Summary of "Miastenia Gravis: ¿Cómo Manejar las Crisis? - Dra. Lina Marcela Hoyos"

Summary of Key Wellness Strategies, Self-Care Techniques, and Productivity Tips for Managing Myasthenia Gravis (MG) Crisis

Understanding Myasthenia Gravis and Crisis:

MG is an autoimmune disease causing muscular weakness due to autoantibodies affecting the neuromuscular junction.
A myasthenic crisis involves progression to ventilatory failure, often requiring emergency respiratory support.
Crisis can be the first manifestation or progression of known MG.

Epidemiology & Clinical Presentation:

Average diagnosis age: ~39 years, with two incidence peaks (<30 years and >70 years).
More common in women, especially younger patients.
Mortality has decreased from ~20% to below 5% with improved management.
Common symptoms: muscle fatigue, ptosis, diplopia, dysphagia, respiratory weakness.
Fatigue worsens with activity and improves with rest and cold.

Triggering Factors for Crisis:

Infections (most common)
Certain medications (antibiotics, anticonvulsants, neuromuscular blockers, calcium channel blockers, lidocaine)
Surgery, pregnancy, extreme temperatures
Sometimes no identifiable trigger (~40% cases)

Clinical Assessment & Red Flags:

Diagnostic Workup:

Antibody testing (acetylcholine receptor, muscle kinase, low-density protein 4)
Neurophysiological tests (repetitive nerve stimulation, single fiber electromyography)
Imaging: Chest CT to evaluate thymus and lung status
Labs: renal, liver, thyroid function, electrolytes, beta-hCG in women of childbearing age, ECG

Respiratory Support & Ventilation:

Ventilatory failure is mixed hypoxic and hypercapnic.
Poor prognostic indicators for intubation include:
- FVC < 20 ml/kg
- MIP < -30 cm H2O
- Max expiratory pressure < 40 cm H2O
Non-invasive ventilation (NIV), especially BiPAP, can reduce need for intubation in selected patients.
NIV contraindicated or likely to fail in patients with:
- Altered consciousness or lethargy
- Excessive secretions
- Severe hypercapnia (PaCO2 > 45-50 mmHg)
Intubation and invasive ventilation required if NIV fails or patient deteriorates.

Pharmacological & Immunotherapy Management:

Avoid Acetylcholinesterase inhibitors during acute crisis due to unpredictable effects and increased secretions.
Immunotherapy options:
- Intravenous immunoglobulin (IVIG): rapid onset, improves symptoms within a week, lasts weeks.
- Plasmapheresis: removes pathogenic antibodies, rapid effect lasting ~4 weeks.
IVIG and Plasmapheresis have comparable efficacy; used based on availability and patient factors.
Steroids: continue if already on them; start only after immunotherapy to avoid symptom worsening.
Immunosuppressants have delayed effect; used for long-term management.
Avoid combining IVIG and Plasmapheresis simultaneously as Plasmapheresis removes immunoglobulin.

Supportive Care:

Monitor and maintain glycemic control.
Provide nutritional support.
Use thromboprophylaxis to prevent clots.
Monitor for and treat infections, cardiovascular complications, and atelectasis.
Early recognition and management in high-dependency or intensive care units is critical.

Prognosis and Follow-up:

Early diagnosis and treatment reduce mortality.
Regular pulmonary function monitoring helps detect deterioration early.
Diaphragmatic ultrasound may be useful for early detection of respiratory muscle weakness.
Aim to minimize duration of mechanical ventilation.

Recognize early signs of myasthenic crisis: respiratory distress, fatigue, dysphagia, ineffective cough.
Monitor respiratory function: respiratory rate, Forced vital capacity, inspiratory pressures, and counting inspiration.
Avoid precipitating medications and treat infections promptly.
Use non-invasive ventilation cautiously, with close monitoring for failure signs.
Intubate early if signs