Malignant Hyperthermia Association Research Articles

Association of malignant hyperthermia and exertional heat illness in young athletes: An analysis of awareness among clinical and athletic first responders.

Malignant hyperthermia (MH), a rare inherited condition seen almost exclusively in the perioperative setting, is triggered by volatile anesthetics or an intravenous paralytic drug, succinylcholine. It can, however, occur without any exposure to anesthetic drugs, being associated with heat illness and rhabdomyolysis, thus presenting a little-known risk to young athletes exercising in hot environments. This study aimed to determine the first responder awareness of MH and its association with heat illness in young athletes within athletic and clinical environments. Awareness within the clinical milieu was assessed by an institutional chart review of 3296 charts. The identified heat illness cases were examined for treatment consistent with the management of a suspected episode of MH. Awareness among first responders in an athletic setting was examined by a survey administered to a total of 1,500 coaches and athletic trainers at the high school level along with emergency medical services providers across the United States. No treatment consistent with the suspicion of MH was noted among clinical first responders, suggesting a lack of awareness. Survey administration also revealed a limited amount of knowledge of MH and its potential role in heat illness. The results point to lack of awareness among pre-hospital and hospital-based first responders of the relationship between MH and heat illness in young athletes. An effort to educate these members of the healthcare community can contribute to an expeditious and life-saving intervention. First responders who may interact with a young athlete have low knowledge of MH and its relationship to heat illness. Similar lack of awareness exists among hospital personnel who care for young individuals with heat illness. Educating the first responders about this condition can speed up the time to intervene and save lives.

Setting the Foundation for an In Situ Simulation Program Through the Development of a Malignant Hyperthermia Simulation in the Operating Room.

This article reviews the VA Manchester Healthcare System's journey to develop a robust simulation program and how an in situ simulation for malignant hyperthermia (MH) laid the foundation. Nurse educators collaborated with a certified registered nurse anesthetist to develop a simulation in the operating room using our MH protocol, which included the support of the Malignant Hyperthermia Association of the United States. The positive reaction from this in situ training led to additional simulation requests for the education department. [J Contin Educ Nurs. 2020;51(11):523-527.].

Risk-Stratifying Patients at an Increased Risk of Malignant Hyperthermia: Improving Safety by Expanding Beyond Classic Tenets

Malignant hyperthermia (MH) is classically described as an autosomal dominant myopathy involving type 1 ryanodine receptor (RYR1), which predisposes affected individuals to potentially life-threatening sequela when exposed to volatile anesthetics or depolarizing skeletal muscle relaxants, such as succinylcholine. In cases where malignant hyperthermia or anesthetic induced rhabdomyolysis (AIR) is triggered, significant morbidity and often mortality can result. In an ambulatory anesthetic setting, family history of malignant hyperthermia and history of anesthetic-related events is typically utilized to screen out susceptible individuals. Furthermore, in cases where suspicion of increased risk for MH susceptibility is present, volatile agents and depolarizing muscle relaxants are avoided, per recommendations of Malignant Hyperthermia Association of US. However, MH phenotype has been found to be inherited with incomplete penetrance and variable expression. Investigations into the molecular genetics of MH have revealed over 400 different variants in the RYR1 gene, with fewer than 40 variants that have been functionally characterized. Exome studies have suggested that the incidence of RYR1 variants in general population is as high as 1 in 2000-3000 persons. These data suggest that potential for triggering malignant hyperthermia is much greater than previously estimated, even if a fulminant reaction is not encountered. Estimates based on genomic analysis call for increased index of suspicion in patient selection for ambulatory anesthesia, compelling for improved risk stratification, as well as improved level of preparedness to treat malignant hyperthermia. This is especially pertinent for providers that administer anesthesia to pediatric populations, as pediatric patients have been documented to exhibit MH/AIR response in the absence of volatile anesthetic exposure.

Dantrolene and Malignant Hyperthermia Carts

(Anesthesiology. 2018;129:225–227) Malignant hyperthermia (MH) is unpredictable, rare, and has a high fatality rate. Fortunately, mortality related to MH has decreased in the past 3 decades, primarily because of increased availability of dantrolene and the education of operating room staff and anesthesia providers. The Malignant Hyperthermia Association of the United States has specified that dantrolene must be available within 10 minutes of all anesthetizing locations.

Cost-Benefit Analysis of Maintaining a Fully Stocked Malignant Hyperthermia Cart Versus an Initial Dantrolene Treatment Dose for Maternity Units

(Anesthesiology. 2018;129:249–259) Understanding the cost-benefit trade-off of maintaining a malignant hyperthermia (MH) cart has important policy implications. The Malignant Hyperthermia Association of the United States recommends that operating room areas have dantrolene immediately available for administration (within 10 min). One approach to dantrolene availability is an MH cart, stocked with dantrolene, other drugs, and supplies, which is cost-effective in areas with a substantial number of general anesthetics. However, labor and delivery units rarely use MH—triggering drugs. If you consider a hospital with 6000 deliveries in a year with a 30% cesarean delivery rate and a 5% general anesthesia rate, general anesthesia will be used <100 times in 1 year. Such a low incidence prompts the question of whether the standard proposed is necessary for maternity units, because, to meet this standard, many maternity units should have their own MH cart. One may question if the resources used to maintain an MH cart may be better utilized on other initiatives that may have a more significant impact on maternal morbidity or mortality (such as a difficult airway cart).

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

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. 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. 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. 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.

Ophthalmic Anesthesia Society 2014 Annual Scientific Meeting Summary

Ophthalmic Anesthesia Society 2014 Annual Scientific Meeting Summary

Implications of National Anesthesia Workload on the Staffing of a Call Center: The Malignant Hyperthermia Consultant Hotline.

Recently, we analyzed data from the American Society of Anesthesiologist's (ASA) Anesthesia Quality Institute (AQI) to report the United States (U.S.) anesthesia workload by time of day and day of the week. The AQI data were reported using the Central Time zone. Times for the N = 613 calls to the Malignant Hyperthermia Association of the United States (MHAUS) Malignant Hyperthermia (MH) Hotline from August 1, 2012, through March 7, 2014, were adjusted similarly. The MH Hotline effectively provides at all times to each anesthesia group an additional board-certified anesthesiologist who has expertise in managing, diagnosing, and/or preventing MH crises. We compared the timing of calls with the MH Hotline consultants relative to times of most anesthesia workload nationally. The interval 6:30 AM to 6:30 PM Central Time on regular workdays accounted for most (P < 0.0001) calls to the MH Hotline (62.5% ± 2.0% [mean ± standard error]). However, the interval accounted for significantly less than the 82.2% of anesthesia minutes and 84.5% of general anesthesia minutes during that interval nationally (both P < 0.0001). Thus, most calls to the MH Hotline occurred when anesthesia groups nationwide were the busiest. Weekends accounted for 15.3% ± 1.5% of MH Hotline calls, significantly greater than the rates of 5.2% of anesthesia minutes and 4.3% of general anesthesia minutes during weekends nationally (both P < 0.0001). Thus, the MH Hotline was used proportionately more often when anesthesia providers have fewer colleagues present and available for consultation (all P < 0.0001). These findings may be expected of other (future) national support centers for anesthesia.

Case Study of Malignant Hyperthermia

<h2>Poster Presentation</h2><h3>Background</h3> The purpose of this case study is to promote awareness and enhance preparedness of the rare and serious condition known as malignant hyperthermia (MH). <h3>Case</h3> A woman presented to the maternity center with ruptured membranes and contractions at 39 weeks gestation and anticipated a routine vaginal delivery. After 12 hours of labor, a cesarean was performed for suspected chorioamnionitis and fetal intolerance of labor. The epidural was utilized for surgical anesthesia. Within 30 minutes of the recovery phase, the woman's vital signs began to change. Rapid nursing assessment revealed tachycardia, tachypnea, changes in blood pressures, decreased pulse oximeter readings, and an increase in temperature to 106.7°F. Additional assistance was summoned by mobilizing the medical and obstetric rapid response teams. The anesthesiologist and obstetrician arrived at the bedside, the MH cart was immediately retrieved, and treatment was rapidly initiated. Within minutes the woman was being cooled with ice and the first dose of dantrolene sodium was being given intravenously (IV). It took a multidisciplinary team approach to provide the woman with rapid treatment and intervention. The team comprised nurses, physicians, anesthesia technicians, respiratory therapists, phlebotomists, ancillary staff, and environmental service personnel. Actions by the team included additional IV access, lab draws, arterial line placement, chest X‐ray, electrocardiogram, placement of a rectal temperature probe, additional medication preparation, and continued assessment of the woman's status. The woman began to show signs of improvement after receiving 20 vials of dantrolene sodium. She was stabilized and transferred to the intensive care unit for continued monitoring and support. <h3>Conclusion</h3> Following a visit from our accrediting body in 2012, it was identified that the obstetric unit was not adequately prepared for a MH crisis event. Recommendations were provided to implement staff education and to develop an MH cart stocked with medications and supplies needed in the event of an emergency. Staff education was initiated and drills were performed to enhance awareness and demonstrate competency. Utilizing resources from the main operating room, pharmacy, and the Malignant Hyperthermia Association of the United States (MHAUS) the MH cart was established and placed on the obstetric unit. Without the recommendations of our accrediting body, staff education, and creation of the MH cart this woman may not have survived this life‐threatening condition.

Cost-effectiveness Analysis of Stocking Dantrolene in Ambulatory Surgery Centers for the Treatment of Malignant Hyperthermia

Background Malignant hyperthermia (MH) is a rare hypermetabolic syndrome of the skeletal muscle and a potentially fatal complication of general anesthesia. Dantrolene is currently the only specific treatment for MH. The Malignant Hyperthermia Association of the United States has issued guidelines recommending that 36 vials (20 mg per vial) of dantrolene remain in stock at every surgery center. However, the cost of stocking dantrolene in ambulatory surgery centers has been a concern. The purpose of this analysis is to assess the cost-effectiveness of stocking dantrolene in ambulatory surgery centers as recommended by the Malignant Hyperthermia Association of the United States. Methods A decision tree model was used to compare treatment with dantrolene to a supportive care-only strategy. Model assumptions include the incidence of MH, MH case fatality with dantrolene treatment and with supportive care-only. Sensitivity analyses were performed to assess the robustness of the estimated cost-effectiveness. Results The estimated annual number of MH events in ambulatory surgery centers in the United States was 47. The incremental effectiveness of dantrolene compared with supportive care was 33 more lives saved per year. The incremental cost-effectiveness ratio was $196,320 (in 2010 dollars) per life saved compared with a supportive care strategy. Sensitivity analysis showed that the results were robust for the plausible range of all variables and assumptions tested. Conclusion The results of this analysis suggest that stocking dantrolene for the treatment of MH in ambulatory surgery centers as recommended by the Malignant Hyperthermia Association of the United States is cost-effective when compared with the estimated values of statistical life used by U.S. regulatory agencies.

Malignant hyperthermia deaths related to inadequate temperature monitoring, 2007-2012: a report from the North American malignant hyperthermia registry of the malignant hyperthermia association of the United States.

AMRA (adverse metabolic or muscular reaction to anesthesia) reports submitted to The North American Malignant Hyperthermia Registry of the Malignant Hyperthermia Association of the United States from 1987 to 2006 revealed a 2.7% cardiac arrest and a 1.4% death rate for 291 malignant hyperthermia (MH) events. We analyzed 6 years of recent data to update MH cardiac arrest and death rates, summarized characteristics associated with cardiac arrest and death, and documented differences between early and recent cohorts of patients in the MH Registry. We also tested whether the available data supported the hypothesis that risk of dying from an episode of MH is increased in patients with inadequate temperature monitoring. We included U.S. or Canadian reports of adverse events after administration of at least 1 anesthetic drug, received between January 1, 2007, and December 31, 2012, with an MH clinical grading scale rank of "very likely MH" or "almost certain MH." We excluded reports that, after review, were judged to be due to pathologic conditions other than MH. We analyzed patient demographics, family and patient anesthetic history, anesthetic management including temperature monitoring, initial dantrolene dose, use of cardiopulmonary resuscitation, MH complications, survival, and reported molecular genetic DNA analysis of RYR1 and CACNA1S. A one-sided Cochran-Armitage test for proportions evaluated associations between mode of monitoring and mortality. We used Miettinen and Nurminen's method for assessing the relative risk of dying according to monitoring method. We used the P value of the slope to evaluate the relationship between duration of anesthetic exposure before dantrolene administration and peak temperature. We calculated the relative risk of death in this cohort compared with our previous cohort by using the Miettinen and Nurminen method adjusted for 4 comparisons. Of 189 AMRA reports, 84 met our inclusion criteria. These included 7 (8.3%) cardiac arrests, no successful resuscitations, and 8 (9.5%) deaths. Of the 8 patients who died, 7 underwent elective surgeries considered low to intermediate risk. The average age of patients who died was 31.4 ± 16.9 years. Five were healthy preoperatively. Three of the 8 patients had unrevealed MH family history. Four of 8 anesthetics were performed in freestanding facilities. In those who died, 3 MH-causative RYR1 mutations and 3 RYR1 variants likely to have been pathogenic were found in the 6 patients in whom RYR1 was examined. Compared to core temperature monitoring, the relative risk of dying with no temperature monitoring was 13.8 (lower limit 2.1). Compared to core temperature monitoring, the relative risk of dying with skin temperature monitoring was 9.7 (1.5). Temperature monitoring mode best distinguished patients who lived from those who died. End-tidal CO2 was the worst physiologic measure to distinguish patients who lived from those who died. Longer anesthetic exposures before dantrolene were associated with higher peak temperatures (P = 0.00056). Compared with the early cohort, the recent cohort had a higher percentage of MH deaths (4/291 vs 8/84; relative risk = 6.9; 95% confidence interval, 1.7-28; P = 0.0043 after adjustment for 4 comparisons). Despite a thorough understanding of the management of MH and the availability of a specific antidote, the risk of dying from an MH episode remains unacceptably high. To increase the chance of successful MH treatment, the American Society of Anesthesiologists and Malignant Hyperthermia Association of the U.S. monitoring standards should be altered to require core temperature monitoring for all general anesthetics lasting 30 minutes or longer.

Malignant hyperthermia and the clinical significance of type-1 ryanodine receptor gene (RYR1) variants: proceedings of the 2013 MHAUS Scientific Conference.

The Malignant Hyperthermia Association of the United States and the Department of Anesthesia at the University of Toronto sponsored a Scientific Conference on November 1-2, 2013 in Toronto, ON, Canada. The multidisciplinary group of experts, including clinicians, geneticists, and physiologists involved in research related to malignant hyperthermia (MH), shared new insights into the pathophysiology of diseases linked to the type-1 ryanodine receptor gene (RYR1) as well as the relationship between MH and "awake MH" conditions, such as exertional rhabdomyolysis and exertional heat illness. In addition, the molecular genetics of MH and clinical issues related to the diagnosis and management of disorders linked to RYR1 were presented. The conference also honoured Dr. David H. MacLennan for his contributions to our understanding of the genetics, pathogenesis, and treatment of MH and other RYR1-related myopathies. This report represents a summary of the proceedings of this conference.

Development and evolution of the MHAUS cognitive aid for malignant hyperthermia

Background Cognitive aids help the stressed practitioner in an emergency setting carry out complex tasks. Ideally, they ensure the completion of key steps and prevent unnecessary ones. Malignant hyperthermia is an emergency event that lends itself to the use of a cognitive aid. Experts associated with the Malignant Hyperthermia Association (MHAUS) first developed a cognitive aid in the form of a “poster” in the mid-1980s.

The sevoflurane washout profile of seven recent anesthesia workstations for malignant hyperthermia-susceptible adults and infants: a bench test study.

Preoperative flushing of an anesthesia workstation is an alternative for preparation of the anesthesia workstation before use in malignant hyperthermia-susceptible patients (MHS). We studied in vitro, using a test lung, the washout profile of sevoflurane in 7 recent workstations during adult and, for the first time, pediatric ventilation patterns. Anesthesia workstations were first primed with 3% sevoflurane for 2 hours and then prepared according to the recommendations of the Malignant Hyperthermia Association of the United States. The flush was done with maximal fresh gas flow (FGF) with a minute ventilation equal to 600 mL × 15, to reach a sevoflurane concentration of <5 parts per million. After flush, 2 clinical situations were simulated in vitro to test the efficiency of preparation: decrease of FGF from max to 10 L/min, or decrease of minute ventilation to 50 mL × 30, to simulate the ventilation of an MHS infant. We report washout delays for MHS patients for previously studied workstations (Primus®, Avance®, and Zeus®) and more interestingly, for machines not previously tested (Felix®, Flow-I®, Perseus®, and Leon®). An increase of sevoflurane concentration was observed when decreasing FGF (except for flow-I® and Leon®) and during simulation of MHS infant ventilation (except for Felix®). This descriptive study strongly suggests that washout profiles may differ for each anesthesia workstation. We advise the use of maximal FGF during preparation and anesthesia. Required flushing times are longer when preparing an anesthesia workstation before providing anesthesia for MHS infants.

Cost-effectiveness Analysis of Stocking Dantrolene in Ambulatory Surgery Centers for the Treatment of Malignant Hyperthermia

Malignant hyperthermia (MH) is a rare hypermetabolic syndrome of the skeletal muscle and a potentially fatal complication of general anesthesia. Dantrolene is currently the only specific treatment for MH. The Malignant Hyperthermia Association of the United States has issued guidelines recommending that 36 vials (20 mg per vial) of dantrolene remain in stock at every surgery center. However, the cost of stocking dantrolene in ambulatory surgery centers has been a concern. The purpose of this analysis is to assess the cost-effectiveness of stocking dantrolene in ambulatory surgery centers as recommended by the Malignant Hyperthermia Association of the United States. A decision tree model was used to compare treatment with dantrolene to a supportive care-only strategy. Model assumptions include the incidence of MH, MH case fatality with dantrolene treatment and with supportive care-only. Sensitivity analyses were performed to assess the robustness of the estimated cost-effectiveness. The estimated annual number of MH events in ambulatory surgery centers in the United States was 47. The incremental effectiveness of dantrolene compared with supportive care was 33 more lives saved per year. The incremental cost-effectiveness ratio was $196,320 (in 2010 dollars) per life saved compared with a supportive care strategy. Sensitivity analysis showed that the results were robust for the plausible range of all variables and assumptions tested. The results of this analysis suggest that stocking dantrolene for the treatment of MH in ambulatory surgery centers as recommended by the Malignant Hyperthermia Association of the United States is cost-effective when compared with the estimated values of statistical life used by U.S. regulatory agencies.

Core myopathies and malignant hyperthermia susceptibility: a review

The core myopathies are a subset of myopathies that present in infancy with hypotonia and muscle weakness. They were formerly considered a rare type of congenital myopathy but are now recognized as being more prevalent. Due to their genetic linkage to mutations in the ryanodine receptor gene (RYR1), core myopathies (in particular, central core disease) carry a high risk of malignant hyperthermia susceptibility. In this review article, we describe the phenotypical, genetic, and histopathological characteristics of core myopathies and further describe the currently understood nature of their risk of malignant hyperthermia. We also review the level of suspicion a clinician should exhibit with a child who has a possible core myopathy or other congenital myopathy presenting for an anesthetic prior to a definitive genetic analysis. For this review article, we performed literature searches using the key words anesthesiology, core myopathies, pediatric neurology, malignant hyperthermia, genetics, ryanodine receptor, and molecular biology. We also relied on literature accumulated by the two authors, who served as hotline consultants for the Malignant Hyperthermia Hotline of the Malignant Hyperthermia Association of the United States (MHAUS) for the past 12years.

Creation of a Guide for the Transfer of Care of the Malignant Hyperthermia Patient from Ambulatory Surgery Centers to Receiving Hospital Facilities

Volatile anesthetics and/or succinylcholine may trigger a potentially lethal malignant hyperthermia (MH) event requiring critical care crisis management. If the MH triggering anesthetic is given in an ambulatory surgical center (ASC), then the patient will need to be transferred to a receiving hospital. Before May 2010, there was no clinical guide regarding the development of a specific transfer plan for MH patients in an ASC. MECHANISM BY WHICH THE STATEMENT WAS GENERATED: A consensual process lasting 18 months among 13 representatives of the Malignant Hyperthermia Association of the United States, the Ambulatory Surgery Foundation, the Society for Ambulatory Anesthesia, the Society for Academic Emergency Medicine, and the National Association of Emergency Medical Technicians led to the creation of this guide. EVIDENCE FOR THE STATEMENT: Most of the guide is based on the clinical experience and scientific expertise of the 13 representatives. The list of representatives appears in Appendix 1. The recommendation that IV dantrolene should be initiated pending transfer is also supported by clinical research demonstrating that the likelihood of significant MH complications doubles for every 30-minute delay in dantrolene administration (Anesth Analg 2010;110:498-507). This guide includes a list of potential clinical problems and therapeutic interventions to assist each ASC in the development of its own unique MH transfer plan. Points to consider include receiving health care facility capabilities, indicators of patient stability and necessary report data, transport team considerations and capabilities, implementation of transfer decisions, and coordination of communication among the ASC, the receiving hospital, and the transport team. See Appendix 2 for the guide.

New Device Simplifies Workstation Preparation for Malignant Hyperthermia-susceptible Patients

Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania. feldmanj@email.chop.eduI read with interest the review article by Kim and Nemergut entitled “Preparation of Modern Anesthesia Workstations for Malignant Hyperthermia-susceptible Patients.”1The authors are to be congratulated on this comprehensive review describing the challenges to preparing a modern anesthesia machine for use with malignant hyperthermia (MH)-susceptible patients. Indeed, their review of the literature suggests that a straightforward method of preparing the machine that can be applied to all workstations has not been determined. Further, the current information on the Malignant Hyperthermia Association of the United States website does not provide practical guidance to prepare all types of anesthesia machines.*For the anesthesia practitioner, reading the available literature does not provide a clear approach to be used in practice.A new device promises to provide an easy method for preparing any anesthesia workstation for MH-susceptible patients in just a few minutes. The Vapor-Clean device (Dynasthetics Inc., Salt Lake City, UT) consists of charcoal filters designed to be placed between the anesthesia machine and the inspiratory and expiratory limbs of the breathing circuit. The rationale for this approach is sound and based on the well-known property of activated charcoal to absorb potent anesthetic vapors that can trigger MH. If a clean breathing circuit is used and the Vapor-Clean device is in place, anesthetic vapor contaminating the internal components of the anesthesia workstation is prevented from reaching the patient. Previous studies have documented the utility of activated charcoal for preparing the anesthesia machine but to date, a convenient device designed and approved by the Food and Drug Administration for this purpose has not existed.2,3A study of the Vapor-Clean has demonstrated that the concentration of anesthetic agents (isoflurane, sevoflurane, and desflurane) in the breathing circuit can immediately be reduced to less than 5 ppm immediately upon placing the device in the circuit.4The concentration of anesthetic vapor that protects the susceptible patient from an MH reaction has never been determined with certainty, but concentrations less than 5 ppm are generally considered acceptable, and the results documented in the abstract exceed that goal.With the introduction of the Vapor-Clean device, a simple approach to rapidly preparing any anesthesia workstation for the MH susceptible patient now exists. Additional studies will likely document the universal utility of this device for all workstations and anesthetic vapors, but given the simplicity of the device and the well-known properties of activated charcoal, I submit that there is sufficient evidence to adopt this device into clinical practice. The manufacturer provides a clear protocol for using the device that can be easily implemented by any practitioner. With the advent of the Vapor-Clean device, it would seem that the challenge of protecting MH susceptible patients from trace amounts of anesthetic vapor has been solved.Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania. feldmanj@email.chop.edu

Future Directions in Malignant Hyperthermia Research and Patient Care

Malignant hyperthermia (MH) is a complex pharmacogenetic disorder of muscle metabolism. To more closely examine the complexities of MH and other related muscle disorders, the Malignant Hyperthermia Association of the United States (MHAUS) recently sponsored a scientific conference at which an interdisciplinary group of experts gathered to share new information and ideas. In this Special Article, we highlight key concepts and theories presented at the conference along with exciting new trends and challenges in MH research and patient care.

Preparation of Modern Anesthesia Workstations for Malignant Hyperthermia–susceptible Patients

Patients with malignant hyperthermia experience an exaggerated metabolic response when exposed to volatile anesthetic gases and succinylcholine. The minimum concentration of anesthetic gas needed to trigger a malignant hyperthermia crisis in humans is unknown and may remain so because of the inherent risks associated with studying the complex nature of this rare and lethal genetic disorder. The Malignant Hyperthermia Association of the United States provides specific instructions on purging anesthesia machines of volatile agents to reduce the risk of exposure. However, these recommendations were developed from studies of older generation machines. Modern anesthesia workstations are more complex and contain more gas absorbing materials. A review of the literature found the current guidelines inadequate to prepare newer generation workstations, which require more time for purging anesthetic gases, autoclaving or replacement of parts, and modifications to the gas delivery system. Protocols must be developed to prepare newer generation anesthesia machines.