Malignant Hyperthermia

Question 1

What is MH? Why does it happen?

Answer 1

A hyper metabolic disorder of skeletal muscle with varied presentation-multiple modes of inheritance, but all have a presumed defect in calcium release channels

Question 2

Possible associations (diseases where someone could have MH)

Answer 2

Osteogenesis imperfecta
Myelomeningocele
History of heat, stress, or exercise induced rhabdomyolysis

Question 3

Testing for MH:

Answer 3

ryanodine contracture test using a skeletal muscle biopsy?

Question 4

Triggers for MH: What’s safe?

Answer 4

Succinylcholine and inhalation agents-local anesthetics and all that other stuff (propofol, etomidate, Benzes) are safe

Question 5

Can MH happen post op?

Answer 5

Yes. It typically develops within 10 minutes to hours after the beginning of the anesthetic.

Question 6

Early signs of MH:

Answer 6

Tachycardia not otherwise explainable is the first sign
Tachypnea (seen in spon. breathing patients)
End tidal CO2 concentrations increasing despite proper ventilation and adequate fresh gas flows-this is one of the earliest and most sensitive/specific sign s
PaCO2 increases to 100-200
Metabolic respiratory acidosis (7.14-6.80)
Hyperkalemia and peaked T waves on EKG
Unstable BP

Question 7

Intermediate signs of MH

Answer 7

Core body temp increases 1-2 degrees every 5 min
Sweating and flushing
cyanosis and a decrease in oxygen saturation
skin mottling
dark blood secondary to increased plasma myoglobin

Question 8

Late signs of MH:

Answer 8

Muscular rigidity
CK concentrations elevated >1,000
Hypercalcemia
pulmonary edema
acute renal failure 
CNS damage-seizures

Question 9

What will the blood gas show in MH

Answer 9

Metabolic and respiratory acidosis without marked oxygen desaturation)

Question 10

How to prepare the anesthesia machine for MH:

Answer 10

Ensure vaporizers are disabled by removing or taping them in the off position
Change CO2 absorbent
Set O2 flow to 10L/min for 20 minutes
Attach a clean, disposable circuit

Question 11

After an uneventful anesthetic in a MH risk patient, then what:

Answer 11

Can be released if no signs after 15 min vital sign monitoring (for an hour), and 1.5 hours of phase 2 PACU monitoring

Question 12

KO Treatment plan for MH: 13 steps 
Dose of dantrolne? 
Goal temp? 
How to tx hyperkalemia? 
How to tx arrhythmias?

Answer 12

1. Call for help, ask for MH cart, and call MH hotline-1800 MH HYPER
2. Discontinue all triggering agents
3. Change to a clean circuit not exposed to volatile anesthetic agents, using a new clean anesthesia machine or an oxygen tank with an Ambu bag
4. Hyperventilate with 100% O2
5. Start dantrolene 2.5 mg/kg bolus every 5 min up to 10 mg/kg and then start an infusion of 1-2 mg/kg/hr
6. Monitor and treat acidosis. Give IV sodium bicarbonate 1-2 mEq/kg guided by pH
7. Cool patient aggressive with cooling blankets, cold IV NS, ice bags. Goal is to get temp to 38-39 degrees Celsius
8. monitor UOP with a Foley catheter. Goal urine is 1-2 mL/kg/hr (use fluids, furosemide, and mannitol 0.25 gm/kg/IV
9. Send off labs-Art/ven blood gas, electrolytes, hepatic function, coat panel, CK, glucose and urine myoglobin. Follow these labs for 24-48 hours
10. Treat hyperkalemia with 0.1-0.2 U/kg of regular insulin and 500 mg/kg of dextrose IV, calcium, or bicarbonate
11. Treat arrhythmias with amiodarone, lidocaine, adenosine, procainamide. do NOT use CCBs.
12. Have surgeon stop surgery or expedite it.
13. Consider placement of arterial line and CVC

Question 13

What is the base deficit?

Answer 13

A base deficit indicates an excess of acid. It refers to the amount of base needed to titrate a serum pH back to normal

Question 14

Post op in a patient with an MH episode:

Answer 14

Alkalinize urine***
Follow CK levels and other labs (electrolytes, liver panel, coats), watch for DIC, follow CNS function
Continue dantrolene 1 mg/kg IV for 4-6 hours for up to 72 hours after MH episode.
submit forms to the registry. Monitor patient for up to 72 hours in ICU