Effects of pH-neutral, bicarbonate-buffered dialysis fluid on peritoneal transport kinetics in children.
BACKGROUND
Due to their superior biocompatibility, pH-neutral solutions are beginning to replace acidic lactate-buffered peritoneal dialysis (PD) fluids. We hypothesized that pH-neutral and acidic solutions might differentially affect peritoneal transport in the early dwell phase, due to differences in ionic shifts and initial peritoneal vasodilation. Such differences may become clinically relevant in patients with frequent short cycles on automated PD (APD).


METHODS
Twenty-five children were treated with a lactate-buffered (35 mmol/L, pH 5.5) or a bicarbonate-buffered PD solution (34 mmol/L, pH 7.4) in randomized order on two sequential days. Each day a four-hour Standardized Permeability Analysis (SPA) was performed, followed by overnight APD (7 cycles, fill volume 1000 mL/m2, dwell time 75 min). Functional peritoneal surface area was dynamically assessed using the three-pore model.


RESULTS
While intraperitoneal pH was constant at 7.41 +/- 0.03 throughout the SPA with bicarbonate fluid, the dialysate remained acidic for more than one hour with lactate solution (pH 7.12 +/- 0.08 at 1 h). Total pore area was 60% higher during the first 30 minutes of the dwell than under steady-state conditions, without a difference between acidic and pH-neutral fluid. Net base gain, intraperitoneal volume kinetics, glucose absorption, ultrafiltration rate, effective lymphatic absorption and the transport of urea, potassium, beta2-microglobulin and albumin were similar with both fluids. However, phosphate and creatinine elimination were 10% lower with bicarbonate PD fluid, resulting in corresponding significant decreases in the 24-hour clearances of these solutes.


CONCLUSIONS
The peritoneal surface area is not measurably influenced by pH-neutral PD fluid. Creatinine and phosphate elimination appears to be slightly reduced with bicarbonate fluid; this observation awaits clarification in extended therapeutical trials.
Schmitt
Claus P
CP
Department of Pediatrics, Ruperto-Carolus University Heidelberg, Heidelberg, Germany. claus_peter_schmitt@med.uni-heidelberg.de
Haraldsson
Börje
B
Doetschmann
Rouven
R
Zimmering
Mirjam
M
Greiner
Christine
C
Böswald
Michael
M
Klaus
Günter
G
Passlick-Deetjen
Jutta
J
Schaefer
Franz
F
D000293:Adolescent; D001331:Automation; D001639:Bicarbonates; D001692:Biological Transport / Q000187:drug effects; D002021:Buffers; D002648:Child; D002675:Child, Preschool; D002940:Circadian Rhythm; D015331:Cohort Studies; D015314:Dialysis Solutions / Q000737:chemistry* / Q000494:pharmacology*; D004058:Diffusion; D005260:Female; D006801:Humans; D006859:Hydrogen / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D007223:Infant; D007700:Kinetics; D008297:Male; D010530:Peritoneal Dialysis; D010531:Peritoneal Dialysis, Continuous Ambulatory; D010537:Peritoneum / Q000378:metabolism*; D010539:Permeability
D001639:Bicarbonates; D002021:Buffers; D015314:Dialysis Solutions; D006859:Hydrogen