Advanced Practice: Respiratory Failure in Myasthenia Gravis Crisis
- As many as 20% of patients with myasthenia gravis experience crisis
- Crisis can be initial manifestation of disease
- Respiratory failure is feared complication
Clinical Presentation of Respiratory Failure in MG Patient
- Increasing weakness (bulbar/proximal extremity/neck)
- Dyspnea usually worse in supine position (increased dependence of diaphragm on gravity)
- Important to remember that patients may not exhibit normal signs of respiratory failure secondary to weakness (ex: accessory muscle use)
- medication noncompliance
- pregnancy/child birth
- drugs (antibiotics, cardiovascular, anesthetics, anticonvulsants, antipsychotics, etc.)
- Most Important Step = Assessment/Monitoring of Respiratory Function
- Vital Capacity (VC) and Max Inspiratory Pressure (aka Negative Inspiratory Force) are most important to monitor during crisis
- Consider intubation if VC below 15-20 ml/kg OR MIP/NIF less negative than -25 to -30 cmH2O
- Often need ICU for frequent monitoring, q2-4 hr respiratory function testing
- Plasma Exchange OR IVIG (rapid acting therapies)
- Glucocorticoids: crisis patients often started on high dose steroids
- Associated with transient worsening of weakness, however less of a concern with concurrent plasma exchange/IVIG
- Stay tuned next week for intubation pearls!
Bird S, Levine J. “Myasthenic Crisis.” UpToDate. 25 August 2016; https://www.uptodate.com/contents/myasthenic-crisis?source=search_result...
Tintinalli, JE. Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 8th ed. NewYork, NY: McGraw-Hill Education LLC, 2016.