• An increase in heart rate is usually the earliest and most consistent sign to be detected. An increase in end-tidal CO2 is usually the most sensitive sign in detecting malignant hyperthermia. While increase temperature and muscle rigidity are hallmark signs of malignant hyperthermia, these manifestations are less sensitive and may not present as early as the tachycardia and elevated end-tidal CO2. Masseter muscle rigidity should be distinguished from skeletal muscle rigidity and occurs early.
  • Earliest sign: tachycardia
  • Most sensitive sign: increase end tidal CO2
  • Hallmark sign: increase in temperature, muscle rigidity
  • Treatment: cardiac arrhythmias with procainamide at an initial dose of 100mg IV. Hyperkalemia treated with regular insulin 10 units IV together with 1 amp of D50, and sodium bicarbonate to help drive potassium intracellularly
  • Etiologic treatment of an MH episode requires dantrolene at an initial dose of 2-3 mg/kg. Cardiac dysrrhythmias should be treated by procainamide at an initial dose of 100mg IV. Management of hyperkalemia to correct the arrhythmia can be achieved with regular insulin 10 units IV together with 1 amp of D50, as well as sodium bicarbonate to help drive potassium intracellularly. Calcium channel blockers such as cardizem are contraindicated because they can cause severe myocardial depression in the presence of dantrolene.