Acceleromyography of the orbicularis oculi muscle II: comparing the orbicularis oculi and adductor pollicis muscles

Methods for Clinical Monitoring of Neuromuscular Transmission in Anesthesiology - A Review

The administration of general anesthesia is a crucial aspect of surgery. However, it can pose significant risks to patients, such as respiratory depression and prolonged neuromuscular blockade. To avoid such complications, it is essential to monitor neuromuscular transmission during anesthesia. While clinical tests have been used for decades to evaluate muscle function, they are now known to be unreliable, and relying on them increases the risk of postoperative complications. Thankfully, there are now six methods available for neuromuscular monitoring during anesthesia: mechanomyography, acceleromyography, electromyography, kinemyography, phonomyography, and compressomyography. Each of these methods differs in terms of their approach and methodology, and their importance in clinical practice varies accordingly. Mechanomyography involves measuring the mechanical response of a muscle to nerve stimulation, while acceleromyography measures the acceleration of muscle contraction. Electromyography records the electrical activity of muscles, while kinemyography tracks muscle movement. Phonomyography records the sound waves produced by contracting muscles, and compressomyography involves monitoring the pressure changes in a muscle during contraction. Overall, understanding the differences between these methods and their clinical significance is crucial for anesthesiologists. This review aims to provide an updated understanding of the current methods available for neuromuscular monitoring during anesthesia, so that anesthesiologists can make informed decisions about patient care and reduce the risk of postoperative complications.

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.

Botulinum Toxin A Injection and Perianesthesia Neuromuscular Monitoring: Case Report and Review

The popularity of looking younger has been facilitated by the availability of botulinum toxin (BoNT) injection. In 2019, over 7.7 million injections of BoNT occurred, making it the number one minimally invasive cosmetic procedure in the United States. With the ease of patients obtaining BoNT in an outpatient setting, coupled with the fact that it is considered a minimally invasive procedure, most patients do not disclose the use of BoNT during the preoperative anesthesia evaluation. This case report involves a female whose recent BoNT injections interfered with neuromuscular (NM) monitoring during anesthesia. Neuromuscular monitoring was performed using the orbicularis oculi muscle with repeated train-of-four (TOF) 0/4. It was not until completion of procedure when the arms were accessible that the adductor pollicis muscle was assessed with a TOF of 2/4. During postoperative follow up, the patient revealed she had received BoNT injections prior to surgery. A review of BoNT pharmacology, barriers to NM monitoring and use of sugammadex are discussed. This case demonstrates the importance of ascertaining BoNT injection history in any case in which access to the ulnar nerve or tibial nerve is not available.

Neuromuscular Blockade Monitoring

Neuromuscular monitoring is essential for optimal management of neuromuscular blocking drugs. Postoperative residual neuromuscular blockade continues to occur with an unacceptably high incidence and is associated with adverse patient outcomes. Use of a peripheral nerve stimulator and subjective tactile or visual assessment is useful for intraoperative management of neuromuscular blockade, especially when the patient's hand is accessible. Quantitative monitoring is necessary for confirmation of adequate reversal and for identification of patients who have recovered spontaneously and therefore should not receive pharmacologic reversal agents. Guidelines, as well as more user-friendly monitoring equipment, have created momentum toward improving routine perioperative neuromuscular monitoring.

Comparison between the trapezius and adductor pollicis muscles as an acceleromyography monitoring site for moderate neuromuscular blockade during lumbar surgery

Acceleromyography at the adductor pollicis located in a distal part of the body may not reflect the degree of neuromuscular blockade (NMB) at the proximally located muscles manipulated during lumbar surgery. We investigated the usefulness and characteristics of acceleromyographic monitoring at the trapezius for providing moderate NMB during lumbar surgery. Fifty patients were randomized to maintain a train-of-four count 1–3 using acceleromyography at the adductor pollicis (group A; n = 25) or the trapezius (group T; n = 25). Total rocuronium dose administered intraoperatively [mean ± SD, 106.4 ± 31.3 vs. 74.1 ± 17.6 mg; P < 0.001] and surgical satisfaction (median [IQR], 7 [5–8] vs. 5 [4–5]; P < 0.001) were significantly higher in group T than group A. Lumbar retractor pressure (88.9 ± 12.0 vs. 98.0 ± 7.8 mmHg; P = 0.003) and lumbar muscle tone in group T were significantly lower than group A. Time to maximum block with an intubating dose was significantly shorter in group T than group A (44 [37–54] vs. 60 [55–65] sec; P < 0.001). Other outcomes were comparable. Acceleromyography at the trapezius muscle during lumbar surgery required a higher rocuronium dose for moderate NMB than the adductor pollicis muscle, thereby the consequent deeper NMB provided better surgical conditions. Trapezius as proximal muscle may better reflect surgical conditions of spine muscle.

Guidelines on muscle relaxants and reversal in anaesthesia

OBJECTIVES

To provide an update to the 1999 French guidelines on "Muscle relaxants and reversal in anaesthesia", a consensus committee of sixteen experts was convened. A formal policy of declaration and monitoring of conflicts of interest (COI) was developed at the outset of the process and enforced throughout. The entire guidelines process was conducted independently of any industrial funding (i.e. pharmaceutical, medical devices). The authors were required to follow the rules of the Grading of Recommendations, Assessment, Development and Evaluation (GRADE®) system to assess the quality of the evidence on which the recommendations were based. The potential drawbacks of making strong recommendations based on low-quality evidence were stressed. Few of the recommendations remained ungraded.

METHODS

The panel focused on eight questions: (1) In the absence of difficult mask ventilation criteria, is it necessary to check the possibility of ventilation via a facemask before muscle relaxant injection? Is it necessary to use muscle relaxants to facilitate facemask ventilation? (2) Is the use of muscle relaxants necessary to facilitate tracheal intubation? (3) Is the use of muscle relaxants necessary to facilitate the insertion of a supraglottic device and management of related complications? (4) Is it necessary to monitor neuromuscular blockade for airway management? (5) Is the use of muscle relaxants necessary to facilitate interventional procedures, and if so, which procedures? (6) Is intraoperative monitoring of neuromuscular blockade necessary? (7) What are the strategies for preventing and treating residual neuromuscular blockade? (8) What are the indications and precautions for use of both muscle relaxants and reversal agents in special populations (e.g. electroconvulsive therapy, obese patients, children, neuromuscular diseases, renal/hepatic failure, elderly patients)? All questions were formulated using the Population, Intervention, Comparison and Outcome (PICO) model for clinical questions and evidence profiles were generated. The results of the literature analysis and the recommendations were then assessed using the GRADE® system.

RESULTS

The summaries prepared by the SFAR Guideline panel resulted in thirty-one recommendations on muscle relaxants and reversal agents in anaesthesia. Of these recommendations, eleven have a high level of evidence (GRADE 1±) while twenty have a low level of evidence (GRADE 2±). No recommendations could be provided using the GRADE® system for five of the questions, and for two of these questions expert opinions were given. After two rounds of discussion and an amendment, a strong agreement was reached for all the recommendations.

CONCLUSION

Substantial agreement exists among experts regarding many strong recommendations for the improvement of practice concerning the use of muscle relaxants and reversal agents during anaesthesia. In particular, the French Society of Anaesthesia and Intensive Care (SFAR) recommends the use of a device to monitor neuromuscular blockade throughout anaesthesia.

Influence of tetanic stimulation on the staircase phenomenon and the acceleromyographic time-course of neuromuscular block: a randomized controlled trial

During neuromuscular monitoring, repeated electrical stimulation evokes muscle responses of increasing magnitude ('staircase phenomenon', SP). We aimed to evaluate whether SP affects time course and twitches' values of an acceleromyographic assessed neuromuscular block with or without previous tetanic stimulation. Fifty adult patients were randomized to receive a 50 Hz tetanic stimulus (S group) or not (C group) before monitor calibration. After 20 min of TOF ratio (TOFr) stimulation rocuronium was administered. Onset time of block (primary endpoint), recovery of T1 to 25%, TOFr to 0.9, and recovery index were compared. We also compared T1 and TOFr at baseline, post-stimulation, and during recovery from block. Moreover the correlation between T1 at maximum recovery and (a) baseline T1 and (b) post-stimulation T1 along with T1/TOFr ratio during recovery were evaluated. After stimulation median T1 increased (32%) in group C and decreased (16%) in group S (P = 0.0001). Onset time (Median [IQR] in seconds) was 90 (29-77) vs. 75 (28-60) in C and S group (P = 0.002). Time [Mean (SD) in minutes] to normalized TOFr 0.9 were 70.13 (14.9) vs. 62.1 (21.2) in C and S groups (P = 0.204). TOFr showed no differences between groups at any time point. T1 at maximum recovery showed a stronger correlation with post-stabilization T1 compared to baseline. (ρ = 0.80 and ρ = 0.85, for C and S groups.) Standard calibration does not ensure twitch baseline stabilization and prolongs onset time of neuromuscular block. TOF ratio is not influenced by SP.

Qualitative Neuromuscular Monitoring: How to Optimize the Use of a Peripheral Nerve Stimulator to Reduce the Risk of Residual Neuromuscular Blockade

This review provides recommendations for anesthesia providers who may not yet have quantitative monitoring and sugammadex available and thus are providing care within the limitations of a conventional peripheral nerve stimulator (PNS) and neostigmine. In order to achieve best results, the provider needs to understand the limitations of the PNS. The PNS should be applied properly and early. All overdosing of neuromuscular blocking drugs should be avoided and the intraoperative neuromuscular blockade should be maintained only as deep as necessary. The adductor pollicis is the gold standard site and must be used for the pre-reversal assessment, also when the ulnar nerve and thumb were not accessible intraoperatively. Spontaneous recovery should be maximized and neostigmine should be administered after a TOF count of 4 has been confirmed at the adductor pollicis. Extubation should not occur within 10 min after administration of an appropriate dose of neostigmine.

Positive and negative staircase effect during single twitch and train-of-four stimulation: a laboratory study in dogs

A positive staircase effect is well documented during neuromuscular monitoring. However, the increase in twitch amplitude may not remain stable over time. We compared the staircase phenomenon and twitch stability during single twitch (ST) or train-of-four (TOF) stimulation in anesthetized dogs. Force of contraction was measured in ten dogs. Each thoracic limb was stimulated with ST 0.1 Hz or TOF q 12 s for 25 min (random order). No neuromuscular blockers were administered. Every 5 min, ST and T1 amplitudes were compared within and between groups. Stability of twitch amplitude (<5 % change in 5 min) was also evaluated. ST and T1 amplitude increased over time without significant differences between groups. After 10 min of ST stimulation, the average ST amplitude had increased significantly to 107 %, and remained unchanged thereafter. T1 amplitude was significantly greater than baseline only at 5 (111 %) and 10 min (109 %); a decline towards baseline occurred thereafter. Stability was reached after 15 min for all dogs in the ST group, however, three dogs continued to have changes >5 % with TOF. An initial increase in ST amplitude remained stable over the observation period, but the increase in T1 amplitude during TOF was frequently followed by a decay. A stable twitch amplitude (variation <5 % in 5 min) was observed in all dogs with ST after 15 min of stimulation, which was not the case during TOF stimulation. Therefore, it appears at least in dogs, that ST might offer some advantages over T1 for measuring twitch amplitude.

Electromyographic response of facial nerve stimulation under different levels of neuromuscular blockade during middle-ear surgery

OBJECTIVE

To investigate facial nerve monitoring in patients receiving the partial nondepolarizing neuromuscular blocking agents (NMBAs), remifentanil and propofol.

METHODS

Patients with normal facial function and advanced middle-ear disease were enrolled. For total intravenous anaesthesia (TIVA), propofol and remifentanil were infused as induction/maintenance anaesthesia. Stimulation thresholds and amplitudes were recorded at each train-of-four (TOF) nerve stimulation level. Time differences between start of TOF and electromyographic (EMG) amplitude decreases (Ti), and between complete recovery of TOF and EMG amplitudes (Tr), were calculated.

RESULTS

Fifteen patients were enrolled. Mean ± SD Ti was 3.4 ± 1.28 min; Tr was 18.7 ± 4.41 min. Amplitude of stimulation was apparent mostly at TOF level 1. In most cases, no or a weak response (<100 µV) was observed at TOF 0. Mean ± SD threshold of electrical stimulation was 0.31 ± 0.10 mA at TOF 1. At TOF > 2, all cases showed EMG response on electrical stimulation.

CONCLUSIONS

Induction of TIVA using propofol and remifentanil provided reliable conditions for delicate microsurgery. Minimal NMBA use, considered as producing TOF levels >1, was sufficient for facial nerve monitoring in neuro-otological surgery.

Assessment of neuromuscular block at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles

PURPOSE

We studied neuromuscular block at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles in anesthetized patients.

METHODS

Fifty-four adult patients undergoing air-oxygen-sevoflurane-fentanyl and epidural anesthesia were randomly divided into orbicularis oris, corrugator supercilii, and adductor pollicis groups of 18 patients each. In the three groups, the degree of neuromuscular block caused by rocuronium 0.6 mg/kg was monitored at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles acceleromyographically.

RESULTS

Onset of neuromuscular block did not significantly differ among the three groups [157 ± 60, 186 ± 73, and 148 ± 45 s; mean ± standard deviation (SD)]. Minimum value of 1st stimulation in train-of-four (T1)/control at the corrugator supercilii group was significantly higher than in the orbicularis oris and adductor pollicis groups (0.108 ± 0.066 vs. 0.021 ± 0.024 and 0.002 ± 0.007; P < 0.001). T1/control at the orbicularis oris group was significantly higher than at the adductor pollicis group 30 min after rocuronium (P < 0.05). T1/control at the corrugator supercilii group was significantly higher than at the orbicularis oris and adductor pollicis groups 10-30 and 10-40 min, respectively, after rocuronium (P < 0.05). Train-of-four ratios at the orbicularis oris and corrugator supercilii groups were significantly higher than at the adductor pollicis group 40-120 min after rocuronium (P < 0.05).

CONCLUSION

The corrugator supercilii muscle is more resistant to rocuronium than the orbicularis oris and adductor pollicis muscles. Recovery of neuromuscular block at the orbicularis oris muscle is slower than that at the corrugator supercilii muscle but was faster than that at the adductor pollicis muscle.

A comparison of the accuracy of ulnar versus median nerve stimulation for neuromuscular monitoring

Background

Inexperienced anesthesiologists are frequently unclear as to whether to stimulate the ulnar or median nerve to monitor the adductor pollicis. The primary purpose of this study was to determine whether monitoring the adductor pollicis by positioning the stimulating electrodes over the median nerve is an acceptable alternative to applying electrodes over the ulnar nerve.

Methods

In 20 patients anesthetized with propofol and remifentanil, one pair of stimulating electrodes was positioned over the ulnar nerve. A second pair was placed over the median nerve on the other hand. The acceleromyographic response was monitored on both hands. Rocuronium 0.6 mg/kg was administered. Single twitch (ST) and train-of-four (TOF) stimulations were applied alternatively to both sites.

Results

None of the patients showed a twitch response at either site after injection of rocuronium. There were no differences in the mean supramaximal threshold, mean initial TOF ratio, or mean initial ST ratio between the two sites. Bland-Altman analysis revealed a bias (limit of agreement) in the TOF and ST ratios over the median nerve of 7% (± 31%) and 26% (± 73%), respectively, as compared with the ulnar nerve. The median nerve TOF ratio was overestimated by 16.2%, as compared with that of the ulnar nerve value, and the median nerve ST ratio was overestimated by 72.9%, as compared to that of the ulnar nerve.

Conclusions

The ulnar and median nerves cannot be used interchangeably for accurate neuromuscular monitoring.

Acceleromyographic monitoring of neuromuscular block over the orbicularis oris muscle in anesthetized patients receiving vecuronium

STUDY OBJECTIVE

To evaluate the level of neuromuscular block acceleromyographically over the orbicularis oris muscle.

DESIGN

Prospective, randomized, controlled study.

SETTING

Operating room of a university-affiliated hospital.

PATIENTS

36 adult, ASA physical status I and II women scheduled for mastectomy with air-oxygen-isoflurane-fentanyl anesthesia.

INTERVENTIONS

Patients were randomized to two groups. In the orbicularis oris group (n=18), the facial nerve was stimulated and movement of the orbicularis oris muscle was measured acceleromyographically. In the control group (n=18), adduction of the thumb was quantified mechanically.

MEASUREMENTS

Onset and recovery of neuromuscular block caused by vecuronium 0.1 mg/kg were compared between the groups.

MAIN RESULTS

Time to onset of neuromuscular block in the orbicularis oris group was significantly shorter than in the control group (176 + or - 52 vs. 220 + or - 34 sec, mean + or - SD; P = 0.004). Times to return of the first, second, third, or fourth (T1, T2, T3, or T4) response of train-of four (TOF), and recovery of T1/control were comparable between the groups. Train-of-four ratio (T4/T1) in the orbicularis oris group was significantly higher than in the control group 50 to 120 minutes after vecuronium administration (P < 0.05).

CONCLUSION

Depth of neuromuscular block can be assessed acceleromyographically over the orbicularis oris muscle. Onset of neuromuscular block is quicker and recovery of TOF ratio is faster over the orbicularis oris muscle than at the thumb in patients receiving vecuronium.

Monitoring of vecuronium-induced neuromuscular block at the sternocleidomastoid muscle in anesthetized patients

PURPOSE

To assess the degree of neuromuscular block acceleromyographically at the sternocleidomastoid muscle.

METHODS

Eighteen adult patients scheduled for air-oxygen-sevoflurane-fentanyl and epidural anesthesia were studied. In the patients, the right accessory nerve and the sternocleidomastoid muscle were stimulated and the contraction of the sternocleidomastoid muscle was evaluated acceleromyographically. Simultaneously, the response of the adductor pollicis muscle was measured electromyographically. Supramaximal stimulating current, degree of maximum neuromuscular block after vecuronium 0.1 mg/kg, and onset of or recovery from vecuronium-induced neuromuscular block were compared between the two muscles.

RESULTS

The supramaximal stimulating current at the sternocleidomastoid muscle was significantly higher than that at the adductor pollicis muscle (54.8 ± 7.1 vs. 33.7 ± 10.3 mA, mean ± SD, P < 0.001). The onset of neuromuscular block at the sternocleidomastoid muscle did not significantly differ from that at the adductor pollicis muscle (214 ± 117 vs. 161 ± 87 s, P = 0.131). The degree of maximum neuromuscular block at the sternocleidomastoid muscle was significantly less than that at the adductor pollicis muscle (93.6 ± 3.1 vs. 99.2 ± 2.5%, P < 0.001). During recovery from neuromuscular block, T1/control and train-of-four ratio measured at the sternocleidomastoid muscle were significantly higher than those at the adductor pollicis muscle 10-30 and 40-120 min after vecuronium, respectively (P < 0.05).

CONCLUSION

The sternocleidomastoid muscle is more resistant to vecuronium than the adductor pollicis muscle. Recovery from neuromuscular block is faster at the sternocleidomastoid muscle than at the adductor pollicis muscle.

Visual evaluation of fade in response to facial nerve stimulation at the eyelid

STUDY OBJECTIVE

The aim of this study is to investigate the probability of visual detection of fade in response to train-of-four (TOF) stimulation, double-burst stimulation3,3 (DBS(3,3)), or DBS(3,2) at the eyelid in comparison to that at the thumb.

DESIGN

This is a randomized single-blinded study.

SETTING

The study took place at the University hospital.

PATIENTS AND MEASUREMENTS

Sixty adult patients underwent general anesthesia.

INTERVENTIONS AND MEASUREMENTS

Patients were randomly divided into either the eyelid group (n = 30) or the thumb group (n = 30). In the eyelid group, at the varying degrees of neuromuscular block caused by vecuronium, TOF, DBS(3,3), or DBS(3,2) were given at the temporal branch of the facial nerve, and the probability of visual detection of fade in response to TOF, DBS(3,3), or DBS(3,2) was determined at the eyelid. Similarly, in the thumb group, the probability of visual detection of fade in response to TOF, DBS(3,3), or DBS(3,2) was examined at the thumb.

MAIN RESULTS

When the true TOF ratios were 0 to 0.60, the probability of detection of TOF fade in the eyelid group was significantly lower than in the thumb group (P < .05). At the true TOF ratios of 0.31 to 0.70, the probability of visual detection of DBS(3,3) fade in the eyelid group was significantly less than in the thumb group (P < .05). When the true TOF ratios were 0.81 to 1.00, the probability of detection of DBS(3,2) fade in the eyelid group was significantly higher than in the thumb group (P < .05).

CONCLUSION

The probability of visual detection of fade in response to TOF or DBS(3,3) is lower at the eyelid than the thumb. In contrast, DBS(3,2) fade tends to be seen more frequently at the eyelid than at the thumb.

Train-of-Four Stimulation for Adductor Pollicis Neuromuscular Monitoring Can Be Applied at the Wrist or Over the Hand

Adductor pollicis stimulation over the ulnar nerve at the wrist is the standard method of monitoring neuromuscular function. Stimulation over a muscle is believed to cause direct muscle contraction, but evidence for this is lacking. In this study we sought to determine whether direct muscle stimulation occurred during stimulation of the adductor pollicis in the hand and whether the responses were comparable to those observed with stimulation at the wrist. In 20 patients anesthetized with sevoflurane, 1 pair of stimulating electrodes was positioned over the ulnar nerve at the wrist. A second pair was placed between the first and second metacarpals on the palmar and dorsal aspects of the hand. The acceleromyographic response was monitored. Rocuronium 0.6 mg/kg was administered. Train-of-four (TOF) stimulations were applied at the wrist site until maximal blockade. Then, stimulation was applied to the hand site. During recovery, both sites were monitored alternately. After injection of rocuronium, 17 of 20 patients showed no twitch response at either site. One patient had a response at both stimulation sites, and two patients had responses only at the wrist site. With a Bland and Altman analysis, TOF ratios during recovery at the hand showed a bias of 0.5% and limits of agreement of +/-11.8% as compared with the wrist. Stimulation in the hand causes no direct muscle stimulation because the response is no more than that produced by stimulation at the wrist. Both sites yield comparable TOF ratios.