What is the best course of action for a Myasthenia Gravis (MG) patient who develops type 2 respiratory failure with fever requiring intubation after Intravenous Immunoglobulin (IVIG) treatment?

Management of Myasthenic Crisis with Post-IVIG Type 2 Respiratory Failure and Fever

This patient requires immediate intubation with mechanical ventilation, initiation of plasmapheresis (preferred over additional IVIG), high-dose IV corticosteroids, broad-spectrum antibiotics for suspected infection, and discontinuation of pyridostigmine while intubated. 1, 2, 3

Immediate Airway and Respiratory Management

• Proceed with intubation using an orotracheal approach for this patient who has already developed type 2 respiratory failure requiring intubation 3, 4
• Place a small-bore duodenal feeding tube rather than a standard nasogastric tube to decrease aspiration risk and improve patient comfort during mechanical ventilation 3, 4
• Ensure ICU-level monitoring with continuous respiratory assessment 1, 2

Immunotherapy Selection: Plasmapheresis Over Repeat IVIG

Initiate plasmapheresis immediately as the preferred immunotherapy in this scenario rather than repeating IVIG, for several critical reasons 3, 4:

• Plasmapheresis is more effective than IVIG specifically for myasthenic crisis involving respiratory failure 3, 4
• The patient has already received IVIG without adequate response (evidenced by progression to respiratory failure), making plasmapheresis the logical next step 5
• Standard regimen: 5 exchanges over 5 days, or consider extended regimen of 7 exchanges over 14 days for severe cases 1
• Critical timing consideration: Sequential therapy (plasmapheresis immediately after IVIG) will remove the immunoglobulin just administered, but given the patient's deterioration despite IVIG, this is acceptable 6

Corticosteroid Therapy

• Administer high-dose IV methylprednisolone 1-2 mg/kg/day or prednisone 1-1.5 mg/kg/day orally if able to take PO 1, 2
• Continue corticosteroids throughout the crisis management 1
• Plan for gradual taper starting 3-4 weeks after initiation based on symptom improvement 1

Medication Management During Intubation

• Discontinue or withhold pyridostigmine in this intubated patient 1, 2
• Strictly avoid medications that worsen myasthenia: β-blockers, IV magnesium (absolutely contraindicated), fluoroquinolones, aminoglycosides, and macrolides 1, 2

Infection Workup and Management

The presence of fever in this myasthenic crisis patient demands aggressive infection evaluation and treatment 2, 7:

• Infection is the most common precipitant of myasthenic crisis, occurring in 65% of cases 7
• Obtain blood cultures, sputum cultures, urinalysis and urine culture, and chest imaging 2
• Initiate broad-spectrum antibiotics immediately while avoiding contraindicated agents (no fluoroquinolones, aminoglycosides, or macrolides) 1, 2
• Monitor closely for ventilator-associated pneumonia (VAP), which occurs in 30% of myasthenic crisis cases and represents the most common complication 7

Cardiac and Myositis Evaluation

Given the post-IVIG timing and fever, evaluate for concurrent complications 1:

• Measure CPK, aldolase, ESR, and CRP to assess for concurrent myositis 1
• Perform ECG and consider transthoracic echocardiogram if CPK or troponin T are elevated to rule out myocarditis 1
• Check for rhabdomyolysis with urinalysis 8

Monitoring Protocol

• Perform daily neurological evaluations 1
• Conduct frequent pulmonary function assessments with negative inspiratory force (NIF) and vital capacity (VC) measurements 1, 2
• Use the single breath count test as a bedside adjunct (patient counts after deep breath; ≥25 correlates with normal respiratory function) 1
• Monitor for complications of immunotherapy and mechanical ventilation 1

Expected Timeline and Prognosis

• Median duration of intubation ranges from 10-12 days with appropriate treatment 9, 7
• Time to disease stabilization typically 8-10 days with plasmapheresis 7
• Median ICU stay approximately 15 days 7
• With aggressive management, complete resolution of symptoms at discharge is expected in survivors 7

Common Pitfalls to Avoid

• Do not administer sequential IVIG after the patient has already received it without response—switch to plasmapheresis instead 3, 4
• Do not continue pyridostigmine in intubated patients—it provides no benefit and may complicate management 1, 2
• Do not delay intubation—early elective intubation before emergent respiratory arrest improves outcomes 2, 3
• Do not overlook infection as both precipitant and complication—VAP is the leading cause of mortality in myasthenic crisis 7
• Do not use contraindicated antibiotics even for documented infections—choose alternative agents that don't worsen myasthenia 1, 2