Hypophosphatemia is observed in patients undergoing nocturnal
hemodialysis.
Phosphate is commonly added to the
dialysate acid bath, but systematic evaluation of the safety and reliability of this strategy is lacking. The objectives of this study were 4-fold. First, we determined whether predictable final
dialysate phosphate concentrations could be achieved by adding varying amounts of Fleet®
enema. Second, we assessed the stability of
calcium (Ca) and
phosphate dialysate levels under simulated nocturnal
hemodialysis conditions. Third, we assessed for Ca-
phosphate precipitate. Finally, we evaluated whether
dialysate containing Fleet®
enema met the current
sterility standards. We added serial aliquots of
enema to 4.5 L of
dialysate acid concentrate and proportioned the
solution on Gambro and Althin/Baxter dialysis machines for up to 8 hours. We measured
dialysate phosphate, Ca, pH, and
bicarbonate concentrations at baseline, and after simulated dialysis at 4 and 8 hours. We evaluated for precipitation visually and by assessing optical density at 620 nm. We used inoculation of
agar to detect bacteria and Pyrotell reaction for
endotoxin. For every 30 mL of Fleet® (1.38 mmol/mL of
phosphate)
enema added, the
dialysate phosphate concentration increased by 0.2 mmol/L. There were no significant changes in
dialysate phosphate, Ca, pH, and
bicarbonate concentrations over 8 hours. No precipitate was observed in the
dialysate by optical density measures at 620 nm for additions of up to 90 mL of
enema. Bacterial and
endotoxin testing met
sterility standards. The addition of Fleet®
enema to
dialysate increases
phosphate concentration in a predictable manner, and no safety problems were observed in our in vitro studies.