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MALIGNANT HYPERTHERMIA

MALIGNANT HYPERTHERMIA. Malignant Hyperthermia Objectives. MH. Things to know and do: Participants will:. MH. 1. be able to explain the: pathophysiology, clinical presentations, testing for and management of malignant hyperthermia and the MHS patient.

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MALIGNANT HYPERTHERMIA

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  1. MALIGNANT HYPERTHERMIA

  2. Malignant Hyperthermia Objectives MH Things to know and do: Participants will: MH 1. be able to explain the: pathophysiology, clinical presentations, testing for and management of malignant hyperthermia and the MHS patient 2. be able to explain the significance of MMR and its management. 3. keep MH somewhere in mind as they monitor patients, and not hesitate to give dantrolene. 4. easily correctly answer the questions in the MH Quiz.

  3. Malignant Hyperthermia MH MH “If any institution does not feel it can manage the MHS child then they should not be anaesthetising any children at all, since it is not the identified child with a nontriggering technique who will cause grief, but the undiagnosed child given a trigger.” Helen Holtby M.B.,B.S. Director of Cardiovascular Anaesthesia Hospital for Sick Children Toronto, Canada PAC List, 10 Dec 04

  4. MH pharmacogenetic hypermetabolic state of skeletal muscle induced by inhalational anesthetics or succinylcholine (and maybe stress/exercise) MH

  5. MH MH Drugs + Genes = Pharmacogenetic

  6. Historical MH MH MH 1960 Denborough and Lovell 1960’s families and pigs Gordon (?) calls it Malignant Hyperthermia 1975 dantrolene saves pigs 1979 FDA approves dantrolene 1980’s muscle biopsy for HCCT 1990’s genetic markers/RYR1

  7. MH MH halothane enflurane isoflurane desflurane sevoflurane

  8. MH MH 200,000 1 (without sux)

  9. MH MH SUX

  10. MH MH 60,000 1 (with sux)

  11. Incidence - Current Concepts Clinically based information: One in 20,000 to 50,000 anesthetics depending on drugs, population Molecular Genetics based information: MH trait in 1 in 2,000-3,000 patients. Low penetrance

  12. MH MH

  13. Normal excitation-contraction coupling MH MH ACh at NMJ depolarizes sarcolemma SR (RYR) releases Ca Ca + troponin actin-myosin slide ATP hydrolyzed SR (RYR?) re-uptake of Ca

  14. MH MH

  15. RYR1 MH MH ryanodine receptor Ca release channel protein (5,032 amino acids) connects SR to T-tubules Ca gate from SR chromosome 19, region 13.1

  16. Excitation-contraction coupling in MH MH MH Defective RYR Ca release channel Too much free intracellular calcium

  17. Too much free Ca MH MH ATP depletion lactic acidosis VO2way up Too much CO2 myonecrosis/rhabdomyolysis/↑↑K myoglobinemia/uria/renal failure

  18. Diagnosis of MH MH MH tachycardia + tachypnea + ETCO2 increasing + metabolic acidosis = MH = dantrolene IV

  19. HCCT for MH MH MH vastus muscle 2-3 months after MH episode nontriggers no dantrolene gentle handling of muscle test within 5 hours About $6,000

  20. Guidelines for Molecular Genetic Testing • Determine MHS by HCCT • If MH positive , screen for known mutation • If mutation positive, test other family members for the mutation • If mutation negative, cannot screen family for mutations or determine MH status

  21. Treatment of an acute episode of MH MH Stop triggers 100% oxygen 10L/min Dantrolene 3 mg/kg To 10 mg/kg Rx metabolic acidosis, HCO3 Cool, iced NS IV Rx dysrhythmias, hyperkalemia Monitor ETCO2, ABGs, K, UOP, clotting tests MH

  22. MH MH verapamil + dantrolene = severe hyperkalemia + myocardial depression

  23. MH MH dantrolene

  24. 5 year-old boy MH MH for T&A halothane induction succinylcholine jaw “stiff” for 3 minutes then relaxed

  25. MH MH

  26. Masseter muscle rigidity (MMR) MH MH amyotonic mytonia temporomandibular joint (TMJ) dysfunction not enough succinylcholine not enough time

  27. The stiff jaw MH subclinical: normal interferes with intubation: 1-3% of children “jaws of steel”: true MMR 50% MHS MH Kaplan

  28. MMR Rosenberg MH MH cancel elective dantrolene 1-2 mg/kg observe overnight (myoglobinuria, fever, hyperkalemia, CPK) muscle biopsy strongly considered

  29. MMR Gordon MH MH AVOID SUX

  30. Malignant hyperthermia susceptible (MHS) patient A safe plan MH MH prepare to treat MH use safe drugs be happy

  31. 7 year-old girl MH MH preop for T&A needles terrify her history of hernia repair: fever and stiff jaw went for muscle biopsy: normal

  32. Malignant hyperthermia susceptible (MHS) patient A safe plan MH MH prepare to treat MH use safe drugs be happy

  33. Malignant Hyperthermia For more information MH MH MHAUS MetroHealthAnesthesia.com Lesson Quiz

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