Malignant Hyperthermia Deaths Related to Inadequate Temperature Monitoring

[wtbcrna, MSN, DNP, CRNA]

"Anesth Analg. 2014 Sep 26. [Epub ahead of print]

[h=1]Malignant Hyperthermia Deaths Related to Inadequate Temperature Monitoring, 2007-2012: A Report from The North American Malignant Hyperthermia Registry of the Malignant Hyperthermia Association of the United States.[/h]Larach MG1, Brandom BW, Allen GC, Gronert GA, Lehman EB.

[h=3]Author information[/h]

[h=3]Abstract[/h][h=4]BACKGROUND::[/h]AMRA (adverse metabolic or muscular reaction to anesthesia) reports submitted to The North American Malignant Hyperthermia Registry of the Malignant Hyperthermia Association of the United States from 1987 to 2006 revealed a 2.7% cardiac arrest and a 1.4% death rate for 291 malignant hyperthermia (MH) events. We analyzed 6 years of recent data to update MH cardiac arrest and death rates, summarized characteristics associated with cardiac arrest and death, and documented differences between early and recent cohorts of patients in the MH Registry. We also tested whether the available data supported the hypothesis that risk of dying from an episode of MH is increased in patients with inadequate temperature monitoring.

[h=4]METHODS::[/h]We included U.S. or Canadian reports of adverse events after administration of at least 1 anesthetic drug, received between January 1, 2007, and December 31, 2012, with an MH clinical grading scale rank of "very likely MH" or "almost certain MH." We excluded reports that, after review, were judged to be due to pathologic conditions other than MH. We analyzed patient demographics, family and patient anesthetic history, anesthetic management including temperature monitoring, initial dantrolene dose, use of cardiopulmonary resuscitation, MH complications, survival, and reported molecular genetic DNA analysis of RYR1 and CACNA1S. A one-sided Cochran-Armitage test for proportions evaluated associations between mode of monitoring and mortality. We used Miettinen and Nurminen's method for assessing the relative risk of dying according to monitoring method. We used the P value of the slope to evaluate the relationship between duration of anesthetic exposure before dantrolene administration and peak temperature. We calculated the relative risk of death in this cohort compared with our previous cohort by using the Miettinen and Nurminen method adjusted for 4 comparisons.

[h=4]RESULTS::[/h]Of 189 AMRA reports, 84 met our inclusion criteria. These included 7 (8.3%) cardiac arrests, no successful resuscitations, and 8 (9.5%) deaths. Of the 8 patients who died, 7 underwent elective surgeries considered low to intermediate risk. The average age of patients who died was 31.4 ± 16.9 years. Five were healthy preoperatively. Three of the 8 patients had unrevealed MH family history. Four of 8 anesthetics were performed in freestanding facilities. In those who died, 3 MH-causative RYR1 mutations and 3 RYR1 variants likely to have been pathogenic were found in the 6 patients in whom RYR1 was examined. Compared to core temperature monitoring, the relative risk of dying with no temperature monitoring was 13.8 (lower limit 2.1). Compared to core temperature monitoring, the relative risk of dying with skin temperature monitoring was 9.7 (1.5). Temperature monitoring mode best distinguished patients who lived from those who died. End-tidal CO2 was the worst physiologic measure to distinguish patients who lived from those who died. Longer anesthetic exposures before dantrolene were associated with higher peak temperatures (P = 0.00056). Compared with the early cohort, the recent cohort had a higher percentage of MH deaths (4/291 vs 8/84; relative risk = 6.9; 95% confidence interval, 1.7-28; P = 0.0043 after adjustment for 4 comparisons).

[h=4]CONCLUSIONS::[/h]Despite a thorough understanding of the management of MH and the availability of a specific antidote, the risk of dying from an MH episode remains unacceptably high. To increase the chance of successful MH treatment, the American Society of Anesthesiologists and Malignant Hyperthermia Association of the U.S. monitoring standards should be altered to require core temperature monitoring for all general anesthetics lasting 30 minutes or longer."

http://www.ncbi.nlm.nih.gov/pubmed/25268394

[jwk]

Hmmm - interesting article. Tachycardia and/or elevated EtCO2 are generally the earlier signs that appear with MH, with an elevated temp occurring a little later. Do you think the index of suspicion is/was too low with tachycardia and hypercarbia? Seems like if you've waited until the temp rises that you're already probably behind in the game.

[wtbcrna, MSN, DNP, CRNA]

Hmmm - interesting article. Tachycardia and/or elevated EtCO2 are generally the earlier signs that appear with MH, with an elevated temp occurring a little later. Do you think the index of suspicion is/was too low with tachycardia and hypercarbia? Seems like if you've waited until the temp rises that you're already probably behind in the game.

I was having this discussion with an MH researcher, and she was saying that anesthesia providers are just not thinking of MH anymore.

My response was the same as yours, if you waited to see the temperature change then you are way behind the curve to treat these patients. I can only imagine that some of these deaths from MH weren't even diagnosed until they got to the PACU.

It is sad to see that such a well known problem is being missed in the OR.

The good news is there is at least two very interesting research pieces coming out about MH. One is looking at the genetics, which is a lot more complex than first thought, and the other may eventually lead to adjunct methods to treat MH that may help decrease mortality.

[subee, MSN, CRNA]

I had a case of MH my very last 24 hour shift as a student many years ago. The abdomen was closed and I noticed that his arms were very stiff. I thought he was light and turned the vent off and noticed that the tidal volume sweep hand (back when the meters were round and analog) and knew right away that I wasn't going home at 7 am. This was about 5 am and we called a code and kept the interns and residents that responded to mix the Dantrolene. That stuff was really difficult to mix. Patient bought an admission to ICU and did well.

When I walked out of that place into a hot and humid August morning, my fear of missing the intellectual excitement of CRNA school was over!

[wtbcrna, MSN, DNP, CRNA]

http://www.medscape.com/viewarticle/828813 The new dantrolene formulation, Ryanodex, will eliminate the problems with mixing dantrolene. It should allow a vial of Ryanodex, which is enough to initially treat at least one patient, in every OR.

[twinsmom788]

Interesting link to genetics. We as OR nurses were very well trained in MH signs, symptoms, and treatment. One thing I've often wondered can a person who has experienced several anesthesias more prone to MH or first time patients more likely to have MH? It's been years since I have thought about this.

[wtbcrna, MSN, DNP, CRNA]

Interesting link to genetics. We as OR nurses were very well trained in MH signs, symptoms, and treatment. One thing I've often wondered can a person who has experienced several anesthesias more prone to MH or first time patients more likely to have MH? It's been years since I have thought about this.

Technically, the more anesthestics a person has had they should be less likely to have an MH episode, but fulminant MH episodes usually happen on the 2-3rd general anesthetic or even the 5th anesthesia.

There are some people, myself included, that think people with MH susceptibility (MHS) will have often have clinically detectable signs, but those signs will often be dismissed as other problems (i.e. pain) and the person resolves spontaneously.

MHS patients are also prone to exertional hyperthermia and exertional rhabdomyolysis. It would probably be prudent if we asked all our general anesthetic patients if they have ever had EH or ER along with the standard MH history.

[twinsmom788]

Thanks so much for the reply.