Measurement and monitoring of neuromuscular blockade

For more than three decades, 'experts' in the clinical pharmacology of neuromuscular blocking agents have advocated routine intraoperative use of peripheral nerve stimulators as monitors of neuromuscular function. This advice is far from universally honored in practice. In part, this dichotomy between 'accepted wisdom' and actual day-to-day practice may stem from a failure to provide the clinician with a peripheral nerve stimulator that does not require subjective evaluation of evoked responses. For 99% of anesthetists, the train-of-four fade ratio is a parameter that they read about but cannot measure. This need no longer be the case.

Small battery operated units are now available that are relatively inexpensive, easy to set up, and provide objective measurement of the train-of-four ratio. Although agreement between the output of these acceleromyographic and piezoelectric sensors with such 'gold standard' technologies as mechanomyography and electromyography is not absolute, it is probably adequate for clinical case management.

It is my hope (and I have no financial interest in any of the cited devices) that the present review will encourage further distribution of objective monitors of neuromuscular function.