Management of Myasthenia Crisis with Respiratory Failure and Fever
This patient requires immediate ICU admission with early elective intubation, IVIG or plasmapheresis, broad-spectrum antibiotics for presumed infection, and continuation of corticosteroids while holding pyridostigmine if intubated. 1
Immediate Respiratory Management
Early elective intubation should be performed now rather than waiting for further deterioration, as the patient is on post-treatment day 8 with respiratory failure and fever suggesting superimposed infection. 2 The presence of fever with respiratory failure in a myasthenia crisis patient indicates high risk for rapid progression, and intubation should not be delayed once deemed necessary. 2
- Intubation should be performed by experienced operators only in a controlled, planned manner to minimize complications. 2
- Avoid non-invasive ventilation (CPAP or NIV) in this setting, as early intubation with invasive positive pressure ventilation is preferred for impending respiratory failure. 2
- Perform frequent pulmonary function monitoring with negative inspiratory force and vital capacity measurements. 1, 3
Immunomodulatory Treatment for Crisis
Administer IVIG 2 g/kg total dose over 5 days (0.4 g/kg/day × 5 days) or plasmapheresis immediately. 1, 3 This is indicated for Grade 3-4 myasthenic exacerbations with respiratory compromise requiring hospitalization. 1
- Continue corticosteroids concurrently during IVIG or plasmapheresis treatment. 1, 3
- Do not use sequential therapy (plasmapheresis followed by IVIG), as it is no more effective than either treatment alone. 1
- If intubated, pyridostigmine may be discontinued or withheld, as it cannot be reliably administered and absorption is unpredictable. 2
Infection Management
The presence of fever on day 8 post-treatment strongly suggests bacterial respiratory infection, which is the most frequent trigger for myasthenic crisis. 4
- Initiate broad-spectrum antibiotics immediately, but strictly avoid fluoroquinolones, aminoglycosides, and macrolides, as these can worsen myasthenic symptoms and precipitate further crisis. 1, 5, 3
- Obtain respiratory cultures, blood cultures, and chest imaging to identify the infectious source. 4
- Consider beta-lactam antibiotics (e.g., ceftriaxone plus vancomycin for hospital-acquired pneumonia) as safer alternatives. 1, 5
Critical Medications to Avoid
Ensure the patient is not receiving any of the following medications that can exacerbate myasthenia:
- β-blockers, IV magnesium, fluoroquinolones, aminoglycosides, macrolides. 1, 5, 3
- Barbiturates (particularly butalbital-containing medications like Fioricet), which pose particular risk for respiratory compromise. 5
- Methocarbamol and orphenadrine, which interfere with pyridostigmine effects. 5
Monitoring Protocol
Perform daily neurologic evaluations and frequent pulmonary function assessments while in the ICU. 1, 3
- Monitor for worsening bulbar symptoms (speech, swallowing difficulties) even though currently preserved. 2, 1
- Assess for signs of myocarditis, as immune-related myositis can involve cardiac muscle with troponin elevation. 2
- Watch for autonomic instability during intubation and mechanical ventilation. 2
Clinical Context and Pitfalls
The preserved neck flexion and absence of ptosis on day 8 post-treatment is somewhat reassuring but does not exclude severe respiratory muscle involvement, as respiratory failure can occur with relatively preserved bulbar and ocular function. 2 The fever suggests that infection, not purely myasthenic crisis, is driving the respiratory failure, making aggressive infection management equally important as immunomodulation. 4
Common pitfall: Delaying intubation while attempting non-invasive ventilation in myasthenic crisis with respiratory failure leads to worse outcomes and more difficult intubation. 2
Common pitfall: Using contraindicated antibiotics (fluoroquinolones, aminoglycosides, macrolides) for the presumed infection will worsen the myasthenic crisis. 1, 5, 3