Initiating High Clearance Rate CRRT Therapy to Improve Hyperammonemia: A Prospective Study

Background: Hyperammonemia is a condition in the setting of liver failure due to excess serum ammonia, which is a nitrogen-containing compound, generated from protein catabolism. In high concentration, it causes life-threatening complications including hepatic encephalopathy and cerebral edema. Renal replacement therapy (RRT) should be implemented early if ammonia level is elevated to prevent complications. This study aims to determine the efficacy of using high clearance rates on CRRT to reduce ammonia levels and improve patient outcomes. Methods: In this prospective study, twelve patients requiring CRRT for hyperammonemia were identified at our tertiary hospital between February 2025 and April 2025. Acute liver failure was caused by etiologies including decompensated alcoholic cirrhosis, metabolic dysfunction-associated liver steatohepatitis, acetaminophen overdose, and acute fatty liver of pregnancy. Initial ammonia levels ranged between 106 and 813 mmol/L. Four patients had cerebral edema from hyperammonemia. Dialysate flow rates were started at 25mL/kg/hr, 30mL/kg/hr, or 40mL/kg/hr, and ammonia levels were trended daily. Length of stay in intensive care (ICU), mental status improvement, and transition to intermittent hemodialysis or cessation were used to determine the efficacy of higher clearance rates. Results: Of eight patients starting at 25mL/kg/hr, three patients died, two transitioned to hemodialysis, two underwent liver transplant, and one is undergoing transplant evaluation. Their average length of stay in the ICU was 13.62 days. Of the other four patients, one patient, who died, started at 30mL/kg/hr, and three started at 40mL/kg/hr. They were all transferred out of the ICU, completely off dialysis, with improvement in mental status, and one underwent liver transplant. Their average length of stay in the ICU was 8.75 days Conclusion: Hyperammonemia can cause life-threatening complications. Intermittent hemodialysis is the preferred method as it rapidly reduces levels, but temporary cessation can lead to a significant rebound effect. This study’s results illustrate that initiating high clearance rate CRRT is beneficial in decreasing ICU length of stay and may improve overall outcomes.