Changes in plasma amino acids during extracorporeal liver support by fractionated plasma separation and adsorption

In patients with liver failure, amino acid dysbalance is common and associated with hepatic encephalopathy. Prometheus is a newly designed extracorporeal liver support system based upon fractionated plasma separation and adsorption (FPSA). We evaluated the influence of FPSA on plasma amino acid patterns in patients with liver failure and hepatic encephalopathy. We studied nine patients with acute-on-chronic liver failure, hepatic encephalopathy, and concomitant renal failure. A single session of FPSA therapy for 5 ± 1 h was performed in all patients. Twenty-six different plasma amino acids were measured by high-performance liquid chromatography before and after FPSA treatment. Total amino acids as well as Fischer index were calculated. Additionally, a variety of clinical and biochemical parameters were assessed. Before FPSA was started, plasma levels of most amino acids were elevated. Plasma ammonia levels correlated with glutamine levels (P < 0.04). During FPSA, plasma levels of nearly all amino acids significantly decreased except for branched-chain amino acids. The Fischer index improved without reaching statistical significance. FPSA therapy tends to normalize plasma amino acids in patients with combined liver and renal failure. This may contribute to positive pathophysiologic effects, especially on hepatic encephalopathy. However, the clinical significance of these findings needs to be further evaluated.