Malignant Hyperthermia Susceptible Patient Research Articles

Postoperative Hyperthermia and Hemodynamic Instability in a Suspected Malignant Hyperthermia–Susceptible Patient: A Case Report

Malignant hyperthermia (MH) is a rare but potentially fatal complication of exposure to certain anesthetic drugs. However, stress-induced MH, initially observed in pigs undergoing intense physical or emotional strain, has been reported in the absence of anesthetic exposure. In this case report, we describe a case of postoperative hyperthermia and cardiac dysfunction suspicious for stress-induced MH occurring after an endobronchial biopsy in a patient with recurrent undiagnosed fevers. We also examine our diagnosis of stress-induced MH and possible preventive measures to avoid this complication.

Intraoperative Awareness with Recall Due to Inadvertent Use of Activated Charcoal Filters

A 57-year-old woman underwent abdominal surgery with a subarachnoid block supplemented by “light” general endotracheal anesthesia consisting of a propofol infusion and a sub-MAC concentration of sevoflurane. The previous case in the same operating room had involved a malignant hyperthermia-susceptible patient, and charcoal filters had been placed in the breathing circuit as a precautionary measure. Because it had not been used on the evening beforehand, the circuit with filters was left in situ with a strip of tape indicating that it was clean. The woman’s anesthesiologist assumed that these filters were heat and moisture exchanger filters in an unused circuit and therefore did not remove them. Subsequently, the patient had awareness with intraoperative recall. This case highlights the potential for inadvertent use of activated charcoal filters with potentially catastrophic results. Such unintended utilization of these products likely can be minimized by improved labeling techniques.

Malignant Hyperthermia Susceptibility and Related Diseases.

This review identifies disease states associated with malignant hyperthermia susceptibility based on genotypic and phenotypic findings, and a framework is established for clinicians to identify a potentially malignant hyperthermia–susceptible patient.

Malignant hyperthermia, a Scandinavian update.

Malignant Hyperthermia (MH) is a rare pharmacogenetic disorder, triggered by halogenated anesthetics and/or succinylcholine. In susceptible individuals, these drugs can activate an explosive life threatening clinical reaction. Leading symptoms are hypercarbia, muscle rigidity, and metabolic acidosis. MH is inherited in an autosomal-dominant manner and linked to mutations in the large ryanodine 1 gene (RYR1) gene in the majority of cases. Very few MH patients have been found to carry mutations in the CACNA1S gene. For this review a large litterature search was carried out and the Swedish MH database consisting of 436 probands who have undergone invitro muscle contraction test (IVCT) during 1984-2014 was analyzed. Twelve different MH causative mutations have been found in Swedish patients so far. These mutations lead to a disturbed calcium balance in striated muscle tissue. A muscle biopsy for the IVCT or finding of an approved causative mutation are required for the diagnosis. A Malignant Hyperthermia susceptible (MHS) patient should be anesthetized with trigger-free anesthesia. There are a few reports of MH-like reactions in patients unrelated to anesthesia. The outcome is dependent on early recognizing of the reaction and fast disconnection of the trigger agents and administration of dantrolene.

Preparation of Datex-Ohmeda Aestiva® and Aisys® anaesthetic machines for use in malignant hyperthermia susceptible patients

Preparation of anaesthesia machines for use by malignant hyperthermia susceptible patients requires purging the machines of halogenated anaesthetic agents. The endpoint of this process is to reach a gas concentration of 5 ppm or less, which has been arbitrarily chosen as the safe limit of exposure to avoid triggering a malignant hyperthermia event. We examined the washout characteristics of sevoflurane and desflurane from the Datex-Ohmeda Aestiva Anaesthesia System and Aisys Anaesthesia Carestation anaesthetic machines. The machines were contaminated for two hours using either sevoflurane 2 vol% or desflurane 6 vol%. At the end of the priming period, the patient breathing circuit and reservoir bag, carbon dioxide absorbent, sampling line and test lung were replaced with uncontaminated components. During the test period, machines were purged using oxygen flows of 10 l/minute. The average time to reach 5 ppm with the Aestiva machines was 51 minutes with sevoflurane and 71 minutes with desflurane. The average time to reach 5 ppm for the Aisys machines was 55 minutes with sevoflurane and 69 minutes with desflurane. All configurations of machines and anaesthetic gases demonstrated a rebound effect in agent concentration above 5 ppm when the fresh gas flow was subsequently reduced from 10 to 2 l/minute. Aestiva and Aisys anaesthetic machines require a prolonged period to adequately purge them of halogenated volatile anaesthetic agent. The rebound effect poses a serious concern, suggesting that after the purging period, fresh gas flows of 10 l/minute should be maintained for the duration of anaesthesia care of the malignant hyperthermia susceptible patient.

Preparation of the Drager Fabius CE and Drager Zeus anaesthetic machines for patients susceptible to malignant hyperthermia

Malignant hyperthermia may follow exposure to trace quantities of inhalational anaesthetics. In susceptible patients, the complete avoidance of these triggers is advised when possible; however, failing this, it is essential to washout or purge the anaesthesia machine of residual inhalational anaesthetics. This study examined the washout profile of sevoflurane from the Drager Fabius CE and the Drager Zeus machines. The washout profile of sevoflurane was measured from the Fabius CE and Zeus anaesthesia machines following a standard period of exposure. The disposable tubing, CO2 absorber and other components of each machine were then replaced to examine their impact on the retention of sevoflurane. The effect of autoclaving the ventilator diaphragm and non-disposable ventilator tube or substituting for a new diaphragm and ventilation tube were examined in later parts of this study. University teaching hospital. Time taken to reach 5 parts per million of sevoflurane when machines underwent standard washout with fresh gas flush. The concentration of sevoflurane reached 5 parts per million in the Fabius CE machines after an mean (SD) of 140 min (46) at a fresh gas flow (FGF) of 10 l min(-1). The time taken for sevoflurane to reach 5 parts per million was significantly reduced when the ventilator diaphragm and non-disposable tube were replaced with either new or autoclaved components [14 or 22 min, respectively (P = 0.017, P = 0.031)]. The concentration of sevoflurane reached 5 parts per million in the Zeus machines after an mean (SD) of 85 min (6) at a fresh gas flow of 10 l min(-1). When the fresh gas flow was increased to 18 l min(-1) (the maximum allowable), the time to reach 5 parts per million was reduced to 16 min. When preparing the Fabius CE for the malignant hyperthermia susceptible patient, remove the vaporiser, replace the disposable tubing, the reservoir bag and the CO2 absorber. Replace the ventilator diaphragm and non-disposable ventilator tube with new or autoclaved components and flush the machine at 10 l min(-1) for at least 36 min. When preparing the Zeus, remove the vaporiser, replace the disposable tubing, the reservoir bag and CO2 absorber and flush at a fresh gas flow of 10 l min(-1) for at least 90 min. In both the Fabius and Zeus, continue at a fresh gas flow of 10 l min(-1) for the duration of the operation.

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

Activated Charcoal Effectively Removes Inhaled Anesthetics from Modern Anesthesia Machines

If a malignant hyperthermia-susceptible patient is to receive an anesthetic, an anesthesia machine that has been used previously to deliver volatile anesthetics should be flushed with a high fresh gas flow. Conflicting results from previous studies recommend flush times that vary from 10 to 104 minutes. In a previously proposed alternative decontamination technique, other investigators placed an activated charcoal filter in the inspired limb of the breathing circuit. We placed activated charcoal filters on both the inspired and expired limbs of several contaminated anesthesia machines and measured the time needed to flush the machine so that the delivered concentrations of isoflurane, sevoflurane, and desflurane would be <5 parts per million (ppm). We next simulated the case for which malignant hyperthermia is diagnosed 90 minutes after induction of anesthesia and measured how well activated charcoal filters limit further exposure. Activated charcoal filters decrease the concentration of volatile anesthetic delivered by a contaminated machine to an acceptable level in <2 minutes. The concentrations remained well below 5 ppm for at least 60 minutes. When malignant hyperthermia is diagnosed after induction of anesthesia, we found that with charcoal filters in place, the current anesthesia machine may be used for at least 67 minutes before the inspired concentration exceeds 5 ppm. Activated charcoal filters provide an alternative approach to the 10 to 104 minutes of flushing that are normally required to prepare a machine that has been used previously to deliver a volatile anesthetic.

Preparation of the Dräger Fabius Anesthesia Machine for the Malignant–Hyperthermia Susceptible Patient

Anesthesia machines must be flushed of halogenated anesthetics before use in patients susceptible to malignant hyperthermia. We studied the kinetics of sevoflurane clearance in the Dräger Fabius anesthesia machine and compared them to a conventional anesthesia machine (Dräger Narkomed GS). Before each trial, the anesthesia machine was contaminated for 2 h with 3% sevoflurane and then prepared by changing the CO(2) absorbent, removing the vaporizer(s), and mounting a clean circuit and artificial lung. The basic flush procedure consisted of oxygen 10 L/min with the ventilator set to a tidal volume of 600 mL at a rate of 10/min. Residual sevoflurane in the inspiratory limb of the circuit was measured using an ambient air analyzer capable of measuring sevoflurane to < 1 ppm. Results were analyzed using log-linear regression of residual concentration as a function of time. This model was used to estimate the time required to achieve a desired residual anesthetic concentration. Times to achieve 10 and 5 ppm in the Dräger Narkomed GS were 11 and 18 min, respectively. For the Dräger Fabius anesthesia machine, times to 10 and 5 ppm were 75 and 104 min, respectively. Several maneuvers to accelerate clearance of residual sevoflurane from the Dräger Fabius resulted in only modest reductions in these times (10 and 5 ppm times 40-50 min and 60-80 min, respectively). Insertion of an activated charcoal filter (QED, Anecare Laboratories, Salt Lake City, UT) into the inspiratory limb of the Dräger Fabius circuit reduced the residual anesthetic concentration to <5 ppm within 10 min; this concentration was maintained for > 6 h despite a fresh gas flow of only 2 L/min after the first 15 min. Preparation of the Dräger Fabius anesthesia machine using conventional flushing techniques required almost 10 times as long as an older, conventional anesthesia machine. If a prolonged flush is impractical or impossible, we describe a procedure using an activated charcoal filter inserted on the inspiratory limb of the breathing circuit which can effectively scrub residual sevoflurane to a concentration < 5 ppm within 10 min. This procedure includes an initial 5 min flush without the activated charcoal filter followed by a 5 min flush with the charcoal filter, after which the machine is ready for use in the malignant hyperthermia-susceptible patient. The charcoal filter must remain on the machine for the remainder of the anesthetic, and the fresh gas flow should be maintained > or = 10 L/min for the first 5 min, and > or = 2 L/min thereafter.

Anesthetic management of a malignant hyperthermia susceptible patient in tongue cancer resection

Anesthetic management of a malignant hyperthermia susceptible patient in tongue cancer resection

Malignant hyperthermia:considerations for ambulatory surgery

Patient care offered on an ambulatory basis continues to grow as evidenced by the high percentage of surgical procedures now being performed in such a setting. Many ambulatory surgical facilities are free standing and remote from the primary hospital location. As the popularity of ambulatory surgical care increases, so does the likelihood of encountering malignant hyperthermia-susceptible patients or of experiencing a malignant hyperthermia crisis. The management of this unique population creates new challenges for the perianesthetic nurse working in the free-standing ambulatory setting. A comprehensive plan of patient care under these circumstances includes (1) the ability to identify the high-risk patient and to plan their care accordingly, (2) early recognition of the signs and symptoms of malignant hyperthermia, and (3) being prepared to promptly and efficiently treat a malignant hyperthermic event. This review article will offer guidelines for managing the malignant hyperthermia-susceptible patient in the remote ambulatory surgical setting.

Fiber-type caffeine sensitivities in skinned muscle fibers from humans susceptible to malignant hyperthermia.

The response to contracture tests may depend upon the relative proportion of muscle fiber types within the muscle specimen. To determine whether a difference in fiber-type caffeine sensitivities exists between malignant hyperthermia susceptible (MHS) and malignant hyperthermia-nonsusceptible (MHN) skeletal muscle, we compared the fiber-type caffeine sensitivities in chemically skinned muscle fibers dissected from vastus lateralis muscle from 15 MHS and 16 MHN patients. Muscle fiber type was determined in each fiber by the difference in strontium-induced tension measurements and in 36 fibers, after contracture testing, by ATPase enzyme histochemistry. Caffeine sensitivity was defined as the threshold concentration inducing more than 10% of the maximal tension obtained with a calcium 1.6 x 10(-2) mM solution. Significant difference in the mean (+/- SD) caffeine sensitivity was found between type I MHS fibers (2.63 +/- 0.85 mM) versus type II MHS fibers (3.47 +/- 1.2 mM) and between type I MHN fibers (5.89 +/- 1.8 mM) versus type II MHN fibers (10.46 +/- 2.6 mM). The mean (+/- SD) caffeine sensitivities for a given muscle fiber type (I or II) were different between groups of MHS and MHN patients. Both type I and II MHS fibers had significantly lower caffeine sensitivities, and this increase in caffeine sensitivity was significantly smaller in type I than in type II fiber. The current study indicates that a truly MHS patient cannot have a false-negative result solely related to abnormal type II fibers contained in a given muscle strip. Although the occurrence of a very high proportion of type I fibers in MHN human muscle could result in a false-positive contracture outcome, such an occurrence is expected to be rare.

Conduite à tenir devant un sujet susceptible de présenter une hyperthermie maligne en cas d'anesthésie et dans la vie quotidienne

Death from malignant hyperthermia (MH) still occurs in France. However, anaesthesia of the MH susceptible (MhS) patient is quite possible without any more risk than for patients who are not MhS. Guidelines have been worked out : « triggerdrugs such as volatile anaesthetics (halothane, enflurane, isoflurane) and depolarizing muscle relaxants must be imperatively avoided ; « non-triggerdrugs should be used, such as nitrous oxide, barbiturates, benzodiazepines, propofol, opiates, nondepolarizing muscle relaxants, amide or ester local anaesthetics at the usual doses without adrenaline. Moreover, dantrolene should be available in all hospitals, 12 bottles being a minimum at hand, or, better, 30 (about 10 mg · kg −1). In some cases, such as emergencies, an unprepared operating theatre, or an unprepared ventilator, the patient should be premedicated with 2.5 mg · kg −1 dantrolene intravenously. The ventilator, the circuit and the operating theatre should not countain any trace of halogenated vapour. The usual parameters, as well as temperature and expired CO 2 concentration, should be closely monitored. MhS patients must also be given counselling. This includes explanations about MH, its genetic features, the main laboratory tests used to detect susceptibility, as well as advice about lifestyle, the use of drugs other than general and local anaesthetics, and a discussion concerning the association of MH with other discases. This councelling is not always easy to provide, because many answers are not, as yet, definitive.