Malignant Hyperthermia Guidelines

Introduction to Malignant Hyperthermia

Malignant hyperthermia susceptibility shows variable penetrance, meaning susceptible individuals may tolerate triggering agents multiple times before experiencing an MH crisis, with the reasons why susceptible individuals may not trigger when exposed to triggering agents not fully understood, as stated by the European Malignant Hyperthermia Group and Association of Anaesthetists guidelines 1
A history of uneventful anesthesia with triggering agents does not rule out MH susceptibility, highlighting the importance of not assuming safety based on previous exposures, according to the Association of Anaesthetists guideline 1

The variable expression of malignant hyperthermia has important clinical implications, including the need to never assume safety based on previous exposures, and to maintain vigilance with every anesthetic, monitoring for early signs of MH, such as unexplained increase in end-tidal CO₂, tachycardia, and rigidity, as recommended by the Association of Anaesthetists guideline 1

The discrepancy between the prevalence of genetic variants associated with MH risk and the incidence of clinical MH episodes suggests complex factors affecting expression, with both genetic and non-genetic factors likely contributing to the reduced penetrance of MH susceptibility, according to the Association of Anaesthetists guideline 1
MH susceptibility is characterized by genetic predisposition, inherited as an autosomal dominant trait with variable penetrance, as stated by the European Malignant Hyperthermia Group 2, 1

Malignant hyperthermia (MH) is a life-threatening condition triggered by certain anesthetic agents, including volatile anesthetics (sevoflurane, desflurane, isoflurane, halothane) and the depolarizing muscle relaxant succinylcholine, as identified by the European Malignant Hyperthermia Group (EMHG) guidelines 3
MH-susceptible patients require trigger-free anesthesia, with the European Malignant Hyperthermia Group providing a strong recommendation that "only trigger-free anesthesia should be used in all MH-susceptible patients" 2, 4
Regional or local anesthesia is preferred when appropriate, and total intravenous anesthesia (TIVA) is the recommended approach when general anesthesia is required, as recommended by the European Malignant Hyperthermia Group 2, 4
Non-depolarizing muscle relaxants like rocuronium are considered safe in MH-susceptible patients, as stated by the European Malignant Hyperthermia Group 3
The following measures are recommended:
Maintain vigilance for early signs of MH (unexplained increase in end-tidal CO2, tachycardia, rigidity) even when using non-triggering agents, as MH susceptibility shows variable penetrance, meaning susceptible individuals may have previously tolerated trigger agents without developing MH, and assuming safety based on previous exposures is a dangerous misconception that can delay diagnosis and treatment, as stated by the European Malignant Hyperthermia Group and Association of Anaesthetists guidelines 4, 1