Neuromuscular monitoring using TOF-Cuff® versus TOF-Scan®: an observational study under clinical anesthesia conditions.

Background: Anesthesia guidelines advise objective neuromuscular monitoring. Acceleromyography, the standard technique used in clinical practice, is commonly used with the train-of-four (TOF) nerve stimulation pattern. Objective of this study was to compare the performance of two devices, TOF-Scan® and TOF-Cuff®.

Methods: This prospective, controlled observational study included patients undergoing surgery in general anesthesia with the need of neuromuscular blockade. Both neuromuscular monitoring devices were simultaneously placed on individual patients. Atracurium (0.5 mg/kg) was administered once. Main outcome measure was return time to TOF ratio ≥90%, secondary outcomes were time to TOF-ratio of 0% (during induction) and time to recovery to TOF-count of two. Results from the two devices were compared by Bland-Altman plots and one-sample t-test (P<0.05).

Results: Mean time to recovery to TOF ratio 90% was 79.6±13.6 min for TOF-Scan® and 70.8±12.8 min for TOF-Cuff® (P<0.001; mean bias 8.9 min, 95% CI: 5.8-12.0). Mean time to TOF-ratio 0% was 164.6±38.8 s for TOF-Scan® and 145.5±44.6 s for TOF-Cuff® (P<0.001; mean bias 19.1 s, 95% CI: 10.0-28.2). Mean time to recovery to TOF count two was 52.8±12.5 min for TOF-Scan® and 45.5±11.1 min for TOF-Cuff® (P<0.001; mean bias 7.3 min, 95% CI: 4.3-10.2).

Conclusions: TOF-Cuff® consistently recorded the endpoints earlier than TOF-Scan®. Despite large intra-individual variations found with both devices, these results could be meaningful in a clinical setting.