Comparison of Phonomyography Prototype With Train-of-Four Watch SX for Neuromuscular Monitoring: A Prospective Observational Study

BACKGROUND: Quantitative neuromuscular monitoring has been advocated to deal with residual neuromuscular block. Phonomyography (PMG) is a technology that captures the acoustic signals yielded by muscle contraction, which is easy to use, anti-interference, and has multiple alternative monitoring sites. Our previous study has developed a PMG prototype for neuromuscular monitoring, and its feasibility was preliminarily verified, but further study on its clinical reliability with different neuromuscular blocking agents (NMBs) is needed. METHODS: This single-center, prospective, observational study compared the effect of a PMG prototype and TOF-Watch SX on neuromuscular monitoring of the ipsilateral adductor pollicis muscle with the use of non-depolarizing and depolarizing NMBs among 102 surgical patients. Patients were divided into 3 groups by NMBs, namely Group C (cisatricurium), Group V (vecuronium), and Group S (succinylcholine). The PMG prototype and TOF-Watch SX were placed at ipsilateral hand of each individual and measured data from NMBs administration to a stable train-of-four ratio (TOFr) ≥ 0.9 or T value ≥ 0.9 were compared. RESULTS: Eighty patients were included in the data analysis. For non-depolarizing NMBs, the PMG prototype recorded a longer onset time compared to TOF-Watch SX (median [interquartile range, IQR], 210 [180–240] seconds vs 150 [135–180] seconds, P < .001, mean bias 48 [40–55]; mean ± [standard deviation, SD], 197 ± 48 seconds vs 159 ± 36 seconds, P < .001, mean bias 38 [28–48]; for Group C and Group V, respectively) and a shorter full recovery time (4014 ± 511 seconds vs 5072 ± 713 seconds, P < .001, mean bias −1058 [−1215 to −901], 3352 ± 791 seconds vs 4931 ± 902 seconds, P < .001, mean bias −1084 [−1237 to −931], for Group C and Group V, respectively). For depolarizing NMBs, the results were similar (94 ± 26 seconds vs 80 ± 25 seconds, P < .001, mean bias 15 [10–19] for onset time; 447 ± 126 seconds vs 689 ± 223 seconds, P < .001, mean bias −242 [−294 to −191] for full recovery time). CONCLUSIONS: When non-depolarizing NMBs were administered, the PMG prototype measured a significantly longer onset and a shorter recovery time compared with TOF-Watch SX. The same trend was also found when depolarizing NMBs were administered. The PMG prototype is clinical feasible and stable but not interchangeable with TOF-Watch SX.