Neuromuscular blockade at the larynx, the diaphragm and the corrugator supercilii muscle: a review

Deep Neuromuscular Block for Endolaryngeal Surgery: A Systematic Review and Meta-Analysis

OBJECTIVES

To determine the safety and efficacy of deep neuromuscular block (NMB) for endolaryngeal surgery.

DATA SOURCES

PubMed, Web of Science, Cochrane Library, Ovid Medline, Embase, China National Knowledge Infrastructure, Wanfang, VIP databases, and trial registry database.

METHODS

Inclusion criteria followed the PICOS principles: Participants, adults undergoing endolaryngeal surgery; Intervention, deep NMB performed during the surgery; Control, no-deep NMB performed; Outcomes, primary outcome: the incidence of clinically acceptable surgical conditions.

SECONDARY OUTCOME

the incidence of intraoperative complications (including vocal fold movement and coughing) and total incidence of postoperative complications [including postoperative residual curarization (PORC), postoperative sore throat (POST), and postoperative nausea and vomiting (PONV)]. Study design, randomized controlled trials (RCTs). Duplicate publications, editorials, letters, abstracts, and reviews were excluded.

RESULTS

Four articles with 242 patients were identified for analysis. The results indicated that compared with no-deep NMB, deep NMB provides a higher incidence of clinically acceptable surgical conditions (98.36% vs. 76.67%; relative ratio [RR] = 1.29, 95% CI: 1.07-1.56), a lower incidence of intraoperative complications (10.83% versus 37.16%; RR = 0.32; 95% CI: 0.21-0.49) (lower incidence of vocal fold movement [1.85% vs. 34%; RR = 0.08, 95% CI: 0.02-0.41] and coughing [15.53% vs. 38.78%; RR = 0.42, 95% CI: 0.27-0.66]). There were no differences in the overall incidence of postoperative complications (RR = 2.10, 95% CI: 0.12-36.40).

CONCLUSIONS

Based on current published evidence, deep NMB provides better surgical conditions with a higher incidence of clinically acceptable surgical conditions and a lower incidence of intraoperative complications (lower incidence of vocal fold movement and coughing) without increasing the overall incidence of postoperative complications.

LEVEL OF EVIDENCE

1 Laryngoscope, 133:2055-2065, 2023.

Peri-operative Hemi-diaphragmatic Variations After Brachial Plexus Block Above the Clavicle: A Prospective Observational Study of the Contralateral Side

OBJECTIVE

Hemi-diaphragm palsy after brachial plexus block above the clavicle (BPBAC) occurs frequently, but few patients develop post-operative pulmonary complications (PPC). We hypothesized that contralateral hemidiaphragm function increases after BPBAC. This contralateral function preserves global diaphragmatic function, avoiding PPC in the case of ipsilateral hemi-diaphragm palsy.

METHODS

This prospective observational cohort study included 64 adult patients undergoing shoulder surgery with planned BPBAC (interscalene brachial plexus block and supraclavicular block). The Thickening Fraction (TF) was measured by ultrasound in both hemi-diaphragms, ipsilateral (TF _ipsilateral) and contralateral (TF_{contralateral}) to the BPBAC, before and after the surgery. TF_global is the sum of TF_ipsilateral and TF_{contralateral}. PPC were defined as occurrences of dyspnea, tachypnea, SpO₂ <90% or SpO₂/FiO₂ <315.

RESULTS

TF_{contralateral} increased significantly (an average of 40%) after BPBAC (p = 0.001), and TF_ipsilateral decreased (an average of 72%). After BPBAC, 86% of patients had a decreased TF_ipsilateral and 59% of patients an increased TF_{contralateral} at post-operatively. Only 17% of patients have PPC.

CONCLUSION

After BPBAC, global diaphragm function decreases because of ipsilateral hemi-diaphragm reduction, but less than expected because of increased contralateral hemi-diaphragm function. As a part of diaphragm function, contralateral hemi-diaphragm function must be checked.

Tracheal intubating conditions in elderly patients when train-of-four count is zero after rocuronium 0.6 or 0.9 mg/kg. A secondary analysis

PURPOSE

The neuromuscular blocking agent rocuronium can be administered to facilitate tracheal intubation. We hypothesized that rocuronium 0.9 mg/kg provided a larger proportion of patients with vocal cords in abducted position compared to rocuronium 0.6 mg/kg at train-of-four (TOF) 0.

METHODS

This secondary analysis was based on 52 elderly surgical patients of which 36 patients received rocuronium 0.6 mg/kg and 16 patients received rocuronium 0.9 mg/kg. Neuromuscular block was monitored with acceleromyography with TOF stimulation at the ulnar nerve. The primary outcome was the proportion of patients with vocal cords in abducted position at TOF 0. Secondary outcomes were intubating conditions evaluated by the Fuchs-Buder scale, the Intubating Difficulty Score (IDS), onset time, and duration of action of rocuronium.

RESULTS

At TOF 0, a significantly larger proportion of patients had vocal cords in abducted position in the rocuronium 0.9 mg/kg group (81%) compared with the rocuronium 0.6 mg/kg group (53%); difference (%) 28, 95% Cl 3-53, P = 0.05. Excellent intubating conditions (Fuchs-Buder) were more common in the rocuronium 0.9 mg/kg group (62.5%); difference (%) 32.5, 95% Cl 4-61), P = 0.03. No significant difference was found in IDS or onset time of rocuronium (difference 19 s, 95% Cl: -5-43). Duration of action was significantly longer (difference 29 min, 95% Cl: 10-47) in the 0.9 mg/kg group.

CONCLUSION

The proportion of patients with vocal cords in abducted position was significantly larger after rocuronium 0.9 mg/kg compared to rocuronium 0.6 mg/kg at TOF 0 monitored at the ulnar nerve.

Adverse events of sugammadex that occurred in a Korean population

Background

With increasing use, the incidence of adverse events associated with sugammadex, a neuromuscular blockade reverser, is increasing. This study aimed to identify and analyze cases of adverse events caused by sugammadex reported in Korean population.

Methods

Out of a total of 12 cases detected using various keywords in the Korean Journal of Anesthesia, Anesthesia and Pain Medicine (Seoul), KoreaMed, PubMed, EMBASE, Web of Science, and The Cochrane Library-CENTRAL from 2013 to December 2020, 10 cases directly associated with sugammadex were selected.

Results

Adverse events included five cases of anaphylaxis, one case of cardiac arrest, one case of profound bradycardia, one case of negative pressure pulmonary edema, and two cases of incomplete recovery. Three patients had American Society of Anesthesiologists physical status ≥ 3, two had emergency surgery, and two had a history of allergic reaction. Neuromuscular monitoring was applied in nine cases. The average dose of sugammadex was 2.87 mg/kg, and there were six cases in which one full vial was used, regardless of the state of neuromuscular recovery. Sugammadex was administered immediately after surgery in two cases, at train of four (TOF) 0 in four cases, at TOF 3 in one case, and after evaluation of the clinical signs only with no neuromuscular monitoring in one case.

Conclusions

Even with neuromuscular monitoring, an excessive dose of sugammadex was observed. Given that adverse events tend to occur within 10 min of administration, continuous monitoring is important even after administration.

Phonomyography on Perioperative Neuromuscular Monitoring: An Overview

Complications related to neuromuscular blockade (NMB) could occur during anesthesia induction, maintenance, and emergency. It is recommended that neuromuscular monitoring techniques be utilized perioperatively to avoid adverse outcomes. However, current neuromuscular monitoring methods possess different shortcomings. They are cumbersome to use, susceptible to disturbances, and have limited alternative monitoring sites. Phonomyography (PMG) monitoring based on the acoustic signals yielded by skeletal muscle contraction is emerging as an interesting and innovative method. This technique is characterized by its convenience, stable signal quality, and multimuscle recording ability and shows great potential in the application field. This review summarizes the progression of PMG on perioperative neuromuscular monitoring chronologically and presents the merits, demerits, and challenges of PMG-based equipment, aiming at underscoring the potential of PMG-based apparatuses for neuromuscular monitoring.

Peri-operative diaphragm ultrasound as a new method of recognizing post-operative residual curarization

Background

This study sought to evaluate the diagnostic accuracy of peri-operative diaphragm ultrasound in assessing post-operative residual curarization (PORC).

Methods

Patients undergoing non-thoracic and non-abdominal surgery under general anaesthesia were enrolled from July 2019 to October 2019 at Peking Union Medical College Hospital. A train-of-four ratio (TOFr) lower than 0.9 was considered as the gold standard for PORC. Diaphragm ultrasound parameters included diaphragmatic excursion (DE) and diaphragm thickening fraction (DTF) during quiet breathing (QB) and deep breathing (DB). The diaphragm excursion fraction (DEF) was calculated as the DE-QB divided by the DE-DB. The diaphragm excursion difference (DED) was defined as DE-DB minus DE-QB. Receiver operating characteristic curve analysis was used to determine the cut-off values of ultrasound parameters for the prediction of PORC.

Results

In total, 75 patients were included, with a PORC incidence of 54.6%. The DE-DB and DED were positively correlated with the TOFr, while the DEF was negatively correlated with the TOFr. The DE-DB cut-off value for predicting PORC was 3.88 cm, with a sensitivity of 85.4% (95% confidence interval [CI]: 70.1–93.9%), specificity of 64.7% (95% CI: 46.4–79.7%), positive likelihood ratio of 2.42 (95% CI 1.5–3.9), and negative likelihood ratio of 0.23 (95% CI: 0.1–0.5). The DED cut-off value was 1.5 cm, with a specificity of 94.2% (95% CI: 80.3–99.3%), sensitivity of 63.4% (95% CI: 46.9–77.9%), positive likelihood ratio of 10.78 (95% CI: 2.8–42.2), and negative likelihood ratio of 0.39 (95% CI: 0.3–0.6).

Conclusions

Peri-operative diaphragm ultrasound may be an additional method aiding the recognition of PORC, with DED having high specificity.

Effects of magnesium sulphate on the onset time of rocuronium at different doses: a randomized clinical trial

Background and aims

Rocuronium may provide excellent onset time, but high doses are required for effective action. Several strategies have managed to shorten rocuronium onset time, including the use of Magnesium Sulphate (MgSO₄).

Methods

One hundred and eighty patients were randomized into six groups according to rocuronium dose received (0.3, 0.6 or 1.2 mg.kg^-1) and the administration of saline or MgSO⁴ (60 mg.kg^-1). Correlations between tissue perfusion and rocuronium onset time was determined by variations in perfusion index.

Results

Median (quartiles) rocuronium onset times were 85.5 (74.0–92.0); 76.0 (52.0–87.0) and 50.0 (41.0–59.5) seconds for 0.3, 0.6 mg.kg^-1 and 1.2 mg.kg^-1 doses, respectively. MgSO₄ decreased rocuronium onset at doses of 0.3 mg.kg^-1 (60.0 [48.0–74.3] seconds) and 0.6 mg.kg^-1 (44.0 [39.0–49.0] seconds) but not at 1.2 mg.kg^-1 (38.0 [33.5–56.3] seconds) (p < 0.001). Perfusion index variations in groups that received MgSO₄ were greater than in controls. A negative correlation between shorten onset and increased perfusion index was observed in rocuronium doses of 0.3 mg.kg^-1 (r = -0.50; p < 0.001) and 0.6 mg.kg^-1 (r = -0.424; p < 0.001), but not for 1.2 mg.kg^-1 dose (r = -0.25; p = 0.07).

Conclusion

MgSO₄ reduces rocuronium onset time at doses of 0.3 mg.kg^-1 and 0.6 mg.kg^-1 being that the latter has a similar effect when compared to the dose of 1.2 mg.kg^-1, with or without the use of MgSO₄.

Trial registry at

http://www.ensaiosclinicos.gov.br/

Registry Number

RBR-96CY3K

Lidocaine Infusion Improves the Functionality of Intraoperative Nerve Monitoring During Thyroid Surgery: A Prospective, Randomized, Double-Blinded Study

BACKGROUND

Intraoperative nerve monitoring (IONM) to assess the recurrent laryngeal nerve function during thyroid surgery is becoming the standard of care across many institutions. The successful deployment and data analysis from the IONM require complete laryngeal relaxation and reflex suppression. We investigated the role of intravenous lidocaine infusion (IVLI) to provide such operating conditions, under a lighter plane of anesthesia and fewer hemodynamic fluctuations.

METHODS

Sixty-five patients were randomly assigned to lidocaine group (LG) or placebo group (PG) based on the computer-generated coding developed by the pharmacy department. The study medication (SM) was delivered by the pharmacist in a pre-filled coded syringe to the investigator 30 min prior to the surgery. All the patients were anesthetized by narcotic and inhalation based general anesthesia. The SM was administered at the rate of 1.5mg/kg/h following a loading dose of 1 mg/kg. Dragonfly® laryngeal surface electrode and Nerveana® nerve locator system were used for IONM during surgery.

RESULTS

The proportion of patients requiring lower strength stimulating current (StMC) at 0.5 mA was significantly higher in the LG than in the PG (X2 (1, N = 61) = 10.1615, P = 0.001434). Similarly, the proportion of patients with the drop in the aggregate impedance level (DAIL) by < 50% at the end of surgery was significantly higher in the LG than in the PG (X2 (1, N = 61) = 15.982, P = 0.000064). In addition, the proportion of patients with the hypotensive episodes requiring rescue medications more than twice during surgery was significantly lower in the LG than in the PG (X2 (1, N = 61) = 0.0183, P < 0.05).

CONCLUSIONS

The enhanced laryngeal relaxation and the reflex suppression afforded by the IVLI could have enabled a lower StMC to elicit a positive signal. The lower StMC promotes less intense laryngeal alterations as evidenced by the lower DAIL in the LG. IVLI can enhance the functionality of the IONM during prolonged operating time and the resultant increased number of IONM stimulations, while providing a stable hemodynamic environment.

Cholinergic Chemotransmission and Anesthetic Drug Effects at the Carotid Bodies

General anesthesia is obtained by administration of potent hypnotics, analgesics and muscle relaxants. Apart from their intended effects (loss of consciousness, pain relief and muscle relaxation), these agents profoundly affect the control of breathing, in part by an effect within the peripheral chemoreflex loop that originates at the carotid bodies. This review assesses the role of cholinergic chemotransmission in the peripheral chemoreflex loop and the mechanisms through which muscle relaxants and hypnotics interfere with peripheral chemosensitivity. Additionally, consequences for clinical practice are discussed.

Effect of intraoperative neuromuscular blockade on postoperative sore throat and hoarseness in patients undergoing spinal surgery: a prospective observational study

Intraoperative neuromuscular blockade affects the resting tension between the vocal cords. We assessed the effect of neuromuscular blockade on postoperative sore throat and hoarseness following tracheal intubation in patients undergoing lumbar spinal surgery in the prone position. Altogether, 99 patients were included; 50 patients did not receive neuromuscular blockade, and 49 patients received moderate neuromuscular blockade during the maintenance of anesthesia. Neuromuscular blockade was performed depending on the use of intraoperative neurophysiological monitoring. The number of intubation attempts, time to achieve tracheal intubation, and duration of intubation were recorded accordingly. The incidence and severity of postoperative sore throat and hoarseness was assessed at 1, 6, and 24 h after surgery. The overall cumulative incidence of postoperative sore throat (60% vs. 59%, respectively; P = 1.000) and postoperative hoarseness (68% vs. 61%, respectively; P = 0.532) did not differ between the no neuromuscular blockade and moderate neuromuscular blockade. The incidence and severity of postoperative sore throat and hoarseness was also not different between the moderate and no neuromuscular blockade at each time point after surgery. Nevertheless, the incidences of postoperative sore throat and hoarseness were quite high. Further studies investigating strategies to alleviate them are warranted accordingly.

Subparalyzing Doses of Rocuronium Reduce Muscular Endurance without Detectable Effect on Single Twitch Height in Awake Subjects

PURPOSE

To test the hypothesis that a low-dose rocuronium acts mainly by means of reducing muscular endurance rather than by reducing momentary force.

METHODS

In a randomized placebo-controlled double-blinded study, eight healthy volunteers were studied in two sets of experiments. In the first set, the subjects made a sustained maximum effort with the dominant hand for 80 seconds while squeezing an electronic handgrip dynamometer at three minutes after intravenous administration of placebo, 0.04 or 0.08 mg/kg rocuronium. Handgrip force at initiation of testing (maximum handgrip force) and after 60 seconds was evaluated. In the second set, the ulnar nerve of the subjects was electrically stimulated every tenth second for at least 10 and a maximum of 30 minutes following the administration of placebo and 0.08 mg/kg rocuronium. Single twitch height of the adductor pollicis muscle was recorded.

RESULTS

There was no significant difference in the effect on maximum handgrip force at time 0 between the three different doses of rocuronium. As compared with placebo, handgrip force after 0.08 mg/kg rocuronium was reduced to approximately a third at 60 seconds (214 N (120-278) vs. 69 (30-166); p=0.008), whereas only a slight reduction was seen after 0.04 mg/kg (187 (124-256); p=0.016). Based on these results, the sustained handgrip force after 0.2 mg/kg at 60 seconds was calculated to be 1.27% (95% CI [0.40, 4.03]) of the maximum force of placebo. No effect on single twitch height after 0.08 mg/kg rocuronium at four minutes after drug administration could be detected.

CONCLUSIONS

Subparalyzing doses of rocuronium show a distinct effect on muscular endurance as opposed to momentary force. The findings support the hypothesis that low doses of rocuronium act mainly by reducing muscular endurance, thereby facilitating, for example, tracheal intubation.

Neuromuscular blockers and reversal agents and their impact on anesthesia practice

Neuromuscular blockers have long been an intricate part of the anesthesia regimen. The scientific progress in pharmacology and physiology has strengthened their clinical relevance, has helped to delineate with precision their medical role, and has enhanced the safety and effectiveness of their use. New frontiers in research will define further the role of these agents in modern anesthesia practice and guide their expanding and discrete clinical applications.

Clove oil induces anaesthesia and blunts muscle contraction power in three Amazon fish species

Clove oil is used as an anaesthetic for many species of fish worldwide; however, relatively few studies have assessed its effectiveness on Amazon fish species and no compelling evidence has ever been reported on the relaxant properties of this oil for skeletal muscle of fish. Thus, the objective of this study was to evaluate the latencies to deep anaesthesia and recovery, along with the myorelaxant effect of clove oil on three Amazon fish species: cardinal tetra, Paracheirodon axelrodi, banded cichlid, Heros severus and angelfish, Pterophyllum scalare, submitted to short-term anaesthetic baths. Fish were assayed in three groups of 60 fish each and individually anaesthetized in a completely randomized design with six clove oil concentrations using 10 fish/species/concentration. Electromyographic recordings from dorsal muscle were performed during stages of induction and recovery in which nine fish/species/stage were used. Deep anaesthesia was attained for all concentrations tested, and no mortalities were observed throughout the experiments and after a 48-h observation period. Concentration of 90 μL L^-1 and above promoted fast deep anaesthesia (< 3 min) and calm recovery in angelfish and cardinal tetra, whereas the concentration of 60 μL L^-1 sufficed to quickly anaesthetize banded cichlid. Times to full recovery were not significantly contrasting among species and occurred within appropriate time threshold (< 5 min). Clove oil exerted a conspicuous depression of muscle contraction power, and therefore can be effectively used as a muscle relaxant agent for P. scalare, P. axelrodi, H. severus and potentially, for other fish species.

Profile of sugammadex for reversal of neuromuscular blockade in the elderly: current perspectives

The number of elderly patients is increasing worldwide. This will have a significant impact on the practice of anesthesia in future decades. Anesthesiologists must provide care for an increasing number of elderly patients, who have an elevated risk of perioperative morbidity and mortality. Complications related to postoperative residual neuromuscular blockade, such as muscle weakness, airway obstruction, hypoxemia, atelectasis, pneumonia, and acute respiratory failure, are more frequent in older than in younger patients. Therefore, neuromuscular blockade in the elderly should be carefully monitored and completely reversed before awakening patients at the end of anesthesia. Acetylcholinesterase inhibitors are traditionally used for reversal of neuromuscular blockade. Although the risk of residual neuromuscular blockade is reduced by reversal with neostigmine, it continues to complicate the postoperative course. Sugammadex represents an innovative approach to reversal of neuromuscular blockade induced by aminosteroid neuromuscular-blocking agents, particularly rocuronium, with useful applications in clinical practice. However, aging is associated with certain changes in the pharmacokinetics of sugammadex, and to date there has been no thorough evaluation of the use of sugammadex in elderly patients. The aim of this review was to perform an analysis of the use of sugammadex in older adults based on the current literature. Major issues surrounding the physiologic and pharmacologic effects of aging in elderly patients and how these may impact the routine use of sugammadex in elderly patients are discussed.

Recovery of laryngeal nerve function with sugammadex after rocuronium-induced profound neuromuscular block

STUDY OBJECTIVE

The aim of this study was to evaluate the efficacy of sugammadex in reversing profound rocuronium-induced neuromuscular block at the laryngeal adductor muscles using motor-evoked potentials (mMEPs).

DESIGN

A prospective observational study.

SETTING

University surgical center.

PATIENTS

Twenty patients with American Society of Anesthesiologists physical class I-II status who underwent propofol-remifentanil anesthesia for the surgery of the thyroid gland.

INTERVENTIONS

Patients were enrolled for reversal of profound neuromuscular block (sugammadex 16 mg/kg, 3 minutes after rocuronium 1.2 mg/kg). To prevent laryngeal nerve injury during the surgical procedures, all patients underwent neurophysiologic monitoring using mMEPs from vocal muscles. At the same time, the registration of TOF-Watch acceleromyograph at the adductor pollicis muscle response to ulnar nerve stimulation was performed; recovery was defined as a train-of-four (TOF) ratio ≥0.9.

MEASUREMENT AND MAIN RESULTS

After injection of 16 mg/kg of sugammadex, the mean time to recovery of the basal mMEPs response at the laryngeal adductor muscles was 70 ± 18.2 seconds. The mean time to recovery of the TOF ratio to 0.9 was 118 ± 80 seconds. In the postoperative period, 12 patients received follow-up evaluation of the vocal cords and no lesions caused by the surface laryngeal electrode during electrophysiological monitoring were noted.

CONCLUSIONS

Recovery from profound rocuronium-induced block on the larynx is fast and complete with sugammadex. In urgent scenarios, "early" extubation can be performed, even with a TOF ratio ≤0.9. However, all procedures to prevent postoperative residual curarization should still be immediately undertaken.

The Intraocular Pressure under Deep versus Moderate Neuromuscular Blockade during Low-Pressure Robot Assisted Laparoscopic Radical Prostatectomy in a Randomized Trial

Background

This study aimed to determine whether continuous deep neuromuscular blockade (NMB) improves the surgical conditions and facilitates robotic-assisted laparoscopic radical prostatectomy (RALRP) under low intra-abdominal pressure (IAP) to attenuate the increase in intraocular pressure (IOP) during CO₂ pneumoperitoneum in the steep Trendelenburg (ST) position.

Methods

Sixty-seven patients undergoing RALRP were randomly assigned to a moderate NMB group (Group M), including patients who received atracurium infusion until the end of the ST position, maintaining a train of four count of 1–2; and the deep NMB group (Group D), including patients who received rocuronium infusion, maintaining a post-tetanic count of 1–2. IOP was measured in all patients at nine separate time points. All RALRPs were performed by one surgeon, who rated the overall and worst surgical conditions at the end of the ST position.

Results

The highest IOP value was observed at T4 (60 min after the ST position) in both Group M (23.3 ± 2.7 mmHg) and Group D (19.8 ± 2.1 mmHg). RALRP was accomplished at an IAP of 8 mmHg in 88% Group D patients and 25% Group M patients. The overall surgical condition grade was 4.0 (3.0–5.0) in Group D and 3.0 (2.0–5.0) in Group M (P < 0.001).

Conclusion

The current study demonstrated that continuous deep NMB may improve surgical conditions and facilitate RALRP at a low IAP, resulting in significant attenuation of the increase on IOP. Moreover, low-pressure pneumoperitoneum, facilitated by deep NMB still provided acceptable surgical conditions.

Trial Registration

ClinicalTrials.gov NCT02109133

Reversal of neuromuscular block with sugammadex: a comparison of the corrugator supercilii and adductor pollicis muscles in a randomized dose-response study

BACKGROUND

Neuromuscular monitoring using the corrugator supercilii muscle is associated with a number of challenges. The aim of this study was to assess reversal of a rocuronium-induced neuromuscular blockade with sugammadex according to monitoring either using the corrugator supercilii muscle or the adductor pollicis muscle. We hypothesized that a larger dose of sugammadex would be required to obtain a train-of-four (TOF) ratio of 1.0 with the corrugator supercilii muscle than with the adductor pollicis muscle.

METHODS

Forty patients aged 20-60 years and 40 patients aged ≥ 70 years were enrolled. After induction of anesthesia, we recorded the corrugator supercilii muscle response to facial nerve stimulation and the adductor pollicis muscle response to ulnar nerve stimulation using acceleromyography. All patients received 1 mg/kg rocuronium. When the first twitch (T1) of TOF recovered to 10% of control values at the corrugator supercilii, rocuronium infusion was commenced to maintain a T1 of 10% of the control at the corrugator supercilii. Immediately after discontinuation of rocuronium infusion, 2 mg/kg or 4 mg/kg of sugammadex was administered. The time for recovery to a TOF ratio of 1.0 and the number of patients not reaching a TOF ratio of 1.0 by 5 min at each dose and muscle was recorded.

RESULTS

When neuromuscular block at the corrugator supercilii was maintained at a T1 of 10% of control, that at the adductor pollicis was deep (post-tetanic count ≤ 5). Sugammadex 4 mg/kg completely antagonized neuromuscular block at both muscles within 5 min. The time to a TOF ratio of 1.0 at the adductor pollicis was significantly longer in the group ≥ 70 years than the group 20-60 years (mean (SD): 178 (42.8) s vs. 120 (9.4) s, P < 0.0001). In contrast, 2 mg/kg sugammadex reversed neuromuscular blockade at the corrugator supercilii but not at the adductor pollicis, with 10 patients in the group 20-60 years and 8 patients in the group ≥ 70 years requiring an additional sugammadex (P < 0.05 vs. 4 mg/kg sugammadex).

CONCLUSION

Sugammadex 4 mg/kg was required to reverse a moderate rocuronium-induced neuromuscular block when the corrugator supercilii muscle is used for monitoring.

Improving the functionality of intra-operative nerve monitoring during thyroid surgery: is lidocaine an option?

Intra-operative nerve monitoring (IONM) is rapidly becoming a standard of care in many institutions across the country. In the absence of neuromuscular blocking agents to facilitate the IONM, the depth of anesthesia required to abolish the laryngo tracheal reflexes often results in profound hemodynamic instability during surgery, necessitating the use of large doses of sympathomimetic amines. The excessive alpha and beta adrenergic effects exhibited by these agents are undesirable in the presence of cardiovascular co-morbidities. Trying to strike a balance frequently results in an unsatisfactory intra-operative course. In the course of the near total thyroidectomy performed on a 60-year-old female, we employed lidocaine infusion at 1.5 mg/kg/hour following a bolus dose of 1 mg/kg. The troublesome laryngo tracheal reflexes were successfully blunted and we were able to moderate the depth of anesthesia resulting in stable hemodynamics. A bispectral index monitor was employed to guard against “recall” and a train of four monitor was used to ensure the absence of inadvertent neuromuscular blockade. During the surgery, there was loss of signal on the left recurrent laryngeal nerve (RLN). The signal strength was restored by rotating the endotracheal tube on its long axis to realign the electrode with the vocal cords under Glidescope^® visualization.

Residual Paralysis: Does it Influence Outcome After Ambulatory Surgery?

Neuromuscular blocking agents are used to facilitate tracheal intubation in patients undergoing ambulatory surgery. The use of high-dose neuromuscular blocking agents to achieve muscle paralysis throughout the case carries an increased risk of residual post-operative neuromuscular blockade, which is associated with increased respiratory morbidity. Visually monitoring the train-of-four (TOF) fade is not sensitive enough to detect a TOF fade between 0.4 and 0.9. A ratio <0.9 indicates inadequate recovery. Quantitative neuromuscular transmission monitoring (e.g., acceleromyography) should be used to exclude residual neuromuscular blockade at the end of the case. Residual neuromuscular blockade needs to be reversed with neostigmine, but it's use must be guided by TOF monitoring results since deep block cannot be reversed, and neostigmine administration after complete recovery of the TOF-ratio can induce muscle weakness. The development and use of new selectively binding reversal agents (sugammadex and calabadion) warrants reevaluation of this area of clinical practice.

Dexamethasone‑induced hyposensitivity to rocuronium in rat diaphragm associated with muscle‑fiber transformation

The aim of the current study was to investigate the effect of chronic dexamethasone (Dex) administration on rat diaphragm function and sensitivity to rocuronium and muscle‑fiber transformation. Adult male Sprague‑Dawley rats were randomized to receive a daily intraperitoneal injection of Dex to evaluate whether alterations in diaphragm function and susceptibility to rocuronium would be induced. In addition, diaphragm contractile properties, histopathology and isometric twitch tensions of nerve‑hemidiaphragm preparations were evaluated. Dex administration led to impaired diaphragm force generation, increased fatigue resistance and a prolonged half‑relaxation time, as well as time‑to‑peak tension. Dex treatment led to desensitization of the rat diaphragm to rocuronium, as demonstrated by a shift of the rocuronium concentration‑twitch tension curves to the right. Histochemical analysis of adenosine triphosphatase revealed that the distribution and cross‑sectional area of type II fibers were decreased in rats exposed to Dex. The present study indicates that chronic Dex treatment induced alterations in muscle function and that susceptibility to rocuronium is associated with muscle fiber‑type transformation, which may aid in directing future administration of muscle relaxants.

Evaluation of surgical conditions during laparoscopic surgery in patients with moderate vs deep neuromuscular block

BACKGROUND

The routine use of neuromuscular blocking agents reduces the occurrence of unacceptable surgical conditions. In some surgeries, such as retroperitoneal laparoscopies, deep neuromuscular block (NMB) may further improve surgical conditions compared with moderate NMB. In this study, the effect of deep NMB on surgical conditions was assessed.

METHODS

Twenty-four patients undergoing elective laparoscopic surgery for prostatectomy or nephrectomy were randomized to receive moderate NMB (train-of-four 1-2) using the combination of atracurium/mivacurium, or deep NMB (post-tetanic count 1-2) using high-dose rocuronium. After surgery, NMB was antagonized with neostigmine (moderate NMB), or sugammadex (deep NMB). During all surgeries, one surgeon scored the quality of surgical conditions using a five-point surgical rating scale (SRS) ranging from 1 (extremely poor conditions) to 5 (optimal conditions). Video images were obtained and 12 anaesthetists rated a random selection of images.

RESULTS

Mean (standard deviation) SRS was 4.0 (0.4) during moderate and 4.7 (0.4) during deep NMB (P<0.001). Moderate block resulted in 18% of scores at the low end of the scale (Scores 1-3); deep block resulted in 99% of scores at the high end of the scale (Scores 4 and 5). Cardiorespiratory conditions were similar during and after surgery in both groups. Between anaesthetists and surgeon, there was poor agreement between scores of individual images (average κ statistic 0.05).

CONCLUSIONS

Application of the five-point SRS showed that deep NMB results in an improved quality of surgical conditions compared with moderate block in retroperitoneal laparoscopies, without compromise to the patients' peri- and postoperative cardiorespiratory conditions. Trial registration The study was registered at clinicaltrials.gov under number NCT01361149.

Successful use of sugammadex in a 'can't ventilate' scenario

A 53-year-old man with hypopharyngeal stenosis following curative chemoradiotherapy for a tongue base tumour presented three years later for an attempt at pharyngeal dilatation. The first attempt 6 months previously was abandoned when awake fibreoptic intubation failed due to partial airway obstruction and desaturation when the fibrescope was advanced. As mask ventilation was anticipated to be possible, a further attempt at intubation after induction of anaesthesia was judged appropriate. The backup plan was jet ventilation via a cricothyroid cannula sited pre-induction. However, neither mask nor jet ventilation proved possible after the induction of anaesthesia and neuromuscular blockade with rocuronium. Swift administration of sugammadex on a background of thorough pre-oxygenation allowed return of spontaneous breathing before the development of hypoxia and so avoided the need for surgical airway rescue. This case demonstrates the utility of sugammadex in restoring spontaneous respiration in a 'can't ventilate' scenario, provided that the airway has not been traumatised by instrumentation.

Monitoring of neuromuscular blockade in one muscle group alone may not reflect recovery of total muscle function in patients with ocular myasthenia gravis

PURPOSE

We report on two patients with ocular myasthenia gravis who received rocuronium, followed later by sugammadex to reverse neuromuscular blockade. Recovery was monitored simultaneously at the adductor pollicis muscle (APM) and the corrugator supercilii muscle (CSM).

CLINICAL FEATURES

Two patients with ocular myasthenia gravis (case 1: 74 yr-old female, 54 kg; case 2: 71 yr-old male, 72 kg) were scheduled for surgery under general anesthesia. Neuromuscular blockade was induced with rocuronium 0.3 mg·kg(-1) after placing two separate monitors at the APM and the CSM, respectively. Additional doses of rocuronium 0.1-0.2 mg·kg(-1) were given to maintain neuromuscular blockade at fewer than two twitches at the APM during surgery. Train-of-four response at the CSM did not show recovery of the twitch after its initial disappearance. At the end of surgery, sugammadex was administered. Twitch height at the APM recovered to the control value in 12 min (case 1) and 13 min (case 2) after sugammadex administration; however, twitch height at the CSM took 26 min (case 1) and 14 min (case 2) to recover to the control value.

CONCLUSION

After rocuronium-induced paralysis in both patients with ocular myasthenia, spontaneous recovery and sugammadex-assisted recovery were slower at the CSM than at the APM. In patients without the disorder, CSM recovery is faster than APM recovery. Thus, in ocular myasthenia gravis, neuromuscular recovery at the APM may not reflect recovery of all muscles.

Evoked electromyography to rocuronium in orbicularis oris and gastrocnemius in facial nerve injury in rabbits

BACKGROUND

Muscles innervated by the facial nerve show different sensitivities to muscle relaxants than muscles innervated by somatic nerves, especially in the presence of facial nerve injury. We compared the evoked electromyography (EEMG) response of orbicularis oris and gastrocnemius in with and without a non-depolarizing muscle relaxant in a rabbit model of graded facial nerve injury.

METHODS

Differences in EEMG response and inhibition by rocuronium were measured in the orbicularis oris and gastrocnemius muscles 7 to 42 d after different levels of facial nerve crush injuries in adult rabbits.

RESULTS

Baseline EEMG of orbicularis oris was significantly smaller than those of the gastrocnemius. Gastrocnemius was more sensitive to rocuronium than the facial muscles (P < 0.05). Baseline EEMG and EEMG amplitude of orbicularis oris in the presence of rocuronium was negatively correlated with the magnitude of facial nerve injury but the sensitivity to rocuronium was not. No significant difference was found in the onset time and the recovery time of rocuronium among gastrocnemius and normal or damaged facial muscles.

CONCLUSIONS

Muscles innervated by somatic nerves are more sensitive to rocuronium than those innervated by the facial nerve, but while facial nerve injury reduced EEMG responses, the sensitivity to rocuronium is not altered. Partial neuromuscular blockade may be a suitable technique for conducting anesthesia and surgery safely when EEMG monitoring is needed to preserve and protect the facial nerve. Additional caution should be used if there is a risk of preexisting facial nerve injury.

Comparison of Evoked Electromyography in Three Muscles of the Hand during Recovery from Non-Depolarising Neuromuscular Blockade

The evoked electromyographic responses to supramaximal train of four stimulation of three muscles, all innervated by the ulnar nerve, were compared during recovery from non-depolarising neuromuscular blockade. The abductor digiti minimi was the most resistant to neuromuscular blockade (P <0.001) and the most repeatable (repeatability coefficient 4.4%) when compared with the adductor pollicis (5.9%) and the first dorsal interosseous (5.8%). The abductor digiti minimi had a bias of 0.1 compared to the adductor pollicis and first dorsal interosseous and its limits of agreement were more acceptable (-0.10 to 0.30) at a train of four ratio of 0.9. The electromyography train of four of the adductor pollicis and first dorsal interosseous at 0.8 is equivalent to an electromyography train of four of 0.9 at abductor digiti minimi.

Testing rocuronium-induced neuromuscular blockade at the stapedius muscle using stapedius reflex measurements

BACKGROUND

Neuromuscular monitoring prior to emergence from anaesthesia has been shown to be necessary to achieve adequate airway protection in order to decrease postoperative pulmonary complications. In the present study we hypothesized that stapedius reflex measurement allows the detection of residual neuromuscular blockade using the stapedius muscle following the administration of rocuronium.

PATIENTS AND METHODS

Parallel stapedius and acceleromyographic measurements were performed on 20 patients undergoing cholecystectomy. Acceleromyographic measurements were continuously performed during the course of anaesthesia, whereas the stapedius reflex was measured on different occasions: (1) after premedication but before anaesthesia induction, (2) after induction, but before administration of muscle relaxant, (3) after administration of muscle relaxant, (4) during the course of surgical anaesthesia at regular intervals, and (5) continuously performed during emergence from anaesthesia, until the stapedius reflex threshold returned to normal.

RESULTS

The intensity of the sound energy at which the stapedius reflex is detectable was similar: 89.5 ± 9.9 dB(mean ± SD) after premedication and after anaesthetic induction. However, after administration of rocuronium, when the twitch height decreased to 5%, the stapedius reflex disappeared, indicating a total block of the stapedius muscle.During the recovery phase (twitch>10%) significantly higher sound energies compared to baseline values were necessary to evoke the reflex, indicating residual inhibition of the stapedius muscle. At the point where stapedius reflex threshold returned to normal the twitch height averaged about 50% showing low sensitivity of the tympanometry in detecting residual neuromuscular blockade.

CONCLUSIONS

The neuromuscular effect of rocuronium on the stapedius muscle can be detected using stapedius reflex measurements. Due to its methodological limitation and low sensitivity, the method cannot be recommended for the monitoring of residual neuromuscular blockade.

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.

Laryngeal morbidity after intubation with or without neuromuscular block in thyroid surgery using recurrent laryngeal nerve monitoring

OBJECTIVE

The avoidance of neuromuscular blocking agents (NMBA) for endotracheal intubation is associated with a higher incidence of laryngeal discomfort and lesions, but could impair effectiveness of intra operative recurrent laryngeal nerve monitoring (IONM).

METHODS

In a retrospective quality assessment study over a period of 30 months, a collective that had been intubated without NMBA was compared with a group, which had received NMBA. Endolaryngeal EMG was accomplished with a MagStim(®)-EMG-electrode.

RESULTS

Out of the 127 patients with 224 nerves at risk (NAR; NMBA 102 NAR, no NMBA 122 NAR), more than 90% received a total intravenous anaesthesia with propofol, and 88% had remifentanil. Laryngeal side effects and damage scores did not differ significantly.

CONCLUSIONS

In this special setting of IONM and thyroid surgery, avoidance of NMBA for endotracheal intubation seems not to increase the incidence of laryngeal side effects and lesions. If endotracheal intubation without NMBA is required, the authors suggest a standardized approach using induction agents as propofol and remifentanil.

[Neostigmine-induced neuromuscular blockade in the corrugator supercilii muscle]

OBJECTIVE

To investigate whether a single dose of neostigmine, administered when the adductor pollicis muscle presents 2 twitches in train-of-four (TOF) stimulation, can reduce the TOF ratio in the corrugator supercilii muscle.

PATIENTS AND METHODS

We designed a case-control study of patients between 18 and 65 years of age classified ASA 1-2. We used 2 accelerometers--1 for the cubital nerve/thumb adductor muscle and 1 for the facial nerve/corrugator supercilii muscle. Neuromuscular blockade was induced with 0.6 mg x kg(-1) of rocuronium, and 40 microg x kg(-1) of neostigmine was administered at the third twitch in the TOF in the thumb adductor. If the TOF ratio in the corrugator supercilii fell by 10% or more at that time, the patient was classified as a case. We recorded the age, sex, weight, height, body mass index, duration of the procedure, and TOF ratio in the corrugator supercilii muscle when the neostigmine was administered.

RESULTS

Ten cases and 10 controls were enrolled. No significant differences between cases and controls were found in any variables except the mean (SD) TOF ratio in the corrugator supercilii muscle: 70.9% (17.8%) in cases and 35.3% (7.8%) in controls (P < .001).

CONCLUSIONS

In our patients, administration of neostigmine after the appearance of the third twitch in TOF stimulation of the thumb adductor was associated with a reduction in the TOF ratio in the corrugator supercilii. The similarity between blockades of the corrugator muscle, the diaphragm, and the larynx is of clinical interest.

Neuromuscular Blockade by Vecuronium during Induction with 5% Sevoflurane or Propofol

This randomized trial investigated whether 5% sevoflurane potentiated neuromuscular blockade by vecuronium. General anaesthesia was induced with 5% sevoflurane in oxygen in 16 patients or with propofol in 16 patients. After loss of consciousness, vecuronium was administered to all participants at randomly assigned doses of 25, 30, 35 or 40 μg/kg. Neuromuscular blockade was assessed by use of acceleromyography to measure responses to train-of-four stimuli in the adductor pollicis and corrugator supercilii muscles. Maximum blockade was significantly more intense in the adductor pollicis among patients in the sevoflurane group than in the propofol group, whereas there was no significant between-group difference at the corrugator supercilii muscles. In both groups, maximum blockade at the corrugator supercilii was significantly less intense than that achieved at the adductor pollicis. In the dose–response analysis, the 50% and 95% effective doses were lower for sevoflurane than for propofol in both muscles, although this did not reach statistical significance. It is concluded that induction of general anaesthesia with sevoflurane might provide improved conditions for intubation and reduce airway problems.

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.