Hybrid dialysis: Recirculation peritoneal dialysis revisited

In a crossover trial, eight patients were studied during one treatment each of automated peritoneal dialysis (APD) end hybrid dialysis (HyD). During HyD, a fixed quantity of peritoneal dialysis fluid (PDF) was continuously removed at a flow rate of 141.3 +/- 23.7 mL/min, dialyzed against the secondary dialysate (250 +/- 53.5 mL/min) generated by the hemodialysis delivery system with single-needle dialysis capability, and the regenerated PDF (PDFHyD) was reinfused into the peritoneal cavity. Despite using a smaller volume (6,195 +/- 737 versus 13,321 +/- 1,201 mL; P < 0.0001) of PDFHyD With a lower glucose concentration (729 +/- 562 versus 1,659 +/- 373 mg/dL; P < 0.0001) and osmolality (331 +/- 79 versus 387 +/- 184 mOsm/kg; P < 0.001) during HyD compared with APD (PDFAPD), weight loss was similar with both treatments (1.4 +/- 1.0 versus 1.6 +/- 1.2 kg). Lactate levels were lower (3.2 +/- 2.5 versus 11.4 +/- 5.4 mEq/L), but pH (7.5 +/- 1.3 versus 5.6 +/- 0.9; P < 0.001) and bicarbonate concentration (22.6 +/- 8.0 versus 11.9 +/- 7.9 mEq/L; P < 0.0001) were greater in PDFHyD than PDFAPD. Although the mean dialysate calcium level was lower (6.0 +/- 0.5 versus 6.9 +/- 1.1 mg/dL; P < 0.001) in PDFHyD, it was more stable throughout the dialysis compared with PDFAPD. A steeper concentration gradient between the blood and dialysate resulted in greater clearance of urea (26.5 +/- 9.1 versus 11.0 +/- 4.7 mL/min; P = 0.04), creatinine (24.1 +/- 11.4 versus 12.0 +/- 7.9 mL/min; P = 0.03), phosphate (19.2 +/- 4.3 versus 9.8 +/- 7.2 mL/min; P = 0.01), and uric acid (15.6 +/- 6.9 versus 9.1 +/- 2.7 mL/min; P = 0.04) and a greater percentage of reduction in values for blood urea nitrogen (20.7% +/- 7.7% versus 11.6% +/- 5.5%; P = 0.02), serum creatinine (16.1% +/- 5.3% versus 6.6% +/- 3.0%; P < 0.001), phosphate (22.7% +/- 8.9% versus 9.8% +/- 4.5%; P = 0.004), and uric acid (15.8% +/- 2.9% versus 6.3% +/- 3.4%; P < 0.001) during HyD than APD. To conclude, HyD is a novel dialytic technique that uses biocompatible bicarbonate-based dialysate to achieve excellent clearance of uremic toxins and ultrafiltration with minimal glucose load. (C) 2000 by the National Kidney Foundation, Inc.