Comparison of electromyography and kinemyography during recovery from non-depolarising neuromuscular blockade.

In this study, two commercially available quantitative neuromuscular function monitoring techniques, electromyography (EMG) and kinemyography (KMG), were compared with respect to repeatability and accuracy during late recovery from neuromuscular blockade. Train-of-four (TOF) ratios were recorded in 30 patients using KMG and EMG at the adductor pollicis muscle. Measurements were taken on the same hand using the Datex-Ohmeda NeuroMuscular Transmission monitor (GE Healthcare, Helsinki, Finland). Instrumental precision was evaluated using the coefficient of repeatability, while accuracy was assessed using the bias and limits of agreement. The coefficients of repeatability were similar for both techniques (0.035 for KMG and 0.043 for EMG), indicating a similar level of precision. KMG overestimated the TOF ratios measured with EMG with a bias of 0.11 (95% limits of agreement: -0.13 to 0.35). At a TOF ratio of 0.90 the bias was 0.08 (95% limits of agreement: -0.08 to 0.25). This means that at a TOF ratio of 0.90 measured with KMG will be approximately equivalent to a TOF ratio of 0.80 measured with EMG at the adductor pollicis muscle, but it may indeed be as low as 0.65 or as high as 1.00. Therefore, TOF ratios measured by KMG and EMG cannot be used interchangeably.

Comparison of evoked electromyography in three muscles of the hand during recovery from non-depolarising neuromuscular blockade.

The evoked electromyographic responses to supramaximal train of four stimulation of three muscles, all innervated by the ulnar nerve, were compared during recovery from non-depolarising neuromuscular blockade. The abductor digiti minimi was the most resistant to neuromuscular blockade (P <0.001) and the most repeatable (repeatability coefficient 4.4%) when compared with the adductor pollicis (5.9%) and the first dorsal interosseous (5.8%). The abductor digiti minimi had a bias of 0.1 compared to the adductor pollicis and first dorsal interosseous and its limits of agreement were more acceptable (-0.10 to 0.30) at a train of four ratio of 0.9. The electromyography train of four of the adductor pollicis and first dorsal interosseous at 0.8 is equivalent to an electromyography train of four of 0.9 at abductor digiti minimi.