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

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