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Myasthenic crisis with impending respiratory failure — SCE Acute Medicine MCQ

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HardAcute Neurological PresentationsMyasthenic crisis with impending respiratory failureSCE Acute Medicine

A 67-year-old man with myasthenia gravis presents with increasing dysphagia and breathlessness after a chest infection. He has weak cough, ptosis, single-breath count of 8 and forced vital capacity 12 mL/kg. ABG shows pH 7.36, PaCO2 5.9 kPa. What is the most appropriate next step in management?

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Correct answer: A — Urgent critical care review for impending ventilatory failure

Bulbar weakness, weak cough and very low vital capacity indicate myasthenic crisis with impending ventilatory failure even before marked acidosis develops. Oral pyridostigmine alone is unsafe and may worsen secretions. Aminoglycosides and beta-blockers can exacerbate myasthenia. The pearl is to act on respiratory mechanics and bulbar signs rather than waiting for profound hypercapnia.

Reference: ABN myasthenia guidance, BNF