A Comparison Between the Adductor Pollicis Muscle and the Abductor Digiti Minimi Muscle Using Electromyography AF-201P in Rocuronium-Induced Neuromuscular Block: A Prospective Comparative Study

Abstract Background The AF-201P, a new electromyography (EMG)-based neuromuscular monitor has been developed recently. The aim of this clinical study was to compare two ulnar nerve innervated muscles: the adductor pollicis (AP) muscle and the abductor digiti minimi (ADM) muscle during the recovery from rocuronium-induced neuromuscular block by using EMG AF-201P. Methods Twenty patients undergoing surgery with general anesthesia were enrolled in the study. During total intravenous general anesthesia, train-of-four (TOF) and post-tetanic counts (PTC) responses following 0.9 mg/kg rocuronium administration were concurrently monitored at the AP and the ADM muscles with EMG AF-201P on the opposite arms. At the end of the surgery, sugammadex 2 mg/kg was administered when TOF counts of 2 was observed at both muscles. The primary outcome of the study was time from administration of rocuronium to first appearance of PTC response (first PTC). The secondary outcomes of the study were time from administration of rocuronium to first reappearance of TOF response (first TOF), time from first PTC to first TOF (PTC-TOF time), time to reappearance of TOF counts of 2, and time from administration of sugammadex to TOF ratio ≥ 0.9. Agreement between the two muscles was assessed using the Bland-Altman analysis. Data are expressed as mean ± standard deviation. Results Nineteen patients were included in the analysis. Time for appearance of the first PTC was significantly faster at the ADM muscle than the AP muscle (32.4 ± 13.1min vs 24.4 ± 11.4min, p = 0.006). Interval time between the first PTC and the first TOF was significantly longer with the ADM muscle than the AP muscle (19.4 ± 7.3min vs 12.4 ± 10.6min, p = 0.019). There were no significant differences in time to TOF counts of 2 and sugammadex-facilitated recovery between the two muscles. Bland-Altman analyses showed acceptable ranges of bias and limits of agreement of the two muscles. Conclusions The ADM muscle showed a good agreement with the AP muscle during rocuronium-induced neuromuscular block but faster recovery of PTC response when using EMG. Trial registration : UMIN-CTR (Registration No. UMIN000044904). Registered 19 July 2021 -Retrospectively registered,