Paul Liszewski, CRNA, DNP

So what’s the deal with Malignant Hyperthermia (MH)? Sounds like the start of a Seinfeld routine, but there’s nothing funny about results of the latest statistics we have about this pharmacogenetic disease. A group of researchers using an MH registry found that the rate of dying from an MH crisis has actually increased in recent years (Larach, Brandom, Allen, Gronert, & Lehman, 2014). It doesn’t make sense because this is not an unknown malady. In our modern day anesthesia world there exists an international society dedicated to the disorder, well-established protocols for managing an MH crisis in the clinical setting, and a readily available antidote. Yet the numbers of reported deaths from MH are higher now more than ever. I’d like to present some of the contributing factors to this trend.

First of all, there is concern about the accuracy of reported MH events compared to the actual incidence in daily anesthesia practice. It would appear that MH occurrences and deaths are under reported. This is not surprising. Most registries rely on voluntary reporting and the limitations of this method of data collection are well known. Health care organizations report a very low percentage of negative events, especially those where errors by providers could be causative factors in negative patient outcomes (Kohn, Corrigan, & Donaldson, 2000). Specific to the retrospective reviews on MH trends in the last 10 years, it was noted that the use of one registry as the primary source for statistics in a study missed a significant number of MH deaths that were reported to other agencies (Larach, Brandom, Allen, Gronert, & Lehman, 2008).

The truth be told, there is no truly accurate numbers on the incidence of Malignant Hyperthermia in the U.S. Since an MH crisis can manifest with a variety of presentations, it is often misdiagnosed in the clinical setting. It is understandable how this difficulty in diagnosing MH and its similarity in clinical signs and symptoms to other hyperthermic disorders like sepsis, thyroid storm and neuroleptic malignant syndrome can lead to inaccuracies in patients discharge records. As evidence, a study that checked the accuracy of International Classification of Diseases, 9th Revision (ICD-9) MH diagnosis codes assigned to patients’ discharge records found about that only 25% were accurate to actual or possible MH events, while another 25% of patients charts were coded as having an MH incident when the patient NEVER had surgery or an anesthetic (Pinyavat et al., 2015). On a side note, this particular study gives more evidence to the notion that “anesthesia is blamed for everything”!

So while registry reporting seems to underestimate and patient hospital records tend to overestimate MH episodes, it would appear that Malignant Hyperthermia is a bigger anesthetic issue in the United States than reflected in the current registry estimations. One study that looked at a large national administrative database and excluded patients with other conditions associated with hyperthermia reported a much higher number of MH cases in the United States than those previously reported to the MH registries (Rosero, Adesanya, Timaran, & Joshi, 2009).

Since MH crises are probably occurring more than we think, the next obvious intervention to address the problem is to raise awareness and diligence. It would be convenient if every MH susceptible patient presented in the same fashion as the engineering student who arrived with a broken leg to the preoperative area of Dr. Michael Densborough’s home hospital in Melbourne, Australia. If you remember this well-documented episode of MH from 1960, the young man refused to receive an anesthetic on the grounds that 10 of his 24 family members had died during surgery and ether anesthesia. Dr. Densborough unfortunately offered the patient a newly marketed volatile anesthetic, Halothane, as an alternative. The young man agreed and he subsequently suffered an MH crisis with anesthesia induction. After a successful resuscitation, the patient and family was studied to determine the hereditary nature of the disease. The botheration with the details of this famous MH incident is it doesn’t correspond to the 21st century MH susceptible patient. For a number of reasons, contemporary studies reveal that many patients who suffer an MH crisis do not communicate a family history of problems with anesthesia and have had successful anesthetics with volatile anesthetic gases in the past (Watson & Brandom, 2015). The take home message is that an unremarkable patient and family history for anesthetic complications should not lower our level of alertness for the telltale signs of MH with every patient. Delays in the administration of dantrolene in an MH crises predictably raises the risk of death.

Last but not least, our routine methods of monitoring for signs of MH is under investigation. Anesthesia providers are aware of the necessity to maintain normothermia in the anesthetized patient. As a means to that end, patients’ temperatures are frequently monitored by convenient methods like the liquid crystal skin temperature strip. These thermometers are adept at measuring the slowly trending temperature of an anesthetized patient, but are slow to respond to the rapidly rising core temperature seen with an MH crisis. Core temperature monitoring, in comparison to the use of skin thermometers or no temperature monitoring at all, has been shown to have a significant predictive value in patient survival from MH during a general anesthetic (Larach, Brandom, Allen, Gronert, & Lehman, 2014). It may become a recommendation to utilize core temperature methods when administering a general anesthetic in order to recognize and promptly treat an episode of MH.


Kohn, L. T., Corrigan, J. M., & Donaldson, M. S. (Eds.). (2000). To err is human: Building a safer health system. Washington, DC: National Academy Press.

Larach, M. G., Brandom, B. W., Allen, G. C., Gronert, G. A., & Lehman, E. B. (2008, Apr). Cardiac arrests and deaths associated with Malignant Hyperthermia in North America from 1987 to 2006. Anesthesiology, 108, 603-611.

Larach, M. G., Brandom, B. W., Allen, G. C., Gronert, G. A., & Lehman, E. B. (2014, December). Malignant Hyperthermia deaths related to indequate temperature monitoring, 2007-2012: A report from the North American Malignant Hyperthermia Registry of the Malignant Hyperthermia Association of the United States. Anesthesia & Analgesia, 119(6), 1359-1366.

Pinyavat, T., Rosenberg, H., Lang, B. H., Wong, C. A., Riazi, S., Brady, J. E., …Li, G. (2015, January). Accuracy of Malignant Hyperthermia diagnoses in hospital discharge records. Anesthesiology, 122, 55-63.

Rosero, E. B., Adesanya, A. O., Timaran, C. H., & Joshi, G. P. (2009, January). Trends and outcomes of Malignant Hyperthermia in the United States, 2000- 2005. Anesthesiology, 110(1), 89-94.

Watson, C. B., & Brandom, B. W. (2015, June). What is your MH IQ? Apsf Newsletter, 1, 3-4.