This month's journal article underscores the importance in border line cases, in particular in patients at high risk of upper airway obstruction, of monitoring carefully the dose of neuromuscular blockers in addition to train of four monitoring. Upper airway dilator musculature seems to be more susceptible to both neostigmine caused weakness as well as to the block caused by neuromuscular blockers. Eikerman M et al. in the BJA 2008 (101) comment that this may result from the different frequencies of neuronal firing (15 to 25 Hz in genioglossus motor units vs. 8 to 13 Hz in the diaphragmatic firing rate).
The mechanism by which neostigmine causes weakness is thought to be one of 3 (or more likely) a combination of the three things: 1) desensitization of nActR, 2) depolarization block and 3) open channel block.
This should be considered anytime the clinician is faced with a patient who is at risk for post operative upper airway obstruction and has received NDMBs.