A 49-year-old woman presented with a 3-month history of progressive breathlessness on exertion and occasional hemoptysis. She had complained of intermittent pleuritic pain, which had deteriorated prior to hospital admission. She received lamotrigine and sodium valproate for epilepsy. On examination, she had a raised erythematous facial rash. She was afebrile, normotensive, and had a normal peripheral pulse. Examination of her chest revealed no abnormality.
ECG findings were normal. Arterial blood gas indexes on room air were as follows: pH, 7.39; Pco2, 34 mm Hg; Po2, 90 mm Hg; HCO3−, 25.6 mmol/L; hemoglobin, 9.0 g/dL, WBC count, 13.7 × 109 g/dL; and platelets, 1,158 × 109/L. Urea and electrolyte levels were normal.