malignant hyperthermia

Question 1

What is Malignant Hyperthermia?

Answer 1

 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

Question 2

his faulty metabolism causes dangerous

Answer 2

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

Question 3

Symptoms of malignant hyperthermia

Answer 3

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

Question 4

Known chemical MH triggers

Answer 4

isoflurane,sevoflurane, desflurane, anectine

Question 5

not MH triggers

Answer 5

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

Question 6

MH Epidemiology

Answer 6

Reports vary from 1:5000-1:100,000 anesthetic procedures

 Occurs in all races & ethnicities`

Question 7

MH mortality

Answer 7

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

Question 8

MH Mortality

 Median age in cases of U.S. deaths

Answer 8

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

Question 9

Clinical Signs of MH

 Specific

Answer 9

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

Question 10

clinical signs of MH  Non-Specific

Answer 10

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

Question 11

 Fulminant MH

Answer 11

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

Question 12

Masseter Muscle Rigidity (MMR):

Answer 12

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

Question 13

Late Onset MH:

Answer 13

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

Question 14

MMR prognostic indicator

Answer 14

Patients with a history of MMR post-anesthetic induction

have a 25-30% chance of having Fulminant MH during their next anesthetic!

Question 15

Other prognostic indicators

Answer 15

 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

Question 16

Why does MH occur?

Answer 16

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

Question 17

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

Answer 17

 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

Question 18

Dantrolene

Answer 18

(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