MH Signs and Symptoms

MH can be difficult to diagnose.

Know who is susceptible:

Download the MH Management Guide

Malignant Hyperthermia may occur in any patient, including patients who have previously had uneventful general anaesthesia.
Not all need to be present to initiate treatment

MH is more likely with: Diagnosed malignant hyperthermia susceptibility after halothane / caffeine contracture test on biopsied muscle, Malignant Hyperthermia susceptible relatives, Significantly & consistently raised resting serum CK, Several very rare muscle disorders.

Know the signs & symptoms:

Early:

  • Prolonged Masseter spasm after suxamethonium – unable to open mouth
  • Inappropriately raised end tidal carbon dioxide or tachypnoea during spontaneous respiration
  • Inappropriate tachycardia
  • Cardiac arrhythmias particularly developing ventricular ectopic beats

Developing:

  • Rapid rise in temperature (0.5oC per 15 min)
  • Progressive respiratory and later metabolic acidosis (ABG)
  • Hyperkalaemia
  • Profuse sweating
  • Cardiovascular Instability
  • Decreased SpO2  or Mottling of skin
  • Generalised Muscular rigidity

Late:

  • “Cola” coloured urine – due to myoglobinuria
  • Generalised Muscle Ache
  • Grossly raised serum CK
  • Coagulopathy
  • Cardiac Arrest

Differential Diagnoses:

  • Inadequate anaesthesia
  • Machine malfunction
  • Sepsis or infection
  • “Thyroid Storm”
  • Ecstasy or other recreational drugs
  • Phaeochromocytoma
  • Neuroleptic Malignant Syndrome
  • Intracerebral infection or haemorrhage

An arterial blood gas is the single most useful investigation to perform