Comparison of a new EMG module, AF-201P, with acceleromyography using the post-tetanic counts during rocuronium-induced deep neuromuscular block: a prospective, multicenter study

Recent advances in neuromuscular monitors have facilitated the development of a new electromyographic module, AF-201P™. The purpose of this study was to investigate the relationship between post-tetanic counts (PTCs) assessed using the AF-201P™ and the acceleromyographic TOF Watch SX™ during rocuronium-induced deep neuromuscular block. Forty adult patients consented to participate in this study. The integrated AF-201P™ stimulating and sensing electrode was placed over the ulnar nerve on the distal volar forearm and the belly of the abductor digiti minimi muscle of one arm. The TOF Watch SX™ was applied with the provided hand adaptor on the opposite arm, to observe twitch responses of the adductor pollicis muscle. After stabilization of train-of-four (TOF) responses, rocuronium 0.9 mg kg^-1 was administered intravenously. Then, PTCs were observed every 3 min using both monitors. Whenever the TOF count was detected with the TOF Watch SX™, rocuronium 0.2 mg kg^-1 was administered, and successive PTC measurements were continued. A total of 1732 paired PTC data points were obtained and analyzed. Regression analysis showed no significant difference in PTCs between the two monitors (PTCs measured by the TOF Watch SX™ = 0.78·PTCs measured by AF-201P™ + 0.21, R = 0.56). Bland-Altman analysis also showed acceptable ranges of bias [95% CI] and limits of agreement (0.3 [0.2 to 0.5] and - 4.6 to 5.3) for the PTCs. The new EMG module, AF-201P™, showed reliable PTCs during deep neuromuscular block, as well as the TOF Watch SX™.