Pharm 21- Malignant Hyperthermia

Question 1

What is malignant hyperthermia?

Answer 1

Autosomally dominant disorder of skeletal muscles
Calcium that is stored in skeletal muscle is released inappropriately causing muscles to contract and stiffen simultaneously

Question 2

Rhabdomyolysis

Answer 2

Skeletal muscle breakdown

Question 3

Faulty metabolism causes what?

Answer 3

Hyperthermia 
Rhabdomyolysis
Run-away hypermetabolism
Acidosis
Flushed skin
Myoglobinuria
Hypotension
Death

Question 4

Hematuria

Answer 4

Cloudy whole blood

Question 5

Hemoglobinura

Answer 5

Only the hemoglobin gets filtered out through kidneys; urine bright red but no cells there

Question 6

How soon do symptoms appear?

Answer 6

Within 1 hour (but can be delayed up to 12 hours)

Question 7

What patient population has the most cases?

Answer 7

Children and young adults < 30 years old

Question 8

What are some known chemical MH triggers?

Answer 8

Volatile Gas and Sux

Question 9

What are not MH triggers?

Answer 9

Intravenous anesthetics (including propofol)
Opiates
Non-depolarizating muscle relaxants
Ketamine
Sedatives and tranquilizers

Question 10

How many anesthetic procedures have MH?

Answer 10

1:5000 - 1:100,000 cases

Question 11

What races does it occur?

Answer 11

All races and ethnicities

Question 12

International Mortality data on MH ranges from what? What is this based on?

Answer 12

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

Question 13

Mean age of cases in US deaths

Answer 13

20

Question 14

What has a high predictive value for increased morbidity and mortality?

Answer 14

“Muscular Build”

Question 15

What is a major positive prognositic indicator?

Answer 15

Preparedness by the medical team

Question 16

Specific Clinical Signs of MH

Answer 16

Muscle Rigidity
Dramatically increase co2 production
Rhabdomyolysis
Profound hyperthermia

Question 17

Non-specific Clinical Signs of MH

Answer 17

Tachycardia
Tachypnea
Acidosis (respiratory and metabolic)
Hyperkalemia

Question 18

MH Clinical Presentations

Answer 18

Fulminant MH
Masseter Muscle Rigidity (MMR)
Late onset MH

Question 19

Fulminant MH

Answer 19

Most common; muscular rigidity extreme hyperthermia, tachycardia. Typically occurs shortly after anesthetic induction

Question 20

Masseter Muscle Rigidity (MMR)

Answer 20

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

Question 21

Late Onset MH

Answer 21

Uncommon; occurs within the first hour of anesthetic terminiaton

Question 22

Patients with a history of MMR post-anesthetic induction have what percent change of having Fulminant MH during their next anesthetic?

Answer 22

25-30 %

Question 23

What are other prognositc indicators?

Answer 23

Patients with muscular disorders: muscular dystrophy, myotonias, Duchennes Disease, becker’s disease, are at much greater risk of FUlminant MH and shouldn’t receive SUX

Question 24

Why does MH occur?

Answer 24

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

Question 25

Treatment of Acute MH ***

Answer 25

Immediately discontinue volatile gas anesthetics and succinylcholine administraiotn
Hyperventilate with 100% oxygen (+/- change out gas tubing)
Give 1-2 mg/kg Bicarb
Dantrolene: 2.5 mg/kg IV push PRN
Cool patient
Tx arrhythmias but don’t give Na channel blockers
Monitor coag and electrolytes

Question 26

Dantrolene (Dantrium)

Answer 26

Blocks 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