Article Notes
- Do not routinely reverse muscle relaxants (65% and 82% respectively US & EU).
- Do not have access to quantitative NMBD monitors (77% and 30%).
- Do not ever use neuromuscular monitors (9% and 19%).
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.
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.)
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.
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.
This 2010 survey found that a significant proportion of both American anesthesiologists and European anaesthetists:
Debaene et al. investigated residual paralysis in the PACU after a single intubating dose of intermediate NMBD in the absence of reversal.
They identified PORC (Post-Operative Residual Curarization = TOFR <0.9) in 45% of patients, with 'time since NMBD' ranging from 30 to 400 minutes.
In a subgroup of patients 2 hours after a single NMBD dose there was still a 37% incidence of PORC.
Additionally there was very wide inter-patient variability, with PORC persisting more than 6 hours in three patients, and several patients with TOFR of only 0.2 after 2 hours.
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.
Schlaich et al. compared intubation using only propofol and remifentanil with the addition of rocuronium at various doses (0.3, 0.45, 0.6 mg/kg) in four groups of 30 patients. Intubating conditions were poor in 40% of those not receiving rocuronium, versus almost universally good conditions (89 of 90) when rocuronium was used.
Researchers compared induction with propofol (2.5 mg/kg), alfentanil (15 µg/kg) and rocuronium (0.6 mg/kg) to using propofol (2.5 mg/kg) and alfentanil (40 µg/kg) alone. Patients who did not receive muscle relaxants experienced more sore throat and hoarseness, more hypotension and bradycardia and a 10 times greater incidence of intubation difficulty.