards of monitoring during anaesthesia and recovery 2021: guideline from the Association of Anaesthetists.Anaesthesia. 2021; 76: 1212-1223Crossref PubMed Scopus (113) Google Scholar The guideline further calls for all locations where patients receive neuromuscular blocking drugs to be equipped with quantitative monitoring devices. A task force of ASA members has produced clinical practice guidelines (2023) on the management of neuromuscular block.7Thilen S.R. Weigel W.A. Todd M.M. et al.American Society of Anesthesiologists practice guidelines for monitoring and antagonism of neuromuscular blockade: a report by the American Society of Anesthesiologists Task Force on neuromuscular blockade.Anesthesiology. 2023; 138: 13-41Crossref PubMed Scopus (42) Google Scholar Eight recommendations were produced according to the strength of available evidence. For optimal anaesthesia care, the panel strongly recommends quantitative monitoring over the use of clinical signs or a qualitative peripheral nerve stimulator (PNS), using the adductor pollicis muscle for neuromuscular monitoring, and recommends against monitoring the eye muscle responses to facial nerve stimulation. An ESAIC task force (2023) simultaneously developed guidelines for the perioperative management of neuromuscular block based on three key topics: the need for neuromuscular blocking agents to facilitate tracheal intubation; the impact of deep block on outcomes from abdominal surgery; and strategies to best diagnose and treat residual neuromuscular block.8Fuchs-Buder T. Romero C.S. Lewald H. et al.Peri-operative management of neuromuscular blockade: a guideline from the European society of Anaesthesiology and intensive care.Eur J Anaesthesiol. 2023; 40: 82-94Crossref PubMed Scopus (32) Google Scholar The key findings in relation to the risk of residual neuromuscular block and harm to patients exactly mirrored the ASA guidelines and called for "the use of ulnar nerve stimulation and quantitative neuromuscular monitoring at the adductor pollicis to exclude residual paralysis." Both documents provide guidance on antagonism and dosing recommendations for sugammadex and neostigmine, dependent on block level and underpinned by quantitative monitoring. However, neither guideline addresses neuromuscular management of the paediatric or critical care populations. The depth of neuromuscular block can be defined based on the train-of-four (TOF) ratio, TOF count, and post-tetanic count (PTC) when using quantitative monitoring (Fig. 1).4Naguib M. Brull S.J. Kopman A. colleagues Consensus statement on perioperative use of neuromuscular monitoring.Anesth Analg. 2018; 127: 71-80Crossref PubMed Scopus (171) Google Scholar This allows for consistency in understanding the applied pharmacology and its relevance to safe clinical care. Relaxation of the upper abdominal muscles, the larynx and the diaphragm requires complete (PTC=0) or deep (PTC≥1, TOF count=0) neuromuscular block. Deep neuromuscular block during laparoscopic surgery may improve outcomes, though evidence is conflicting. Surgical conditions are improved in many patients studied using deep block (PTC=0–5) but the clinical benefit is marginal and study shortcomings are evident.8Fuchs-Buder T. Romero C.S. Lewald H. et al.Peri-operative management of neuromuscular blockade: a guideline from the European society of Anaesthesiology and intensive care.Eur J Anaesthesiol. 2023; 40: 82-94Crossref PubMed Scopus (32) Google Scholar There is insufficient evidence for reduced postoperative pain or decreased incidence of perioperative complications. Instead, individualised titration of depth of neuromuscular block is best guided by monitoring and surgical conditions.8Fuchs-Buder T. Romero C.S. Lewald H. et al.Peri-operative management of neuromuscular blockade: a guideline from the European society of Anaesthesiology and intensive care.Eur J Anaesthesiol. 2023; 40: 82-94Crossref PubMed Scopus (32) Google Scholar Moderate block (TOFC=1–3) is likely to be sufficient to keep the patient immobile in most surgeries, provided adequate levels of anaesthesia are maintained. Coughing, respiratory efforts and other involuntary movements may be addressed by deepening the level of anaesthesia (with additional volatile anaesthetic, propofol or opioids). Adequacy of anaesthesia, including use of processed EEG, should be confirmed before giving additional neuromuscular blocking drugs. The need to ensure adequate anaesthesia during neuromuscular block was highlighted by the 5th National Audit Project (NAP5) study of accidental awareness under general anaesthesia.9Raval A.D. Anupindi V.R. Ferrufino C.P. Arper D.L. Bash L.D. Brull S.J. Epidemiology and outcomes of residual neuromuscular blockade: a systematic review of observational studies.J Clin Anesth. 2020; 66109962Crossref PubMed Scopus (14) Google Scholar On return of the 4th twitch of a TOF sequence, two levels of block can be defined: shallow block (TOF ratio <0.4); and minimal block (TOF ratio 0.4–0.9) (Fig. 1). There is a wide range of symptoms and signs, even at minimal block in the extubated patient, including reduced vital capacity and hand grip strength, impaired swallowing, increased pulmonary aspiration risk, upper airway obstruction, diplopia, subjective feelings of weakness, delayed recovery and reduced chemoreceptor-mediated response to hypoxia. Acceptable recovery is reached once the TOF ratio recovers to ≥0.9, but even when TOF ratio=1.0, most postsynaptic receptors are still occupied by the neuromuscular blocking agent; thus, forced vital capacity is only partially recovered, and the acute ventilatory response to hypoxia is depressed from normal.10Fortier L.P. McKeen D. Turner K. et al.The RECITE study: a Canadian prospective, multicenter study of the incidence and severity of residual neuromuscular blockade.Anesth Analg. 2015; 121: 366-372Crossref PubMed Scopus (143) Google Scholar The larynx, diaphragm, upper abdominal, and corrugator supercilii muscles display relative resistance to neuromuscular block. Their rich blood supply ensures a rapid onset (wash-in) of non-depolarising neuromuscular block, but a limited peak effect and a rapid recovery (wash-out). By contrast, the most sensitive muscles (ocular, pharyngeal and genioglossus) are slowest to recover. Other factors, such as the number of postsynaptic receptors relative to fibre size, also contribute to the differential muscle sensitivity. Inadequate recovery signs include diplopia, swallowing difficulty, genioglossus muscle weakness and result in an increased risk of upper airway obstruction and pulmonary aspiration. The adductor pollicis and the orbicularis oculi muscle responses suggest similar sensitivity. The ulnar nerve/adductor pollicis muscle unit is recommended for quantitative neuromuscular block monitoring because of ease of access to the hand and close correlation with recovery of most sensitive muscles, providing an extra level of safety . Onset of block and recovery times vary greatly. The predicted onset time for standard intubation doses of 2×ED95 (ED95=amount of drug required to reduce baseline twitch height by 95%) of rocuronium ranges from 2 to 3 min, but multiple factors affect it: young age, female sex, rapid injection rate, use of priming, coadministration of ephedrine, all shorten onset time; whereas esmolol increases it. The duration of neuromuscular block may be prolonged with increasing age, female sex, pregnancy, coexisting renal or hepatic disease and by drugs including magnesium, esmolol and aminoglycoside antibiotics. Notwithstanding any of these factors, there is wide variability in time-to-twitch and TOF ratio depression and achieving ideal conditions for intubation. Recovery time also varies greatly. Two hours after a single intubating dose of vecuronium, rocuronium or atracurium, 37% of patients had TOF ratios <0.9, and 11% had ratios <0.7.11Carvalho H. Verdonck M. Cools W. Geerts L. Forget P. Poelaert J. Forty years of neuromuscular monitoring and postoperative residual curarisation: a meta-analysis and evaluation of confidence in network meta-analysis.Br J Anaesth. 2020; 125: 466-482Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar The median (range) duration of action of cisatracurium is 57 (37–81) min, rocuronium is 63 (33–119) min and vecuronium is 62 (35–137) min, revealing the variable and often prolonged duration of action of neuromuscular blocking drugs in some patients.12Grosse-Sundrup M. Henneman J.P. Sandberg W.S. et al.Intermediate acting non-depolarizing neuromuscular blocking agents and risk of postoperative respiratory complications: prospective propensity score matched cohort study.BMJ. 2012; 345: e6329Crossref PubMed Scopus (212) Google Scholar Even small doses of rocuronium (20–25 mg, or 1×ED95) may result in incomplete spontaneous recovery in up to 20% of patients after 2 h.13Martinez-Ubieto J. Ortega-Lucea S. Pascual-Bellosta A. et al.Prospective study of residual neuromuscular block and postoperative respiratory complications in patients reversed with neostigmine versus sugammadex.Minerva Anestesiol. 2016; 82: 735-742PubMed Google Scholar Appreciating the differences in muscle sensitivity explains why patients may still respond to laryngoscopy and intubation, why these responses may be present even when a measured adductor pollicis TOF ratio is reduced to zero and why 'time-based' decisions on readiness for intubation (or extubation) are flawed. Monitoring throughout anaesthesia allows variability between patients to be appreciated, based on individual neuromuscular responses. The current definition of residual neuromuscular block is a TOF ratio <0.9; its incidence ranges from 0% to 90.5% (median 30%).14Kirmeier E. Eriksson L.I. Lewald H. et al.POPULAR ContributorsPost-anaesthesia pulmonary complications after use of muscle relaxants (POPULAR): a multicentre, prospective observational study.Lancet Respir Med. 2019; 7: 129-140Abstract Full Text Full Text PDF PubMed Scopus (222) Google Scholar The Canadian RECITE study (performed before the registration of sugammadex in Canada) revealed a residual neuromuscular block rate of 65% at tracheal extubation, with patients managed at the discretion of anaesthetists, using neostigmine and subjective (qualitative) evaluation of peripheral nerve stimulator (PNS) responses.15Blobner M. Hunter J.M. Meistelman C. et al.Use of a train-of-four ratio of 0.95 versus 0.9 for tracheal extubation: an exploratory analysis of POPULAR data.Br J Anaesth. 2020; 124: 63-72Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar A meta-analysis of 53 studies and 12,664 patients over four decades, showed residual neuromuscular block rates of 33.1% with no neuromuscular monitoring (management guided by clinician experience and patient clinical signs) and 30.6% when using qualitative assessment.16Murphy G.S. Szokol J.W. Avram M.J. et al.Intraoperative acceleromyography monitoring reduces symptoms of muscle weakness and improves quality of recovery in the early postoperative period.Anesthesiology. 2011; 115: 946-954Crossref PubMed Scopus (131) Google Scholar Clinical tests of recovery (sustained head lift, sustained hand grip, tongue depressor tests) all fail to reliably detect residual neuromuscular block. With sensitivity rates of 10–30% and positive predictive values (precision) ∼50%, residual neuromuscular block cannot be excluded unless TOF ratios are <0.4, exposing patients to considerable harm.4Naguib M. Brull S.J. Kopman A. colleagues Consensus statement on perioperative use of neuromuscular monitoring.Anesth Analg. 2018; 127: 71-80Crossref PubMed Scopus (171) Google Scholar Use of a PNS allows subjective (tactile or visual) detection of TOF count and PTC, but only provides an unreliable estimate of recovery by evaluating fade of the fourth twitch compared with the first twitch (T4/T1) response. Whereas detection of moderate (TOF count 1–3) and deep (PTC >1) block is possible using a PNS, readiness for tracheal extubation (defined as TOF ratio ≥0.9) CANNOT be determined by subjective (non-quantitative) means. Statements such as 'four strong twitches are present' or 'there is no fade' are demonstrably false and do not guarantee adequate neuromuscular recovery. Fade assessed subjectively (visual or tactile means) cannot be detected reliably when the TOF ratio is >0.4, with a resultant wide gap (TOF ratio 0.4–0.9) when using subjective monitoring. This degree of block can only be appreciated when using quantitative measurement of the TOF ratio. When using double-burst stimulation (DBS), fade of the second of the two mini-tetanic responses cannot be detected reliably when the DBS (or TOF) ratio is >0.6. Although the gap using DBS is narrower (TOF ratio 0.6–0.9) than that of TOF (TOF ratio 0.4–0.9) when using subjective means, neither pattern can safely and reliably determine the adequacy of recovery, and their use should be abandoned (Figure 1 online video). Acceleromyography (AMG) and electromyography (EMG) monitors are most applicable in clinical practice. Both freestanding portable devices and devices integrated to widely used patient monitoring systems are available. Though no longer commercially available, the TOF-Watch (Organon, Cork, Ireland) was the first device used widely in clinical practice and has been evaluated against the 'gold standard' of mechanomyography (MMG). Acceleromyography devices utilise the principle of Newton's law: force = mass×acceleration. When a piezoelectric sensor is applied to the thumb (fixed mass) and stimulated, the acceleration in response to stimulation is directly proportional to the force of contraction. A resultant electrical signal is processed and displayed as a numerical value/ratio. There are some caveats with AMG use. Firstly, the thumb must be allowed to move unimpeded, otherwise readings are inaccurate—for example, when arms are tucked under surgical drapes and inaccessible during surgery. Two or three serial TOF measurements at 15-s intervals should always be taken, before deciding an action (need for top-up doses, determining block level, ensuring recovery after reversal) (Figure 2 online video). Secondly, unlike with MMG and EMG, the baseline TOF ratio often exceeds 1.0 (100%), with figures as high as 1.4 (140%). This 'reverse fade' is an idiosyncrasy of the technology, as supramaximal current (stimuli) should always induce maximal (therefore, equal) responses (Figure 3 online video). The mechanism is uncertain but is likely because of the elastic recoil of the thumb not returning to baseline after each TOF stimulus.17Ledowski T. O'Dea B. Meyerkort L. Hegarty M. von Ungern-Sternberg B.S. Postoperative residual neuromuscular paralysis at an Australian tertiary children's hospital.Anesthesiol Res Pract. 2015; 2015410248Google Scholar For this reason, AMG devices should be calibrated with a baseline (supramaximal) value, before neuromuscular block, and 'normalised' to determine a target ratio of 0.9 for recovery. For example, with a baseline value of 1.2, recovery to 0.9 requires a ratio of 1.08. Some AMG devices cap the ratio at 1.0 (100%) and calculate the TOF ratio as the fourth response (T4) compared with the second response (T2), or T4/T2 ratio, rather than the typical T4/T1 comparison. In clinical practice these manipulations may make relatively little difference, but they present a limitation of AMG-derived values. There is also evidence that AMG precedes EMG recovery,18Kalsotra S. Rice-Weimer J. Tobias J.D. Intraoperative electromyographic monitoring in children using a novel pediatric sensor.Saudi J Anaesth. 2023; 17: 378-382Crossref PubMed Scopus (0) Google Scholar that for AMG, recovery to 0.95 or above is required to avoid postoperative pulmonary complications19Kheterpal S. Vaughn M.T. Dubovoy T.Z. et al.Sugammadex versus neostigmine for reversal of neuromuscular blockade and postoperative pulmonary complications (STRONGER): a multicenter matched cohort analysis.Anesthesiology. 2020; 132: 1371-1381Crossref PubMed Scopus (160) Google Scholar and the ESAIC guideline recommends recovery to 1.0 when raw (uncalibrated non-normalised) ratios are used.8Fuchs-Buder T. Romero C.S. Lewald H. et al.Peri-operative management of neuromuscular blockade: a guideline from the European society of Anaesthesiology and intensive care.Eur J Anaesthesiol. 2023; 40: 82-94Crossref PubMed Scopus (32) Google Scholar A new generation of AMG devices enhances accuracy by using three-directional sensors, which account for the multidirectional movement of the adducting thumb in response to ulnar nerve stimulation. Some manufacturers claim that their products do not require calibration. In practical terms, the TOF ratio using AMG should be as close to 1.0 as possible, realising that even at this level of recovery, most (>75%) postsynaptic receptors are still blocked. Despite these caveats, AMG monitors are widely available, are simple to apply and use and an extensive evidence base shows their superiority over clinical and qualitative methods of recovery using peripheral nerve stimulation.16Murphy G.S. Szokol J.W. Avram M.J. et al.Intraoperative acceleromyography monitoring reduces symptoms of muscle weakness and improves quality of recovery in the early postoperative period.Anesthesiology. 2011; 115: 946-954Crossref PubMed Scopus (131) Google Scholar Electromyography devices measure the peak-to-peak amplitude or area under the waveform curve of the evoked muscle action potential to measure the intensity of the response. Electromyography and MMG monitoring are closely matched. There are advantages to using electrical, rather than mechanical signals. Electromyography reflects more accurately the response at the neuromuscular junction (where all neuromuscular blocking agents work), is not affected by changes in muscle contractility and responses are independent of hand position and thumb movement. Hypothermia does impact EMG responses (but less than AMG or MMG), as does interference from surgical electrocautery. The response to ulnar nerve stimulation can be measured at the adductor pollicis, abductor digiti minimi and at the first dorsal intraosseous muscles. Several EMG devices are now commercially available. These require proprietary stimulating-recording strip use and placement, are easily applied, speedily calibrated and provide accurate 'close to gold standard readings.' Target recovery is acceptable at TOF ratios >0.9. Electromyography monitoring is the 'ideal quantitative monitor' in the evidence-based consensus opinion of an expert group.4Naguib M. Brull S.J. Kopman A. colleagues Consensus statement on perioperative use of neuromuscular monitoring.Anesth Analg. 2018; 127: 71-80Crossref PubMed Scopus (171) Google Scholar Kinemyography (KMG) measures the distortion (proportional to the force of contraction) of a piezoelectric sensor placed between the thumb and index finger, in response to ulnar nerve stimulation. It is subject to a large bias, its limits of agreement are wide, and like AMG, it is position-dependant though there is no associated reverse fade. The TOF-Cuff (RGB Medical Devices, Madrid, Spain) uses a form of compressomyography, with stimulating and recording sensors integrated within a blood pressure cuff; it measures upper arm muscle response to neurostimulation of nerves of the brachial plexus. Onset and recovery do not correlate with responses at the ulnar nerve using AMG and EMG and appear to reflect more closely the resistant central muscles, including the larynx and diaphragm. Recent guidelines have identified the ideal site for neuromuscular block monitoring in routine clinical practice; the adductor pollicis muscle response to ulnar nerve stimulation is best suited to perioperative monitoring.7Thilen S.R. Weigel W.A. Todd M.M. et al.American Society of Anesthesiologists practice guidelines for monitoring and antagonism of neuromuscular blockade: a report by the American Society of Anesthesiologists Task Force on neuromuscular blockade.Anesthesiology. 2023; 138: 13-41Crossref PubMed Scopus (42) Google Scholar, 8Fuchs-Buder T. Romero C.S. Lewald H. et al.Peri-operative management of neuromuscular blockade: a guideline from the European society of Anaesthesiology and intensive care.Eur J Anaesthesiol. 2023; 40: 82-94Crossref PubMed Scopus (32) Google Scholar This most closely approximates the sensitive muscle groups needing longer times to recovery. Posterior tibial nerve stimulation may be used, but the time course for recovery of the flexor hallucis brevis muscle may differ by several minutes from recovery of the adductor pollicis muscle. The facial nerve should not be used for monitoring. The ASA practice guide strongly recommends against using the eye muscles for neuromuscular monitoring.7Thilen S.R. Weigel W.A. Todd M.M. et al.American Society of Anesthesiologists practice guidelines for monitoring and antagonism of neuromuscular blockade: a report by the American Society of Anesthesiologists Task Force on neuromuscular blockade.Anesthesiology. 2023; 138: 13-41Crossref PubMed Scopus (42) Google Scholar If the facial muscles are monitored, lower stimulating currents are necessary to reduce the risk of direct muscle stimulation. In addition, the relative resistance of some eye muscles to neuromuscular blocking drugs may falsely indicate presence of neuromuscular transmission, resulting in excessive dosing. There may be an assumption of adequate recovery when this is not the case, leading to premature awakening and tracheal extubation. There is a five-fold greater risk of residual neuromuscular block with facial nerve compared with ulnar nerve monitoring.20Li G. Freundlich R.E. Gupta R.K. et al.Postoperative pulmonary complications' association with sugammadex versus neostigmine: a retrospective registry analysis.Anesthesiology. 2021; 134: 862-873Crossref PubMed Scopus (46) Google Scholar If the facial nerve is monitored during anaesthesia, the ulnar nerve response should always be measured at the end of surgery, before waking the patient and tracheal extubation. Neostigmine is an anticholinesterase drug requiring coadministration of glycopyrrolate or atropine to counter its muscarinic effects. Neostigmine is characterised by a ceiling effect, a variable (and slow) antagonistic action, and by requiring high levels of spontaneous recovery to guarantee safe (complete) antagonism.7Thilen S.R. Weigel W.A. Todd M.M. et al.American Society of Anesthesiologists practice guidelines for monitoring and antagonism of neuromuscular blockade: a report by the American Society of Anesthesiologists Task Force on neuromuscular blockade.Anesthesiology. 2023; 138: 13-41Crossref PubMed Scopus (42) Google Scholar,8Fuchs-Buder T. Romero C.S. Lewald H. et al.Peri-operative management of neuromuscular blockade: a guideline from the European society of Anaesthesiology and intensive care.Eur J Anaesthesiol. 2023; 40: 82-94Crossref PubMed Scopus (32) Google Scholar Dosing (for both aminosteroidal and benzylisoquinolinium agents) is dependent on the level of block at the time of reversal and should be based on patient's actual body weight. For antagonism of minimal block (TOF ratio >0.40), the recommended neostigmine dose is 30 μg kg−1, and maximal antagonism may be reached within 10 min (Fig. 3). In the presence of moderate (TOF count 1–3) or shallow (TOF ratio <0.4) block, neostigmine reversal time may be prolonged and must be accompanied by quantitative monitoring to demonstrate adequate recovery. The maximum dose of neostigmine is 50 μg kg−1 and a variable period (up to 20–30 min) may be required for reversal. Investigators have compared reversal with neostigmine at tactile reappearance of twitches 1–4, measuring time to achieve TOF ratio of 0.9 using MMG.21Pandit J.J. Andrade J. Bogod D.G. et al.Royal college of anaesthetists; association of anaesthetists of great Britain and Ireland. 5th national audit Project (NAP5) on accidental awareness during general anaesthesia: summary of main findings and risk factors.Br J Anaesth. 2014; 113: 549-559Abstract Full Text Full Text PDF PubMed Scopus (311) Google Scholar At fourth twitch reappearance the mean time was 10 min, but the range was 5–26 min. Patients receiving i.v. anaesthesia all achieved recovery by 10 min; in contrast with only 60% of patients receiving sevoflurane.21Pandit J.J. Andrade J. Bogod D.G. et al.Royal college of anaesthetists; association of anaesthetists of great Britain and Ireland. 5th national

The Project for Universal Management of Airways (PUMA) group is to be commended on its consensus guideline for preventing unrecognised oesophageal intubation [1]. This is an excellent document, an example of global collaboration in airway standards, and important given the catastrophic consequences of this complication. Particularly useful is the call to arms for routine videolaryngoscopy use, and for carbon dioxide and pulse oximetry monitoring for all. Likewise, the human factors elements of communication and engagement with airway assistants and other healthcare providers present. We would like to comment on a few aspects of the paper. The novel concept for many of us, of verbalising what we see during tracheal intubation, is excellent. Recommendations include: to list what is seen during “sequential exposure of anatomy” at laryngoscopy, and then to verbalise and confirm the presence of sustained exhaled carbon dioxide and adequate oxygenation after intubation. Is there not a missing key element to verbalise? Namely that after visualising the structures, further verbal commentary is provided; that the tracheal tube has passed through the glottic opening, anterior to the arytenoid cartilages, the cuff is below the vocal cords, and the depth of tube insertion then noted? This should be followed by correct cuff inflation (aided by cuff pressure manometry), securing the tracheal tube, with clinical and capnographic confirmation to follow. This is a crucial aspect, the concept of the first attempt being the best one and, as for any tracheal intubation, there are two questions: is the tracheal tube in the trachea and not the oesophagus; and is it correctly positioned in the trachea, i.e. in far enoughbut not too far. Another key recommendation is that clinical examination should not be used to exclude oesophageal intubation. The reason given for this is that, for all the known cases with fatal outcomes, breath sounds were heard. However, we are concerned that downplaying clinical examination will lead to a further reduction of clinical monitoring in airway management, to the detriment of patients. There is still an important value in ‘look, listen, feel’ and the use of clinical signs, for us all, but especially so in a low-resource environment. The presence of videolaryngoscopes and carbon dioxide monitoring will remain (rightly) aspirational. Many oesophageal intubations will be recognised by the ‘feel at ventilation’ and by the absence of chest movements and breath sounds. The downplaying of clinical signs and experience may hinder, especially where confirmatory capnography is not available or not working. We agree that clinical signs should never be taken in isolation, and that they may be misleading, but we see value in the rapid and concurrent use of clinical evidence of ‘bag feel’, chest movement and auscultation, alongside capnography. We also agree with the concept of a reduced threshold for tracheal tube removal in the absence of a sustained rise and fall in carbon dioxide. Finally, the authors recommend a lowered threshold for removal of tracheal tubes in the absence of adequate capnography traces. As they acknowledge, this will result in tube removals in the presence of technical capnograph issues and in clinical situations such as severe bronchospasm and anaphylaxis. No doubt this will generate much debate amonganaesthetists.

References 1. Klein AA, Meek T, Allcock E, et al. Recommendations for standards of monitoring during anaesthesia and recovery 2021. Anaesthesia 2021;76: 1212–23. 2. Audrey De Jong A, Pardo E, Rolle A, Bodin-Lario S, Pouzeratte Y, Jaber S. Airway management for COVID-19: a move towards universal videolaryngoscope?. Lancet Respiratory Medicine 2020;8: 555. 3. Sullivan EH, Gibson LE, Berra L, et al. In-hospital airway management of COVID-19 patients.Critical Care 2020;24: 292.

This guideline updates and replaces the 5th edition of the Standards of Monitoring published in 2015. The aim of this document is to provide guidance on the minimum standards for monitoring of any patient undergoing anaesthesia or sedation under the care of an anaesthetist. The recommendations are primarily aimed at anaesthetists practising in the UK and Ireland, but it is recognised that these guidelines may also be of use in other areas of the world. Minimum standards for monitoring patients during anaesthesia and in the recovery phase are included. There is also guidance on monitoring patients undergoing sedation and during transfer. There are new sections specifically discussing capnography, sedation and regional anaesthesia. In addition, the indications for processed electroencephalogram and neuromuscular monitoring have been updated.

1Consultant, Department of Anaesthesia, Guy’s and St. Thomas’NHS Foundation Trust, London, UK, Council Member, Association of Anaesthetists andCo-Chair of theWorking Party 2Consultant, Department of Anaesthesia, University Hospitals of Coventry andWarwickshire, Coventry, UK, Difficult Airway Society representative andCo-Chair of theWorking Party 3Consultant andHonoraryClinical Senior Lecturer, Imperial College London, London, UK 4Chair, TheAssociation for Anaesthetic and Respiratory Device Suppliers, Bromley, UK 5 Specialist Trainee, South East Scotland School of Anaesthesia, UK andMember of theAssociation of Anaesthetists TrainingCommittee 6 Ergonomics expert, Link Ergonomics, Nottingham, UK 7Consultant, Department of Anaesthesia, Guy’s and St. Thomas’NHS Foundation Trust, London, UK and President of Regional Anaesthesia (RA), UK 8Consultant, Department of Anaesthesia, Imperial CollegeHealthcareNHS Trust, London, UK, andCouncilMember, Royal College of Anaesthetists 9 Consultant inMedical Devices, Edinburgh, UK

We read with interest the editorial by Hunter1Hunter J.M. Optimising conditions for tracheal intubation: should neuromuscular blocking agents always be used?.Br J Anaesth. 2018; 120: 1150-1153Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar on the need for routine use of neuromuscular blocking agents (NMBA) for tracheal intubation after the recent Cochrane systematic review by Lundstrøm and colleagues.2Lundstrøm L.H. Duez C.H.V. Nørskov A.K. et al.Avoidance of use of neuromuscular blocking agent for improving conditions during tracheal intubation: a Cochrane systematic review.Br J Anaesth. 2018; 120: 1381-1393Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar The editorial makes a plea to use NMBAs for all intubations ‘unless there is a specific contraindication to their use’. Moreover, Hunter1Hunter J.M. Optimising conditions for tracheal intubation: should neuromuscular blocking agents always be used?.Br J Anaesth. 2018; 120: 1150-1153Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar refers to ‘excellence of anaesthetic technique being paramount’, implying that NMBA use provides such, and that ‘this maxim should not be lost in idiosyncratic practice’, namely the avoidance of NMBA for intubation. Hunter1Hunter J.M. Optimising conditions for tracheal intubation: should neuromuscular blocking agents always be used?.Br J Anaesth. 2018; 120: 1150-1153Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar further states that ‘perhaps avoidance of use of NMBAs is not primarily because of concern over side effects, but simply to try something new and to add another gimmick to ones armamentarium’. The implication is that having an NMBA as part of an anaesthetic technique for intubation is good practice, and not doing so is suboptimal. We do not contest the point made by Hunter1Hunter J.M. Optimising conditions for tracheal intubation: should neuromuscular blocking agents always be used?.Br J Anaesth. 2018; 120: 1150-1153Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar that intubation performed without the use of NMBAs can be harmful to patients. The findings by Lundstrøm and colleagues2Lundstrøm L.H. Duez C.H.V. Nørskov A.K. et al.Avoidance of use of neuromuscular blocking agent for improving conditions during tracheal intubation: a Cochrane systematic review.Br J Anaesth. 2018; 120: 1381-1393Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar are clear for adult patients, notwithstanding study quality, heterogeneity, and definitions of difficulty: without or with NMBA use, difficult tracheal intubation rates of 56.3% vs 4.7%, difficult direct laryngoscopy rates of 7.2% vs 3.3%, and ‘sore throat’ rates of 38.2% vs 27.3% were reported. However, we believe that NMBA-free intubation is both a necessary skill to acquire and one that can be safely performed. Indeed, in response to a similar editorial by Sneyd and O'Sullivan,3Sneyd J.R. O’Sullivan E. Tracheal intubation without neuromuscular blocking agents: is there any point?.Br J Anaesth. 2010; 104: 535-537Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar a number of clinicians practising paediatric anaesthesia4Simon L. Boucebci K.J. Orliaguet G. Aubineau J.V. Devys J.M. Dubousset A.M. A survey of practice of tracheal intubation without muscle relaxants in paediatric patients.Paediatr Anaesth. 2002; 12: 36-42Crossref PubMed Scopus (60) Google Scholar described the use of NMBA-free intubation of children, their technique, their reasons for doing so, and their experience with its safe and atraumatic use. Many practising this technique will simply not recognise an incidence of tracheal intubation difficulty in half of their patients. Dose finding studies comparing different anaesthetic regimens without NMBA were excluded from the meta-analysis because of the absence of comparator NMBA groups. Such studies show a far lower incidence of intubation difficulty and are more reflective of real-world anaesthesia practice by those avoiding NMBA use.5Alexander R. Olufolabi A.J. Booth J. El-Moalem H.E. Glass P.S. Dosing study of remifentanil and propofol for tracheal intubation without the use of muscle relaxants.Anaesthesia. 1999; 54: 1037-1040Crossref PubMed Scopus (93) Google Scholar The addition of videolaryngoscopy to NMBA-free anaesthesia further improves airway management and minimises morbidity from sore throat and hoarseness.6Nakanishi T. Yoshimura M. Sakamoto S. Toriumi T. Postoperative laryngeal morbidity and intubating conditions using the McgrathTM MAC videolaryngoscope with or without neuromuscular blockade: a randomised, double blind, non-inferiority trial.Anaesthesia. 2018; 73: 990-996Google Scholar There is an important need to develop and retain the skill of intubating without NMBA for some, albeit rare, clinical situations: patients allergic to NMBAs, patients with myotonias and other neuromuscular/muscular disorders, and patients at high risk for malignant hyperthermia, for example. There are also surgical requirements for NMBA avoidance, including the need to preserve nerve function to allow neuromonitoring during certain operations. We would argue this skill should not be used for the first time in an emergency situation where there is an absolute or relative contraindication to NMBA use. Avoidance of NMBAs has other valid reasons too, acknowledging their potential harmful consequences. Hunter1Hunter J.M. Optimising conditions for tracheal intubation: should neuromuscular blocking agents always be used?.Br J Anaesth. 2018; 120: 1150-1153Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar refers to the rare incidence of anaphylaxis. Rare too is the incidence of accidental awareness under general anaesthesia (AAGA) highlighted in the 5th National Audit Project; 97% of all cases of AAGA involved the use or indeed misuse of NMBAs, with approximately one-half occurring at induction.7Pandit J.J. Cook T.M. the NAP5 Steering PanelNAP5Accidental awareness during general anaesthesia. The Royal College of Anaesthetists and Association of Anaesthetists of Great Britain and Ireland. National Audit Project, London, London2014Google Scholar Much more common though, is the issue of residual neuromuscular block (NMB). Occurring daily in our recovery rooms, this is of the order of 40%,8Naguib M. Kopman A.F. Ensor J.E. Neuromuscular monitoring and postoperative residual curarisation: a meta-analysis.Br J Anaesth. 2007; 98: 302-316Abstract Full Text Full Text PDF PubMed Scopus (194) Google Scholar despite progress in monitoring and drug availability, and is often unrecognised given the widespread absence of monitoring, and the practice of dosing and antagonising NMB ‘by rote’ or based on ‘elapsed time’. Poor quality of intubation in some ‘paralysed patients’ is perhaps reflected by Hunter's1Hunter J.M. Optimising conditions for tracheal intubation: should neuromuscular blocking agents always be used?.Br J Anaesth. 2018; 120: 1150-1153Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar acknowledgement of a sore throat rate of 27.3%, even for those receiving NMBAs, and a call for improvements in practice. Standard anaesthesia practice, with NMBA administration and without NMB monitoring at induction, does not guarantee airway reflex suppression and atraumatic intubation, given the wide variation in patient responses. Avoidance or reduced use of NMBAs requires a focus on adequate delivery of hypnotic and opioid drugs, which practitioners will be very aware of, in order to ensure adequate anaesthesia, reflex suppression, and facilitate airway management. NMBAs are a key component for intubation, but we should balance their risks and benefits, and make every effort to ensure adequate anaesthesia delivery and optimal conditions for safe intubation. It is not just about ‘what we give’, it is about ‘how well we give it’. The authors declare that they have no conflicts of interest. Optimising conditions for tracheal intubation: should neuromuscular blocking agents always be used?British Journal of AnaesthesiaVol. 120Issue 6Preview‘Striving to be better, oft we mar what's well.’Shakespeare, 1605–6. King Lear Full-Text PDF Open ArchiveShould neuromuscular blocking agents always be used for tracheal intubation? Reply to Br J Anaesth 2018; 122: e8–9British Journal of AnaesthesiaVol. 122Issue 1PreviewEditor—I thank Dr Rodney and colleagues1 for their interest in my editorial2 and for their comments. I accept that there is a need for anaesthetists to gain experience in tracheal intubation without the use of neuromuscular blocking agents (NMBAs) for the uncommon instances when their use is contraindicated. However, my major concern was that the robust and impelling evidence (despite the marked heterogeneity) provided by Lundstrom and colleagues3 of the benefits of using NMBAs for tracheal intubation should not be treated lightly. Full-Text PDF Open Archive

The fifth national audit project handbook publication 1, 2 is a welcome additional resource and we thank the authors for collating this. Inadequately monitored neuromuscular blockade (NMB) is the key risk factor for accidental awareness under general anaesthesia (AAGA). However, we are disappointed that the authors failed to reinforce the need for quantitative NMB monitoring as the sole means of ensuring return of a train of four ratio > 0.9 and of avoiding harmful sequelae, including AAGA. The ‘other suitable measure’ referred to presumably includes clinical assessment and qualitative NMB monitoring, which are proven to be of no value in assessing the ‘minimum criterion for adequacy of motor capacity’ 3-5. For patients at high risk of AAGA, we find the statements in the ‘Induction’ section to be contradictory. On the one hand, stating that ‘standard induction doses for intravenous agents should be the norm’, then on the other hand, ‘when intentionally reducing doses, the increased risk of AAGA should be recognised’. There are no standard induction doses for patients, high or low risk, with wide variation in pharmacodynamic responses. This can only be appreciated by combining clinical signs (the absence of response to painful stimulus, for example, jaw thrust before instrumenting the airway or administering a NMB) and by increased use of processed EEG monitors. The recently published total intravenous anaesthesia guidelines recommend processed EEG monitoring for patients receiving NMBs (as do the 2015 Association of Anaesthetists standards of monitoring guidelines 3). The guidelines call for anaesthetists to better understand and interpret processed EEG, and not just to rely on an index number as an indicator of anaesthesia depth 6. Using adequate clinical and processed EEG monitoring removes the need to warn patients of inadequate anaesthesia delivery. All patients should receive adequate anaesthesia with appropriate cardiorespiratory support as needed and processed EEG monitoring should commence before induction of anaesthesia and continue until at least the end of surgery. Transfers from anaesthetic room to theatre (and recovery room) are risk periods for AAGA (‘mind the gap’). We wonder if UK anaesthetists might evolve to inducing anaesthesia in the operating room to allow continuous safe administration of anaesthetic drugs, oxygen and uninterrupted monitoring? ‘Classic RSI’ (predetermined doses of thiopentol and succinylcholine without opioid use) is now rarely practiced in the UK 7. The higher incidence of AAGA associated with RSI suggests that it's time to change practice – to administer adequate, titrated doses of induction drugs before administering NMBs. An extra few seconds should be taken to ensure loss of consciousness. Concerns about ensuring oxygenation during the apnoeic period can be mitigated by mask ventilation and/or by using high-flow nasal oxygen. Managing patient expectations is always key. The authors suggested words describing patient experience are useful, but we feel there is unnecessary emphasis on the likes of ‘feeling a tube in the mouth’ at induction and of experiencing ‘periods of weakness’. Any such sensations at induction indicate a failure of anaesthesia delivery, and should not be described as normal.

We would like to comment on two recent papers covering aspects of neuromuscular blockade management. Firstly, Choi et al. compared tracheal intubating conditions and reversal characteristics of neostigmine and sugammadex, for moderate and deep neuromuscular blockade respectively 1. Choi's study predictably demonstrates that rocuronium 0.9 mg.kg−1 (ED95 = 3) compared with 0.45 mg.kg−1 (ED95 = 1.5) produces deeper levels of blockade, which will better obtund the relatively resistant laryngeal and diaphragmatic reflexes, at ‘like for like’ levels of anaesthesia. The study confirms that sugammadex, in a dose-dependent fashion, reverses even deep blockade quicker and more predictably than does neostigmine from moderate blockade 2. However, the authors acknowledge the potential bias in assessing intubation conditions, given that the intubator was not blinded to the study group. It is also unclear if the surgeon evaluating operating conditions was blind to the study groups, a further potential source of bias. Moreover, there were high levels of patient exclusions (60% of screened patients), the majority with a high body mass index. There was no mention of difficult airway cases, exclusion of both groups being a concern for wider interpretation of these findings. Choi demonstrated that deep neuromuscular block produced better intubating and surgical operating conditions. However, the clinical significance of this is questionable. In the ‘moderate block’ group, 19 of 21 patients achieved either good (15) or excellent (4) intubation conditions. Assessment of surgical conditions was based on a Likert scale from 1 (extremely dissatisfied) to 7 (extremely satisfied). There were 15 patients with a score of 6 or 7 in the moderate block group, compared with 19 such patients in the deep block group, scores of 6 and 7 being deemed acceptable. In practice, vocal cord immobility to produce quality intubating and surgical conditions may be achieved by adjusting the combination of hypnotic, opioid and neuromuscular blocking drugs, and applying topical laryngeal local anaesthesia, and is not reliant exclusively on ‘paralysis’. Choi's study demonstrated wide variability in response to rocuronium 0.45 mg.kg−1. Such pharmacokinetic variation can only be detected by utilising neuromuscular block monitoring, from induction through all phases, with neuromuscular block recovery achieved by appropriate reversal and demonstrated by quantitative measurement of train-of-four (TOF) ratio, before emergence. Secondly, McGill and Yoon describe a quality improvement program for reversal from neuromuscular blockade, with compulsory neuromuscular monitoring and targeted reversal 3. They showed not only a reduction in the incidence of residual neuromuscular block (TOF ratio < 0.9) from 30.7% to 14.7%, but importantly, a reduction in critical respiratory events from 25% to 14%. Having demonstrated these benefits, they plan to extend this practice across their healthcare region. This confirms the work of Baillard et al. who demonstrated similar changes in practice over a 10-year study period 4. They introduced quantitative nerve stimulator monitoring along with education about avoiding excessive use of neuromuscular blocking drugs, and about appropriate use of reversal agents. A reduction of residual block from 62% to 3% was achieved by increasing the rates of both monitoring (from 2% to 60%) and appropriate reversal (from 6% to 42%). Education, training, and a strategy including quantitative block monitoring, used from induction to recovery from anaesthesia, can eliminate residual block and improve airway management and surgical operating conditions, and allows targeted block management, with measured certainty replacing ‘best guess’ 5.

Background The burden of treatable surgical diseases in children in low- and middle-income countries (LMICs) is greater than that of malaria, HIV/AIDS and TB combined. World Health Organisation member states are required to scale up access to emergency and essential surgery for children by 2030 as part of universal health coverage. There is a critical shortage of anaesthetists trained to look after children in LMICs. The aim of this project was to deliver the Safer Anaesthesia From Education (SAFE) Paediatric course in East and Central Africa, and to evaluate the impact of this training programme. Methods The SAFE Paediatric anaesthesia course is a three-day short course developed by GOSH paediatric anaesthetists in collaboration with the Association of Anaesthetists of Great Britain and Ireland (AAGBI), World Federation of Societies of Anaesthesiologists (WFSA) and Association of Anaesthesiologists of Uganda (AAU). It focuses on common paediatric surgical conditions encountered in LMICs. A one-day Train-The-Trainer (TTT) course was also established to train future SAFE faculty. Results A total of nine SAFE courses were delivered. ‘SAFE fellows’ conducted follow-up interviews in Uganda, Zambia and Malawi. 46/57 (81%) faculty members who completed the TTT course taught on a subsequent SAFE course. 381 delegates completed the course. Mean MCQ scores increased from 37.6/50 pre-course to 43.4/50 post-course and skills scores increased from 5.8/10 to 8/10 (p<0.001). Follow-up showed significantly higher mean MCQ (pre-course 37.6/50, follow-up 41.5/50) and skills test scores (pre-course(5.8/10), follow-up(8.2/10)). All interviewed delegates reported increased confidence in providing paediatric anaesthesia. Conclusion The SAFE paediatric anaesthesia course provides high quality education for anaesthetists in LMICs. Knowledge and skills improve and are retained at follow-up. SAFE course training results in changes in paediatric anaesthesia practice and improved patient outcomes. Delivery of the SAFE training through UK/LMIC anaesthesia health partnerships builds links between paediatric anaesthetists internationally.

Cook and Kelly's correspondence suggests the time has come to abandon the classic laryngeal mask airway along with the Macintosh laryngoscope and the Cormack and Lehane classification of the laryngeal view 1. We would caution against the universal replacement of 1st generation supraglottic airway devices (SAD) with 2nd generation devices, in particular relating to their usefulness for specific patient sub-groups (e.g. children), the need for versatility and choice, training and maintaining skills, and impact on departmental equipment costs. We are interested to know which 2nd generation device(s) have been chosen for use in the Royal United Hospital in Bath, particularly for children. In the paediatric population, issues with current 2nd generation devices are not uncommon 2 and are particularly noticeable when using them in children at the extremes of the recommended weight ranges. A survey of 240 UK anaesthetists showed that adoption of 2nd-generation devices for use in children has been slow, with 88% of respondents preferentially using 1st generation devices, citing safety concerns as the determining factor 3. Though this may change as devices continue to improve, trainees in particular must maintain their skill in using cuffed 1st generation devices for safety. There has been a significant move towards use of the i-gel® (Intersurgical Lts, Wokingham, Berks, UK) in our hospital. While other 2nd generation devices are locally available (such as the LMA1 ProSealTM) (Teleflex Inc, Wayne, PA, USA) and the LMA SupremeTM (Teleflex Inc.), these are rarely used by non-airway specialist anaesthetists. Although the i-gel may reduce postoperative complications often associated with cuffed devices such as sore throat, dysphonia and dysphagia 4, we believe these risks can also be reduced for cuffed SADs with education and attention to detail. This includes correct insertion technique and cuff inflation, with routine cuff pressure monitoring 5. One 1st generation SAD which is widely used in both adult and paediatric practice is the flexible laryngeal mask. This device is beneficial for optimal surgical access and emergence conditions in shared airway procedures, oral, ophthalmological and head and neck surgeries 6. Promoting departmental policy for use of only 2nd generation SAD (with likely one brand chosen for both departmental cost and training efficiency) significantly reduces available options and skill when faced with a poor fit or performance failure in the individual patient. The minimum three-fold price differential for currently available disposable 2nd generation devices would also significantly add to departmental costs, if 1st generation devices were abandoned completely. Appropriate choice and informed clinical decision-making is key to selecting appropriate patient groups for whom 1st generation devices may be used with minimal risk, and others who would benefit from the additional features of 2nd generation devices (higher cuff seal pressures, integral bite blocks and a gastric drain tube to isolate the GI tract). There is a long track record of 1st generation SAD use in millions of patients worldwide 7. The problems with inappropriate SAD use and aspiration, as highlighted in NAP4 8, do not reflect failings in the device but rather failings in anaesthetist's choice and decision-making. Second generation devices are a key element of an airway management strategy and should be available and used, as part of an armamentarium, rather than as sole devices. As clinicians we should select appropriate airway devices, use correct techniques, and have back up options, rather than applying a ‘one device fits all’ approach.