Kinetic comparison of different acute dialysis therapies

Recent clinical data indicate both ultrafiltration rate (Qf) and timing of treatment initiation in continuous renal replacement therapy (CRRT) and therapy frequency in intermittent hemodialysis (HD) influence survival in critically ill patients with acute renal failure (ARF). In this study, kinetic modeling is used to compare effective dose delivery by three acute dialysis therapies: continuous venovenous hemofiltration (CVVH), daily HD, and sustained low-efficiency dialysis (SLED). A modified equivalent renal clearance (EKR) approach to account for the initial unsteady-state stage during dialysis is employed. Effective small solute clearance in CVVH is found to be 8% and 60% higher than in SLED and daily HD, respectively. Differences are more pronounced for middle and large solute categories, and EKR in CVVH is approximately 2-fold and 4-fold greater than the corresponding values in daily HD and SLED, respectively. The superior middle and large solute removal for CVVH is due to the powerful combination of convection and continuous operation. In CVVH, a decrease in the initial BUN from 150 to 50 mg/dL is predicted to decrease TAC and, therefore, increase EKR by approximately 35%. After clinical validation, the quantification method presented in this article could be a useful tool to assist in the dialytic management of critically ill ARF patients.