Malignant Hyperthermia

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Malignant Hyperthermia

• Michael Watts
• 9/19/05

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Case

• KL is a 13y/o WF here for Right Radius/Ulna ORIF
• In review of history pt. is found to have a hx of
  malignant hyperthermia
• No other problems

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History

• Pt. has hx of hyperthermia as reported by mother
• At age 8 during tonsillectomy pt. developed high
  fever, vomiting, and hallucinations
• Hospitalized for 4 days
• Mother has positive biopsy for MH

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Malignant Hyperthermia
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Malignant Hyperthermia

• Sustained contraction of muscle in response to
  anesthetic drugs
• 1/15000 peds 1/50000 adults
• Many unaware
• 50 have fam hx of MH

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Pathophysiology

• Calcium channels in muscle
• Alters hydrophilic amino-terminal portion of
  ryanodine receptor
• Efflux of Calcium from Sarcoplasmic Reticulum
• Muscle tetany

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Clinical Manifestation

• Hypercarbia (most sensitive)
• Tachycardia
• Tachypnea
• Hyperthermia (late manifestation)
• HTN
• Dysrhythmias
• Acidosis
• Hypoxemia
• Hyperkalemia
• Skeletal Muscle rigidity (masseter muscles)
• Myoglobinuria

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Signs

• Early sign uexplained sinus tachycardia
• Resp/Met Acidosis
• Transient dilation of vascular smooth muscle
• Vascular spasm cyanosis irreversible
• Hyperthermia secondary to increased heat
  production and decreased loss

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What to do?

• 1. Call for help
• 2. Stop triggering agent
• 3. Hyperventilate with 100 O2
• 4. Finish or abort procedure
• 5. Administer Dantrolene
• 6. Cool patient (cool saline, cooling blanket,
  ice bags, nasogastric lavage)
• 7. Change to a clean circuit

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What to do?

• 8. Monitor and treat acidosis
• 9. Promote Urine Output
• 10. Treat hyperkalemia
• 11. Treat dysrhythmias (procainamide, CaCl)
• 12. Monitor Creatine Kinase, urine myoglobin,
  coagulation

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Dantrolene

• Dantrolene blocks calcium release from
  sarcoplasmic reticulum

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What did we do for our case?

• Avoid agents causing MH
• Avoid Succinylcholine, volatile gases
• Remove vaporizers
• Flush machine with O2 for 10 min
• Keep cooling blanket / cool saline / dantrolene
  on hand
• MH cart

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Our case

• Propofol for induction
• Nimbex for paralysis
• Nitrous Oxide for maintenance
• Case was uneventful
• Monitored in PACU, AFVSS

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Sniffing Position