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Videira identified that in addition to the interval since last NMBD, anesthetists commonly used the adequacy of spontaneous minute ventilation as a decision heuristic for deciding on the need for reversal.
“The adequacy of the breathing pattern was also cited heavily … This visual cue may be erroneously interpreted as a sufficient sign for tracheal extubation, instead of a necessary one. This heuristic assesses function of the diaphragm, not of the upper airway muscles.”
Videira RL Vieira JE. What rules of thumb do clinicians use to decide whether to antagonize nondepolarizing neuromuscular blocking drugs? Anesth. Analg. 2011 Nov 1;113(5):1192-6.
  Daniel Jolley
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The authors conclude that one-quarter of PACU desaturations below 90%, almost-half of desaturations below 80%, and almost one-third of re-intubations could be attributable to intermediate NMBD.
Grosse-Sundrup M, Henneman JP, Sandberg WS et al. Intermediate acting non-depolarizing neuromuscular blocking agents and risk of postoperative respiratory complications: prospective propensity score matched cohort study. BMJ. 2012 Jan 1;345:e6329.
  Daniel Jolley
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Interestingly, they found the risk of respiratory complications to be greater in those having shorter procedures (< 2 hours) presumably because of the shorter time between relaxant and extubation.
Grosse-Sundrup M, Henneman JP, Sandberg WS et al. Intermediate acting non-depolarizing neuromuscular blocking agents and risk of postoperative respiratory complications: prospective propensity score matched cohort study. BMJ. 2012 Jan 1;345:e6329.
  Daniel Jolley
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This is a very significant and large study, and should give us pause to ponder the consequences of invasive airway management and surgery requiring muscle relaxation. It is also important to note that qualitative neuromuscular monitoring (as opposed to quantitative) appears to offer no risk reduction, consistent with other research in this area.
Nonetheless, the retrospective nature of this study means these relationships should not necessarily be viewed as causal. This is not a study of an intervention per se, but the association between certain perioperative characteristics that may be unavoidable (e.g. using muscle relaxants).
An important paper for any concerned anaesthetist or anesthesiologist to read in full.
Grosse-Sundrup M, Henneman JP, Sandberg WS et al. Intermediate acting non-depolarizing neuromuscular blocking agents and risk of postoperative respiratory complications: prospective propensity score matched cohort study. BMJ. 2012 Jan 1;345:e6329.
  Daniel Jolley
summary
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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.
Grosse-Sundrup M, Henneman JP, Sandberg WS et al. Intermediate acting non-depolarizing neuromuscular blocking agents and risk of postoperative respiratory complications: prospective propensity score matched cohort study. BMJ. 2012 Jan 1;345:e6329.
  Daniel Jolley
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Observation of pharyngeal function in 14 awake volunteers demonstrated pharyngeal dysfunction and increased aspiration risk at TOF ratios < 0.90.
“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.)
Eriksson LI, Sundman E, Olsson R et al. Functional assessment of the pharynx at rest and during swallowing in partially paralyzed humans: simultaneous videomanometry and mechanomyography of awake human volunteers. Anesthesiology. 1997 Nov 1;87(5):1035-43.
  Daniel Jolley
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Murphy et al. showed in this randomised, non-blinded trial that patients monitored with quantitative acceleromyography before extubation experienced less PORC, less desaturation below 90% (0% versus 21%) and less airway obstruction (0% versus 11%) during transport to the PACU.
Once in the PACU these patients also experienced less frequent, shorter duration and less severe hypoxic events.
Murphy GS, Szokol JW, Marymont JH et al. Intraoperative acceleromyographic monitoring reduces the risk of residual neuromuscular blockade and adverse respiratory events in the postanesthesia care unit. Anesthesiology. 2008 Sep 1;109(3):389-98.
  Daniel Jolley
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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.
Ledowski T, O'Dea B, Meyerkort L et al. Postoperative Residual Neuromuscular Paralysis at an Australian Tertiary Children's Hospital. Anesthesiol Res Pract. 2015 Jan 1;2015:410248.
  Daniel Jolley
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This is a great review to start with, providing a good overview of many of the myths regarding the use of neuromuscular blocking drugs that are still widely believed and practised by the global anaesthesia community.
All five of Fink & Hollman's 'myths' still hold today after reviewing the latest research in these areas.
Fink H Hollmann MW. Myths and facts in neuromuscular pharmacology. New developments in reversing neuromuscular blockade. Minerva Anestesiol. 2012 Apr 1;78(4):473-82.
  Daniel Jolley
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Schreiber demonstrated a 27% incidence of PORC (Post-operative Residual Curarization/Paralysis = TOF ratio <0.9) after surgery between 60 and 90 minutes long.
Schreiber JU, Mucha E, Fuchs-Buder T. Residual paralysis following a single dose of atracurium: results from a quality assurance trial. Eur J Anaesthesiol. 2010 Nov 1;27(11):993-4.
  Daniel Jolley