Comparison of the TOFscan and the TOF-Watch SX during recovery of neuromuscular function

Background: Quantitative neuromuscular monitoring is required to ensure neuromuscular function has recovered completely at the time of tracheal extubation. The TOFscan (Drager Technologies, Canada) is a new three-dimensional acceleromyography device that measures movement of the thumb in multiple planes. The aim of this observational investigation was to assess the agreement between nonnormalized and normalized train-of-four values obtained with the TOF-Watch SX (Organon, Ireland) and those obtained with the TOFscan during recovery from neuromuscular blockade. Methods: Twenty-five patients were administered rocuronium, and spontaneous recovery of neuromuscular blockade was allowed to occur. The TOFscan and TOF-Watch SX devices were applied to opposite arms. A preload was applied to the TOFWatch SX, and calibration was performed before rocuronium administration. Both devices were activated, and train-of-four values were obtained every 15 s. Modified Bland-Altman analyses were conducted to compare train-of-four ratios measured with the TOFscan to those measured with the TOF-Watch SX (when train-of-four thresholds of 0.2 to 1.0 were achieved). Results: Bias and 95% limits of agreement between the TOF-Watch SX and the TOFscan at nonnormalized train-of-four ratios between 0.2 and 1.0 were 0.021 and -0.100 to 0.141, respectively. When train-of-four measures with the TOF-Watch SX were normalized, bias and 95% limits of agreement between the TOF-Watch SX and the TOFscan at ratios between 0.2 and 1.0 were 0.015 and -0.097 to 0.126, respectively. Conclusions: Good agreement between the TOF-Watch SX with calibration and preload application and the uncalibrated TOFscan was observed throughout all stages of neuromuscular recovery.