Better preservation of cognitive faculty in continuous ambulatory peritoneal dialysis

We employed the so-called event-correlated potential (ECP) P300, a neurophysiological test which explores the circuits of attention and memory in the brain and is altered in subjects with a dismetabolic or degenerative encephalopathy, in order to evaluate the cognitive faculty in two groups of uremic patients [18 on continuous ambulatory peritoneal dialysis (CAPD), 15 on hemodialysis (HD)] comparable with respect to age and time on dialysis. The values of latency (msec) of P300 resulted in CAPD patients 356 +/- 26 in CZ (central zero electrodes) and 357.5 +/- 25 in PZ (parietal zero electrodes), not significantly different from the values in normal controls (341 +/- 14.5 in CZ and 340 +/- 15.6 in PZ) and in HD patients postdialysis (354 +/- 24.4 in CZ and 354 +/- 25.6 in PZ). On the contrary, the predialytic values of HD patients (384 +/- 25.6 CZ and 385 +/- 25.5 in PZ) were significantly different from the postdialytic values and from the values of CAPD patients and controls (p < 0.01). These results support the conclusion that HD is able to restore a normal cognitive faculty only transiently in the postdialytic phase, while CAPD maintains this important function steadily close to the normal range, thus being clearly better than HD.