A Case of Suspected Malignant Hyperthermia During Desflurane Administration

Abstract

We thank Dr. Celebioglu for his comments regarding our report on a case of suspected malignant hyperthermia (MH) during desflurane anesthesia [1]. His main concern seems to be an inappropriate evaluation and management of this case. Due to the limited scope of a case report, parameters irrelevant to the diagnosis or treatment of MH-such as hemoglobin, coagulation parameters, or blood chemistry-were not mentioned. However, all the values questioned by Dr. Celebioglu were within the normal range. Because our patient was otherwise healthy and scheduled for a diagnostic procedure of short duration, it was not deemed necessary to obtain a preoperative arterial blood gas analysis, as demanded by Dr. Celebioglu. Furthermore, it should be noted that an increase in creatine phosphokinase, indicative of muscle destruction, is a late symptom in MH not necessarily found in abortive cases like the one we described. Contrary to the concerns of Dr. Celebioglu, propofol, nitrous oxide, and the other drugs used to provide anaesthesia in our patient are not triggers of MH. Thus, of all the drugs administered, desflurane alone, as a volatile anesthetic, had the potential to trigger MH in susceptible patients. Therefore, it is to be considered the only relevant substance in this context. Various textbooks state [2] that it is not recommended to waste time and efforts by changing the anesthetic circuit. A high fresh gas flow washes out the volatile anesthetic within minutes. Considering the low solubility of desflurane and provided that single-use polyolefine tubings are used, only very small concentrations of anesthetics can be traced in the anesthetic circuit [3]. Therefore, it is safe to rapidly terminate the surgical procedure after all triggering drugs have been discontinued. In the case reported, the surgical procedure was terminated as fast as possible. As for the dantrolene therapy, the dose was based on the clinical course of the episode. It seemed safe to discontinue the dantrolene infusion, as the patient did not show any further signs of increased metabolism. Furthermore, as already mentioned, the angiography room in our neurosurgical department is a remote area to provide anesthesia. Because the boy was stable, it seemed safe to transfer him to the intensive care unit for further treatment, instead of waiting for the dantrolene to arrive. It is true that MH is generally regarded as a dominantly inherited condition. Therefore, the positive test result in the in vitro contracture test in the mother, in combination with the symptoms described during anesthesia in the boy, strongly suggests that the boy has inherited his mother's MH susceptibility. However, as the results of Islander et al. [4], suggest, a polygenic or recessive inheritance cannot be ruled out in some families. For this reason, the boy and his father will also be scheduled for an in vitro contracture test. Andrea Michalek-Sauberer, MD Hermann Gilly, PhD Department of Anesthesiology and General Intensive Care; University of Vienna; A-1090 Vienna, Austria