MH

Question 1

Masseter Muscle Spasm: What would you want to know?

Answer 1

Circumstances
- Type of anesthesia
- Severity, treatment, subsequent workup
- Review record
Family history of anesthesia complications

Question 2

Masseter Muscle Spasm: What would you do?

Answer 2

Significant (jaws of steel, intense & prolonged)

• D/C triggering agents
• Cancel case if elective
• Secure airway (ETT, nasal intubation, surgical airway)
• Immediately initiate MH treatment
• Monitor 12-24 hrs

Less intense and short in duration
- Continue case using non-triggering agents and careful monitoring

*30-50% MH susceptibility

Question 3

MH: Signs

Answer 3

Early:
1. Increased EtCO2
2. Tachycardia/Tachypnea
3. Mixed acidosis
4. Masseter spasm/trismus
Later:
1. Hyperthermia
2. Muscle rigidity
3. Myoglobinuria
4. Arrhythmias
5. Cardiac arrest

Question 4

MH: What Would You Do?

Answer 4

1. Get help. Get MH cart/Dantrolene. Notify surgeon.
   - Discontinue triggering agents
   - Hyperventilate w/ 100% O2, high flow 10 L/min
   - Halt procedure if possible
2. Rapidly give Dantrolene or Ryanodex 2.5 mg/kg, continue giving until patient stable
3. Bicarb for metabolic acidosis
4. Cool if core temp >39
5. Dysrhythmias
6. Hyperkalemia - hypervent, bicarb, glucose/insulin, calcium
7. Labs: ABG, potassium, CK, urine myoglobin, coags, lactate
8. Monitor UO (1-2 mL/kg/hr)
9. Arrange ICU bed, continue Dantrolene/Ryanodex x24 hrs

Question 5

MH: DDx

Answer 5

Light anesthesia
Hypoventilation
Hypoxemia
Insufflation of CO2
Over-heating (external)
Thyroid storm
Pheochromocytoma
NMS
Serotonin syndrome