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Flashcards in malignant hyperthermia Deck (18):
1

What is Malignant Hyperthermia?

 MH is an autosomally dominant disorder of skeletal muscles.
 Calcium that’s stored in skeletal muscle is released inappropriately causing muscles to contract & stiffen simultaneously. extensor stronger than flexor. go into extension during seizure

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his faulty metabolism causes dangerous

hyperthermia, skeletal muscle breakdown (rhabodmyolysis), run-away hypermetabolism, acidosis, flushed skin, myoglobinuria (what’s this?) oxygen store in muscle, hypotension, and death

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Symptoms of malignant hyperthermia

typically appear within one hour (but can be delayed up to ~12 hours)
 Most cases occur in children and young adults <30 years old

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Known chemical MH triggers

isoflurane,sevoflurane, desflurane, anectine

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not MH triggers

-Intravenous anesthetics (including Propofol) -Opiates -Non-depolarizing muscle relaxants -Ketamine
-Sedatives and Tranquilizers.

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MH Epidemiology

Reports vary from 1:5000-1:100,000 anesthetic procedures
 Occurs in all races & ethnicities`

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MH mortality

International mortality data on MH ranges from 1.4%- 20.0% which appears to be based entirely on the speed of MH diagnosis and therapy initiation!
MH Mortality

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MH Mortality
 Median age in cases of U.S. deaths

20 yrs. A “muscular build” was identified as having a high predictive
value for increased morbidity and mortality
 Again, retrospective analysis identified preparedness by the medical team as a major positive prognostic indicator. time is trauma

9

Clinical Signs of MH
 Specific

 Muscle Rigidity
 Dramatically increase CO2 production
 Rhabdomyolysis  Profound hyperthermia

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clinical signs of MH  Non-Specific

 Tachycardia
 Tachypnea  Acidosis (both respiratory &
metabolic)  Hyperkalemia

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 Fulminant MH

(most common): muscular rigidity, extreme hyperthermia, tachycardia. Typically occurs shortly after anesthetic induction

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Masseter Muscle Rigidity (MMR):

profound jaw muscle rigidity after succinylcholine administration; may be an early sign of MH

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Late Onset MH:

(uncommon): Occurs within the first hour of anesthetic termination

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MMR prognostic indicator

Patients with a history of MMR post-anesthetic induction
have a 25-30% chance of having Fulminant MH during their next anesthetic!

15

Other prognostic indicators

 Patients with muscular disorders such as muscular dystrophy, various “myotonias”, Duchenne’s Disease, Becker’s Disease, etc. are at much greater risk of Fulminant MH and shouldn’t receive succinylcholine

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Why does MH occur?

A mutation in the ryanodine receptor gene (RYR1) in skeletal muscles affects the muscles’ ability to properly utilize calcium.

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Treatment of acute MH. KNOW!!!!!!!!!!!!!

 Immediately discontinue volatile gas anesthetics and succinylcholine administration
 Hyperventilate with 100% oxygen (+/- change out gas tubing)
 Give 1-2 mg/kg bicarbonate  Give Dantrolene at a dose of 2.5mg/kg IV push and
repeat PRN
Cool patient
 Treat arrhythmias but DO NOT GIVE CALCIUM CHANNEL BLOCKERS!!!
 Monitor coagulation and electrolytes (why?) acidosis and K will be hyped up

18

Dantrolene

(Dantrium)
Dantrolene blocks the release of calcium from skeletal muscle’s sarcoplasmic reticulum which prevents the pathologically massive, prolonged release of calcium through the RYR1 channels which is the etiology of Fulminant MH