16th February 2025

A 32-year-old lady with known myasthenia gravis presents to the Emergency Department with three days of fatigue, diplopia, dysphagia and difficulty breathing, worsening over the last 12 hours.

A 32-year-old lady with known myasthenia gravis presents to the Emergency Department with three days of fatigue, diplopia, dysphagia and difficulty breathing, worsening over the last 12 hours. She has taken three days of nitrofurantoin for a urinary tract infection prescribed by her general practitioner.

On examination, she has bilateral ptosis, proximal muscle weakness, a poor cough and a respiratory rate of 26. Auscultation of the chest is normal. Her oxygen saturations are 95% on room air, her heart rate is 85, her blood pressure is 111/71 and her temperature is 36.6.

She has so far been treated with intravenous antibiotics and pyridostigmine PO.

Arterial blood gas: pH 7.35, pO2 11.1 kPa, pCO2 6.6 kPa, HCO3 24 mEq/L.

On spirometry, she has an FVC of 0.87 L. Her weight is 73 kg.

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