Consensus Statement of the Malignant Hyperthermia Association of the United States on Unresolved Clinical Questions Concerning the Management of Patients With Malignant Hyperthermia

Case Report of the Use of an Intravascular Cooling Device in the Management of Malignant Hyperthermia

Malignant hyperthermia (MH) is a rare, life-threatening condition caused by alterations in skeletal muscle calcium channels inherited through an autosomal dominant pattern. The use of specific agents in anesthesia such as inhaled anesthetics and succinylcholine can precipitate a hyperthermic crisis. Patients experience a rapid increase in muscle rigidity, secondary to skeletal muscle calcium dysregulation, leading to acute rhabdomyolysis and possible hyperthermia. Providers must have a high index of suspicion of this disease process because early diagnosis is critical to mortality reduction. Management centers around removal of the offending agent, dantrolene, and supportive care including cooling if hyperthermic. Intravascular cooling devices have been used in thermodynamic regulation after cardiac arrest and have shown to be more effective than dermal cooling techniques; however, they have not been well described in other disease processes. The following case report is the first to describe a patient suffering from MH to undergo invasive intravenous cooling in order to counteract the effects of this life-threatening disease.

Epidemiological and clinical features of malignant hyperthermia: A scoping review

Malignant hyperthermia (MH) is a potentially fatal inherited pharmacogenetic disorder related to pathogenic variants in the RYR1, CACNA1S, or STAC3 genes. Early recognition of the occurrence of MH and prompt medical treatment are indispensable to ensure a positive outcome. The purpose of this study was to provide valuable information for the early identification of MH by summarizing epidemiological and clinical features of MH. This scoping review followed the methodological framework recommended by Arksey and O'Malley. PubMed, Embase, and Web of science databases were searched for studies that evaluated the epidemical and clinical characteristics of MH. A total of 37 studies were included in this review, of which 26 were related to epidemiology and 24 were associated with clinical characteristics. The morbidity of MH varied from 0.18 per 100 000 to 3.9 per 100 000. The mortality was within the range of 0%-18.2%. Identified risk factors included sex, age, disorders associated with MH, and others. The most frequent initial clinical signs included hyperthermia, sinus tachycardia, and hypercarbia. The occurrence of certain signs, such as hypercapnia, delayed first temperature measurement, and peak temperature were associated with poor outcomes. The epidemiological and clinical features of MH varied considerably and some risk factors and typical clinical signs were identified. The main limitation of this review is that the treatment and management strategies were not assessed sufficiently due to limited information.

Evaluation of Malignant Hyperthermia Features in Patients with Pathogenic or Likely Pathogenic RYR1 Variants Disclosed through a Population Genomic Screening Program

BACKGROUND

Malignant hyperthermia (MH) susceptibility is a heritable musculoskeletal disorder that can present as a potentially fatal hypermetabolic response to triggering anesthesia agents. Genomic screening for variants in MH-associated genes RYR1 and CACNA1S provides an opportunity to prevent morbidity and mortality. There are limited outcomes data from disclosing variants in RYR1, the most common MH susceptibility gene, in unselected populations. The authors sought to identify the rate of MH features or fulminant episodes after triggering agent exposure in an unselected population undergoing genomic screening including actionable RYR1 variants.

METHODS

The MyCode Community Health Initiative by Geisinger (USA) is an electronic health record-linked biobank that discloses pathogenic and likely pathogenic variants in clinically actionable genes to patient-participants. Available electronic anesthesia and ambulatory records for participants with actionable RYR1 results returned through December 2020 were evaluated for pertinent findings via double-coded chart reviews and reconciliation. Descriptive statistics for observed phenotypes were calculated.

RESULTS

One hundred fifty-two participants had an actionable RYR1 variant disclosed during the study period. None had previous documented genetic testing for MH susceptibility; one had previous contracture testing diagnosing MH susceptibility. Sixty-eight participants (44.7%) had anesthesia records documenting triggering agent exposure during at least one procedure. None received dantrolene treatment or had documented muscle rigidity, myoglobinuria, hyperkalemia, elevated creatine kinase, severe myalgia, or tea-colored urine. Of 120 possibly MH-related findings (postoperative intensive care unit admissions, hyperthermia, arterial blood gas evaluation, hypercapnia, or tachycardia), 112 (93.3%) were deemed unlikely to be MH events; 8 (6.7%) had insufficient records to determine etiology.

CONCLUSIONS

Results demonstrate a low frequency of classic intraanesthetic hypermetabolic phenotypes in an unselected population with actionable RYR1 variants. Further research on the actionability of screening for MH susceptibility in unselected populations, including economic impact, predictors of MH episodes, and expanded clinical phenotypes, is necessary.

EDITOR’S PERSPECTIVE

A Single-Center Retrospective Review of Patients with Suspected Malignant Hyperthermia Susceptibility

Purpose The diagnosis of malignant hyperthermia susceptibility (MHS) has significant implications for the perioperative period that may persist for generations. Anesthetic medication options are reduced, anesthetic workstations require preparation to reduce exposure to inhaled volatile anesthetics, and patients may be excluded from surgery at ambulatory centers. In this study, we sought to better characterize the etiology of MHS diagnoses in our health system and the downstream effects of this diagnosis on anesthetic care. Methods We retrospectively reviewed the electronic medical records of 55 patients with a documented concern for MHS who received care at University of Florida (UF) Health between 2014 and 2020. We characterized the etiology of the patient's MHS diagnosis, whether this diagnosis was supported by formal genetic or muscle contracture testing, and the details of the recorded anesthetics that were delivered to these patients. Results The 55 patients with suspected MHS were evenly split between those with a family history of malignant hyperthermia (MH) (28/55) and those with a concern for MHS in their personal medical history (27/55). Of the 28 patients with a family history of MH, 16 reported that the affected family member was a first-degree relative, and two of these 16 reported that the affected family member had undergone confirmatory muscle contracture testing. Of the 27 patients with a personal history suspicious for MHS, two had undergone confirmatory genetic testing, and two patients had anesthetic records available for review where intraoperative MH was suspected and treated with dantrolene. An additional four patients were told of a concern about MHS due to another underlying diagnosis. No patients with a personal history suspicious of MHS had undergone confirmatory muscle contracture testing. These 55 patients underwent 87 anesthetics, and exclusively non-triggering anesthetic techniques were utilized in nearly all cases. In pediatric patients, some perioperative challenges were identified, related to the avoidance of mask inhalational induction. Only six of these 87 anesthetics occurred at our ambulatory surgery centers, a proportion (6.9%) lower than that of the general surgical population at UF Health (20.0%). Conclusions Among patients suspected to be MH susceptible in our health system over a six-year period, a minority (8/55) were supported by clear records of a prior MH event, confirmatory genetic or muscle contracture testing, or an underlying diagnosis closely linked to MH. The vast majority had limited documentation supporting their MH risk but continued to be treated with non-triggering anesthetics and were less likely to have surgery at an ambulatory surgery center than our overall surgical population. Among pediatric patients, some anesthetic challenges related to delivering non-triggering anesthetics were identified. Improving the documentation of index cases of MH and increasing referrals to clinical geneticists and genetic testing may be a viable route to decreasing the proportion of suspected MHS patients with a poorly characterized risk profile.

The Knowledge Profile, Competence and Pending Problems of Chinese Anesthesiologists in Dealing with Malignant Hyperthermia: A Cross-Sectional Survey

Purpose

The National Remote Emergency System for Malignant Hyperthermia (MH-NRES) is an applet in China, designed to help anesthesiologists manage MH crisis. However, there is limited information about encountered difficulties in dealing with MH among Chinese anesthesiologists. The purpose of the study was to explore the current competency and encountered difficulties in the management of MH, as a key first step for assessing the potential user needs to develop the MH-NRES.

Methods

The hospitals of different levels in different provinces across China were invited to participate in an online survey from November to December 2021. Anesthesiologists completed the online questionnaire containing four sections including demographic information, knowledge, competency, and continuing education about MH.

Results

A total of 1357 valid questionnaires were completed from anesthesiologists, most respondents (66.7%, n = 905) correctly answered the MH trigger drugs included volatile anesthetics and succinylcholine. However, most respondents (77.0%, n = 1045) did not know that the recommended initial dose of domestic dantrolene. Up to 83.9% (n = 1138) stated that their hospitals did not store dantrolene for MH emergency. More than half of respondents thought that it would take more than one hour to obtain dantrolene in emergency. Less work experiences, lower levels of hospital and educations and professional titles were associated with lower competency scores in managing MH. Only 31.0% (n = 936) reported that their hospital had ever conducted MH continuing education curricula. Scenario simulation is the training method that most interests the participants (79.0%, n = 1072) but a whopping 46.9% (n = 637) never received simulation.

Conclusion

The study indicated that difficulty in obtaining dantrolene, lack of competency in management of MH, difficulty in obtaining professional help, and poor teamwork were the main problems of most anesthesiologists in face of MH.

Clinical Features of Suspected Malignant Hyperthermia in China from 2015 to 2020: A Retrospective Study from China Malignant Hyperthermia Emergency Assistance Group

Purpose

Malignant hyperthermia (MH) is a rare but fatal pharmacogenetic disorder, triggered by inhalational anesthetics or succinylcholine. Since the first nonprofit academic organization China Malignant Hyperthermia Emergency Assistance WeChat-based Group (CMHEA Group) was established in 2015, they have actively participated in the diagnosis and treatment of MH patients. Based on the CMHEA Group, the aim of the study was to retrospectively analyze the characteristics of suspected MH in China from 2015 to 2020.

Methods

We conducted a retrospective analysis of the suspected MH patients from 2015 to 2020, for analyzing the current clinical diagnosis, treatment and prognosis of MH in China.

Results

A total of 58 suspected MH cases occurred from 2015 to 2020, of these, 36 cases were collected with detailed data. The MH clinical grading score of 36 patients ranged from 33 to 73, with a median of 55. Abnormal hyperthermia and hypercarbia were the most common early signs of MH. Four patients were confirmed carrying six different potential MH-causative mutations. Of the total 58 cases, 14 patients (24.1%) received dantrolene and the whole mortality rate was 53.4%. Compared to the patients not receiving dantrolene treatment, the survival rate of patients receiving dantrolene treatment was significantly higher than that of patients not receiving dantrolene (78.6% vs 36.4%, p = 0.007).

Conclusion

The current main diagnostic methods of suspected MH in China are still clinical diagnosis. Hence, it is critical to keep dantrolene for immediate accessibility with the introduction of domestic dantrolene to China. The WeChat group model has played an important but limited role in quick diagnosis and treatment of MH.

Management of patients susceptible to malignant hyperthermia: A surgeon's perspective

OBJECTIVES

Malignant hyperthermia (MH) susceptibility caries broad implications for the care of pediatric surgical patients. While precautions must often be taken for only a vague family history, two options exist to assess MH-susceptibility. We evaluate the use of MH precautions and susceptibility testing at a freestanding children's hospital.

METHODS

This single institution retrospective cohort study identified patients of any age who received general anesthetics utilizing MH precautions over a five-year period. The electronic medical record was further queried for patients diagnosed with MH. The indication for MH precautions and uses of susceptibility testing are assessed. Secondary outcomes included a diagnosis of bona fide MH.

RESULTS

A total of 125 patients received 174 anesthetics with MH precautions at a mean age of 114 months (0-363 months). Otolaryngology was the procedural service most frequently involved in the care of the cohort (n = 45; 26%). A reported personal or family history of MH (n = 102; 59%) was the most common indication for precautions, followed by muscular dystrophy (n = 29; 17%). No MH events occurred in the cohort and further review of ICD-9 and -10 diagnosis codes found no MH diagnoses. No study subjects received muscle biopsy and contracture testing and only 5 (4%) underwent genetic testing for genomic variants known to cause MH susceptibility. A case example is given to highlight the implications of a reported MH history.

CONCLUSION

Otolaryngologists should maintain a familiarity with the precautions necessary to manage patients at risk for MH and MH-like reactions. Without an accessible test to rule out susceptibility, surgeons must rely on a careful history to appropriately utilize precautions. An inappropriate label of "MH-susceptible" may result in decreased access to care and treatment delays.

Consensus guidelines on perioperative management of malignant hyperthermia suspected or susceptible patients from the European Malignant Hyperthermia Group

Malignant hyperthermia is a potentially fatal condition, in which genetically predisposed individuals develop a hypermetabolic reaction to potent inhalation anaesthetics or succinylcholine. Because of the rarity of malignant hyperthermia and ethical limitations, there is no evidence from interventional trials to inform the optimal perioperative management of patients known or suspected with malignant hyperthermia who present for surgery. Furthermore, as the concentrations of residual volatile anaesthetics that might trigger a malignant hyperthermia crisis are unknown and manufacturers' instructions differ considerably, there are uncertainties about how individual anaesthetic machines or workstations need to be prepared to avoid inadvertent exposure of susceptible patients to trigger anaesthetic drugs. The present guidelines are intended to bundle the available knowledge about perioperative management of malignant hyperthermia-susceptible patients and the preparation of anaesthesia workstations. The latter aspect includes guidance on the use of activated charcoal filters. The guidelines were developed by members of the European Malignant Hyperthermia Group, and they are based on evaluation of the available literature and a formal consensus process. The most crucial recommendation is that malignant hyperthermia-susceptible patients should receive anaesthesia that is free of triggering agents. Providing that this can be achieved, other key recommendations include avoidance of prophylactic administration of dantrolene; that preoperative management, intraoperative monitoring, and care in the PACU are unaltered by malignant hyperthermia susceptibility; and that malignant hyperthermia patients may be anaesthetised in an outpatient setting.

Anaesthesia and neuromuscular disorders: what a neurologist needs to know

Neurologists are often asked for specific advice regarding patients with neuromuscular disease who require general anaesthesia. However, guidelines on specific neuromuscular disorders do not usually include specific guidelines or pragmatic advice regarding (regional and/or general) anaesthesia or procedural sedation. Furthermore, the medical literature on this subject is mostly limited to publications in anaesthesiology journals. We therefore summarise general recommendations and specific advice for anaesthesia in different neuromuscular disorders to provide a comprehensive and accessible overview of the knowledge on this topic essential for clinical neurologists. A preoperative multidisciplinary approach involving anaesthesiologists, cardiologists, chest physicians, surgeons and neurologists is crucial. Depolarising muscle relaxants (succinylcholine) should be avoided at all times. The dose of non-depolarising muscle relaxants must be reduced and their effect monitored. Patients with specific mutations in RYR1 (ryanodine receptor 1) and less frequently in CACNA1S (calcium channel, voltage-dependent, L type, alpha 1S subunit) and STAC3 (SH3 and cysteine rich domain 3) are at risk of developing a life-threatening malignant hyperthermia reaction.

Isoflurane Induced Malignant Hyperthermia in a Patient with Glucose 6-Phosphate Dehydrogenase Deficiency and Growth Hormone Abuse

Malignant hyperthermia is a pharmacogenetic disorder in the regulation of calcium in skeletal muscles which is related to an uninhibited muscle hypermetabolic reaction to potent inhalation agents, the depolarizing muscle relaxant succinylcholine, and to stressors such as vigorous exercise and heat. MH is diagnosed by the clinical presentation of the disease and laboratory testing. There are a few previous studies working on if there is an association between the occurrence of malignant hyperthermia and the existence of glucose 6-phosphate dehydrogenase (G6PD) deficiency, and there was no report on growth hormone doping in the literature. So, our main goal was to show this rare case of malignant hyperthermia seen in a G6PD patient with growth hormone abuse who underwent surgery and to find if there is an association between G6PD deficiency, growth hormone abuse, and malignant hyperthermia. Our patient was a 17-year-old boy with right lower quadrant abdominal pain and tenderness who underwent appendectomy. At the end of the operation, the patient developed with an increased heart rate (sinus tachycardia), increased body temperature and end-tidal carbon dioxide (ETCO2) level, masseter muscle rigidity, and then, generalized body rigidity, so the malignant hyperthermia susceptibility was considered. The patient was managed by cooling down the patient and the administration of dantrolene. We could hypothesize that malignant hyperthermia might be associated with G6PD deficiency as a triggering factor, but has no association with recombinant human growth hormone (rhGH) abuse. Another main lesson which this study tells us is to make a careful and proper history taking before going on an operation for preoperative evaluation and identification of patients with any form of suspicious drug abuse in order not to receive volatile inhalational agents and, also, performing some preventive measures including avoidance of heat extremes and restricting athletic activity in a patient with a history of malignant hyperthermia, and if the malignant hyperthermia susceptibility is suspected, urgent management should be carried out. As the association between G6PD deficiency, human growth hormone abuse, and malignant hyperthermia has remained unclear up-to-date, further potent studies are seriously needed in the future.

Cost-benefit relationship of keeping dantrolene stocks from the point of view of healthcare institutions

Introduction: Malignant hyperthermia (MH) is an acute syndrome triggered by certain anesthetic medications. Dantrolene is the only specific treatment for MH crises. Without treatment, lethality may be as high as 80%. In Colombia, it is not mandatory to keep dantrolene supplies in stock. Objective: To establish the cost-benefit ratio, from the perspective of healthcare institutions, of keeping dantrolene supplies in stock in the operating theater. Methods: Using a decision tree, a Monte Carlo simulation was run with 10,000 scenarios to determine the median annual cost of keeping full or partial stocks (36 or 12 vials x 20 mg, respectively) of dantrolene. For the option of not keeping supplies in stock, the cost threshold was calculated where the expected value of both alternatives of the decision tree is equalized. Indifference curves were constructed for complete and partial supplies. Results: The median annual cost was estimated at 6.6 million Colombian pesos (COP) for full dantrolene supplies, and at COP 2.2 million for partial supplies. The median economic consequence threshold for 1 death due to the unavailability of dantrolene was estimated at COP 18.5 million for full supplies, and at COP 57.0 million for partial supplies. Conclusion: If, as a result of the unavailability of dantrolene, the economic consequences of a death due to MH exceed the threshold of COP 57.0 or COP 18.5 million, the purchase of full or partial stocks, respectively, is justified.

Skeletal muscle CaV1.1 channelopathies

Ca_V1.1 is specifically expressed in skeletal muscle where it functions as voltage sensor of skeletal muscle excitation-contraction (EC) coupling independently of its functions as L-type calcium channel. Consequently, all known Ca_V1.1-related diseases are muscle diseases and the molecular and cellular disease mechanisms relate to the dual functions of Ca_V1.1 in this tissue. To date, four types of muscle diseases are known that can be linked to mutations in the CACNA1S gene or to splicing defects. These are hypo- and normokalemic periodic paralysis, malignant hyperthermia susceptibility, Ca_V1.1-related myopathies, and myotonic dystrophy type 1. In addition, the Ca_V1.1 function in EC coupling is perturbed in Native American myopathy, arising from mutations in the Ca_V1.1-associated protein STAC3. Here, we first address general considerations concerning the possible roles of Ca_V1.1 in disease and then discuss the state of the art regarding the pathophysiology of the Ca_V1.1-related skeletal muscle diseases with an emphasis on molecular disease mechanisms.

Malignant Hyperthermia Update

Malignant hyperthermia (MH) is a rare but potentially lethal skeletal muscle disorder affecting calcium release channels. It is inherited in a mendelian autosomal dominant pattern with variable penetration. The initial clinical manifestations are of a hypermetabolic state with increased CO2 production, respiratory acidosis, increased temperature, and increased oxygen demands. If diagnosed late, MH progresses to multi-organ system failure and death. Current data suggest that mortality has improved to less than 5%. The gold standard for ruling out MH is the contracture test. Genetic testing is also available. MH-susceptible individuals should be clearly identified for safe administration of future anesthetics.

Nursing Interventions of Intraoperative Malignant Hyperthermia in Patients With Scoliosis: A Report of 3 Cases

INTRODUCTION

The report summarizes the intraoperative rescue and nursing intervention of malignant hyperthermia (MH) in the correction surgery for 3 patients with spinal deformity. Although rare, MH may occur in up to 1 of 5000 cases.

INTERVENTION

The key points of nursing care include preoperative MH risk assessment, MH early warning, cessation of anesthetic, use of a validated scoring system, and initiation of cooling measures.

CONCLUSION

Prompt nursing recognition and team-fcoused interventions provided successful rescue of 3 patients with MH.

Malignant Hyperthermia-Susceptible Adult Patient and Ambulatory Surgery Center: Society for Ambulatory Anesthesia and Ambulatory Surgical Care Committee of the American Society of Anesthesiologists Position Statement

This document represents a joint effort of the Society for Ambulatory Anesthesia (SAMBA) and the Ambulatory Surgical Care Committee of the American Society of Anesthesiologists (ASA) concerning the safe anesthetic care of adult malignant hyperthermia (MH)-susceptible patients in a free-standing ambulatory surgery center (ASC). Adult MH-susceptible patients can safely undergo a procedure in a free-standing ASC assuming that proper precautions for preventing, identifying, and managing MH are taken. The administration of preoperative prophylaxis with dantrolene is not indicated in MH-susceptible patients scheduled for elective surgery. There is no evidence to recommend an extended stay in the ASC, and the patient may be discharged when the usual discharge criteria for outpatient surgery are met. Survival from an MH crisis in an ASC setting requires early recognition, prompt treatment, and timely transfer to a center with critical care capabilities.