Comparison of kinemyography and electromyography during onset of and recovery from non-depolarising neuromuscular blockade: prospective observational study.

BACKGROUND: Quantitative neuromuscular monitoring is essential for the safe management of neuromuscular blockade. Although electromyography (EMG) is increasingly regarded as a reference technique, kinemyography (KMG) remains widely used in clinical practice; however, clinically relevant differences between these modalities during onset and recovery of neuromuscular blockade are not fully understood. METHODS: In this prospective observational study, adult patients undergoing general anaesthesia with non-depolarising neuromuscular blocking agents were simultaneously monitored using EMG and KMG applied to opposite hands, and onset and recovery times of neuromuscular block were compared between modalities; additionally, a novel EMG-derived parameter (T1%) was explored as a marker of recovery. RESULTS: In the 137 analysed patients, EMG and KMG differed during onset and recovery, with greater and only statistically significant disagreement during onset (EMG 158 ± 74 s vs. KMG 118 ± 68 s, P < 0.001; recovery: EMG 27 ± 22 min vs. KMG 24 ± 21 min, P = 0.242). T1% tended to be higher with sugammadex than with spontaneous recovery (P = 0.074). CONCLUSIONS: KMG and EMG are not interchangeable for perioperative neuromuscular monitoring; the observed disagreement suggests that KMG may overestimate neuromuscular block, whereas EMG-based monitoring may provide a safer approach. The EMG-derived parameter T1% appears promising but requires further validation before routine clinical use.