Nagy, György M.

Background: There is little data available in infants on the extent to which inhalational anesthetics prolong the effects of neuromuscular blocking agents compared with intravenous agents. Here, we assessed the differences between the neuromuscular blocking effects (duration and recovery time) of a single dose of rocuronium during propofol vs. sevoflurane anesthesia. Methods: The prospective study enrolled 20 infants (4–12 months of age) scheduled for craniosynostosis surgery, randomly assigned to receive general anesthesia maintenance with sevoflurane or propofol. All patients received 0.6 mg/kg rocuronium as a single bolus dose to facilitate tracheal intubation and surgery. Primary study endpoint was the clinical duration of rocuronium, from administration until spontaneous recovery to a train-of-four ratio (TOFR) > 0.90. Secondary endpoints were times for reappearance of the first, second, third, and fourth twitches of the TOF (T1, T2, T3 and T4, respectively) in the two patient groups. Results: There were no differences in the infants’ age (sevoflurane maintenance: 5.8 ± 2.4 months; propofol maintenance: 6.7 ± 3.1 months, p = 0.47) or weight (sevoflurane: 7722 ± 1644 g; propofol: 7433 ± 1782 g, p = 0.71). Rocuronium onset time was 101.0 ± 55.0 s in the sevoflurane group and 83.4 ± 47.9 s in the propofol group (p = 0.46). Total duration of anesthesia was comparable in the sevoflurane (122.0 ± 23.8 min) and propofol (107.7 ± 25.2 min, p = 0.18) groups. Rocuronium recovery to TOFR > 0.9 required 136 min (CI: 123.7–149.5 min) in the sevoflurane group and 61.5 min (CI: 58.0–101.0 min) in the propofol group (p < 0.001). Conclusions: In infants, sevoflurane maintenance enhances the neuromuscular blocking effect of a single, 0.6 mg/kg BW dose of rocuronium as compared to propofol maintenance. After discontinuation of sevoflurane, additional time is necessary to reach the acceptable TOFR >0.9 needed before tracheal extubation. The present study further underscores the importance of objective (quantitative) neuromuscular monitoring in infants to guide intraoperative management and prevent residual neuromuscular block.

Background The paucity of easy-to-use, reliable objective neuromuscular monitors is an obstacle to universal adoption of routine neuromuscular monitoring. Electromyography (EMG) has been proposed as the optimal neuromuscular monitoring technology since it addresses several acceleromyography limitations. This clinical study compared simultaneous neuromuscular responses recorded from induction of neuromuscular block until recovery using the acceleromyography-based TOF-Watch SX and EMG-based TetraGraph. Methods Fifty consenting patients participated. The acceleromyography and EMG devices analyzed simultaneous contractions (acceleromyography) and muscle action potentials (EMG) from the adductor pollicis muscle by synchronization via fiber optic cable link. Bland–Altman analysis described the agreement between devices during distinct phases of neuromuscular block. The primary endpoint was agreement of acceleromyography- and EMG-derived normalized train-of-four ratios greater than or equal to 80%. Secondary endpoints were agreement in the recovery train-of-four ratio range less than 80% and agreement of baseline train-of-four ratios between the devices. Results Acceleromyography showed normalized train-of-four ratio greater than or equal to 80% earlier than EMG. When acceleromyography showed train-of-four ratio greater than or equal to 80% (n = 2,929), the bias was 1.3 toward acceleromyography (limits of agreement, –14.0 to 16.6). When EMG showed train-of-four ratio greater than or equal to 80% (n = 2,284), the bias was –0.5 toward EMG (–14.7 to 13.6). In the acceleromyography range train-of-four ratio less than 80% (n = 2,802), the bias was 2.1 (–16.1 to 20.2), and in the EMG range train-of-four ratio less than 80% (n = 3,447), it was 2.6 (–14.4 to 19.6). Baseline train-of-four ratios were higher and more variable with acceleromyography than with EMG. Conclusions Bias was lower than in previous studies. Limits of agreement were wider than expected because acceleromyography readings varied more than EMG both at baseline and during recovery. The EMG-based monitor had higher precision and greater repeatability than acceleromyography. This difference between monitors was even greater when EMG data were compared to raw (nonnormalized) acceleromyography measurements. The EMG monitor is a better indicator of adequate recovery from neuromuscular block and readiness for safe tracheal extubation than the acceleromyography monitor. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

BACKGROUND: There is a need for easy to use, reliable neuromuscular monitors (NMMs). This multicenter, prospective, unblinded study compared the discomfort associated with neurostimulation in unmedicated healthy volunteers when using the new electromyography (EMG)-based TetraGraph and acceleromyography (AMG)-based TOF-Watch NMMs. The secondary aim was to compare the repeatability of the train-of-four (TOF) ratios (TOFRs) obtained with the 2 devices. METHODS: The TOF measurements of 135 volunteers from 3 university hospitals were analyzed (age: 38.3 ± 12 years [mean ± standard deviation [SD]]; male/female ratio = 63:72). The left or right ulnar nerve was stimulated at the wrist in TOF mode with 20, 30, 40, and 50 mA stimulating current intensities with both devices in random order. The TOF-Watch used standard electrocardiography (ECG) electrodes (Red Dot; 3M Health Care) for nerve stimulation. The stimulating surface area of 1 ECG electrode is 113 mm 2 . The piezoelectric probe was attached to the thumb, and a hand adapter was used to ensure consistency of AMG measurements. The TetraGraph uses proprietary surface strip electrodes for nerve stimulation and muscle action potential recording, whose stimulating surface area is roughly twice as big as that of standard ECG electrodes (228.5 mm 2 ). The volunteers were asked to rate the discomfort associated with neurostimulation on a 0–10 verbal numerical rating scale (VNRS) score anchored with 0 (no pain) and 10 (worst pain ever experienced). A linear mixed-effects model was used to evaluate the difference in VNRS scores between devices. P <.05 was accepted as the level of significance. RESULTS: In the linear mixed-effects model, there were no differences in VNRS scores between devices at any of the stimulating current intensities, P = .38. The median (range) VNRS scores obtained with TOF-Watch and TetraGraph devices were 2 (0–7) vs 2 (0–8) at 20 mA, 3 (1–9) vs 3 (1–9) at 30 mA, 5 (1–10) vs 5 (1–10) at 40 mA, and 5 (1–10) vs 6 (1–10) at 50 mA stimulating current intensities. The mean of the 1469 TOFRs obtained with TetraGraph was 100.43% ± 7.74% (standard error = 0.2%). Due to technical difficulties, the repeatability of the TOFRs could not be determined. CONCLUSIONS: Despite the different size and design of the stimulating electrodes, the 2 NMMs caused the same level of discomfort in unmedicated healthy volunteers.