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Malignant Hyperthermia

- Discussion:
    - malignant hyperthermia of anesthesia is autosomal dominant condition;
    - it is rare disorder that appears to involve excessive release of calcium from sarcoplasmic reticulum in response to anesthetic agents;
    - neuromuscular pts (eg DMD), esp those with  are more susceptible to malignant hyperthermia, a chemically induced genetic myopathy;
    - malignant hyperthermia may occur w/ use of succinylcholine & halothane;
    - dx requires a muscle biopsy, the caffeine-halothane contracture test remains the best way to screen for susceptibility;

- Clinical Manifestations:
    - severe muscular rigidity and rhabdomyolysis;
    - body temperature rises, often at an alarming rate;
    - hypotension, profuse tachycardia and other arrhythmias, hypoxia, hypercapnia;

- Labs:
    - metabolic acidosis (lactic acidosis), hyperkalemia, and DIC;
    - elevated CPK

- Treatment:
    - prompt treatment of malignant hyperthermia is esstential;
    - body temp may be lowered w/ cooling blanket, iced IV, & ice packs;
    - intermittent ABG and bicarbonate as appropriate for metabolic acidosis;
    - insulin and glucose are provided as appropriate for hyperkalemia;
    - Dantrolene: 1 mg/kg/min upt 10 mg/kg/min;
            - continue until all symptoms have resolved for 6 hours;
    - r/o coagulopathy;
    - beware of myoglobinuria and resulting renal failure; (see rhabdomyolysis)

Malignant hyperthermia.  

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