Malignant Hyperthermia

Malignant Hyperthermia is one of the most devastating anesthesia related complications.  It is a pharmacogenetic clinical syndrome that in its classical form. occurs during anesthesia with volatile halogenated alkanes such as halothane. isoflurance/ desflurance, and /or muscle relaxant like succinylcholine.

The Fulminant malignant hyperthermia produce muscle hypermetabolism with rapidly increasing body temperature by as much as 1ºC in 5 minutes ,and extreme acidosis as a result of acute loss of control of intracellular ionized calcium.

About 50-80% of the genotyped patients had their disease linked to the RyR1 gene and L-type Ca2t channel

 

EARLY SIGNS

  • Elevated end-tidal CO2
  • Tachynea and/or Tachycardia
  • Masseter Spasm(with succinylcholine)
  • Generalized muscle rigidity
  • Metabolic+ Respiratory acidosis
  • Profuse sweating
  • Mottling of skin
  • Cardiac Arrchythmias
  • Unstable blood pressure

LATE SIGNS

  • Hyperkalemia
  • Rapid ↑ in cone Body Temp
  • ↑ creatine phosphokinases
  • Myoglobinemia
  • Myoglobinuria
  • Cardiac Arrest
  • DIC

 

 

Treatment of Malignant Hyperthermia

  1. Discontinue all triggering agents.
  2. Hyperventilate with 100% Oxygen with a fresh flow to atleast 10 L/min.
  3. IV Dantrolene 2.5mg/kg to a total dose of 10mg/kg every 5-10 minutes until symptoms subside.
  4. Bicarbonate (1-4 mEq/Kg IV) to correct metabolic acidosis.
  5. Fever control: Iced fluids, cooing body surface, and if necessary, use a heat exchanger with a pump Oxygenator cooling should be halted at 38ºC to prevent inadvertent Hypothermia.
  6. Monitor and treat arrhythmias
  7. Maintain urinary output >1-2ml/kg/h
  8. Hyperkalemia if present, treat with bicarbonates ,glucose, and insulin (10U of regular insulin and 50ml of 50% Dextrose)
  9. Analyze coagulation studies, blood gases, temperature, muscle tone, electrolytes, urine output, CK
  10. Once initial reaction is controlled, continue monitoring  in the ICU for 24-48 hours

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