AMINO-ACID LOSS AND PLASMA-CONCENTRATION DURING CONTINUOUS HEMODIAFILTRATION

Amino acid loss, plasma concentration, and the relationship between am ino acid intake and balance during continuous hemodiafiltration (CHD) were investigated in a prospective, nonrandomized study of trauma pati ents exhibiting the systemic inflammatory response with acute renal fa ilure. Data were compared with those from a group of similar patients who had maintained renal function (control). Both groups received simi lar amounts of nonprotein calories (3015 +/- 753 nonprotein calories p er day in the control group vs 3077 +/- 1018 nonprotein calories per d ay in the CHD group) and amino acids (2.24 +/- 0.36 g/kg per day in th e control group vs 2.19 +/- 0.48 g/kg per day in the CHD group) via th e parenteral route. Amino acid solutions were either 19% or 45% branch ed-chain amino acid enriched. Studies were performed every 12 hours fo r a maximum of 6 days. Amino acid loss was 2.5 +/- 2.3 g/12 h in the c ontrol group vs 6.6 +/- 2.4 g/12 h in the CHD group (p < .0001). Incre asing the dialysate rate from 15 to 30 mL/min increased amino acid los s from 5.7 +/- 1.7 to 7.9 +/- 2.6 g/12 h (p < .0001). Amino acid loss was unrelated to amino acid intake but was directly related to plasma amino acid concentration, CHD effluent volume, and the efficiency of f iltration as measured by the ratio of filtered urea nitrogen to blood urea nitrogen (R2 = .69). A linear relationship was found between amin o acid intake and balance (R2 = .991). The patterns of plasma amino ac id concentrations were consistent with metabolic changes wrought by a combination of sepsis and multiple organ dysfunction and type of amino acid intake but seemed unaffected by increased amino acid loss in CHD effluent. Amino acid losses were 2 to 3 times greater from CHD than f rom normal kidney. However, CHD amino acid losses may not be clinicall y significant unless amino acid intake is restricted to levels used ty pically in traditional hemodialysis.