ALTERNATE REPETITION OF SHORT FOREFILTRATION AND BACKFILTRATION REDUCES CONVECTIVE ALBUMIN LOSS

An effective therapeutic means to remove relatively large polypeptide uremic toxins seems to be a hemofiltration (HF) or hemodiafiltration ( HDF) employing a larger-pore membrane, that is, a protein-permeable me mbrane. With either method, however, a significant amount of albumin w ill be lost into the ultrafiltrate or dialysate. Now, repetition of al ternate short fore- and backfiltrations may prevent the development of the ultrafiltration-induced higher albumin concentration on the membr ane surface (protein concentration polarization), where a single foref iltration time is shorter than the time needed for completion of prote in concentration polarization. Since the albumin concentration on the protein-permeable membrane surface will be one of the determinants of albumin loss by convection, such HDF treatment may reduce protein loss into the dialysate. To examine this assumption, we alternately repeat ed short and rapid fore- and backfiltrations (push/pull HDF) through a protein-permeable membrane, each less than 1 second in duration and a t each filtration volume of 15 ml, where a pyrogen-free dialysate was supplied. The present results indicated that the albumin amount lost b y push/pull HDF was approximately one-third of that by conventional HD F. Nevertheless, the reduction rates of beta(2)-microglobulin and myog lobin were significantly greater by push/pull HDF than by conventional HDF.