Topic 21: Malignant Hyperthermia

Question 1

What kind of disorder is MH?

Answer 1

autosomally dominant disorder of skeletal muscles.
Calcium that’s stored in skeletal muscle is released inappropriately causing muscles to contract & stiffen simultaneously

Question 2

When Ca that is stored in skeletal muscle is released – causing muscles to contract and stiffen – what Dangerous/Negative things can happen?

Answer 2

This faulty metabolism causes dangerous
hyperthermia, skeletal muscle breakdown (rhabodmyolysis), run-away hypermetabolism, acidosis, flushed skin, myoglobinuria (what’s this?), hypotension, and death

Question 3

When do symptoms of malignant hyperthermia typically appear ?

Answer 3

within one hour (but can be delayed up to ~12 hours)

Question 4

What age range is most cases of MH?

Answer 4

children and young adults - <30yo
Median age in cases of U.S. deaths was 20 years
A “muscular build” was identified as having a high predictive value for increased morbidity and mortality

Question 5

Known chemical triggers of MH? (4)

Answer 5

Forane, Sevoflurane, Supranem Anectine

Question 6

NOT chem triggers of MH?

Answer 6

Intravenous anesthetics
Opiates
non-depolarizing muscle relaxants
Ketamin
sedatives and tranquilizers

Question 7

International mortality data on MH ranges %%? based on what??!!

Answer 7

1.4%-20.0% which appears to be based entirely on the speed of MH diagnosis and therapy initiation! !!

Question 8

Clinical Signs of MH - Specific (4)

Answer 8

Muscle Rigidity
Dramatically CO2 production
Rhabdomyolysis
Profound hyperthermia

Question 9

Clinical Signs of MH - NonSpecific (4)

Answer 9

Tachycardia
Tachypnea
Acidosis (both respiratory & metabolic)
Hyperkalemia

Question 10

Masseter Muscle Rigidity (MMR):

Answer 10

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

Question 11

MMR

Answer 11

Masseter Muscle Rigidity

Question 12

Fulminant MH:

Answer 12

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

Question 13

Late Onset MH:

Answer 13

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

Question 14

MMR prognostic indicator

Patients with a history of MMR post-anesthetic induction have a ___ chance of having _____ during their next anesthetic!

Answer 14

25-30%

Fulminant MH

KNOW

Question 15

Why does MH occur? mutation in what??????

Answer 15

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

Question 16

Treatment of MH- DANTROLENE DOSE???

Answer 16

Give Dantrolene at a dose of 2.5mg/kg IV push and repeat PRN

Question 17

Treatment of MH - what do you do with arrhythmias?

Answer 17

Treat arrhythmias but DO NOT GIVE CALCIUM CHANNEL BLOCKERS!!!

Question 18

Treatment of MH – what to do with the gas situation?

Answer 18

Immediately discontinue volatile gas anesthetics and succinylcholine administration
Hyperventilate with 100% oxygen (+/ -change out gas tubing)

Question 19

Treatment of MH – What drugs do you give??

Answer 19

Give 1-2 mg/kg bicarbonate

Give Dantrolene at a dose of 2.5mg/kg IV push and repeat PRN

Question 20

Treatment of MH - Temp of patient ?

monitor what?

Answer 20

Cool Patient

Monitor coagulation and electrolytes

Question 21

Dantrolene — how does it work????

Answer 21

(Dantrium)
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

Question 22

Malignant Hyperthermia – WIKIPEDIA definition

Answer 22

Malignant hyperthermia (MH) or malignant hyperpyrexia[1] is a rare life-threatening condition that is usually triggered by exposure to certain drugs used for general anesthesia, specifically the volatile anesthetic agents and the neuromuscular blocking agent, succinylcholine. In susceptible individuals, these drugs can induce a drastic and uncontrolled increase in skeletal muscle oxidative metabolism, which overwhelms the body’s capacity to supply oxygen, remove carbon dioxide, and regulate body temperature, eventually leading to circulatory collapse and death if not treated quickly.