ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
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Comparative Study
Middle-molecule clearance in CRRT: in vitro convection, diffusion and dialyzer area.
Several studies have attempted to compare different doses and modes of therapy in continuous renal replacement therapies in critically ill patients. It is commonly asserted in the literature that convective therapies can achieve higher clearance of middle molecules than achieved by dialysis alone. However, regardless of the actual prescription, most therapies will actually contain a mixture of both diffusive and convective clearance. ⋯ In the smaller dialyser, middle molecule clearance was higher when a diffusive therapy (CVVHD) was prescribed versus a convective therapy (postdilution CVVH). We hypothesized that high ultrafiltration rates in the smaller dialyzer resulted in a concentration polarization at the membrane that formed a prefilter, limiting middle-molecule clearance. This effect has implications for design and analysis of clinical trials of continuous renal replacement therapy (CRRT).