Ipsilateral and Simultaneous Comparison of Responses from Acceleromyography- and Electromyography-based Neuromuscular Monitors

Machine learning based analysis and detection of trend outliers for electromyographic neuromuscular monitoring

PURPOSE

Neuromuscular monitoring is frequently plagued by artefacts, which along with the frequent unawareness of the principles of this subtype of monitoring by many clinicians, tends to lead to a cynical attitute by clinicians towards these monitors. As such, the present study aims to derive a feature set and evaluate its discriminative performance for the purpose of Train-of-Four Ratio (TOF-R) outlier analysis during continuous intraoperative EMG-based neuromuscular monitoring.

METHODS

Patient data was sourced from two devices: (1) Datex-Ohmeda Electromyography (EMG) E-NMT: a dataset derived from a prospective observational trial including 136 patients (21,891 TOF-R observations), further subdivided in two based on the type of features included; and (2) TetraGraph: a clinical case repository dataset of 388 patients (97,838 TOF-R observations). The two datasets were combined to create a synthetic set, which included shared features across the two. This process led to the training of four distinct models.

RESULTS

The models showed an adequate bias/variance balance, suggesting no overfitting or underfitting. Models 1 and 2 consistently outperformed the others, with the former achieving an F1 score of 0.41 (0.31, 0.50) and an average precision score (95% CI) of 0.48 (0.35, 0.60). A random forest model analysis indicated that engineered TOF-R features were proportionally more influential in model performance than basic features.

CONCLUSIONS

Engineered TOF-R trend features and the resulting Cost-Sensitive Logistic Regression (CSLR) models provide useful insights and serve as a potential first step towards the automated removal of outliers for neuromuscular monitoring devices.

TRIAL REGISTRATION

NCT04518761 (clinicaltrials.gov), registered on 19 August 2020.

Area under the curve and amplitude of the compound motor action potential are clinically interchangeable quantitative measures of neuromuscular block: a method comparison study

Background

Current guidelines recommend quantitative neuromuscular block monitoring during neuromuscular blocking agent administration. Monitors using surface electromyography (EMG) determine compound motor action potential (cMAP) amplitude or area under the curve (AUC). Rigorous evaluation of the interchangeability of these methods is lacking but necessary for clinical and research assurance that EMG interpretations of the depth of neuromuscular block are not affected by the methodology.

Methods

Digitised EMG waveforms were studied from 48 patients given rocuronium during two published studies. The EMG amplitudes and AUCs were calculated pairwise from all cMAPs classified as valid by visual inspection. Ratios of the first twitch (T1) to the control T1 before administration of rocuronium (T1c) and train-of-four ratios (TOFRs) were compared using repeated measures Bland-Altman analysis.

Results

Among the 2419 paired T1/T1c differences where the average T1/T1c was ≤0.2, eight (0.33%) were outside prespecified clinical limits of agreement (-0.148 to 0.164). Among the 1781 paired TOFR differences where the average TOFR was ≥0.8, 70 (3.93%) were outside the prespecified clinical limits of agreement ((-0.109 to 0.134). Among all 7286 T1/T1c paired differences, the mean bias was 0.32 (95% confidence interval 0.202-0.043), and among all 5559 paired TOFR differences, the mean bias was 0.011 (95% confidence interval 0.0050-0.017). Among paired T1/T1c and TOFR differences, Lin's concordance correlation coefficients were 0.98 and 0.995, respectively. Repeatability coefficients for T1/T1c and TOFR were <0.08, with no differences between methods.

Conclusions

Quantitative assessment neuromuscular block depth is clinically interchangeable when calculated using cMAP amplitude or the AUC.

A Practical Dosing Algorithm for Deep Neuromuscular Blockade during Total Intravenous Anesthesia: ROCURITHM

BACKGROUND

The number of trials investigating the effects of deep neuromuscular blockade (NMB) on surgical conditions and patient outcomes is steadily increasing. Consensus on which surgical procedures benefit from deep NMB (a posttetanic count [PTC] of 1 to 2) and how to implement it has not been reached. The European Society of Anaesthesiology and Intensive Care does not advise routine application but recommends use of deep NMB to improve surgical conditions on indication. This study investigates the optimal dosing strategy to reach and maintain adequate deep NMB during total intravenous anesthesia.

METHODS

Data from three trials investigating deep NMB during laparoscopic surgery with total intravenous anesthesia (n = 424) were pooled to analyze the required rocuronium dose, when to start continuous infusion, and how to adjust. The resulting algorithm was validated (n = 32) and compared to the success rate in ongoing studies in which the algorithm was not used (n = 180).

RESULTS

The mean rocuronium dose based on actual bodyweight for PTC 1 to 2 was (mean ± SD) 1.0 ± 0.27 mg · kg-1 ·h-1 in the trials, in which mean duration of surgery was 116 min. An induction dose of 0.6 mg ·kg-1 led to a PTC of 1 to 5 in a quarter of patients after a mean of 11 min. The remaining patients were equally divided over too shallow (additional bolus and direct start of continuous infusion) or too deep; a 15-min wait after PTC of 0 for return of PTC to 1 or higher. Using the proposed algorithm, a mean 76% of all 5-min measurements throughout surgery were on target PTC 1 to 2 in the validation cohort. The algorithm performed significantly better than anesthesiology residents without the algorithm, even after a learning curve from 0 to 20 patients (42% on target, P ≤ 0.001, Cohen's d = 1.4 [95% CI, 0.9 to 1.8]) to 81 to 100 patients (61% on target, P ≤ 0.05, Cohen's d = 0.7 [95% CI, 0.1 to 1.2]).

CONCLUSIONS

This study proposes a dosing algorithm for deep NMB with rocuronium in patients receiving total intravenous anesthesia.

EDITOR’S PERSPECTIVE

Accuracy and Precision of Three Acceleromyographs, Three Electromyographs, and a Mechanomyograph Measuring the Train-of-four Ratio in the Absence of Neuromuscular Blocking Drugs

BACKGROUND

The accuracy and precision of currently available, widely used acceleromyograph and electromyograph neuromuscular blockade monitors have not been well studied. In addition, the normalization of the train-of-four ratio from acceleromyography (train-of-four ratio [T4/T1] divided by the baseline train-of-four ratio) has not been validated in comparison to mechanomyography.

METHODS

Enrolled patients had surgery under general anesthesia with a supraglottic airway and without any neuromuscular blocking drugs. Three acceleromyograph monitors, three electromyograph monitors, and a mechanomyograph built in the authors' laboratory were tested. Most patients had an electromyograph and the mechanomyograph on one arm and a third monitor on the contralateral arm. Train-of-four ratios were collected every 12 to 20 s for the duration of the anesthetic. At least 1,000 train-of-four ratios were recorded for each device. Gauge repeatability and reproducibility analysis was performed.

RESULTS

Twenty-eight patients were enrolled. In total, 9,498 train-of-four ratio measurements were collected. Since no neuromuscular blocking drugs were used, the expected train-of-four ratio was 1.0. All of the acceleromyograph monitors produced overshoot in the train-of-four ratio (estimated means, 1.10 to 1.13) and substantial variability (gauge SDs, 0.07 to 0.18). Normalization of the train-of-four ratio measured by acceleromyography improved the estimated mean for each device (0.97 to 1.0), but the variability was not improved (gauge SDs, 0.06 to 0.17). The electromyograph and the mechanomyograph monitors produced minimal overshoot (estimated means, 0.99 to 1.01) and substantially less variation (gauge SDs, 0.01 to 0.02). For electromyography and mechanomyography, 0.3% of all train-of-four ratios were outside of the range 0.9 to 1.1. For acceleromyography, 27 to 51% of normalized train-of-four ratios were outside the range of 0.9 to 1.1.

CONCLUSIONS

Three currently available acceleromyograph monitors produced overshoot and substantial variability that could be clinically significant. Normalization corrected the overshoot in the average results but did not reduce the wide variability. Three electromyograph monitors measured the train-of-four ratio with minimal overshoot and variability, similar to a mechanomyograph.

EDITOR’S PERSPECTIVE

Pediatric Intraoperative Electromyographic Responses at the Adductor Pollicis and Flexor Hallucis Brevis Muscles: A Prospective, Comparative Analysis

BACKGROUND

Peripheral nerve stimulation with a train-of-four (TOF) pattern can be used intraoperatively to evaluate the depth of neuromuscular block and confirm recovery from neuromuscular blocking agents (NMBAs). Quantitative monitoring can be challenging in infants and children due to patient size, equipment technology, and limited access to monitoring sites. Although the adductor pollicis muscle is the preferred site of monitoring, the foot is an alternative when the hands are unavailable. However, there is little information on comparative evoked neuromuscular responses at those 2 sites.

METHODS

Pediatric patients undergoing inpatient surgery requiring NMBA administration were studied after informed consent. Electromyographic (EMG) monitoring was performed simultaneously in each participant at the hand (ulnar nerve, adductor pollicis muscle) and the foot (posterior tibial nerve, flexor hallucis brevis muscle).

RESULTS

Fifty patients with a mean age of 3.0 ± standard deviation (SD) 2.9 years were studied. The baseline first twitch amplitude (T1) of TOF at the foot (12.46 mV) was 4.47 mV higher than at the hand (P <.0001). The baseline TOF ratio (TOFR) before NMBA administration and the maximum TOFR after antagonism with sugammadex were not different at the 2 sites. The onset time until the T1 decreased to 10% or 5% of the baseline value (T1) was delayed by approximately 90 seconds (both P =.014) at the foot compared with the hand. The TOFR at the foot recovered (TOFR ≥0.9) 191 seconds later than when this threshold was achieved at the hand (P =.017). After antagonism, T1 did not return to its baseline value, a typical finding with EMG monitoring, but the fractional recovery (maximum T1 at recovery divided by the baseline T1) at the hand and foot was not different, 0.81 and 0.77, respectively (P =.68). The final TOFR achieved at recovery was approximately 100% and was not different between the 2 sites.

CONCLUSIONS

Although this study in young children demonstrated the feasibility of TOF monitoring, interpretation of the depth of neuromuscular block needs to consider the delayed onset and the delayed recovery of TOFR at the foot compared to the hand. The delay in achieving these end points when monitoring the foot may impact the timing of tracheal intubation and assessment of adequate recovery of neuromuscular block to allow tracheal extubation (ie, TOFR ≥0.9).

Evolution of a laboratory mechanomyograph

Mechanomyography is currently the accepted laboratory reference standard for quantitative neuromuscular blockade monitoring. Mechanomyographs are not commercially available. Previously, a mechanomyograph was built by our laboratory and used in several clinical studies. It was subsequently redesigned to improve its usability and functionality and to accommodate a wider range of hand sizes and shapes using an iterative design process. Each version of the redesigned device was initially tested for usability and functionality in the lab with the investigators as subjects without electrical stimulation. The redesigned devices were then assessed on patients undergoing elective surgery under general anesthesia without neuromuscular blocking drugs. Since the patients were not paralyzed, the expected train-of-four ratio was 1.0. The device accuracy and precision were represented by the train-of-four ratio mean and standard deviation. If issues with the device's useability or functionality were discovered, changes were made, and the redesign processes repeated. The final mechanomyograph design was used to collect 2,362 train-of-four ratios from 21 patients. The mean and standard deviation of the train-of-four ratios were 0.99 ± 0.030. Additionally, the final mechanomyograph design was easier to use and adjust than the original design and fit a wider range of hand sizes. The final design also reduced the frequency of adjustments and the time needed for adjustments, facilitating data collection during a surgical procedure.

Validation of a convolutional neural network that reliably identifies electromyographic compound motor action potentials following train-of-four stimulation: an algorithm development experimental study

Background

International guidelines recommend quantitative neuromuscular monitoring when administering neuromuscular blocking agents. The train-of-four count is important for determining the depth of block and appropriate reversal agents and doses. However, identifying valid compound motor action potentials (cMAPs) during surgery can be challenging because of low-amplitude signals and an inability to observe motor responses. A convolutional neural network (CNN) to classify cMAPs as valid or not might improve the accuracy of such determinations.

Methods

We modified a high-accuracy CNN originally developed to identify handwritten numbers. For training, we used digitised electromyograph waveforms (TetraGraph) from a previous study of 29 patients and tuned the model parameters using leave-one-out cross-validation. External validation used a dataset of 19 patients from another study with the same neuromuscular block monitor but with different patient, surgical, and protocol characteristics. All patients underwent ulnar nerve stimulation at the wrist and the surface electromyogram was recorded from the adductor pollicis muscle.

Results

The tuned CNN performed highly on the validation dataset, with an accuracy of 0.9997 (99% confidence interval 0.9994-0.9999) and F1 score=0.9998. Performance was equally good for classifying the four individual responses in the train-of-four sequence. The calibration plot showed excellent agreement between the predicted probabilities and the actual prevalence of valid cMAPs. Ten-fold cross-validation using all data showed similar high performance.

Conclusions

The CNN distinguished valid cMAPs from artifacts after ulnar nerve stimulation at the wrist with >99.5% accuracy. Incorporation of such a process within quantitative electromyographic neuromuscular block monitors is feasible.

Good clinical research practice (GCRP) in pharmacodynamic studies of neuromuscular blocking agents III: The 2023 Geneva revision

The set of guidelines for good clinical research practice in pharmacodynamic studies of neuromuscular blocking agents was developed following an international consensus conference in Copenhagen in 1996 (Viby-Mogensen et al., Acta Anaesthesiol Scand 1996, 40, 59-74); the guidelines were later revised and updated following the second consensus conference in Stockholm in 2005 (Fuchs-Buder et al., Acta Anaesthesiol Scand 2007, 51, 789-808). In view of new devices and further development of monitoring technologies that emerged since then, (e.g., electromyography, three-dimensional acceleromyography, kinemyography) as well as novel compounds (e.g., sugammadex) a review and update of these recommendations became necessary. The intent of these revised guidelines is to continue to help clinical researchers to conduct high-quality work and advance the field by enhancing the standards, consistency, and comparability of clinical studies. There is growing awareness of the importance of consensus-based reporting standards in clinical trials and observational studies. Such global initiatives are necessary in order to minimize heterogeneous and inadequate data reporting and to improve clarity and comparability between different studies and study cohorts. Variations in definitions of endpoints or outcome variables can introduce confusion and difficulties in interpretation of data, but more importantly, it may preclude building of an adequate body of evidence to achieve reliable conclusions and recommendations. Clinical research in neuromuscular pharmacology and physiology is no exception.

Comparison of onset of neuromuscular blockade with electromyographic and acceleromyographic monitoring: a prospective clinical trial

BACKGROUND

Reliable devices that quantitatively monitor the level of neuromuscular blockade after neuromuscular blocking agents' administration are crucial. Electromyography and acceleromyography are two monitoring modalities commonly used in clinical practice. The primary outcome of this study is to compare the onset of neuromuscular blockade, defined as a Train-Of-Four Count (TOFC) equal to 0, as measured by an electromyography-based device (TetraGraph) and an acceleromyography-based device (TOFscan). The secondary outcome was to compare intubating conditions when one of these two devices reached a TOFC equal to 0.

METHODS

One hundred adult patients scheduled for elective surgery requiring neuromuscular blockade were enrolled. Prior to induction of anesthesia, TetraGraph electrodes were placed over the forearm of patients' dominant/non-dominant hand based on randomization and TOFscan electrodes placed on the contralateral forearm. Intraoperative neuromuscular blocking agent dose was standardized to 0.5 mg.kg-1 of rocuronium. After baseline values were obtained, objective measurements were recorded every 20 seconds and intubation was performed using video laryngoscopy once either device displayed a TOFC = 0. The anesthesia provider was then surveyed about intubating conditions.

RESULTS

Baseline TetraGraph train-of-four ratios were higher than those obtained with TOFscan (Median: 1.02 [0.88, 1.20] vs. 1.00 [0.64, 1.01], respectively, p < 0.001). The time to reach a TOFC = 0 was significantly longer when measured with TetraGraph compared to TOFscan (Median: 160 [40, 900] vs. 120 [60, 300] seconds, respectively, p < 0.001). There was no significant difference in intubating conditions when either device was used to determine the timing of endotracheal intubation.

CONCLUSIONS

The onset of neuromuscular blockade was longer when measured with TetraGraph than TOFscan, and a train-of-four count of zero in either device was a useful indicator for adequate intubating conditions.

CLINICAL TRIAL NUMBER AND REGISTRY

URL NCT05120999, https://clinicaltrials.gov/ct2/show/NCT05120999.

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.

The impact of electrosurgical devices on electromyography-based neuromuscular monitoring during abdominal laparotomy: a case series

The present study aimed to evaluate the effect of electrosurgical devices on neuromuscular monitoring using an electromyography (EMG)-based neuromuscular monitor during abdominal laparotomy. Seventeen women (aged 32-64 years) undergoing gynecological laparotomy under total intravenous general anesthesia were enrolled in the study. A TetraGraph™ was placed to stimulate the ulnar nerve and to monitor the abductor digiti minimi muscle. After device calibration, train-of-four (TOF) measurements were repeated at intervals of 20 s. Rocuronium 0.6 to 0.9 mg/kg was administered for induction, and additional doses of 0.1 to 0.2 mg/kg were administered to maintain TOF counts ≤ 2 during the surgery. The primary outcome of the study was the ratio of measurement failure. The secondary outcomes of the study were the total number of measurements, the number of measurement failures, and the most extended consecutive number of measurement failures. The data are expressed as median (range). Of the 3091 (1480-8134) measurements, the number of measurement failures was 94 (60-200), resulting in a failure ratio of 3.5% (1.4-6.5%). The most extended consecutive number of measurement failures was 8 (4-13). All attending anesthesiologists were able to maintain and reverse neuromuscular blocks under EMG guidance. This prospective observational study demonstrated that the use of EMG-based neuromuscular monitoring does not seem to be heavily affected by electrical interference during lower abdominal laparotomic surgery. Trial registration This trial was registered in the University Hospital Medical Information Network under registration number UMIN000048138 (registration date; June 23, 2022).

Neuromuscular Weakness and Paralysis Produced by Snakebite Envenoming: Mechanisms and Proposed Standards for Clinical Assessment

Respiratory and airway-protective muscle weakness caused by the blockade of neuromuscular transmission is a major cause of early mortality from snakebite envenoming (SBE). Once weakness is manifest, antivenom appears to be of limited effectiveness in improving neuromuscular function. Herein, we review the topic of venom-induced neuromuscular blockade and consider the utility of adopting clinical management methods originally developed for the safe use of neuromuscular blocking agents by anesthesiologists in operating rooms and critical care units. Failure to quantify neuromuscular weakness in SBE is predicted to cause the same significant morbidity that is associated with failure to do so in the context of using a clinical neuromuscular block in surgery and critical care. The quantitative monitoring of a neuromuscular block, and an understanding of its neurophysiological characteristics, enables an objective measurement of weakness that may otherwise be overlooked by traditional clinical examination at the bedside. This is important for the initial assessment and the monitoring of recovery from neurotoxic envenoming. Adopting these methods will also be critical to the conduct of future clinical trials of toxin-inhibiting drugs and antivenoms being tested for the reversal of venom-induced neuromuscular block.

Assessment of the New Acceleromyograph TOF 3D Compared with the Established TOF Watch SX: Bland-Altman Analysis of the Precision and Limits of Agreement between Both Devices-A Randomized Clinical Comparison

The new acceleromyograph TOF 3D was compared with the established TOF Watch SX in patients undergoing elective laparoscopic gynecological surgery. Neuromuscular transmission was assessed by simultaneous recording with both devices. Measurements were performed simultaneously at the left and the right M. adductor pollicis (Group A, 25 patients), or the M. corrugator supercilii (Group CS, 25 patients). The repeatability, time course, and limits of agreement (Bland-Altman) were compared. The primary endpoint was the 90% train-of-four recovery time (TOFR 0.9). Other endpoints included onset time of block, maximum T1 depression, time to 25% T1 recovery, the recovery time course of T1 response, and TOF ratio, respectively. In group CS, the repeatability coefficient of the TOF 3D was lower (4.66 (1.6)) than of the TOF Watch SX (6.02 (1.9); p = 0.026). In group A, the onset of the block was faster when measured by the TOF 3D (98.7 (30) s vs. 112.2 (36) s (mean (SD)); p = 0.032). In group A, time to recovery to a TOFR of 90% was measured earlier by the TOF 3D (bias −0.71 min, limits of agreement from −8.94 to +7.51 min). The TOF 3D provides adequate information with high precision and sensitivity. It is suitable even for measurement sites with small muscle contractions such as the M. corrugator supercilii.

A modified TOF-ratio to assess rocuronium-induced neuromuscular block: a comparison with the usual TOF-ratio

BACKGROUND

The TOFscan is an acceleromyographic neuromuscular monitor that calculates and displays two measurements: first, a train-of-four (TOF) ratio, or ratio of the fourth twitch in the TOF-sequence, T4, and the first twitch, T1 (T4/T1). In addition, a second, modified ratio is displayed (T4/Tr), which refers to the ratio between T4 and a reference twitch (Tr), calculated as the mean value of the four twitches in a TOF-sequence [Tr = (T1 + T2 + T3 + T4)/4]. T4/Tr is calculated before establishment of neuromuscular block.

METHODS

This prospective observational study included 35 adult patients. NMB induced by a rocuronium bolus of 0.6 mg/kg was continuously monitored at the adductor pollicis with the TOFscan and both TOF-ratios were simultaneously assessed. Primary outcome was the comparison of recovery to a TOF-ratio ≥ 0.9 calculated as T4/T1 and T4/Tr.

RESULTS

The first value of the T4/T1 ≥ 90% was 90.9 (1.1) % and the simultaneously calculated T4/Tr was 69.6 (9.3) %, P <  0.001. The first value of the T4/Tr ≥ 90% was 90.5 (1.1) %, the simultaneously T4/T1 was 97.3 (2.5) %, P <  0.001. Time from injection of rocuronium to a TOF-ratio ≥ 90% was 56.2 ± 17.1 min for the T4/T1 and 65.3 ± 19.3 min for the T4/Tr, P < 0.001. During onset, a TOF ratio ≤ 20% was reached 145.5 (50.5) s after rocuronium when considering T4/T1, and 114.5 (45) s with the T4/Tr, P <  0.001.

CONCLUSION

The present study shows the limitations of the usually determined acceleromyographic TOF ratio (T4/T1) in determining adequate neuromuscular recovery. The T4/T1 ratio significantly overestimates recovery compared with the T4/Tr ratio. Clinical decisions of adequate neuromuscular recovery based on the new T4/Tr ratio may reduce the incidence of residual paralysis and improve patient safety.

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.