Observational Cohort Study of TetraGraph^® Electromyography Compared to Standard Acceleromyography Monitoring

Background/Objectives: Current guidelines recommend objective neuromuscular monitoring to ensure patient safety during neuromuscular blockade. Acceleromyography using train-of-four (TOF) stimulation is most commonly used to assess neuromuscular function. This study compares a new electromyography-based monitor with an established acceleromyography device for neuromuscular monitoring when mounted on a restricted arm. Methods: This prospective, controlled observational study enrolled patients undergoing surgery with general anesthesia requiring neuromuscular blockade. Two neuromuscular monitoring systems were used simultaneously: the standard acceleromyography device (Philips IntelliVue MX550) and the electromyography-based TetraGraph^® monitor on the opposite arm. Atracurium was administered as the neuromuscular blocking agent. The TetraGraph^® arm was restricted during surgery. The primary outcome was the time for the TOF ratio to return to ≥90%. Secondary endpoints included the time to reach a TOF count of 0 during induction. Data were analyzed using Bland-Altman plots and a paired t-test. Results: Mean time to recovery to TOF ratio ≥ 90% was 67 min (±21.4) for IntelliVue MX 550 and 75.8 min (±22.3) for TetraGraph^® (p = 0.0001; mean bias 8.9 min, 95% confidence intervals (CIs) 5.99-11.8). The mean time to reach a TOF count of 0 was 180.6 s (±7.8) for IntelliVue and 200 s (±8.2) for TetraGraph^® (p = 0.0217; mean bias 19 s, 95% CI 2.96-35.8). Conclusions: TetraGraph^® consistently recorded the endpoints later than IntelliVue, reflecting slower onset and recovery times. However, substantial intra-individual variability was observed with both devices during recovery from neuromuscular block. The observed differences may have clinical implications, such as when assessing readiness for extubation.