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Created May 21, 2015, last updated over 3 years ago.
Collection: 7, Score: 5733, Trend score: 0, Read count: 6158, Articles count: 37, Created: 2015-05-21 02:09:10 UTC. Updated: 2021-07-04 02:14:06 UTC.Notes
An extensive collection of research debunking a range of myths and misconceptions regarding the way we use neuromuscular blocking drugs.
- Myth 1: Modern relaxants are so reliable and predictable that monitoring is unnecessary.
- Myth 2: Post-op residual paralysis is neither common or important.
- Myth 3: Post-op residual paralysis is easy to identify.
- Myth 4: Sugammadex makes residual paralysis a non-issue. (it might, but only if it is routinely available and used!)
- Myth 5: Using propofol and remifentanil we can avoid relaxants for intubation all together.
- Myth 6: Neuromuscular blockade has no effect on BIS.
And bonus myth: deep relaxation is necessary for improving surgical access during laparoscopy.
Daniel Jolley
A narrative article describing the myths can be found here:
Neuromuscular myths: we need to do better!
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Collected Articles
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Minerva anestesiologica · Apr 2012
ReviewMyths and facts in neuromuscular pharmacology. New developments in reversing neuromuscular blockade.
Fink & Hollman describe and refute several commonly-held myths regarding neuromuscular pharmacology. Their evidence-supported arguments are:
- Intubating patients without muscle relaxants is less safe and sub-optimal.
- Even if you know muscle relaxant pharmacokinetics, it is sufficiently unpredictable that neuromuscular monitoring and reversal is still necessary.
- Post-operative residual curarization (PORC) is clinically significant with real consequences.
- Postoperative residual curarization (PORC) is common.
- Postoperative residual curarisation (PORC) (TOFR < 0.9) can only be diagnosed with a quantitative neuromuscular monitor. Clinical tests are insufficient and poorly sensitive.
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Post-operative residual paralysis is common.
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Randomized Controlled Trial Multicenter Study Comparative Study
Incidence and duration of residual paralysis at the end of surgery after multiple administrations of cisatracurium and rocuronium.
After repeated rocuronium administration there is wide inter-patient variability in the time to recover muscle function.
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Anesthesia and analgesia · Jul 2010
A survey of current management of neuromuscular block in the United States and Europe.
Most anaesthetists and anesthesiologists incorrectly estimate the incidence of post-operative residual paralysis to be less than 1%.
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Letter
Residual paralysis following a single dose of atracurium: results from a quality assurance trial.
Schreiber demonstrated a 27% incidence of PORC (Post-operative Residual Curarization/Paralysis = TOF ratio <0.9) after surgery between 60 and 90 minutes long.
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Anesthesia and analgesia · Aug 2015
Multicenter Study Observational StudyThe RECITE Study: A Canadian Prospective, Multicenter Study of the Incidence and Severity of Residual Neuromuscular Blockade.
Postoperative residual neuromuscular blockade continues to be common and is experienced by the majority of patients receiving muscle relaxants.
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Anesthesiol Res Pract · Jan 2015
Postoperative Residual Neuromuscular Paralysis at an Australian Tertiary Children's Hospital.
This small (N=64) post-operative audit of children receiving muscle relaxants in an Australian tertiary paediatric hospital identified a 28% incidence of post-operative residual paralysis, measured immediately before extubation.
Worryingly, the incidence of residual paralysis was even higher in the subgroup reversed with neostigmine (38%), which the authors attribute to anaesthetists not waiting long enough after administration.
Severe residual paralysis (TOFR < 0.7) was observed in 7% of cases.
Only 23% of anaesthetists used intra-operative neuromuscular monitoring.
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Randomized Controlled Trial
Intraoperative acceleromyographic monitoring reduces the risk of residual neuromuscular blockade and adverse respiratory events in the postanesthesia care unit.
Quantitative neuromuscular monitoring reduces the incidence of post-operative residual paralysis, desaturation and airway obstruction.
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Observation of pharyngeal function in 14 awake volunteers demonstrated pharyngeal dysfunction and increased aspiration risk at TOF ratios < 0.90.
summary“Partial neuromuscular paralysis caused by atracurium is associated with a four- to fivefold increase in the incidence of misdirected swallowing. … The majority of misdirected swallows resulted in penetration of bolus to the larynx.”
(Sundman in a 2000 follow-up study: The incidence and mechanisms of pharyngeal and upper esophageal dysfunction in partially paralyzed humans: pharyngeal videoradiography and simultaneous manometry after atracurium.)
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Partial paralysis with TOFR < 0.9 causes pharyngeal dysfunction and misdirected swallowing, increasing the risk of aspiration.
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Randomized Controlled Trial
The influence of residual neuromuscular block on the incidence of critical respiratory events. A randomised, prospective, placebo-controlled trial.
Post-operative residual paralysis is associated with a greater incidence of desaturation in the post-anaesthesia care unit.
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This very large cohort study demonstrated an association between use of intermediate-duration NMBD and risk of postoperative desaturation and reintubation requiring ICU admission, and a similar association with these outcomes and neostigmine reversal.
Qualitative neuromuscular monitoring did not reduce this risk.
Study population was all patients at Massachusetts General Hospital undergoing general anaesthesia including a muscle relaxant over a 4 year period, and who were extubated at the end of the procedure.
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Randomized Controlled Trial Clinical Trial
Is the diagnosis of significant residual neuromuscular blockade improved by using double-burst nerve stimulation?
Although DBS is more sensitive than TOFC, manual assessment of DBS fade can only detect residual paralysis at TOF ratio < 0.7.
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Anesthesia and analgesia · Nov 2011
What rules of thumb do clinicians use to decide whether to antagonize nondepolarizing neuromuscular blocking drugs?
In anesthesia practice, inadequate antagonism of neuromuscular blocking drugs (NMBD) may lead to frequent prevalence of residual neuromuscular block that is associated with morbidity and death. In this study we analyzed the clinical decision on antagonizing NMBD to generate hypotheses about barriers to the introduction of experts' recommendations into clinical practice. ⋯ In our institution, the clinical decision to antagonize NMBD is mainly based on the pharmacological forecast and a qualitative judgment of the adequacy of the breathing pattern. Clinicians judge themselves as better skilled at avoiding residual block than they do their colleagues, making them overconfident in their capacity to estimate the duration of action of intermediate-acting NMBD. Awareness of these systematic errors related to clinical intuition may facilitate the adoption of experts' recommendations into clinical practice.
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Reversal with sugammadex may reduce the incidence of post-operative residual paralysis and consequent morbidity.
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Randomized Controlled Trial
Effects of sugammadex on incidence of postoperative residual neuromuscular blockade: a randomized, controlled study.
Reversal with sugammadex may dramatically reduce the incidence of post-operative residual paralysis.
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Randomized Controlled Trial
Postoperative impairment of motor function at train-of-four ratio ≥0.9 cannot be improved by sugammadex (1 mg kg-1).
Recovery of train of four ratio to > 0.9 signifies adequate recovery of muscle function after neuromuscular blockade.
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Calabadion is a new heterocyclic molecule that offers rapid and complete reversal of both aminosteroids, such as rocuronium, and benzylisoquinoline NMBDS, such as cisatracurium.
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Randomized Controlled Trial Comparative Study
Comparison of two induction regimens using or not using muscle relaxant: impact on postoperative upper airway discomfort.
Intubation without muscle relaxant is associated with greater incidence of sore throat, hoarseness, hypotension, bradycardia and intubation difficulty.
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Randomized Controlled Trial Comparative Study
Intubating conditions and side effects of propofol, remifentanil and sevoflurane compared with propofol, remifentanil and rocuronium: a randomised, prospective, clinical trial.
In 83 patients researchers compared intubation with propofol 1.5 mg/kg, remifentanil 0.30 μg/kg/min & sevoflurane 1.0 MAC to intubation with the same propofol & remifentanil dose, along with rocuronium 0.45 mg/kg.
Acceptable intubating conditions were 18% more frequent in the muscle relaxant group than in those receiving propofol/remi/sevo.
Incidence of laryngeal injury, hoarseness and sore throat was similar between the two groups - which is different to the result from an earlier, larger study of intubation without relaxant: Comparison of two induction regimens using or not using muscle relaxant: impact on postoperative upper airway discomfort.
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Acta Anaesthesiol Scand · Jul 2000
Randomized Controlled Trial Clinical TrialRemifentanil and propofol without muscle relaxants or with different doses of rocuronium for tracheal intubation in outpatient anaesthesia.
Intubation using propofol and remifentanil without muscle relaxant is associated with a greater incidence of poor intubating conditions.
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Researchers induced awake paralysis in 10 volunteers using separately both suxamethonium and rocuronium. Both the BIS A2000 (2003) and BIS Vista monitor (2013) were tested.
BIS decreased immediately after paralysis and did not fully recover until muscle recovery. BIS values decreased to as low as 44, despite the subject being awake.
In more than half of the 20 trials the BIS value decreased to below 60 at some point. In one case this lasted for almost 4 minutes, representing 76% of the total paralysis time for that subject.
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Editorial Comment
Restrict relaxants, be aware, and know the limitations of your depth of anaesthesia monitor.
Interesting editorial accompanying Dr Peter Schuller's excellent study of BIS values in awake, paralysed volunteers.
The editors make a very interesting point critiquing the probabilistic, database-based approach to processed-EEG awareness monitors like BIS: (emphasis added)
summary"This database-driven approach may have limitations, in particular for the detection of intraoperative wakefulness: it is very unlikely that data from an awake and paralyzed subject are included in this database. Therefore, the resulting anaesthesia index has not been trained with a dataset that contains this clinical situation..."
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Anesthesia and analgesia · Aug 2003
The bispectral index declines during neuromuscular block in fully awake persons.
Using an Aspect A-1000 BIS monitor, researchers demonstrated a drop in Bispectral Index Score in awake, paralysed volunteers to low values ranging from 9 to 64.
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Awareness occurred in 1 in 19,000 general anaesthetics, resulting in distress in 51% of cases and longterm harm in 41%. BIS monitoring was used in 5% of cases of awareness.
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Anesthesia and analgesia · Jan 2015
ReviewLaparoscopic surgery and muscle relaxants: is deep block helpful?
It has been hypothesized that providing deep neuromuscular block (a posttetanic count of 1 or more, but a train-of-four [TOF] count of zero) when compared with moderate block (TOF counts of 1-3) for laparoscopic surgery would allow for the use of lower inflation pressures while optimizing surgical space and enhancing patient safety. We conducted a literature search on 6 different medical databases using 3 search strategies in each database in an attempt to find data substantiating this proposition. In addition, we studied the reference lists of the articles retrieved in the search and of other relevant articles known to the authors. ⋯ First, monitoring of neuromuscular function is still essential and second, antagonism of deep block necessitates doses of sugammadex of ≥4.0 mg/kg. Thus, maintenance of deep block has substantial economic repercussions. There are little objective data to support the proposition that deep neuromuscular block (when compared with less intense block; TOF counts of 1-3) contributes to better patient outcome or improves surgical operating conditions.
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Randomized Controlled Trial
Electromyographic activity of the diaphragm during neostigmine or sugammadex-enhanced recovery after neuromuscular blockade with rocuronium: A study in anaesthetised healthy volunteers.
Reversal with sugammadex produces better recovery of diaphragm function than neostigmine reversal.
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Comparative Study
Comparative Effectiveness of Calabadion and Sugammadex to Reverse Non-depolarizing Neuromuscular-blocking Agents.
The authors evaluated the comparative effectiveness of calabadion 2 to reverse non-depolarizing neuromuscular-blocking agents (NMBAs) by binding and inactivation. ⋯ Calabadion 2 reverses NMB induced by benzylisoquinolines and steroidal NMBAs in rats more effectively, i.e., faster than sugammadex. Calabadion 2 is eliminated in the urine and well tolerated in rats.
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Anesthesia and analgesia · Aug 2013
Multicenter StudyReversal with sugammadex in the absence of monitoring did not preclude residual neuromuscular block.
Sugammadex use does not avoid either the need or benefit of neuromuscular monitoring, although it does result in less residual neuromuscular block than neostigmine reversal.
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Randomized Controlled Trial
Neostigmine Administration after Spontaneous Recovery to a Train-of-Four Ratio of 0.9 to 1.0: A Randomized Controlled Trial of the Effect on Neuromuscular and Clinical Recovery.
Neostigmine administration after clinical recovery of neuromuscular function to TOFR ≥ 0.9 appears to be neither beneficial or detrimental.
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Observational Study
Duration of the action of rocuronium in patients with BMI of less than 25: An observational study.
Duration of rocuronium action directly correlates with BMI.
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Meta Analysis Comparative Study
Deep vs. moderate neuromuscular blockade during laparoscopic surgery: A systematic review and meta-analysis.
Previous studies have reported that deep neuromuscular block (posttetanic-count 1 to 2 twitches) improves surgical conditions during laparoscopy compared with moderate block (train-of-four count: 1 to 2 twitches). However, comparisons of surgical conditions were made using different scales and assessment intervals with variable results. ⋯ Deep block was associated with excellent or good surgical rating more frequently than moderate block. However, this finding was not consistent on subgroup analyses based on frequencies of assessment of surgical conditions and abdominal pressure. Further studies are required to address the heterogeneity and power shortage demonstrated by the trial sequential analysis.
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Why is this important?
First, because it identifies new novel risk factors for residual neuromuscular block (experienced surgeon, non-CRNA anesthesia provider...) and secondly, because the subtext reveals the lengths our specialty goes to avoid simply monitoring using qualitative NMB monitoring (TOFR)!
What did they find?
Rudolph et al. created a REsidual neuromuscular block Prediction Score (REPS) using Massachusetts General PACU data, applying covariate analysis to identify 10 risk factors, some more surprising than others:
- Hepatic failure
- Neurological disease
- High-neostigmine dose > 60 mcg/kg
- Metastatic solid tumour
- Female sex
- Less than 120 min between NMBD administration and extubation
- Aminosteroid NMBD
- BMI more than 35
- Absence of nurse anaesthetist (CRNA)
- Having an experienced surgeon
Be smart:
These risk factors might suggest patients who need more careful monitoring, but you will probably be better off just using qualitative monitoring routinely. The utility of REPS itself is only modest with NPV & PPVs of 85% each.
The other takeaway is that rNMB is still demonstratably common, occurring in 20% of this cohort!
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Multicenter Study Observational Study
Use of a train-of-four ratio of 0.95 versus 0.9 for tracheal extubation: an exploratory analysis of POPULAR data.
The prospective observational European multicentre cohort study (POPULAR) of postoperative pulmonary complications (NCT01865513) did not demonstrate that adherence to the recommended train-of-four ratio (TOFR) of 0.9 before extubation was associated with better pulmonary outcomes from the first postoperative day up to hospital discharge. We re-analysed the POPULAR data as to whether there existed a better threshold for TOFR recovery before extubation to reduce postoperative pulmonary complications in patients who had quantitative neuromuscular monitoring (87% acceleromyography). ⋯ A post hoc analysis of patients receiving quantitative monitoring of neuromuscular function suggests that postoperative pulmonary complications are reduced for TOFR > 0.95 before tracheal extubation compared with TOFR > 0.9.
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Comment Multicenter Study Comparative Study Observational Study
Sugammadex versus Neostigmine for Reversal of Neuromuscular Blockade and Postoperative Pulmonary Complications (STRONGER): A Multicenter Matched Cohort Analysis.
Five percent of adult patients undergoing noncardiac inpatient surgery experience a major pulmonary complication. The authors hypothesized that the choice of neuromuscular blockade reversal (neostigmine vs. sugammadex) may be associated with a lower incidence of major pulmonary complications. ⋯ Among a generalizable cohort of adult patients undergoing inpatient surgery at U.S. hospitals, the use of sugammadex was associated with a clinically and statistically significant lower incidence of major pulmonary complications.
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Review Meta Analysis
Forty years of neuromuscular monitoring and postoperative residual curarisation: a meta-analysis and evaluation of confidence in network meta-analysis.
Use of quantitative neuromuscular monitoring significantly reduces the incidence of postoperative residual curarisation.
pearl