A 35-year-old male patient with severe hepatic encephalopathy due to liver failure presents with confusion, lethargy, and asterixis. Laboratory tests show significantly elevated ammonia levels (210 µmol/L) and impaired kidney functions (urea 55 mmol/L and creatinine 210 µmol/L). Lactate and bicarbonate levels in blood gas are at 10 mmol/L and 14 mmol/L respectively. Despite maximal medical therapy, including lactulose and rifaximin, the patient's condition worsens. Continuous Renal Replacement Therapy (CRRT) is initiated.
Right Answer:A. To provide continuous clearance of ammonia and maintain hemodynamic stability; consider using a high-efficiency dialysis filter and anticoagulation management. In a patient with severe hepatic encephalopathy and hyperammonemia, CRRT is employed primarily for continuous clearance of ammonia and to maintain hemodynamic stability. This mode of dialysis provides a more controlled and gradual removal of toxins compared to intermittent hemodialysis, which can be better tolerated by critically ill patients. While fluid management and electrolyte correction (Option B) are important in CRRT, the primary reason in this case is ammonia clearance. Removal of small solutes (Option C) and nutritional support (Option D) are relevant but not the primary focuses here.
Clinical Pearls: CRRT and hyperammonemia in hepatic dysfunction CRRT can be beneficial in the management of hyperammonemia due to hepatic dysfunction, particularly in cases of acute liver failure. In a recent retrospective observational study involving 54 patients with acute liver failure, ammonia levels significantly decreased throughout CRRT, from a median of 151 µmol/L to 52 µmol/L by day 5. A high-efficiency Dialysis Filter is essential for effectively clearing ammonia. These filters have higher permeability and larger pore sizes, allowing for better clearance of small molecules like ammonia than standard hemodialysis filters. The recommended CRRT dose is typically around 50 mL/kg/h of effluent flow rate. This higher dose helps reduce ammonia levels faster, targeting levels below 100 µmol/L. Anticoagulation Management is challenging in patients with liver failure due to coagulopathy in ALF patients. Early initiation (started within 4 hours of diagnosis) and prolonged use of CRRT is most effective. CRRT can improve survival by preventing severe hyperammonemia and its complications.
Wrong Answer: B. To manage fluid overload and electrolyte imbalances; consider adjusting dialysate composition
Wrong Answer: C. To improve removal of small solutes; consider using low-efficiency filters for longer sessions
Wrong Answer: D. To decrease protein catabolism; consider nutritional support during CRRT
