A Comparison of the Neuromuscular Blocking Effects of Atracurium, Mivacurium, and Vecuronium on the Adductor Pollicis and the Orbicularis Oculi Muscle in Humans

Comment: The most interesting aspect of this study is that it introduces a new technique for assessing neuromuscular function at the orbicularis oculi muscle. This may be particularly important because several studies have indicated that the sensitivity to, and time course of, neuromuscular block at the orbicularis oculi more closely reflect the laryngeal muscles and diaphragm than does the adductor pollicis muscle. However, responses at the orbicularis oculi heretofore have been difficult to quantify. Whereas it is relatively easy to achieve force transduction monitoring of the adductor pollicis, this cannot be as readily accomplished at the orbicularis oculi muscle. Likewise, electromyographic monitoring has been difficult to accomplish over the relatively small orbicularis oculi muscle. The present study has applied accelerometry with seemingly good results. However, it seems as if each new means of monitoring neuromuscular function raises as many questions as it answers. By using accelerometry, the authors did not find the anticipated clear-cut differences between the time courses at the orbicularis oculi and adductor pollicis muscles after each dose of each relaxant. After additional experience is gained with monitoring at the orbicularis oculi, we hopefully will learn whether the findings more accurately reflect what is occurring at the neuromuscular junction. At this point, suffice it to say that accelerometry may provide a valuable means for quantifying responses at a muscle, which reflects the degree of block at vital airway muscles.