Figure 45

Solute removal. In a highly permeable membrane, smaller molecules (ie, urea and creatinine) are transported at a faster rate from the blood to dialysate than are larger molecules, enhancing solute removal. Similarly, glucose (a small solute used in the peritoneal dialysis solution to generate osmotic force for ultrafiltration across the peritoneal membrane) is also transported faster, but in the opposite direction. This high transporter dissipates the osmotic force more rapidly than does the low transporter. Both osmotic and glucose equilibriums are attained eventually in both groups, but sooner in the high transporter group. Intraperitoneal volume peaks and begins to diminish earlier in the high transporter group. When the membrane is less permeable, solute removal is lower, ultrafiltration volume is larger at 2 hours or more, and glucose equilibriums are attained later.

Consequently, intraperitoneal volume peaks later. Ultrafiltration in a low transporter peaks late during dwell time. Therefore, a low transporter continues to generate ultrafiltration even after 8 to 10 hours of dwell. The solute creatinine dialysate to plasma ratio (D/P) increases linearly during the dwell time. Patients with average solute transfer rates have ultrafiltration and mass transfer patterns between those of high and low transporters. NIPD—nightly intermittent peritoneal dialysis; NTPD—nighttime tidal peritoneal dialysis; DAPD—daytime ambulatory peritoneal dialysis; CAPD—con-tinuous ambulatory peritoneal dialysis; CCPD (NE)—continuous cyclic peritoneal dialysis (night exchange); CCPD (DE)—continu-ous cyclic peritoneal dialysis (day exchange). (From Twardowski [11]; with permission.)

Serum and dialysate

1.5% dextrose dialysis solutions i-1-1-r-

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