A 60-year-old man with known alcoholic liver disease presents with increasing abdominal distension, confusion, and a tremor. On examination, he is jaundiced, has shifting dullness, and asterixis. Blood tests show: Na+ 128 mmol/L, K+ 3.0 mmol/L, Urea 15 mmol/L, Creatinine 150 µmol/L, Bilirubin 80 µmol/L, Albumin 25 g/L, INR 1.8. What is the most important initial management step to address his confusion?