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Discussion

Clinical discussion... as requested!

Okay, so a few months ago I was in the ENT room at my clinical site doing some peds cases. A 2 yr. old presents for BMT (ear tubes), otherwise healthy besides seasonal allergies and freq. ear infections. Upon reviewing the anesthesia pre-op assessment that was completed in pre-admission testing, it is noted that the child has a questionable family history of malignant hyperthermia. Supposedly, the child's aunt has been diagnosed with MH. The child himself has never had anesthesia and has never been tested. The child's mother recently had a lap chole but does not have access to her records and is unaware if she was given a non-triggering anesthetic. The anesthesiologist I am with would like to cancel the case and have the child tested for MH before proceeding, but the parents become very upset and insist that the procedure be completed because the child is miserable and having very severe hearing difficulties. Unfortunately, this is not the first case of the day and the questionable history of MH has not been picked up by the physician assistant in PAT. So, what now?

Questions:

Would you proceed with the case, and if so, how would you proceed?

How does one test for MH exactly?

Describe the pathophysiology of MH.

List the triggering agents for MH.

Describe the treatment of suspected intra-op MH.

Which patients are at risk of MH?

Featured Replies

i think, at the very least, a further inquiry into child's risk of developing malignant hyperthermia is justified before proceeding with the tube placement. as healthcare PROFESSIONALS we often need to educate patients about risks and benefits of treatment. while having a child who is miserable with ear infections is difficult - so is planing a funeral for a child after a tragic outcome of an ELECTIVE procedure.

No way I am going to take the liability for this case so I would call the MDA to deal with it.

  • Author

Well as a student of course I was working with an MDA but as a CRNA you are just as liable as the MDA. You can't just turf the case because you don't want to deal with it!!

We came very close to cancelling the case but in the end we proceeded under pressure from both the parents and the surgeon. We did educate the parents about MH and did make them promise to get the child tested in the future. We ended up using a non-triggering anesthetic which required a lot more work on our part.... any guesses how we did it? Anyone care to take a stab at the questions I posed above?

  • Guides
Okay, so a few months ago I was in the ENT room at my clinical site doing some peds cases. A 2 yr. old presents for BMT (ear tubes), otherwise healthy besides seasonal allergies and freq. ear infections. Upon reviewing the anesthesia pre-op assessment that was completed in pre-admission testing, it is noted that the child has a questionable family history of malignant hyperthermia. Supposedly, the child's aunt has been diagnosed with MH. The child himself has never had anesthesia and has never been tested. The child's mother recently had a lap chole but does not have access to her records and is unaware if she was given a non-triggering anesthetic. The anesthesiologist I am with would like to cancel the case and have the child tested for MH before proceeding, but the parents become very upset and insist that the procedure be completed because the child is miserable and having very severe hearing difficulties. Unfortunately, this is not the first case of the day and the questionable history of MH has not been picked up by the physician assistant in PAT. So, what now?

Questions:

Would you proceed with the case, and if so, how would you proceed?

How does one test for MH exactly?

Describe the pathophysiology of MH.

List the triggering agents for MH.

Describe the treatment of suspected intra-op MH.

Which patients are at risk of MH?

1. Only after consulting further w/ parents, surgeon, and another anesthesia provider.

2. "The Caffeine Halothane Contracture Test (CHCT), a test performed on freshly biopsied muscle, is the "gold standard" for diagnosis of MH." http://www.mhaus.org/index.cfm/fuseaction/OnlineBrochures.Display/BrochurePK/71A5AFFC-1BC7-4A36-970C6FDB27999FE5.cfm

3. What Drugs trigger MH and are Not Safe?

Inhaled General Anesthetics

Choroform (Trichloromethane, Methyltrichloride)

Desflurane

Enflurane

Halothane

Isoflurane

Methoxyflurane

Sevoflurane

Trichloroethylene

Xenon (Rarely Used)

Depolarizing Muscle Relaxants Trigger MH

Succinylcholine (Suxamethonium)

Also, soda lime, breathing tubes, and breathing bags should be new since trace amounts could be detrimental to the patient or changed out immediately if MH is suspected.

http://www.mhaus.org/index.cfm/fuseaction/Content.Display/PagePK/AnestheticList.cfm

4. Treatment is dantrolene, ventilation with 100% O2, and cooling measures if fever is present.

5. "MH or MH-like events however, have occurred in patients with underlying muscle diseases, such as muscular dystrophy and myotonia. Such patients typically display muscle weakness. MH has been linked to a rare disorder of muscle called Central Core disease and King Denborough Syndrome, a rarer muscle syndrome.

Additionally, patients with certain forms of muscular dystrophy may develop life-threatening disturbances and muscle destruction on exposure to the triggering agents for MH. The clinical event may resemble MH in many ways, but is not considered "true" MH. In patients with Duchenne muscular dystrophy, succinylcholine should always be avoided or rhabdomyolysis may occur. Potent volatile agents may produce rhabdomyolysis in time, but most believe that brief exposure is a small risk. Patients with muscle disorders should be carefully evaluated by their anesthesiologist prior to surgery.

Hypokalemic and hyperkalemic periodic paralysis are also associated with risk for MH. Hyperkalemic cardiac arrest may occur when MH-trigger agents are administered to muscular dystrophy patients.

Patients with osteogenesis imperfecta often develop fever during anesthesia. Myotonic patients will develop muscle rigidity with succinylcholine. There have been a few MH cases reported in patients with carnitine palmityl transferase deficiency and it is recommended to stay away from MH triggers in such patients. Neuroleptic Malignant Syndrome (NMS) is a syndrome that resembles MH but is precipitated by drugs acting centrally on dopaminergic pathways in the brain." http://www.mhaus.org/index.cfm/fuseaction/Content.Display/PagePK/MedicalFAQs.cfm

Great Questions!!

Keep 'em coming I start CRNA school next month!

According to the link http://www.intelihealth.com/IH/ihtIH/WSIHW000/9339/24695.html the possible presence of genetic MH can only be tested at a few labs in the country and is done by muscle biopsy. (Further complicating matters is that the muscle sample must be fresh, alas, the pt must BE there for the test.)

Most of your other questions are also answered here. (I'd be curious if their answers follow a standard protocol of sorts.)

Hmm, non-triggering anesthetic in a two year old? My guess is that you gave him a healthy dose of po versed, maybe with some fentanyl, and got him relaxed enough that you could get an iv in him, then used propofol gtt while masking him (with adequately flushed machine, new circuit & absorbers) with n20/O2 for the placement of the tubes? am I close?

Good scenario. I have seen one case of MH and it is something I will never forget. It is my understanding that any agent can trigger MH, but it is mostly seen with succinylcholine.

This will not make me popular, but I don't work with anesthesiologists, so I assume my own liability. Nurses talk WAY too much about legal issues. I am very diligent and administer good anesthesia and am not worried about lawsuits or protecting my license.

Ali

We've done them as a local only after po versed...and done a o2/n2o mask for iv then propofol as a tiva.

  • Author

Great job, wtbcrna, for not even being an official SRNA yet!!

This is what we ended up doing: The kid already had p.o. Versed on board, but was still kinda squirmy, so we gave some IM Ketamine (I can't remember the exact dose we gave but I was told that a good sedation dose would be to give an IV induction dose IM). My peds rotation is my very last one so you can understand how freaked out I was at this whole situation because I hadn't even done peds yet! Anyhoo, we changed the soda lime on the machine, removed the vaporizers so we wouldn't accidently use them, and flushed the machine at 10 liters for about 15 min. or so. We then started an IV and used a Prop gtt. The case turned out fine it was just a lot of extra work. And of course, we monitored EtCO2 and temp. the whole time just in case. Which leads me to another question: What is the FIRST indicator of MH, and what is the most SENSITIVE indicator of MH?

And whoever posted this is right, the Halothane contracture test is only done at like 6 centers in the U.S so I imagine getting tested is difficult for some people.

you could try po versed and ketamine with local

ketamine will potentially interfere with determining whether MH is occurring. It causes tachycardia that can be profound....

I remember in the 80s it was also thought to be a triggering agent.

Oral or nasal versed is a good preop, then IV, the propofol...safest course.

I was under the impression that MH could be triggered by Versed.... is this only with IV administration?

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