Analysis of Changes over Time in Blood Amino Acids During Online Haemodiafiltration Dialysis in Acute Liver Failure Patients with Hepatic Encephalopathy

Abstract

Acute liver failure (ALF) is a disease associated with severe symptoms, including rapid deterioration of liver function and impaired consciousness. Recently, online hemodiafiltration (OLHDF), an artificial liver replacement therapy, has attracted attention as a treatment option for comatose ALF. In this study, changes over time in blood aromatic amino acids (AAAs) and ammonia (NH₃), the causative agents of hepatic coma, during OLHDF in patients with ALF were analysed. Nine patients aged 20 years or older with high-grade hepatic encephalopathy admitted to the Kagoshima University Hospital Emergency Centre between October 2020 and September 2021 were included. OLHDF settings were blood flow 100 mL/min, dialysate flow 300 mL/min, and replacement fluid flow 100 mL/min. The analysis items were blood NH₃ concentration before and after OLHDF, blood amino acid concentration from before to 24 hours after the start of OLHDF, and the presence or absence of conscious awakening after OLHDF. Of the 11 amino acids measured in this study, the AAAs (tyrosine and phenylalanine) had concentrations higher than the reference range before the start of OLHDF, but were within the reference range 24 hours after OLHDF. NH₃ was significantly reduced and the conscious awakening rate was 88.9%. When NH₃ and AAAs, which were considered causative agents of hepatic coma and whose concentrations were higher than the reference range, were removed by OLHDF, the level of consciousness improved significantly. Regarding branched chain amino acids (BCAAs: valine, isoleucine, and leucine), which is considered a protective factor in hepatic coma, the concentration range before starting OLHDF was within the reference range, but the concentration 24 hours after starting OLHDF was below the reference range. The Fisher ratio, the ratio of BCAAs to AAAs, increased from before to after 24 hours starting OLHDF, but was lower than the reference range. Therefore, supplementation should be considered if OLHDF is continued for a longer period of time. Changes over time of 11 amino acids and NH₃ in patients with ALF coma were analysed. NH₃ and AAAs, which were abnormally high, decreased to within the reference range 24 hours after the start of OLHDF and the level of consciousness improved. On the other hand, BCAAs, which is considered a protective factor in hepatic coma, the concentration 24 hours after starting OLHDF was below the reference range. Further studies are needed to elucidate the changes in biologically useful substances during OLHDF.

Keywords: Acute liver failure (ALF); Amino acids; Ammonia (NH3); Intensive care unit (ICU); Online haemodiafiltration (OLHDF).