Abstract: PUB490
Ammonia Clearance in Acute Liver Failure with Continuous Venovenous Hemodiafiltration
Session Information
Category: Trainee Case Report
- 701 Dialysis: Hemodialysis and Frequent Dialysis
Authors
- Zaman, Warda, UCSD, San Diego, California, United States
- Woodell, Tyler, UCSD, San Diego, California, United States
Introduction
Hyperammonemia in acute liver failure and inborn errors of metabolism can cause life-threatening cerebral edema. While intermittent hemodialysis clears ammonia more rapidly, continuous renal replacement therapy (CRRT) is often used in acute liver failure due to hemodynamic instability and rebound of ammonia levels. Kidney Disease Improving Global Outcomes guidelines recommend an hourly effluent of 20-25 mL/kg/hr delivery with CRRT, but whether this applies to cases of hyperammonemia is unknown. We report the first case to our knowledge measuring the clearance of ammonia using continuous venovenous hemodiafiltration (CVVHDF) in a patient with acute kidney injury and hyperammonemia.
Case Description
A 27-year old previously healthy Hispanic man with alcohol overuse presented with one week of malaise, abdominal pain, and confusion after taking acetaminophen for flu-like symptoms. Physical exam was notable for obtundation, asterixis, scleral icterus; and laboratory studies were remarkable AST and ALT > 6000U/L; total bilirubin 9.1mg/dL; INR 6.3; ammonia 107uMol/L; and serum creatinine 4.7 mg/dL. Urine microscopy revealed multiple tubular epithelial casts and head CT showed diffuse sulcal narrowing. A diagnosis of grade 3 hepatic encephalopathy due to intracerebral edema from hyperammonemia from acute liver failure complicated by oliguric acute tubular necrosis was established, and the patient was listed for liver transplantation with a MELD of 40. CVVHDF was initiated on hospital day 1 with a total effluent of 33 mL/kg/hr was delivered (12 mL/kg/hr dialysis and 21 mL/kg/hr ultrafiltration). On hospital day 3, after 36 hours of uninterrupted CRRT, serum ammonia was 77 umol/L, effluent ammonia was 19 umol/L, and hourly effluent was 2700 mL. Using the Cordoba equation, we calculated an ammonia clearance of 11 mL/min. The patient’s acute liver failure resolved without need for transplantation. He was transitioned to intermittent hemodialysis on hospital day 4, and achieved renal recovery becoming free from renal replacement therapy on hospital day 13. His most recent serum creatinine is 0.8 mg/dL.
Discussion
In this case of hyperammonemia, ammonia clearance was modest despite delivering an effluent volume that exceeded KDIGO practice guidelines. Given the increasing attention that CRRT is receiving for treatment of hyperammonemia, more work is needed to determine the optimal dose and method of CRRT in such instances.