Malignant Hyperthermia

DR. ABDUL AZIZ AL HAZAZIRESIDENT IN ANAESTHESIA AND CRITICAL CARE

SUPERVISED BY

DR. DJURBERG HANSSENIOR CONSULTANT ANAESTHETIST

MALIGNANT HYPERTHERMIA

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Goals and Objectives

DefinitionIncidenceAetiologyClinical presentationTriggering and safe agentsManagement of MH crisisAnaesthesia for MH-susceptible patientsConclusion

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Definition MH was first described by Dr Michael Denbo-rough in 1960. It is an acute hyper-metabolic state. Susceptible patients when exposed to a triggering agent. reduction in the reuptake of calcium by the sarcoplasmic reticulum

◦ Acidosis, ◦ Tachycardia◦ Hypercarbia◦ Qlycolisis ◦ Hypoxemia, ◦ Heat production (hyperthermia).

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Incidence Incidence is about 1 in 10–15 000.

◦ 1: 40,000 in Adults◦ 1:15,000in Children

Previously mortality (70–80%). Young adults, especially males. Minor surgical procedures

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Changes in Incidence Education ETCO2

Dantrolene

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Aetiology Genetically related and inherited disease. Ryanodine receptor gene deficiency on chromosome 19

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Clinical Presentation No one sign is unique to MH. The clinical signs:

◦ Muscle rigidity ◦ Hyperkalemia ◦ High CK◦ Myoglobinurea ◦ Tachycardia ◦ Increased CO2 ◦ Metabolic acidosis

An unexplained increase in ETCO2 and a concomitant tachycardia. (Important to exclude other more common causes) Masseter muscle spasm (early warning sign) Increase in temperature (late sign)

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Signs of Fulminant MH Episode

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Triggering AgentsInhalation Anaesthetic Agents Choroform (Trichloromethane, Methyltrichloride) Desflurane Enflurane Halothane Isoflurane Methoxyflurane Sevoflurane Trichloroethylene Xenon (Rarely Used)

Depolarizing Muscle Relaxants Succinylcholine (Suxamethonium)

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Safe Agents

Barbiturates / Intravenous Anesthetics Diazepam Etomidate (Amidate) Hexobarbital Ketamine (Ketalar) Methohexital (Brevital) Midazolam Propofol (Diprivan) Thiopental (Pentothal)

Inhaled Non-Volatile General Anesthetic: Nitrous Oxide

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Safe Agents

Local Anaesthetics: Amethocaine Articaine Bupivicaine Dibucaine Etidocaine Lidocaine (Xylocaine) Levobupivacaine Mepivicaine (Carbocaine) Procaine (Novocain) Prilocaine (Citanest) Ropivacaine

Narcotics (Opioids): Alfentanil (Alfenta) Codeine (Methyl

Morphine) Fentanyl (Sublimaze) Hydromorphone (Dilaudid) Meperidine (Demerol) Methadone Morphine Naloxone Oxycodone Remifentanil Sufentanil (Sufenta)

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Safe Agents

Safe Muscle Relaxants: Arduan (Pipecuronium) Curare (The active ingredient is Tubocurraine) Gallamine Metocurine Mivacron (Mivacurium) Neuromax (Doxacurium) Nimbex (Cisatracurium) Norcuron (Vecuronium) Pavulon (Pancuronium) Tracrium (Atracurium) Zemuron (Rocuronium)

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ABCs of Managing Malignant

Hyperthermia

A Ask about personal and family past history of MH or Adverse Anaesthesia reactions Be Aware of clinical signs of MH.

B Body temperature monitoring

C Capnographic monitoring

D Dantrolene

ABCs of Managing Malignant Hyperthermia

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Intra-operativeA Awareness

Airway

B Breathing Body temperature high (late sign).

C Capnography Circulation: cardiac arrhythmias, tachy/bradycardia, hyper/hypotension.

D Drugs (succinylcholine, potent halogens)?

E Exposure/ Examine the patient: skin color, perfusion, temperature, urine color, extremities, muscle tone.

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Emergency Treatment Ask for Help. Ask for the MH cart and for dantrolene. Stop anesthesia triggering agents and the surgery. Hyperventilate with 100% oxygen. Cooling, if the patient is hot: insert large intravenous bore

catheters. Call MH Hotline:

1-800-644-9737 or 1-315-464-7079 DANTROLENE: give dantrolene IV, 2.5 mg/kg, and repeat the dose

until the signs are controlled. Check Electrolytes, especially potassium.

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Dantrolene for MH Crisis

20 mg/60 ml (sterile water) = 1 mg/3ml 70 kg patient:

2.5 mg/kg = 175 mg or 525 ml (9 vials)

~10 mg/kg = 700 mg or 2100 ml (35 vials)

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Secondary TreatmentA Acidosis?

B Bicarbonate?

C Circulation/monitoring

D Dysrhythmias

E Electrolytes

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Cont…F Follow up:

A: ABG

B: Body temperature (core)

C: CO2(end tidal), CK, Coagulation tests.

D: Diuresis

E: Electrolytes.

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Anaesthesia for MH-susceptible patient

A Anesthesia machine preparation Anesthesia

B Body temperature monitoring.

C Capnography

D Dantrolene Discharge, if no problems, after 2.5 hours.

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Timeline of patient injury Within minutes…

◦ Death from hyperkalemia induced arrhythmia Within hours…

◦Death from DIC and/or MOSF Within days…

◦Rhabdomyolysis induced Renal failure◦Cerebral edema / Coma

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Conclusion

MH is a potentially lethal genetic disorder. Mortality rate is >70% without treatment (DANTROLENE) !!! With treatment mortality < 5% Pattern of clinical signs are consistent but individual signs are non-

diagnostic Need high index of suspicion when patients develop

hyperdynamic/hypermetabolic signs.

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