Equis ISSN 2398-2977

Malignant hyperthermia

Contributor(s): David Brunson, Graham Munroe

Introduction

  • Malignant hyperthermia is a clinical syndrome.
  • Cause: suspected genetic abnormality of skeletal muscle consistent with known channelopathies in swine, dogs and people. Triggering factors include volatile anesthetic agents, succinylcholine and environmental factors, eg stress.
  • Signs: tachypnea, progressive increase in end-tidal and arteria CO2 despite controlled ventilation, hypertension, tachycardia and elevated body temperature, intra-operative arrhythmias (PCVs) and post-operative myositis (hard muscles).
  • Diagnosis: history and clinical signs.
  • Treatment: remove inciting stimulus, reduce temperature +/- administration of dantrolene sodium solution.
  • Prognosis: good if treated early; high mortality if not rapidly diagnosed and treated - recurrence likely with re-exposure to inciting stimulus.

Pathogenesis

Etiology

  • Evidence of similar disorders in 3 other species suggests possible genetic predisposition.

Predisposing factors

General

Specific

  • Possibly linked to other genetic disorders of muscle.

Pathophysiology

  • Clinical signs believed to be the result of inappropriate release of calcium by the sarcoplasmic reticulum of muscle tissue.
  • This causes muscle contraction and heat production.

Timecourse

  • Timecourse can vary from minutes to hours following precipitating factor.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Aleman M, Brosnan, R J et al (2005) Malignant hyperthermia in a horse anesthetized with halothane. J Vet Intern Med 19 (3), 363-367 PubMed.

Other sources of information

  • Colahan P T, Mayhew E D, Merritt A M & Moore J N (1999) Eds. Equine Medicine and Surgery. Vol II. 5th edn. Mosby. ISBN: 0815117434.


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