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Frequently Asked Questions


Please select a question from the list below.


  1. What drugs trigger MH?
  2. What anesthetic drugs are safe?
  3. Should MH patients be pre-treated with Dantrolene?
  4. How many vials of Dantrolene should be stocked?
  5. How long does an MH patient need to be monitored after a non-triggering anesthetic?
  6. How should a patient with family history of MH be managed?
  7. Where should a muscle biopsy for MH take place?

What drugs trigger MH?

All the inhalation anesthetics (desflurane, sevoflurane, isoflurane, methoxyflurane halothane, enflurane) and succinylcholine (a depolarizing muscle relaxant) are considered MH triggers.

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What anesthetic drugs are safe?

Barbiturates, propofol, ketamine, etomidate, benzodiazepine, nitrous oxide, all the non depolarizing muscle relaxants, and all the local anesthetics are safe.

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Should MH patients be pre-treated with Dantrolene?

No. If non triggering anesthetics are used, there is no need to pre-treat with Dantrolene.

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How many vials of Dantrolene should be stocked?

A minimum of 36 vials of Dantrolene should be available. The initial dose is 2.5 mg/kg with a suggested upper limit of 10 mg/kg; for a 70 kg patient this would be 36 vials.

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How long does an MH patient need to be monitored after a non-triggering anesthetic?

According to MHAUS guidelines, there is no need for extended stay or more frequent monitoring for an MH patient who received a non-triggering, uneventful anesthetic. As long as a non-triggering anesthetic was used, they can be candidates for day surgery procedures.

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How should a patient with family history of MH be managed?

The patient should be referred to MHIU for assessment/counseling, and possible testing. However, until his/her status is known, a trigger-free anesthetic should be administered.

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Where should a muscle biopsy for MH take place?

Only centers with a standard protocol for the caffeine-halothane contracture test are eligible to perform the diagnostic muscle biopsy. Please see our list of eligible centers.


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