1st April 2022

A 78-year-old man with a history of atrial fibrillation presents with sudden onset abdominal pain and diarrhoea

A 78-year-old man with a history of atrial fibrillation presents with sudden onset abdominal pain and diarrhoea. He reports that the pain is constant and that he has never had this type of pain before. On examination, his temperature is 38.7ºC, pulse 103 bpm and respiratory rate 30/min. His abdomen is tender with generalised guarding. Blood tests reveal the following:

• Hb: 14.6 g/dl (Men: 13.5 – 18.0; Women: 11.5 – 16.0)Na+: 141 mmol/l (135 – 145)
• K+: 5.0 mmol/l (3.5 – 5.0)
• pH: 7.29 (7.35 – 7.45)
• pCO₂: 2.9 (4.5 – 6.0)
• pO₂: 12.1 (10 – 14)
• HCO₃: 14 mmol/l (22 – 28)
• Lactate: 6.3 (<2)

What is the most likely diagnosis?

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