Testing for Malignant Hyperpyrexia

[Michael de Sousa]

I have a concern with MH.

Nowadays it is really easy to give a non-triggering anesthetic. If I get a patient with known MH, or a relative of an MH patient, or even anybody remotely suspected of MH (perhaps a vague history of getting "hot" during a previous GA), then I give them a propofol infusion. Easy. No need to do cumbersome, invasive muscle biopsy tests.

Well I think there is still the need to test. What we are ending up with is a generation of patients who are suspected of MH but not biopsy-proven MH. Sure we can give them all non-triggering GA's. But what happens next generation? Do we suspect all their relatives to be MH psoitive as well? How far do we suspect? Will the history of suspected MH get reliably transmitted within the family?

I think we are already seeing a group of patients that have such a vague history, because their relative were not tested. It is easy to envisage a relative of a suspected MH patient slipping through the system and not give the history and then get a volatile anesthetic.

We still need to test all suspected MH patients, if not pre-op, then certainly post-op (or ideally as aprt of their current operation).

[Emma Davey M.D.]

As I understand it, there is a genetic test in development (commercially available?) for MH. This would make the issue a non-issue would it not?

[gasman]

There is a reliable genetic test for the porcine model of MH. The human situation is more complex. While many MH-susceptible patients have a specific ryanodine receptor defect that can be identified with genetic testing, there is much heterogeneticity in human MH patients. I.e. there are multiple genetic mutations that can predispose to MH and therefore a single genetic test will not pick up all variants, making any single genetic test unreliable. If a patient is identified with a specific genetic defect, then all relatives would be reliably picked up with a test for that mutation. But screening a patient with a vague history, or even known MH with an unkown genotype variant is not feasable at present.


The halothane caffeine contracture test remains the standard as it tests the final common (clinical) pathway of the disorder.

[Russell Coupland]

And so the original argument remains valid - by being less-than-diligent in testing, we are breeding a generation of MH-susceptible people who will not be known as MH susceptible.