Caution for psychiatrists: malignant hyperthermia risks with the anesthetic agent succinylcholine (Suxamethonium) during electroconvulsive therapy.

BACKGROUND: Malignant hyperthermia is a potentially lethal condition triggered by specific anesthetic drugs, especially a depolarizing muscle relaxant of succinylcholine (Suxamethonium). Despite the frequent use of succinylcholine with electroconvulsive therapy (ECT), there has been no reported case of potentially lethal malignant hyperthermia following ECT. In addition, the time interval between the administration of succinylcholine and the onset of malignant hyperthermia has not been outlined in the context of ECT. CASE PRESENTATION: We present the case of a 79-year-old woman suffering from severe depression, who experienced severe malignant hyperthermia due to succinylcholine administration during an ECT session. She presented with a high fever of 40.2 °C, tachycardia of 140/min, hypertension with a blood pressure exceeding 200 mmHg, significant muscle rigidity, and impaired consciousness. These symptoms emerged two hours after ECT, which occurred in a psychiatric ward rather than an operating room, and reached their peak in less than 24 h. She was given 60 mg of dantrolene, which quickly reduced the muscular rigidity. Subsequently, she received two additional doses of 20 mg and 60 mg of dantrolene, which brought her fever down to 36.2 °C and completely eased her muscle rigidity within two days after ECT. CONCLUSIONS: This is the first reported case of potentially lethal malignant hyperthermia after ECT. In addition, it highlights the delayed onset of malignant hyperthermia following an ECT procedure, emphasizing the necessity for psychiatrists to recognize its onset even after the treatment. In the light of potentially lethal consequences of malignant hyperthermia, it is critically important for psychiatrists to closely monitor both intraoperative and postoperative patient's vital signs and characteristic physical presentations, promptly identify any symptomatic emergence, and treat it immediately with dantrolene.

The Influence of Acid-Base Balance on Anesthetic Muscle Relaxants: A Comprehensive Review on Clinical Applications and Mechanisms.

Muscle relaxants have broad application in anesthesiology. They can be used for safe intubation, preparing the patient for surgery, or improving mechanical ventilation. Muscle relaxants can be classified based on their mechanism of action into depolarizing and non-depolarizing muscle relaxants and centrally acting muscle relaxants. Non-depolarizing neuromuscular blocking drugs (NMBDs) (eg, tubocurarine, atracurium, pipecuronium, mivacurium, pancuronium, rocuronium, vecuronium) act as competitive antagonists of nicotine receptors. By doing so, these drugs hinder the depolarizing effect of acetylcholine, thereby eliminating the potential stimulation of muscle fibers. Depolarizing drugs like succinylcholine and decamethonium induce an initial activation (depolarization) of the receptor followed by a sustained and steady blockade. These drugs do not act as competitive antagonists; instead, they function as more enduring agonists compared to acetylcholine itself. Many factors can influence the duration of action of these drugs. Among them, electrolyte disturbances and disruptions in acid-base balance can have an impact. Acidosis increases the potency of non-depolarizing muscle relaxants, while alkalosis induces resistance to their effects. In depolarizing drugs, acidosis and alkalosis produce opposite effects. The results of studies on the impact of acid-base balance disturbances on non-depolarizing relaxants have been conflicting. This work is based on the available literature and the authors' experience. This article aimed to review the use of anesthetic muscle relaxants in patients with acid-base disturbances.

Prolonged duration of action of suxamethonium in pregnant and postpartum patients: A registry study.

BACKGROUND: Suxamethonium is hydrolysed by butyrylcholinesterase (BChE) and a low BChE activity can result in a prolonged duration of action of suxamethonium. The BChE activity is reduced during pregnancy and postpartum period by up to 33%. However, it can also be reduced by mutations in the BChE gene. In this study, we assessed BChE activity and mutations in the BChE gene in pregnant and postpartum patients with prolonged duration of action of suxamethonium. It was hypothesised that at least 30% of patients with a low BChE activity did not have a mutation in the BChE gene. METHODS: In this registry study we focused on pregnant and postpartum patients with a history of prolonged duration of action of suxamethonium referred to the Danish Cholinesterase Research Unit (DCRU) between March 2007 and January 2023. Primary outcome was the proportion of patients without a mutation among patients with a low BChE activity. Secondary outcomes were the proportion of patients with a low BChE activity and the proportion of patients with a mutation out of the total number of patients. RESULTS: A total of 40 patients were included and among patients with a low BChE activity, 6% (95% CI: 1%-21%) did not have a mutation. Out of the total number of included patients referred to the DCRU, 90% (95% CI: 76%-97%) had a mutation and 94% (95% CI: 80%-99%) had a low BChE activity. CONCLUSION: Among pregnant and postpartum patients with a history of prolonged duration of action of suxamethonium and a low BChE activity, 6% did not have a mutation in the BChE gene. Our findings suggest that during pregnancy and postpartum clinically relevant prolonged duration of action of suxamethonium rarely occurs in genotypically normal patients.

[Update: Neuromuscular Blockade during General Anesthesia]. / Update: Muskelrelaxierung in der Anästhesie.

The correct use of muscle relaxants and neuromuscular monitoring during anesthesia has been subject of controversial discussions for decades. Particularly important in clinical practice are identification and management of residual neuromuscular blockages and avoidance of associated complications. Despite the differences in the molecular mechanisms of action between depolarizing and non-depolarizing muscle relaxants the blockade of the postsynaptic nicotinic acetylcholine receptor remains a common ending pathway. Due to its unfavorable side effect profile, succinylcholine should only be used in justified exceptional cases. The use of muscle relaxants generally reduces the complication rate in airway management. However, even the single use of muscle relaxants increases the likelihood of postoperative pulmonary complications. These complications associated with the use of muscle relaxants, such as residual neuromuscular blockade, must be anticipated. The application of guideline-based approaches, including continuous neuromuscular monitoring and the application of muscle relaxant reversal agents, may significantly reduce the rate of adverse events associated with the use of muscle relaxants.

Suspected Pseudocholinesterase Deficiency During Left Thyroid Lobectomy and Isthmusectomy: A Case Report.

BACKGROUND: Pseudocholinesterase (butyrylcholinesterase) deficiency is an acquired or inherited condition in which decreased plasma levels of the pseudocholinesterase enzyme lead to an inability to metabolize the neuromuscular blocking agents succinylcholine and mivacurium, prolonging their paralytic effects. This often results in delayed extubation and additional intensive care requirements in the postoperative period. CASE DESCRIPTION: We describe a case of suspected pseudocholinesterase deficiency in a previously healthy 59-year-old female who underwent a left thyroid lobectomy and isthmusectomy. The patient received 120 mg of succinylcholine chloride before intubation. The patient did not meet extubation criteria following the completion of the procedure approximately two hours after receiving succinylcholine chloride. The patient was transferred to the ICU for respiratory support and for the medication to clear from the patient's system. The patient regained muscle control approximately four hours after receiving succinylcholine chloride and was extubated without complication. The patient shared post-extubation that she had a blood relative with the diagnosis of pseudocholinesterase deficiency. CONCLUSION: Pseudocholinesterase deficiency is rare but can result in potentially serious complications following the administration of succinylcholine chloride, mivacurium, or ester local anesthetics due to reduced metabolism and subsequently increased pharmacodynamic effects. Given the widespread use of succinylcholine chloride as a neuromuscular blocking agent, such as in this case, providers must be aware of the presentation, pathophysiology, diagnosis, and management. Additionally, this case demonstrates the importance of thoroughly inquiring about any personal or family history of anesthetic complications during a preoperative assessment.

Post-intubation analgesia and sedation following succinylcholine vs. rocuronium in the emergency department.

BACKGROUND: Succinylcholine and rocuronium are the most commonly utilized neuromuscular blocker agents (NMBAs) for rapid sequence intubation (RSI) in the emergency department (ED). The duration of action of rocuronium is significantly longer (∼30 min) compared to succinylcholine (∼10 min) and previous studies have shown that patients receiving rocuronium are more likely to have longer time to sedation initiation following RSI. Furthermore, patients receiving rocuronium may be more likely to experience awareness with paralysis than those receiving succinylcholine. The primary goal for this study was to evaluate the association between NMBA use during RSI and post-intubation sedation and analgesia practices in the ED. METHODS: This was a retrospective, multicenter cohort study including patients 18 years and older that received succinylcholine or rocuronium during RSI in the ED between September 1, 2020 and August 31, 2021. Patients were excluded if they were intubated prior to ED arrival, experienced an out-of-hospital or in ED cardiac arrest, or received sugammadex within 60 min of rocuronium administration. Patients were screened in reverse chronological order until the targeted sample size was achieved and all data was abstracted from the electronic health record. The primary outcome was the time to initiation of analgesia or sedation. Secondary outcomes included dose of sedatives or analgesia administered at 30- and 60 min, and medications administered for post-intubation sedation or analgesia. FINDINGS: A total of 200 ED patients were included of which 100 received succinylcholine and 100 received rocuronium. There was no difference in the median time to initiation of analgesia or sedation between the succinylcholine and rocuronium groups (10 vs 8.5 min, p = 0.82) or in Kaplan-Meier cumulative probabilities (p = 0.17). At 60 min post-RSI, those receiving succinylcholine received significantly higher median doses of propofol (20 µg/kg/min vs. 10 µg/kg/min; p = 0.02) and fentanyl [100 µg vs. 84.2 µg; p = 0.02]. CONCLUSION: While no differences were observed in the time to initiation of post-intubation sedation or analgesia in ED patients receiving succinylcholine compared to rocuronium, differences in the intensity of post-intubation regimens was observed. Further investigation is needed to evaluate the adequacy of sedation following RSI in the ED.

Traumatic brain injury and RSI is rocuronium or succinylcholine preferred?

PURPOSE OF REVIEW: Traumatic brain injury is widespread and has significant morbidity and mortality. Patients with severe traumatic brain injury often necessitate intubation. The paralytic for rapid sequence induction and intubation for the patient with traumatic brain injury has not been standardized. RECENT FINDINGS: Rapid sequence induction is the standard of care for patients with traumatic brain injury. Historically, succinylcholine has been the agent of choice due to its fast onset and short duration of action, but it has numerous adverse effects such as increased intracranial pressure and hyperkalemia. Rocuronium, when dosed appropriately, provides neuromuscular blockade as quickly and effectively as succinylcholine but was previously avoided due to its prolonged duration of action which precluded neurologic examination. However, with the widespread availability of sugammadex, rocuronium is able to be reversed in a timely manner. SUMMARY: In patients with traumatic brain injury necessitating intubation, rocuronium appears to be safer than succinylcholine.

Postintubation Sedation After a Formulary Change From Succinylcholine to Rocuronium in a Critical Care Transport Organization.

OBJECTIVE: Rocuronium is increasingly used as a first-line neuromuscular blocker (NMB) in rapid sequence intubation by transport teams. Prior work has shown that rocuronium is associated with a delay in postintubation sedation compared with intubation with succinylcholine. METHODS: Boston MedFlight is a consortium-based transport organization. In 2017, the intubation protocol and formulary for Boston MedFlight was changed to replace succinylcholine with rocuronium. We performed a retrospective review of patients intubated by the critical care transport teams from January 2017 through December 2019. RESULTS: We analyzed data for 264 intubations, 92 with succinylcholine and 172 with rocuronium. Ketamine and etomidate were the most common induction agents. The mean time from NMB administration to the first dose of sedation was 9.2 minutes (95% confidence interval, 5.4-23.7) for the succinylcholine cohort and 14.8 minutes (95% confidence interval, 8.4-38.0; P < .001) for the rocuronium cohort. After neuromuscular blockade, the total hourly weight-adjusted fentanyl dose was significantly lower for patients intubated with rocuronium compared with succinylcholine. CONCLUSIONS: Intubation with rocuronium was associated with a longer time until the administration of sedation and decreased postneuromuscular blockade fentanyl administration compared with intubation with succinylcholine. These findings suggest opportunities for improvement in sedation and analgesia practices after rocuronium rapid sequence intubation.

Impact of duloxetine on succinylcholine-induced postoperative myalgia after direct microlaryngoscopic surgeries: Randomized controlled double-blind study.

BACKGROUND: Succinylcholine is a preferred muscle relaxant for rapid sequence intubation. Postoperative myalgia (POM) is one of its commonest adverse effects with unknown pathogenesis. Various modalities were examined to reduce POM. We hypothesized that duloxetine may reduce the incidence and severity of fasciculation or succinylcholine-induced POM in outpatient surgeries. METHODS: This randomized double-blinded trial involved controlled 70 adult participants scheduled for elective direct microlaryngoscopic surgeries. Before induction of general anesthesia by 2 h, 35 patients received duloxetine 30 mg orally (group D) and 35 patients received similar oral starch placebo capsules (group C). Fasciculations, POM, sedation score, time to first rescue analgesia, total analgesic consumption 24 h after surgery, patients' satisfaction, and adverse effects were recorded. RESULTS: Incidence of fasciculation was 77.1% and 94.3% in groups D and C (p value = 0.04), whereas its severity was not significant between groups (p value = 0.09). Incidence and severity of POM were significantly lower in group D (p values = 0.004 and 0.021). Positive correlation was recorded between fasciculations and POM scores (r = 0.732 and p < 0.001). Time required for first analgesia was prolonged in group D (p value < 0.001) with less total analgesic consumption (p value = 0.039). The potassium and creatine kinase levels showed significant differences between both groups after 30 min and 24 h, respectively (p value < 0.05). Sedation scores and patients' satisfaction were better in duloxetine group (p value < 0.05) with no severe complications. CONCLUSIONS: Preoperative oral duloxetine 30 mg administration decreased incidence and severity of succinylcholine-related muscle POM and fasciculations. It was also effective in reducing postoperative rescue analgesic requirement with better patients' satisfaction and no serious adverse effects.

Rapid Sequence Induction With a Standard Intubation Dose of Rocuronium After Magnesium Pretreatment Compared With Succinylcholine: A Randomized Clinical Trial.

BACKGROUND: Succinylcholine remains the muscle relaxant of choice for rapid sequence induction (RSI) but has many adverse effects. High-dose rocuronium bromide may be an alternative to succinylcholine for RSI but recovery times are nearly doubled compared with a standard intubating dose of rocuronium. Magnesium sulfate significantly shortens the onset time of a standard intubating dose of rocuronium. We set out to investigate whether intravenous (IV) pretreatment with MgSO4 followed by a standard intubating dose of rocuronium achieved superior intubation conditions compared with succinylcholine. METHODS: Adults were randomized to receive a 15-minute IV infusion of MgSO4 (60 mg·kg-1) immediately before RSI with propofol 2 mg·kg-1, sufentanil 0.2 µg·kg-1 and rocuronium 0.6 mg·kg-1, or a matching 15-minute IV infusion of saline immediately before an identical RSI, but with succinylcholine 1 mg·kg-1. Primary end point was the rate of excellent intubating conditions 60 seconds after administration of the neuromuscular blocking agent and compared between groups using multivariable log-binomial regression model. Secondary end points were blood pressure and heart rate before induction, before and after intubation, and adverse events up to 24 hours postoperatively. RESULTS: Among 280 randomized patients, intubating conditions could be analyzed in 259 (133 MgSO4-rocuronium and 126 saline-succinylcholine). The rate of excellent intubating conditions was 46% with MgSO4-rocuronium and 45% with saline-succinylcholine. The analysis adjusted for gender and center showed no superiority of MgSO4-rocuronium compared with saline-succinylcholine (relative risk [RR] 1.06, 95% confidence interval [CI], 0.81-1.39, P = .659). The rate of excellent intubating conditions was higher in women (54% [70 of 130]) compared with men (37% [48 of 129]; adjusted RR 1.42, 95% CI, 1.07-1.91, P = .017). No significant difference between groups was observed for systolic and diastolic blood pressures. Mean heart rate was significantly higher in the MgSO4-rocuronium group. The percentage of patients with at least 1 adverse event was lower with MgSO4-rocuronium (11%) compared with saline-succinylcholine (28%) (RR 0.38, 95% CI, 0.22-0.66, P < .001). With saline-succinylcholine, adverse events consisted mainly of postoperative muscle pain (n = 26 [19%]) and signs of histamine release (n = 13 [9%]). With MgSO4-rocuronium, few patients had pain on injection, nausea and vomiting, or skin rash during the MgSO4-infusion (n = 5 [4%]). CONCLUSIONS: IV pretreatment with MgSO4 followed by a standard intubating dose of rocuronium did not provide superior intubation conditions to succinylcholine but had fewer adverse effects.

Neuromuscular Blockade and Reversal Practice Variability in the Outpatient Setting: Insights From US Utilization Patterns.

BACKGROUND: Neuromuscular blockade (NMB) is a critical part of many surgical procedures. Data on practice patterns of NMB agents (NMBAs) and NMB reversal in recent years in the US ambulatory surgical care setting are limited. METHODS: This retrospective analysis of US adult outpatients was conducted using the Premier Healthcare Database. We describe anesthesia practice trends in NMB management and assess the association of patient, procedural, and site characteristics with NMB reversal approach using multivariable logistic regression. RESULTS: Approximately 5.2 million outpatient surgical encounters involving NMB and 4.6 million involving rocuronium or vecuronium between January 2014 and June 2019 were included. Following the introduction of sugammadex to US clinical practice (~2016), there was an increased use of rocuronium or vecuronium and a decrease in succinylcholine alone. Before 2016, NMB was pharmacologically reversed with neostigmine in approximately two-thirds of outpatient encounters. Over time, active reversal increased; by 2019, 42.3% and 36.0% of encounters were reversed by neostigmine and sugammadex, respectively, with 21.7% undergoing spontaneous recovery. Choice of NMBA (rocuronium or vecuronium alone), time since 2016, obesity, peripheral vascular disease, and procedures on the digestive, ocular, and female genital systems (vs musculoskeletal procedures) were independently and positively associated with pharmacologic reversal (versus spontaneous reversal). Conversely, advanced age; Western geography; and cardiovascular, endocrine, hemic/lymphatic, respiratory, and ear, nose, and throat procedures were independently and negatively associated with pharmacologic reversal of NMB.Among pharmacologic reversals, time since 2016 was positively and independently associated with sugammadex compared with neostigmine (odds ratios [ORs], ranged from 1.8 in 2017 to 3.2, P < .0001 in 2019). Those administered rocuronium or vecuronium without succinylcholine, with increased age and history of certain comorbidities, and those undergoing ocular or respiratory procedures (compared with musculoskeletal) were positively associated with reversal with sugammadex and endocrine procedure negatively and independently associated with reversal with sugammadex. There was variability in the association of several factors with NMB reversal choices by geographic region, particularly in patients' race, ethnicity, and size of affiliated hospital. CONCLUSIONS: Overall, active pharmacological reversal of NMB increased in US adult outpatients following the introduction of sugammadex, although there remains significant practice variability. The multifactorial relationship between patient-, procedural-, and environmental-level characteristics and NMB management is rapidly evolving. Additional research on how these anesthesia practice patterns may be impacted by the shift to the ambulatory care setting and how they may impact patient outcomes and health disparities is warranted.

Prolonged apnea after ECT in organophosphorus poisoning - the need to redefine norms.

BACKGROUND: Poisoning and deaths by organo-phosphorous (OP) compounds are one of the major causes of death in developing and poor countries, and a common admission in the emergency ward and the ICU. OP compounds act by irreversibly binding to pseudocholinesterase enzyme and hence prolong the apnea in patients being given suxamethonium. We present a unusual case of OP poisoning (OPP) in which prolonged apnea ensued in a patient of severe depression following MECT (modified electroconvulsive therapy) in which suxamethonium was used as muscle relaxant, in whom we were cautious of the side-effect of prior organophosphorus poisoning. Since the cases of OPP are very high worldwide, a thorough knowledge of the interaction of the action of the drug and the receptors on which it acts takes pride of place. This article highlights the nuances in the field of psychiatry and anaesthesia in diagnosis and management of prolonged apnea after ECT. CASE PRESENTATION: A 53/F patient consumed OP 38 days prior to MECT. Since existing literature recommend a delay of 4 weeks and a subminimal dose of suxamethonium to prevent prolonged apnea, both these points were taken into consideration. Despite 38 days post exposure to OP, and a dose of succinylcholine of < 0.3 mg/kg, the patient remained apneic for 3 h. Suxamethionum apnea was managed with elective ventilation. After recovery, patient had no residual effect. Subsequently her pseudocholinesterase levels were done which were found to be very low. CONCLUSION: This case is being presented to emphasize that behaviour of post synaptic receptors cannot be relied upon after OP poisoning and pseudocholinesterase levels needs to be mandatorily checked, irrespective of duration post-exposure. In strong suspects dibucaine number and fluoride number also needs to be estimated.

Succinylcholine and postoperative pulmonary complications: a retrospective cohort study using registry data from two hospital networks.

BACKGROUND: Neuromuscular blocking agents (NMBAs) with a non-depolarising mechanism of action carry the risk of postoperative residual paralysis and are associated with postoperative pulmonary complications (POPC). Owing to the shorter duration of action, the depolarising NMBA succinylcholine may be associated with less postoperative residual paralysis, and hence fewer POPC. We tested the association of succinylcholine administration during anaesthesia and POPC. METHODS: In a retrospective cohort study of registry data from two large US academic medical centres, 244 850 adult noncardiac surgical patients undergoing general anaesthesia were included. The primary outcome was POPC, defined as post-extubation haemoglobin oxygen de-saturation to <90%, or re-intubation requiring intensive care unit admission within 7 days after surgery. The association between succinylcholine and POPC and its dose-dependency were tested in a hierarchical fashion using a multivariable logistic regression model. RESULTS: A total of 13 206 patients (5.4%) experienced POPC. Use of succinylcholine was associated with increased risk of POPC (adjusted odds ratio [ORAdj]=1.11; 95% confidence interval [CI], 1.06-1.16; P<0.001; adjusted risk=5.18%; 95% CI, 5.06-5.30 without and 5.69%; 95% CI, 5.53-5.85 with succinylcholine), with a dose-dependent relationship (ORAdj=1.08; 95% CI, 1.05-1.11 per mg kg-1; P<0.001). In patients receiving non-depolarising NMBAs, succinylcholine further increased the risk of POPC (ORAdj=1.08; 95% CI, 1.03-1.14; P=0.001). The association between succinylcholine and POPC was modified (P=0.03 for interaction) by the duration of surgery with higher odds of POPC in patients undergoing surgeries of <2 vs ≥2 h (ORAdj=1.24; 95% CI, 1.15-1.33 and 1.05; 95% CI, 1.00-1.10, respectively). CONCLUSIONS: In contrast to our prediction, succinylcholine administration was associated with an increased risk of POPC. This association was dose-dependent and magnified in surgeries of shorter duration.

Factors associated with post-intubation sedation after emergency department intubation: A Report from The National Emergency Airway Registry.

BACKGROUND: Previous work has suggested low rates of post-intubation sedation in patients undergoing endotracheal intubation (ETI) in the emergency department (ED) with limited data examining factors associated with sedation use. Utilizing a national database; we sought to determine the frequency of post-intubation sedation and associated factors. METHODS: We performed a retrospective analysis of a prospectively collected database (National Emergency Airway Registry (NEAR) from 25 EDs from January 1, 2016 to December 31, 2017). Patients were considered to have received post-intubation sedation if they received any of the following medications within 15 min of ETI completion; propofol, midazolam, diazepam, ketamine, etomidate, fentanyl, and morphine. We calculated odds ratios for post-intubation sedation. RESULTS: Of the 11,748 eligible intubations, 9099 received post-intubation sedation (77.5%) while 2649 did not (22.5%). Pre-intubation hypotension (odds ratio; 95% confidence Interval) (0.27; 0.24-0.31) and post-intubation hypotension (0.27; 0.24-0.31) were associated with lower odds of post-intubation sedation. Patients with a medical indication compared to a traumatic indication for ETI had higher odds of receiving post-intubation sedation (1.16; 1.05-1.28) as did those that underwent rapid sequence intubation (15.15; 13.56-16.93). Use of succinylcholine was associated with a higher odd of post-intubation sedation compared to a long-acting neuromuscular blocking agent (i.e. rocuronium or vecuronium) (1.89; 1.68-2.12). CONCLUSION: Post-intubation sedation rates in NEAR are higher than previously reported and multiple factors including the indication for intubation and succinylcholine use, are associated with higher odds of receiving post-intubation sedation.

The optimal dose of succinylcholine for rapid sequence induction: a systematic review and meta-analysis of randomized trials.

BACKGROUND: The evidence base for the widely accepted standard regimen of succinylcholine for rapid sequence induction (1.0 mg kg- 1) remains unclear. METHODS: We performed a systematic review and meta-analysis of randomized trials comparing any succinylcholine regimen with the standard regimen (1.0 mg kg- 1) and reporting on intubating conditions and/or apnoea times. Results were expressed as absolute risk differences (ARD) for dichotomous data and mean differences (MD) for continuous data. RESULTS: We retrieved six trials with relevant data of 864 patients (ASA 1 or 2, aged 18-65 years, body mass index < 30 kg m- 2). Four regimens (0.3, 0.4, 0.5, 0.6 mg kg- 1) were compared with 1.0 mg kg- 1 in at least three trials each, and three (0.8, 1.5, 2 mg kg- 1) in one each. With 0.3 to 0.5 mg kg- 1, the likelihood of excellent intubating conditions was significantly decreased (ARD - 22% to - 67%). With 0.3 and 0.4 mg kg- 1, but not with 0.5, 0.6, 0.8, 1.5 and 2.0 mg kg- 1, the likelihood of unacceptable intubating conditions was significantly increased (ARD + 22% and + 32%, respectively). With 2.0 mg kg- 1, but not with 0.8 or 1.5 mg kg- 1, the likelihood of excellent intubating conditions was significantly increased (ARD + 23%). Apnoea times were significantly shorter with regimens ≤0.8 mg kg- 1 (MD - 1.0 to - 3.4 min) but were not reported with 1.5 or 2.0 mg kg- 1. CONCLUSIONS: With succinylcholine regimens ≤0.5 mg kg- 1, excellent intubating conditions are less likely and apnoea times are shorter, compared with 1 mg kg- 1. With 0.3 and 0.4 mg kg- 1, unacceptable intubating conditions are more common. Succinylcholine 1.5 mg kg- 1 does not produce more often excellent conditions compared with 1 mg kg- 1, while 2.0 mg kg- 1 does, but the database with these regimens is weak and apnoea times remain unknown. Limited information size and strong statistical heterogeneity decrease the certainty of the evidence.

Dose-response assessment for impaired memory from chronic exposure to domoic acid among native American consumers of razor clams.

Domoic acid (DA) is a marine neurotoxin that accumulates in filtering shellfish during harmful algal blooms. A health protection limit of 20 ppm DA in razor clams (RC) has been set based principally upon an episode of acute DA toxicity in humans that included Amnesic Shellfish Poisoning among survivors. The objective of this study was to determine the dose-response relationship between estimated DA exposure through RC consumption and memory loss in Washington state Native Americans from 2005 to 2015. Results from total learning recall (TLR) memory scores were compared before and after the highest DA exposures. A decrease in TLR was related to DA dose (p < 0.01) regardless whether the effect was assumed to be transient or lasting, and whether the dose was expressed as an average daily dose or an average dose per meal. Benchmark dose modeling identified BMDL10 values of 167 ng/kg-day and 2740 ng/kg-meal assuming a transient effect, and 196 ng/kg-day and 2980 ng/kg-meal assuming no recovery of function occurs. These DA dose thresholds for a measurable memory function reduction observed in this study of clam consumers are well below the safe acute dose underpinning the current regulatory DA limit of 20 ppm (ca. 60 µg/kg).

Blockade of Hemichannels Normalizes the Differentiation Fate of Myoblasts and Features of Skeletal Muscles from Dysferlin-Deficient Mice.

Dysferlinopathies are muscle dystrophies caused by mutations in the gene encoding dysferlin, a relevant protein for membrane repair and trafficking. These diseases are untreatable, possibly due to the poor knowledge of relevant molecular targets. Previously, we have shown that human myofibers from patient biopsies as well as myotubes derived from immortalized human myoblasts carrying a mutated form of dysferlin express connexin proteins, but their relevance in myoblasts fate and function remained unknown. In the present work, we found that numerous myoblasts bearing a mutated dysferlin when induced to acquire myogenic commitment express PPARγ, revealing adipogenic instead of myogenic commitment. These cell cultures presented many mononucleated cells with fat accumulation and within 48 h of differentiation formed fewer multinucleated cells. In contrast, dysferlin deficient myoblasts treated with boldine, a connexin hemichannels blocker, neither expressed PPARγ, nor accumulated fat and formed similar amount of multinucleated cells as wild type precursor cells. We recently demonstrated that myofibers of skeletal muscles from blAJ mice (an animal model of dysferlinopathies) express three connexins (Cx39, Cx43, and Cx45) that form functional hemichannels (HCs) in the sarcolemma. In symptomatic blAJ mice, we now show that eight-week treatment with a daily dose of boldine showed a progressive recovery of motor activity reaching normality. At the end of this treatment, skeletal muscles were comparable to those of wild type mice and presented normal CK activity in serum. Myofibers of boldine-treated blAJ mice also showed strong dysferlin-like immunoreactivity. These findings reveal that muscle dysfunction results from a pathophysiologic mechanism triggered by mutated dysferlin and downstream connexin hemichannels expressed de novo lead to a drastic reduction of myogenesis and favor muscle damage. Thus, boldine could represent a therapeutic opportunity to treat dysfernilopathies.

The Effect of Pregabalin on the Prevention of Succinylcholine-Induced Fasciculation and Myalgia.

PURPOSE: This study evaluates the effect of pregabalin on fasciculation and myalgia after using succinylcholine. DESIGN: This randomized double-blind prospective study was conducted among 100 patients aged 20 to 60 years old. METHODS: Pregabalin (300 mg) and placebo (in capsule form) were placed in similar containers. The results were analyzed by SPSS 23 software, and statistical analysis consisted of χ2 test and t test, and a P value less than .05 was considered significant. FINDINGS: The mean pain score in the group receiving pregabalin was lower than the placebo group. According to the χ2 test, there was a significant difference between the two groups in the frequency of fasciculation (P = .003). Mean fasciculation severity in the pregabalin group was lower than placebo group. According to t test, there was a significant difference in the mean fasciculation severity between the two groups (P = .002). CONCLUSIONS: This study showed that 300 mg of pregabalin was effective in reducing postoperative fasciculation and myalgia in patients treated with succinylcholine.

Anaesthetic management for hiatal hernia repair in a child with Bartter's syndrome: A case report.

Bartter syndrome is a rare disorder characterized by reduced sodium chloride transport in the distal nephrons of the kidney. Its clinical features are renal salt wasting, hypokalemic metabolic alkalosis, elevated renin and aldosterone levels with normal or low blood pressure, polyuria, hypercalciuria and malnutrition. The pathophysiologic and biochemical changes in these patients should be kept in mind when considering anaesthetic management. This case report describes our management in a nineteen months old, 3.6 kg weight male child with Bartter's syndrome who underwent elective repair of hiatal hernia and gastrostomy.

Succinylcholine Use and Dantrolene Availability for Malignant Hyperthermia Treatment: Database Analyses and Systematic Review.

BACKGROUND: Although dantrolene effectively treats malignant hyperthermia (MH), discrepant recommendations exist concerning dantrolene availability. Whereas Malignant Hyperthermia Association of the United States guidelines state dantrolene must be available within 10 min of the decision to treat MH wherever volatile anesthetics or succinylcholine are administered, a Society for Ambulatory Anesthesia protocol permits Class B ambulatory facilities to stock succinylcholine for airway rescue without dantrolene. The authors investigated (1) succinylcholine use rates, including for airway rescue, in anesthetizing/sedating locations; (2) whether succinylcholine without volatile anesthetics triggers MH warranting dantrolene; and (3) the relationship between dantrolene administration and MH morbidity/mortality. METHODS: The authors performed focused analyses of the Multicenter Perioperative Outcomes Group (2005 through 2016), North American MH Registry (2013 through 2016), and Anesthesia Closed Claims Project (1970 through 2014) databases, as well as a systematic literature review (1987 through 2017). The authors used difficult mask ventilation (grades III and IV) as a surrogate for airway rescue. MH experts judged dantrolene treatment. For MH morbidity/mortality analyses, the authors included U.S. and Canadian cases that were fulminant or scored 20 or higher on the clinical grading scale and in which volatile anesthetics or succinylcholine were given. RESULTS: Among 6,368,356 queried outcomes cases, 246,904 (3.9%) received succinylcholine without volatile agents. Succinylcholine was used in 46% (n = 710) of grade IV mask ventilation cases (median dose, 100 mg, 1.2 mg/kg). Succinylcholine without volatile anesthetics triggered 24 MH cases, 13 requiring dantrolene. Among 310 anesthetic-triggered MH cases, morbidity was 20 to 37%. Treatment delay increased complications every 10 min, reaching 100% with a 50-min delay. Overall mortality was 1 to 10%; 15 U.S. patients died, including 4 after anesthetics in freestanding facilities. CONCLUSIONS: Providers use succinylcholine commonly, including during difficult mask ventilation. Succinylcholine administered without volatile anesthetics may trigger MH events requiring dantrolene. Delayed dantrolene treatment increases the likelihood of MH complications. The data reported herein support stocking dantrolene wherever succinylcholine or volatile anesthetics may be used.