COMPARISON OF DIFFERENT PERITONEAL-DIALYSIS MODALITIES WITH RESPECT TO HOST-DEFENSE

The currently available dialysis fluids are toxic for phagocytic cells and inhibit their function. As at present there is no fluid compatibl e with host defense, the impact of modified peritoneal dialysis techni ques on the antibacterial defense of the peritoneal cavity was studied . Tidal peritoneal dialysis, a modified automated technique in which o nly a part of the infused dialysate is drained and replaced with each exchange, was studied for its theoretical advantages over complete dra inage techniques on preservation of peritoneal defenses. The presence of an already buffered residual volume during TPD results in less extr eme changes in intraperironeal pH during treatment and more or less bl unts the noxious effects of fresh PD fluids. However, the differences observed are rather subtle and may not translate into clear clinical b enefits. As the physico-chemical characteristics of dialysis solutions change following their instillation into the peritoneal cavity, the e ffect of dwell time on phagocyte function and effluent opsonic activit y was studied. Prolonged dwell time enhanced both opsonic activity and phagocytic capacity significantly. To investigate whether the long di urnal dwell time inherent to CCPD might contribute to the lower perito nitis rare associated with this technique, we studied the effect of dw ell time on effluent opsonic activity and peritoneal macrophage functi on in well-matched CAPD and CCPD patients. No differences were observe d in peritoneal macrophage (PMO) function or effluent opsonic activity between matched CAPD-Y and CCPD patients when dwell times were equal. In both patient groups prolongation of dwell time enhanced PMO functi ons as well as effluent opsonic activity, thereby providing a better h ost defense. The improve ment in peritoneal defenses may, in part, be responsible for the lower peritonitis incidence observed among CCPD-tr eated patients in a prospective, randomized study comparing peritoniti s rates in CAPD with Y-set and CCPD. Peritoneal dialysis techniques ar e currently available that appear to have less detrimental effects on peritoneal defense compared to CAPD.