Comparison of the TetraGraph and TOFscan for monitoring recovery from neuromuscular blockade in the Post Anesthesia Care Unit

Intraoperative electromyographic monitoring in children using a novel pediatric sensor

Background

Train-of-four (TOF) monitoring is essential in optimizing perioperative outcomes as a means to assess the depth of neuromuscular blockade and confirm recovery following the administration of neuromuscular blocking agents (NMBAs). Quantitative TOF monitoring has been limited in infants and children primarily due to lack of effective equipment. The current study evaluates a novel electromyography (EMG)-based TOF monitor with a recently developed pediatric-sized self-adhesive sensor in infants and children.

Methods

Consented pediatric patients undergoing inpatient surgery requiring the administration of NMBAs were enrolled. The EMG electrode was placed along the ulnar nerve on the volar aspect of the distal forearm. The muscle action potentials from the adductor pollicis muscle were recorded throughout surgery at 20-second intervals. Data from the monitor's built-in memory card were later retrieved and analyzed.

Results

The final study cohort included 51 patients who ranged in age from 0.2 to 7.9 years and in weight from 4.2 to 36.0 kilograms. Thirty patients weighed less than 15 kgs. Supramaximal stimulus current intensity (mA) at a pulse width of 200 μsec was 30 mA in 8%; 40 mA in 29%; 50 mA in 16%; and 60 mA in 20% of the patients. Supramaximal stimulus current intensity (mA) at a pulse width of 300 μsec was 50 mA in 4%; 60 mA in 24%. The muscle action potential baseline amplitude was 8.7 ± 3.3 mV and recovered to 7.2 ± 3.7 mV after antagonism of neuromuscular blockade. The average baseline TOF ratio was 100 ± 3% and recovered to 98 ± 7% after antagonism of neuromuscular blockade. No technical issues were noted with application of the sensor or subsequent use of the monitor.

Conclusion

Neuromuscular monitoring can be performed intraoperatively in pediatric patients who are less than 8 years of age using a novel commercially available EMG-based monitor with a recently developed pediatric sensor. The novel sensor allows use of an EMG-based monitor in infants and children in whom acceleromyography or subjective (visual) observation of the TOF response may not be feasible. Automatic detection of neuromuscular stimulating parameters (supramaximal current intensity level, baseline amplitude of the muscle action potential) was feasible in pediatric patients of all sizes including those weighing less than 15 kilograms or when there was limited access to the extremity being monitored.

Intraoperative Monitoring of Neuromuscular Blockade

There is a global trend of new guidelines highly recommending quantitative neuromuscular monitoring in the operating room. In fact, it is almost certain that quantitatively monitoring the depth of intraoperative muscle paralysis may permit the rational use of muscle relaxants and avoid some of the major related complications, namely postoperative pulmonary complications. A specific culture related to this issue is necessary to integrate quantitative monitoring of muscle relaxants as part of a major monitoring entity in anesthetized patients. For this purpose, it is necessary to fully understand the physiology, pharmacology and concept of monitoring as well as the choice of pharmacological reversal, including the introduction of sugammadex a decade ago.

Comparison of visual and electromyographic assessments with train-of-four stimulation of the ulnar nerve: a prospective cohort study

PURPOSE

The use of a peripheral nerve stimulator to assess the level of neuromuscular blockade tasks the anesthesia clinician with subjectively assessing the response to neurostimulation. In contrast, objective neuromuscular monitors provide quantitative information. The purpose of this study was to compare subjective evaluations from a peripheral nerve stimulator with objective measurements of neurostimulation responses from a quantitative monitor.

METHODS

Patients were enrolled preoperatively, and intraoperative neuromuscular blockade management was at the discretion of the anesthesiologist. Electromyography electrodes were placed over the dominant or nondominant arm in a randomized fashion. Following onset of nondepolarizing neuromuscular blockade, the ulnar nerve was stimulated, the response was measured with electromyography, and anesthesia clinicians, who were blinded to the objective measurements, subjectively (visually) evaluated the response to neurostimulation.

RESULTS

Fifty patients were enrolled and 666 neurostimulations were performed at 333 different time points. Anesthesia clinicians subjectively overestimated the response of the adductor pollicis muscle following neurostimulation of the ulnar nerve 155/333 (47%) of the time when compared with objective electromyographic measurements. When subjective evaluations and objective measurements differed to any degree, subjective evaluations were higher than objective measurements 155/166 (92%) of the time (95% CI, 87 to 95; P < 0.001), representing significant evidence that subjective evaluation overestimates the response to train-of-four stimulation.

CONCLUSIONS

Subjective observations of a "twitch" do not consistently correspond to objective measurements of neuromuscular blockade with electromyography. Subjective evaluation overestimates the response to neurostimulation and may be unreliable for determining the depth of block or confirming adequate recovery.

Performance of a new auxiliary device based on wrist brace to improve accuracy and feasibility in neuromuscular monitoring with acceleromyography in prone-positioned patients undergoing lumbar spine surgery: a prospective randomized clinical trial

Accuracy of acceleromyography (AMG) is not be comparable to that of mechanomyography or electromyography (EMG). In particular, the prone position may reduce the accuracy and feasibility of AMG. We developed a new device based on wrist brace to allow free thumb movement and fix the other parts of the hand and wrist. We aimed to test whether the brace applied to the AMG would increase precision of AMG and agreement with the EMG in the prone position. Fifty-seven patients, undergoing lumbar surgery under general anesthesia, were randomly assigned to groups to which AMG was applied with or without (no) brace (29 in group B vs. 28 in group NB). EMG was performed in the contralateral arm. Repeatability coefficients of the first twitch height (T1) and train-of-four (TOF) ratio were assessed from nine consecutive measurements during spontaneous recovery from rocuronium-induced neuromuscular block and the AMGs of the two groups were compared in prone position. The agreement between AMG and EMG in each group was assessed using the Bland-Altman method. In group B, the repeatability coefficient of T1 was significantly lower during the recovery to T1 of 25% and TOF ratio of 0.9 (P = 0.017 and 0.033, respectively), indicating higher precision. The mean differences of bias (95% limits of agreement) between AMG and EMG in TOF ratio of 0.9 were 6.839 (- 26.54 to 40.22) in group NB and 3.922 (- 21.83 to 29.67) in group B. The wide limits of agreement in group NB was slightly narrowed in group B but without significance. Trial registration: registered on the UMIN Clinical Trials Registry in August 2020 (UMIN000041310).

Feasibility of intraoperative quantitative neuromuscular blockade monitoring in children using electromyography

Background:

Quantitative train-of-four (TOF) monitoring remains essential in optimizing anesthetic outcomes by assessing the depth and recovery from neuromuscular blockade. Despite this, residual neuromuscular blockade, defined as a TOF ratio <0.90, remains a concern in both adult and pediatric patients. Quantitative TOF monitoring has seen limited use in infants and children primarily due to a lack of effective equipment. This study evaluates a new electromyography (EMG)-based TOF monitor in pediatric patients undergoing inpatient surgical procedures including laparoscopic (restricted arm access) surgery.

Methods:

Pediatric patients undergoing inpatient surgery requiring the administration of neuromuscular blocking agents (NMBAs) were enrolled. The EMG electrodes were placed along the ulnar nerve on the volar aspect of the arm to provide neurostimulation. The muscle action potentials from the abductor digiti minimi muscle were recorded. Neuromuscular responses were recorded by the device throughout surgery at 20-s intervals until after tracheal extubation. Data recorded on the monitor's built-in memory card were later retrieved and analyzed.

Results:

The study cohort included 100 pediatric patients (62% male). The average age was 11 years (IQR: 8, 13) and the average weight was 39.6 kg (30, 48.7). Automatic detection of supramaximal stimulus was obtained in 95% of patients. The muscle action potential mean baseline amplitude (in mV) was 7.5 mV (6, 9.2). The baseline TOF ratio was 100% (100, 104). After administration of a neuromuscular blocking agent, monitoring of the TOF ratio was successful in 93% of the patients. After antagonism of neuromuscular blockade, monitoring was possible in 94% of patients when using an upgraded algorithm. The baseline amplitude recovered to 6.5 mV (5, 7.8), and the TOF ratio recovered to a mean of 90.1% (90,97) before tracheal extubation.

Conclusion:

Our results indicate that neuromuscular monitoring can be performed intraoperatively in pediatric patients weighing between 20 and 60 kg using the new commercially available EMG-based monitor. Automatic detection of neuromuscular stimulating parameters (supramaximal current intensity level and baseline amplitude of the muscle action potential) by an adult neuromuscular monitor is feasible in pediatric patients receiving nondepolarizing neuromuscular blocking agents.

A comparison of accelerometric monitoring by TOF Watch® SX and electromyographic monitoring by Tetragraph® for recovery from neuromuscular blockade

BACKGROUND

Neuromuscular monitoring has become a standard of care for management of anesthesia. While acceleromyography (AMG) is the most common technology used in clinical practice, guidelines suggest that electromyographic (EMG) devices are ideal for quantitative neuromuscular monitoring. The Tetragraph® is an EMG monitor that has recently been marketed.

STUDY OBJECTIVE

The aim of this study is to assess the agreement during recovery from neuromuscular blockade of this new monitor with the TOF Watch® SX, and to compare intraobserver variability for the two devices.

DESIGN

Single-center, prospective, observational clinical study.

SETTING

Operating room.

PATIENTS

Twenty-three patients were enrolled and twenty patients were included in the analysis.

INTERVENTION

A comparison of TOF-ratios measured sequentially from the same hand with the Tetragraph and TOF Watch SX was conducted during spontaneous recovery of neuromuscular function from patients that received rocuronium during surgery.

MAIN OUTCOME MEASURES

We used Bland-Altman plots for repeated measures to compare TOF-ratios obtained sequentially by the two devices. Subsequent measures with the same device were used to calculate intraobserver variability for each monitor.

MAIN RESULTS

The bias between AMG and EMG for TOF-ratios range between 0.2 and 1.0 was 0.13 (95% CI 0.08 to 0.18) and the limits of agreement (LoA) were - 0.11 (95% CI -0.20 to -0.06) and 0.37 (95% CI 0.32 to 0.46), respectively. Agreement slightly improved for TOF-ratios higher than 0.8 compared with lower TOF-ratios: the bias was 0.12 (95% CI 0.08 to 0.17) and 0.13 (95% CI 0.08 to 0.19), respectively. EMG relative intraobserver variability was lower compared with AMG (2.0%, IQR 0.0% to 4.5% vs. 3.2%, IQR 1.2% to 6.0%, P = 0.001).

CONCLUSIONS

Bias between the TOF Watch SX and the Tetragraph TOF-ratios is in line with previous results for AMG and EMG monitors.