A 28-year-old woman with myasthenia gravis presents with progressive dyspnoea, inability to count above 6 in a single breath, and paradoxical abdominal movement. Forced vital capacity is 1.2 L (predicted 3.4 L). What is the MOST appropriate immediate management?

• A Increase pyridostigmine dose to 120 mg every 4 hours
• B Elective intubation and mechanical ventilation ✓
• C Initiate plasma exchange immediately and avoid intubation
• D Administer neostigmine IV test dose to differentiate myasthenic from cholinergic crisis

Explanation

This is a myasthenic crisis with impending respiratory failure. Absolute criteria for intubation include FVC <15–20 mL/kg (approximately <1.0–1.4 L in average adults), NIF < −20 cmH2O, or rapid deterioration. With FVC of 1.2 L (<35% predicted) and clinical signs of respiratory failure, elective intubation before acute decompensation is the priority ('20/30/40 rule'). Increasing pyridostigmine may worsen cholinergic crisis if misdiagnosed; IVIG/plasma exchange are started concurrently but do not replace airway protection.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.