Administration of Anaesthetic Triggering Agents to Patients Tested Malignant Hyperthermia Normal and Their Relatives in New Zealand: An Update

Abstract

Testing for malignant hyperthermia in New Zealand involves two tests-in vitro contracture testing of excised lateral quadriceps muscle and DNA analysis. In vitro contracture testing is regarded as the gold standard in malignant hyperthermia diagnosis but several publications have questioned the reliability of a normal result. Analysis of 479 anaesthetic records in 280 patients or their descendants throughout New Zealand who had tested negative for malignant hyperthermia, demonstrated there was no evidence of malignant hyperthermia episodes in this group who had been administered anaesthetic triggering agents. A wide range of anaesthetics were used over the study period. Analysis of each anaesthetic record was undertaken using the malignant hyperthermia grading scale which determines the likelihood that an anaesthetic event represents a malignant hyperthermia episode. Confirmation of the negative results was further supported by normal DNA analysis of patients in 48% of anaesthetics. There are advantages to using inhalational agents in certain situations and although demonstrating a zero risk of a malignant hyperthermia episode is not statistically possible, evidence in this large series suggests that the risk of an episode in these patients is extremely low and may be negligible. We suggest that anaesthetic triggering agents can be used safely in patients with normal in vitro contracture tests, and in their descendants.

A multi-dimensional analysis of genotype–phenotype discordance in malignant hyperthermia susceptibility

“…A large study in New Zealand, found no evidence of malignant hyperthermia episodes in 479 anaesthetic records from 280 patients who had tested negative on the IVCT. 26 However, with an estimated sensitivity of 97%, 8 it is possible that the CHCT produced a falsenegative result in our patient. False-negative CHCT results as well as cases of discordance between the negative IVCT results and the positive RYR1 genotype have been reported by MH research groups around the world.…”

Anesthesia for muscle biopsy to test susceptibility to malignant hyperthermia

“…On the other hand, patients without MH susceptibility (with negative IVCT) may be safely exposed to triggering agents. 28 However, it is imperative to bear in mind that the isolated genetic test does not rule out the diagnosis of MH susceptibility due to the genetic heterogeneity of this syndrome and the presence of more than one mutation in some families. 2 , 8 …”

Epidemiological and clinical features of malignant hyperthermia: A scoping review

“…In this review, 11 articles summarized the trigger agent usage in patients diagnosed with MH. 19,20,26,27,32,38,39,[46][47][48][49] Among these studies, most cases used volatile anesthetics, and there was a low incidence of MH triggered by succinylcholine only. However, succinylcholine could increase the incidence of MH in combination with volatile anesthetics.…”