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Answers on p 379.
A 72 year old man with manic depression, who had recently started lithium treatment, presented to casualty with a two day history of severe nausea and vomiting. His serum urea and electrolytes were normal (sodium 139 mmol/l, potassium 4.1 mmol/l, creatinine 94 mmol/l, and urea 5 mmol/l) and he was discharged from the accident and emergency department with a presumptive diagnosis of gastroenteritis.
He represented 12 hours later with persistent vomiting and oliguric prerenal failure initially thought to be secondary to lithium toxicity. There was only minimal tenderness in the epigastrium but no signs of peritonism or abdominal masses; his pulse was 90 beats/min and blood pressure 105/50 mm Hg without a visible jugular venous pressure. His blood urea was now 28 mmol/l, sodium 141 mmol/l, potassium 4.3 mmol/l, and creatinine 310 mmol/l, with normal full blood count, blood gases, creatinine kinase, amylase, urine microscopy, a subtherapeutic lithium concentration 0.35 mmol/l (normal range 0.4–0.8 mmol/l), and an electrocardiograph showed sinus tachycardia only. His central venous pressure was low (−2 mm Hg) and he was resuscitated with fluids. Chest radiography was performed (figs 1 and 2) and a nasogastric tube was inserted but with some difficulty, draining only 100 ml of gastric juice. Twelve hours later his symptoms still had not improved. His renal function was unchanged and his vomitus had now become blood stained.
- What do the chest radiographs show?
- What single diagnostic investigation is required?