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Department of Anesthesiology, University Hospital Hamburg-Eppendorf, Hamburg, Germany
To the Editor:
With great interest we read the report by Hoenemann et al. concerning a case of delayed onset of malignant hyperthermia (MH) during inhaled anesthesia with desflurane (1). This report seem to support the assumption that desflurane might be a "weak" trigger of MH compared to other volatile anesthetics. However, this report raises two relevant issues.
First, the onset of MH may be delayed also after administration of other trigger substances (2–5). In previous reports onset times of 9 (3) or 18 h (4), respectively, after isoflurane and succinylcholine administration have been described. Furthermore, a review of the database of the North American MH Registry presenting desflurane-related MH events showed that the onset times for MH after halothane were not significantly different from those after desflurane (6). Therefore, it must be stated that onset times are no clinical indicator for the trigger potency of anesthetics, and consequently it has to be clarified that desflurane is a trigger of MH like all other volatile anesthetics and must be avoided in all patients susceptible to MH.
Second, the authors stated that a causal link between desflurane and the observed symptoms was confirmed by postoperative testing. This is not correct. An in vitro contracture test (IVCT) according to the standard procedure of the European MH Group has been performed, but this test failed to give an unambiguous result due to technical problems. On the one hand, it would be interesting to know which problems occurred, because for our knowledge this is the first time that such problem was presented in the literature. On the other hand, it should be explained whether the authors recommended to perform the IVCT in this patient for a second time, or performed the IVCT in the direct family members, respectively.
Further studies are needed to investigate which factors might modify the onset and course of MH. First steps in this direction were made and it could be demonstrated that in vitro contracture test results depend on different malignant hyperthermia-associated ryanodine receptor gene mutations (7). Whether these observations are of relevance also under in vivo conditions, however, remain unclear until now.
References
St. Marienhospital Vechta, Vechta, Germany
In Response:
In this reply I would like to thank Drs. Wappler and Fiege for their comments on our case report on the delayed onset of malignant hyperthermia (MH) during inhaled anesthesia with desflurane (1). In fact, desflurane is a trigger of MH compared with other volatile anesthetics.
First, onset time is no clinical indicator for the trigger potency of volatile anesthetics, and we never mentioned this in our case report. Second, we did not confirm the MH by postoperative testing and he is correct. We are sorry about that misleading title.
The in vitro contracture test (IVCT) according to the standard procedure of the European MH Group and all the other tests have been performed or organized by Prof. Mortier (Abteilung für Neuropädiatrie, Kinderklinik der Ruhr-Universität, St. Josef-Hospital, Gudrunstr. 56, 44791 Bochum, Germany). He was so kind to give us all results at the end of the tests. I cannot make comments on the postoperative testing or on the statement of Dr. Wappler about technical problems. In fact, it was the first time that Prof. Mortier had such a problem with the IVCT, and he discussed all results with the patient and her family. To my knowledge, the family rejected the chance to perform a second IVCT.
Professor Mortier is a well-known specialist and his laboratory is listed as MH center on the homepage of the European MH Group (www.emhg.org). For any questions regarding this case and the postoperative testing, I would be happy to get all interested scientists in contact with Prof. Mortier.
Regarding the failed IVCT, I completely agree that further studies are necessary to investigate this problem, and it is of major interest which factors modify onset and course of MH.
Reference
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