A 45-year-old male with a 17-year history of chronic hepatitis B reports decreased stamina, occasional abdominal distension, and weight loss over the past year. One week ago, he developed diarrhea and abdominal pain after consuming contaminated food, which improved with medication. However, over the past 3 days, he developed fever, significant abdominal pain and distension, yellow urine, and markedly decreased urine output. On admission: alert but agitated and talkative, chronic liver disease facies, mild icterus of the sclera, prominent liver palms, spider angiomas, no abnormalities in heart and lungs; abdominal distension, tenderness in the lower abdomen, mild rebound tenderness, positive ascites sign. Emergency labs: WBC 9.8×10<sup>9</sup>/L (neutrophils 89%), K<sup>+</sup> 3.4 mmol/L, Na<sup>+</sup> 137 mmol/L, Cl<sup>-</sup> 98 mmol/L, blood ammonia 96 μmol/L. The key determinant of successful treatment for this patient is: