Quantitative Neuromuscular Monitoring Permits Early Diagnosis of Abnormal Butyrylcholinestrase: Two Case Studies Demonstrating Prevention of Awareness from Premature Awakening.

Administration of succinylcholine to patients with a variant in the butyrylcholinesterase (BChE) gene increases the risk of anesthesia emergence prior to recovery from neuromuscular blockade (NMB). Application of quantitative neuromuscular monitoring (NMM) can identify residual NMB. We present two patients with abnormal BChE gene variants. In the first case, quantitative monitoring was applied too late to prevent awareness, but allowed diagnosis and prevented admission to the intensive care unit. In the second case, monitoring was applied prior to NMB, which enabled early diagnosis and prevented premature awakening from anesthesia. These cases illustrate the importance of quantitative NMM, even in short cases and with short-acting depolarizing agents such as succinylcholine. The clinical implications of this report include a more consistent use of NMM to identify and manage patients with undiagnosed abnormal BChE and to prevent premature anesthesia emergence.

The feasibility of the posterior tibial nerve-flexor hallucis brevis pathway applied in neuromuscular monitoring: a multicentric, controlled, and prospective clinical trial.

This study aimed to investigate the clinical viability of utilizing the flexor hallucis brevis as an alternative site for neuromuscular monitoring compared to the conventional adductor pollicis. Patients were recruited from three medical centers. Cis-atracurium was administered, and two monitors were employed independently to assess neuromuscular blockade of the adductor pollicis and the ipsilateral flexor hallucis brevis, following a train of four (TOF) pattern until TOF ratios exceeded 0.9 or until the conclusion of surgery. Statistical analysis revealed significant differences in onset time, duration of no-twitch response, spontaneous recovery time, and total monitoring time between the two sites, with mean differences of -53.54 s, -2.49, 3.22, and 5.89 min, respectively (P < 0.001).The posterior tibial nerve-flexor hallucis brevis pathway presents a promising alternative for neuromuscular monitoring during anesthesia maintenance. Further investigation is warranted to explore its utility in anesthesia induction and recovery. Trial registration: The trial was registered at www.chictr.org.cn (20/11/2018, ChiCTR1800019651).

A compressomyograph train of four monitoring device.

The monitoring of the neuromuscular blockade is critical for patient's safety during and after surgery. The monitoring of neuromuscular blockade often requires the use of Train of Four (TOF) technique. During a TOF test two electrodes are attached to the ulnar nerve, and a series of four electric pulses are applied. The electrical stimulation causes the thumb to twitch, and the amount of twitch varies depending on the amount of neuromuscular blockade in patient's system. Current medical devices used to assist anesthesiologists to perform TOF monitoring often require free hand movement and do not provide accurate or reliable results. The goal of this work is to design, prototype and test a new medical device that provides reliable TOF results when thumb movement is restricted. A medical device that uses a pressurized catheter balloon to detect the response thumb twitch of the TOF test is created. An analytical model, numerical study, and mechanical finger testing were employed to create an optimum design. The design is tested through a pilot human subjects study. No significant correlation is reported with subjects' properties, including hand size.

Improving Neuromuscular Monitoring Through Education-Based Interventions and Studying Its Association With Adverse Postoperative Outcomes: A Retrospective Observational Study.

BACKGROUND: We assessed the association between education-based interventions, the frequency of train-of-four (TOF) monitoring, and postoperative outcomes. METHODS: We studied adults undergoing noncardiac surgery from February 1, 2020 through October 31, 2021. Our education-based interventions consisted of 3 phases. An interrupted time-series analysis, adjusting for patient- and procedure-related characteristics and secular trends over time, was used to assess the associations between education-based interventions and the frequency of TOF monitoring, postoperative pulmonary complications (PPCs), 90-day mortality, and sugammadex dosage. For each outcome and intervention phase, we tested whether the intervention at that phase was associated with an immediate change in the outcome or its trend (weekly rate of change) over time. In a sensitivity analysis, the association between education-based interventions and postoperative outcomes was adjusted for TOF monitoring. RESULTS: Of 19,422 cases, 11,636 (59.9%) had documented TOF monitoring. Monitoring frequency increased from 44.2% in the first week of preintervention stage to 83.4% in the final week of the postintervention phase. During the preintervention phase, the odds of TOF monitoring trended upward by 0.5% per week (odds ratio [OR], 1.005; 95% confidence interval [CI], 1.002-1.007). Phase 1 saw an immediate 54% increase (OR, 1.54; 95% CI, 1.33-1.79) in the odds, and the trend OR increased by 3% (OR, 1.03; 95% CI, 1.01-1.05) to 1.035, or 3.5% per week (joint Wald test, P < .001). Phase 2 was associated with a further immediate 29% increase (OR, 1.29; 95% CI, 1.02-1.64) but no significant association with trend (OR, 0.96; 95% CI, 0.93-1.01) of TOF monitoring (joint test, P = .04). Phase 3 and postintervention phase were not significantly associated with the frequency of TOF monitoring (joint test, P = .16 and P = .61). The study phases were not significantly associated with PPCs or sugammadex administration. The trend OR for 90-day mortality was larger by 24% (OR, 1.24; 95% CI, 1.06-1.45; joint test, P = .03) in phase 2 versus phase 1, from a weekly decrease of 8% to a weekly increase of 14%. However, this trend reversed again at the transition from phase 3 to the postintervention phase (OR, 0.82; 95% CI, 0.68-0.99; joint test, P = .05), from a 14% weekly increase to a 6.2% weekly decrease in the odds of 90-day mortality. In sensitivity analyses, adjusting for TOF monitoring, we found similar associations between study initiatives and postoperative outcomes. TOF monitoring was associated with lower odds of PPCs (OR, 0.69; 95% CI, 0.55-0.86) and 90-day mortality (OR, 0.79; 95% CI, 0.63-0.98), but not sugammadex dosing (mean difference, -0.02; 95% CI, -0.04 to 0.01). CONCLUSIONS: Our education-based interventions were associated with both TOF utilization and 90-day mortality but were not associated with either the odds of PPCs or sugammadex dosing. TOF monitoring was associated with reduced odds of PPCs and 90-day mortality.

Comparative performance of stimpod electromyography with mechanomyography for quantitative neuromuscular blockade monitoring.

PURPOSE: The purpose of this study was to compare the Stimpod electromyograph neuromuscular blockade monitor to mechanomyography, which is widely considered to be the reference standard. METHODS: The Stimpod electromyograph was used with its designated electrode array on the same hand as the mechanomyograph. Pairs of train-of-four measurements were recorded every 0.5-2 min. When the train-of-four count was zero on the electromyograph monitor, pairs of post tetanic count measurements were recorded every 2.5 min, instead of train-of-four measurements. Measurements were recorded from immediately after induction of anesthesia until just before emergence. Stimulation current was set to 60 mA with a duration of 200 microsec. The mechanomyography recording system recorded each twitch waveform for analysis. High resolution electromyograph waveforms were also recorded using a datalogger accessory provided by the manufacturer, facilitating inspection of individual waveforms. The administration of neuromuscular blocking drugs was left up to the discretion of the anesthesia care team. RESULTS: Twenty-three patients contributed 1,088 data pairs suitable for analysis. Bland-Altman analysis of 415 pairs of train-of-four ratios showed a bias of 0.028 and limits of agreement of -0.18 and 0.24. Two hundred seventy-three train-of-four count data pairs were compared by Cohen's quadratically weighted kappa which was calculated to be 0.44, indicating moderate agreement. Three hundred thirty-eight post tetanic count data pairs were compared by Cohen's quadradically weighted kappa which was calculated to be 0.80, indicating substantial agreement. CONCLUSION: The electromyograph produced results that were comparable to the mechanomyograph.

Standardization of the Extent and Timing of Rectus Diastasis Repair in Abdominoplasty Cases with TOF Neuromuscular Monitoring: A Clinical Study.

Despite the close focus on the anterior abdominal wall and the classification, maneuvers and materials related to the rectus abdominis and its fascia, there is no established standard concerning the extent of plication. The anterior abdominal wall is a musculoaponeurotic structure and a dynamic motor system with innervation and tonus. Therefore, the timing of the plication is as important as the suture technique and material, since the muscle relaxant will lose its effect in varying time periods. The aims of our study were to determine the change in the amount of plication between groups with and without muscle relaxants before plication and whether the amount of this change can be standardized using train-of-four (TOF) monitoring. In 2022 and 2023, 12 women aged between 25 and 48 years with a body mass index between 24 and 38 years were included in the study. Neuromuscular blockade was monitored by train-of-four (TOF) monitoring in all patients. Maximum plication areas at above-zero TOF value and zero TOF value were calculated and compared with each other. The reduction in the area of group 1, which represents the phase without muscle relaxant, and group 2, which represents the phase with neuromuscular blockade, were compared using the t-test. When assessed for above-zero TOF, the area between plication lines (a, a') was always smaller than the area between the plication lines (b, b') when the TOF value was zero. The t test comparison of group 1, which includes (a, a') values, and group 2, which includes (b, b') values, resulted in a value of p = 0.000. All cases, the plication value obtained with above-zero TOF value was lower than the plication value when the TOF value was zero. This difference was also confirmed statistically on a group basis. This suggests that neuromuscular measurements should be taken during the plication phase in the routine flow of surgery. Muscle relaxants are not routinely administered to patients undergoing abdominoplasty or rectus diastasis repair who are already under sufficient analgesia, unless there is a pressure alert on the anesthesia device. The surgeon cannot always determine the degree of muscle laxity accurately by palpation. TOF monitoring is a cost-effective quantitative method that can be easily and quickly performed, accurately determining the timing of muscle-fascia plication of the rectus abdominis. Through this approach, the anterior abdominal wall can be plicated with maximum tightness and maximum aesthetic gain can be obtained.Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Neuromuscular end-point predictive capability of published rocuronium pharmacokinetic/pharmacodynamic models: An observational trial.

BACKGROUND: Objective neuromuscular monitoring remains the single most reliable method to ensure optimal perioperative neuromuscular management. Nevertheless, the prediction of clinical neuromuscular endpoints by means of Pharmacokinetic (PK) and Pharmacodynamic (PD) modelling has the potential to complement monitoring and improve perioperative neuromuscular management.s STUDY OBJECTIVE: The present study aims to assess the performance of published Rocuronium PK/PD models in predicting intraoperative Train-of-four (TOF) ratios when benchmarked against electromyographic TOF measurements. DESIGN: Observational trial. SETTING: Tertiary Belgian hospital, from August 2020 up to September 2021. PATIENTS AND INTERVENTIONS: Seventy-four patients undergoing general anaesthesia for elective surgery requiring the administration of rocuronium and subject to continuous EMG neuromuscular monitoring were included. PK/PD-simulated TOF ratios were plotted and synchronised with their measured electromyographic counterparts and their differences analysed by means of Predictive Error derivatives (Varvel criteria). MAIN RESULTS: Published rocuronium PK/PD models overestimated clinically registered TOF ratios. The models of Wierda, Szenohradszky, Cooper, Alvarez-Gomez and McCoy showed significant predictive consistency between themselves, displaying Median Absolute Performance Errors between 38% and 41%, and intra-individual differences (Wobble) between 14 and 15%. The Kleijn model outperformed the former with a lower Median Absolute Performance Error (16%, 95%CI [0.01; 57]) and Wobble (11%, 95%CI [0.01; 34]). All models displayed considerably wide 95% confidence intervals for all performance metrics, suggesting a significantly variable performance. CONCLUSIONS: Simulated TOF ratios based on published PK/PD models do not accurately predict real intraoperative TOF ratio dynamics. TRIAL REGISTRATION: NCT04518761 (clinicaltrials.gov), registered on 19 August 2020.

Effects of the attachment method of the stimulating electrodes Nihon-Kohden NM-345Y™ and changes in forearm position on stimulus current values during calibration in electromyography-based neuromuscular monitoring: a single-center experimental study.

PURPOSE: The traditionally recommended method for attaching electromyography (EMG) electrodes (NM-345Y™) during EMG-based neuromuscular monitoring developed by Nihon-Kohden may decrease the monitoring accuracy when forearm limb position changes. This study investigated methods for attaching stimulating electrodes that maintained stable EMG-based neuromuscular monitoring accuracy, regardless of forearm limb position changes. METHODS: This single-center experimental study recruited 28 healthy adults from October 2022 to December 2022. The NM-345Y™ was attached to the forearm using three patterns: Pattern N, electrodes attached according to the attachment pattern recommended by Nihon-Kohden; Pattern U, electrodes attached along the ulnar nerve identified using an ultrasound device; Pattern C, electrodes attached where the ulnar nerve crosses the line connecting the centers of the anode and cathode of the stimulating electrodes. The stimulus current values during calibration were measured at three forearm positions for each attachment pattern: supination 90 degrees; pronation 0 degrees; pronation 90 degrees. The differences in stimulus current values caused by forearm position changes were calculated as the difference between values at supination 90 degrees and pronation 0 degrees and between values at supination 90 degrees and pronation 90 degrees. RESULTS: Pattern C showed significantly smaller differences than Pattern N between the stimulus current values at supination 90 degrees and pronation 0 degrees (p = 0.018) and between the stimulus current values at supination 90 degrees and pronation 90 degrees (p = 0.008). CONCLUSION: Crossing the ulnar nerve with the line connecting the anode and cathode of the stimulating electrodes may stabilize EMG-based neuromuscular monitoring accuracy.

Educating anaesthetists on neuromuscular monitoring: the challenges continue.

The need to introduce guidelines on neuromuscular monitoring emphasising the use of quantitative techniques that record the train-of-four ratio is now recognised by an increasing number of national anaesthetic societies in the Western world. But the challenge of convincing individual anaesthetists to adopt and use this practice routinely remains. For >10 yr, it has been recognised that all staff in anaesthetic departments need to have regular training in modern neuromuscular monitoring techniques. We discuss a publication in this journal that describes the challenges of setting up multicentre training in Spain to expand the use of quantitative neuromuscular monitoring and their short-term results.

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.

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).

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).

Effect of quantitative versus qualitative neuromuscular blockade monitoring on rocuronium consumption in patients undergoing abdominal and gynecological surgery: a retrospective cohort study.

The level of neuromuscular blockade can be assessed by subjective (qualitative) and objective (quantitative) methods. This study aims to compare the dosage of the neuromuscular blocking agents (NMBA) rocuronium and the need for reversion by sugammadex between those methods. A retrospective, observational analysis was conducted. In the tactile qualitative-neuromuscular monitoring-group (tactile NMM) (n = 244), muscle contractions were assessed tactilely. In the quantitative neuromuscular monitoring-group (n = 295), contractions were accessed using an acceleromyograph. Primary endpoints were dosage of rocuronium per minute operation-time (milligram per kilogram bodyweight per minute (mg/kgBW/min)), count of repeated rocuronium administrations and use of sugammadex. Secondary endpoints were: NMM use before repeated NMBA application or extubation, time to extubation, post-operative oxygen demand. A total of n = 539 patients were included. n = 244 patients were examined with tactile NMM and 295 patients by quantitative NMM. Quantitative NMM use resulted in significantly lower rocuronium dosing (tactile NMM: 0.01 (± 0.007) mg/kgBW/min vs. quantitative NMM: 0.008 (± 0.006) mg/kgBW/min (p < 0.001)). In quantitative NMM use fewer repetitions of rocuronium application were necessary (tactile NMM: 83% (n = 202) vs. quantitative NMM: 71% (n = 208) p = 0.007). Overall, 24% (n = 58) in the tactile NMM-group, and 20% (n = 60) in the quantitative NMM-group received sugammadex ((p = 0.3), OR: 1.21 (0.81-1.82)). Significantly fewer patients in the quantitative NMM-group required oxygen-supply postoperative (quantitative NMM: 43% (n = 120)) vs. tactile NMM: 57% (n = 128)) (p = 0.002). The use of quantitative assessment of NMBA results in a lower overall dosage and requires fewer repetitions of rocuronium application. Therefore, quantitative monitoring systems should be used to monitor NMBA intraoperatively to reduce NMBA dosing, while achieving continuous neuromuscular blockade.

A survey on the availability, usage and perception of neuromuscular monitors in Europe.

PURPOSE: Neuromuscular blocking agents (NMBAs) are routinely administered to patients in a multiplicity of anesthetic settings. Absence of postoperative residual neuromuscular block is widely considered an anesthetic patient safety mandate. Despite the increasing availability of a wider range of commercial quantitative neuromuscular monitors, the availability and use of neuromuscular monitoring devices is deemed to be suboptimal even in countries with above-average health system ratings. The present study aims to more precisely characterize the perceived availability, cost sensitivity and usability of neuromuscular monitoring devices within European anesthesia departments. METHODS: A pre-registered internet-based survey assessing the availability, cost sensitivity and usability of neuromuscular monitoring devices was distributed as e-mail newsletter by the European Society of Anaesthesiology and Intensive Care (ESAIC) to all of its active full members. The survey was available online for a total of 120 days. RESULTS: Having targeted a total of 7472 ESAIC members, the survey was completed by a total of 692 anesthesiologists (9.3%) distributed across 37 different European countries. Quantitative monitors were reported to be proportionally more available than qualitative ones (87.6% vs. 62.6%, respectively), as well as in greater monitor-per-operating room ratios. Most anesthesiologists (60.5%) expressed moderate confidence in quantitative monitors, with artifactual recordings and inaccurate measurements being the most frequently encountered issues (25.9%). The commercial pricing of quantitative devices was considered more representative of a device's true value, when compared to qualitative instruments (average cost of €4.500 and €1.000 per device, respectively). CONCLUSION: The availability of quantitative NMM in European operating theaters has increased in comparison with that reported in previous decades, potentially indicating increasing monitoring rates. European anesthesiologists express moderate confidence in quantitative neuromuscular monitors, along with a sentiment of adequate pricing when compared to their qualitative counterparts. Trust in quantitative monitors is marked by caution and awareness for artifactual recordings, with a consequent expectation that developments focusing on accuracy, reliability and ergonomics of neuromuscular monitors be prioritized.

2023 American Society of Anesthesiologists Practice Guidelines for Monitoring and Antagonism of Neuromuscular Blockade: A Report by the American Society of Anesthesiologists Task Force on Neuromuscular Blockade.

These practice guidelines provide evidence-based recommendations on the management of neuromuscular monitoring and antagonism of neuromuscular blocking agents during and after general anesthesia. The guidance focuses primarily on the type and site of monitoring and the process of antagonizing neuromuscular blockade to reduce residual neuromuscular blockade.