Kinemyography (KMG) versus Electromyography (EMG) neuromuscular monitoring in pediatric patients receiving cisatracurium during general anesthesia

Estimation of the effect-site equilibration rate constant using the time-to-peak effect of muscle relaxants measured by train-of-four stimulation during general anesthesia induction

Background

The concept of the effect-site concentration of anesthetic agents is important. The effect compartment model can be explained using the concepts of effect-site concentration and effect-site equilibration rate constant (k_e0). This study confirms that the time-to-peak effect (t_pe) can be measured easily in clinical practice by applying a priming dose and train-of-four (TOF) during general anesthesia induction, and k_e0 can be calculated from the t_pe of the four muscle relaxants that are commonly used in general anesthesia.

Methods

Eighty patients who received general anesthesia were divided into the succinylcholine, rocuronium, atracurium, or vecuronium groups. Priming doses of muscle relaxants were administered. The effects of muscle relaxants were quantified by recording the twitch response of the adductor pollicis muscle after stimulating the ulnar nerve. The t_pe was measured at the lowest TOF value. k_e0 was calculated from the measured t_pe.

Results

The k_e0 values of the succinylcholine, rocuronium, atracurium, and vecuronium groups were 0.076 (0.030)/min, 0.228 (0.122)/min, 0.062 (0.011)/min, and 0.077 (0.019)/min, respectively.

Conclusions

It is possible to estimate k_e0 from the t_pe of muscle relaxants using a priming dose and TOF during general anesthesia induction.

Comparison of Kinemyography and Electromyography during Spontaneous Recovery from Non-Depolarising Neuromuscular Blockade

This study compared two commercially available quantitative neuromuscular function monitoring techniques, kinemyography (KMG) and electromyography (EMG), to assess whether KMG could be used interchangeably with EMG to exclude residual neuromuscular blockade (RNMB). Train-of-four (TOF) ratios were recorded every 20 seconds using KMG at the adductor pollicis and EMG at the first dorsal interosseous of the same hand during spontaneous recovery from shallow neuromuscular blockade. TOF ratios were compared using Bland–Altman analysis for repeated measurements. The precision of each device was assessed by the repeatability coefficient. Agreement between devices was assessed by the bias and limits of agreement. Clinically acceptable agreement was defined as a bias <0.025 within limits of agreement ±0.05. We recorded 629 sets of TOF ratios from 23 patients. The repeatability coefficient for KMG was 0.05 (95% confidence interval [CI] 0.05 to 0.06) and for EMG 0.10 (95% CI 0.10 to 0.11). Overall, the bias of KMG TOF ratios against EMG TOF ratios was 0.11 (95% CI 0.10 to 0.12), with limits of agreement −0.11 to 0.32. In the 0.80 to 0.99 TOF range, the bias was 0.08 (95% CI 0.06 to 0.09) and the limits of agreement were-0.12 to 0.27. Overall, TOF ratios measured by KMG were on average 0.11 higher than EMG. In the 0.80 to 0.99 TOF range, KMG TOF ratios were 0.08 higher. EMG and KMG are not interchangeable because the bias is large and the limits of agreement are wide. Thus a maximum TOF ratio of 1.0 on KMG may not exclude RNMB.