Comparative Study Of Amino Acids Clearance Between Various Doses And Modes Of Continuous Renal Replacement Therapy

Objective:To evaluate the effects of different modes and doses of continuous renal replacement therapy(CRRT) on the clearance of amino acids.Methodology:Four patients requiring CRRT due to acute kidney injury were enrolled in this study. An Edward CRRT machine and AV-600filter was used for CRRT. During each treatment session, the CRRT mode and dose was switched as following order every20minutes:continuous veno-venous hemodialysis (CVVHD)2000ml/h,4000ml/hr, continuous veno-venous hemofiltration (CVVH) through pre-dilution route (pre-CVVH)2000ml/h,4000ml/h, CVVH through post-dilution route (post-CVVH)2000ml/h,4000ml/h. Each time before the switching of mode or dose, blood samples were drawn from the pre-filter site (before replacement fluid infusion in pre-CVVH mode) and post-filter site, as well as effluent samples. All specimen were measured for urea nitrogen(UN),Creatinine (Cr),5essential amino acids (Valine, Methionine, Isoleucine, Leucine, Lysine),2semi-essential amino acids (Arginine, Histidine), and5non-essential amino acids (Aspartic acid, Glumatic acid, Glycine, Citrulline, Ornithine). Sieving coefficient(SC) and clearance of all the above-mentioned solutes were calculated based on the measured data.Results:The SCs of Aspartate acid and Glumatic acid were (0.5±0.04)and (0.48±0.07), respectively;and the SCs of other10amino acids were nearly0.85. During various dose and mode, clearances of UN and Cr were comparable. With the dose of2000ml/h, the clearances of UN/Cr under the CVVHD, Pre-CVVH, post-CVVH modes were32.7/32.68ml/min,23.95/24.69ml/min,32.62/32.22ml/min, respectively; while with the dose of4000ml/h, the clearances of UN/Cr under the CVVHD, Pre-CVVH, post-CVVH modes were62.73/63.31ml/min,45.59/48.09ml/min, and65.16/66.41ml/min, respectively. In all modes and doses, the clearance of Aspartic acid and Glumatic acid was much lower than other10amino acids, but without obvious differences of clearance between the10amino acids. With the dose of2000ml/hr, the clearances of Aspartate acid/Glumatic acid under the CVVHD, Pre-CVVH, post-CVVH modes were18.08/16.79ml/min,13.39/13.33ml/min and19.10/19.58ml/min, respectively; while the clearance of other10amino acids were28.31-32.18ml/min,21.64-24.9ml/min and27.28-32.38ml/min, respectively. With the dose of4000ml/hr, the clearances of Aspartate acid/Glumatic acid under the CVVHD, Pre-CVVH, post-CVVH modes were36.95/32.88ml/min,29.37/26.86ml/min and37.82/34.79ml/min, respectively; while the clearance of other10amino acids were59.18-64.8ml/min,46.71-50.64ml/min and58.83-65.1ml/min, respectively. Conclusions:The mode of CRRT has an impact on the clearance of amino acids, but the effect of CRRT dose is more dominant.