Composition Of Replacement Fluid And Dialysate For Crrt

Composition of dialysate and replacement fluids used for continuous renal replacement therapy (CRRT). One of the key features of any dialysis method is the manipulation of metabolic balance. In general, this is achieved by altering composition of dialysate or replacement fluid . Most commercially available dialysate and replacement solutions have lactate as the base; however, bicarbonate-based solutions are being utilized more and more [17,18].

Replacement 17 mL/min Prefilter Prefilter

Prepump Prepump

BFR 83 mL/min BFR 117 mL/min

Blood pump BFR 100 mL/min

Blood pump BFR 100 mL/min

Postfilter BFR 100 mL/min

Filter

Ultrafiltrate

FIGURE 19-16

Effect of site of delivery of replacement fluid: pre- versus postfilter continuous venovenous hemofiltration with ultrafiltration rate of 1 L/hour. Replacement fluids may be administered pre- or postfilter, depending on the circuit involved . It is important to recognize that the site of delivery can influence the overall efficacy of the procedure. There is a significant effect of fluid delivered prepump or postpump, as the amount of blood delivered to the filter is reduced in prepump dilution. BFR—blood flow rate.

FIGURE 19-17

Pre- versus postfilter replacement fluid: effect on filtration fraction. Prefilter replacement tends to dilute the blood entering the circuit and enhances filter longevity by reducing the filtration fraction; however, in continuous venovenous hemofiltration (CVVH) circuits the overall clearance may be reduced as the amount of solute delivered to the filter is reduced.

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