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Archive August 2020 XXI, No. 8

Malignant Hyperthermia Myth-Busting

Refuting common misconceptions about the rare disorder will give your staff the knowledge they need to keep patients safe.

Ronald Litman

Ronald Litman, DO, ML


EXPERT OPINION Ronald Litman, DO, ML, became familiar with common questions about MH during his time as the medical director of the MHAUS hotline.

MYTH #1: A post-op fever is indicative of MH
FACT: Many clinicians worry that MH may begin in the postoperative period with a fever as the presenting sign, and anesthesia providers are typically taught that MH can occur as late as 48 hours after surgery. This is incorrect. Postoperative hyperthermia (a temperature > 38°C) without additional signs of MH is relatively common and is not typically associated with an eventual diagnosis of MH. Nearly all cases of postoperative MH begin to demonstrate signs of onset within 10 minutes of discontinuing the triggering agent (volatile anesthesia gas).

MYTH #2: A high fever many hours after administration of succinylcholine is a symptom of MH
FACT: A common call we received on the MHAUS hotline involved scenarios similar to this one: An elderly patient with underlying respiratory disease presents to the emergency room with pneumonia and respiratory distress. The docs there determine the patient is in respiratory failure and requires tracheal intubation. Etomidate and succinylcholine are administered, intubation is performed and the patient is sent to the intensive care unit to receive further treatment. Later that night, the patient develops a high fever, sometimes exceeding 40ºC. The ICU staff believes a patient with a high fever who received succinylcholine could be experiencing MH. Although the administration of succinylcholine alone is rarely associated with MH, there are no known cases where MH begins to develop many hours later — and manifest solely as a high fever — without additional signs of MH. This patient's uncommonly high fever is most likely related to their underlying infectious process. We are not aware of any of these cases that ultimately proved to be caused by MH.

MYTH #3: MH does not occur after administration of succinylcholine alone
FACT: Most MH cases are associated with the administration of a volatile anesthetic gas with or without succinylcholine. Many anesthesia providers are under the impression that because the use of succinylcholine is so common — and MH is so unusual — that the two are not related. Although rare, we are aware of cases of proven MH that occurred after administration of succinylcholine alone. However, unlike Myth #2, the clinical syndrome usually manifests as marked muscle rigidity (generalized or confined to the masseter muscles), respiratory and metabolic acidosis, rhabdomyolysis and high temperature.

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