A model to predict optimal dialysate flow.

Diffusive clearance depends on blood (Qb) and dialysate flow (Qd) rates and the overall mass transfer area coefficient (KoA) of the dialyzer. In this article we describe a model to predict an appropriated AutoFlow (AF) factor (AF factor = Ratio Qd/Qb), that is able to provide adequate Kt/V for hemodialysis patients (HDP), while consuming lower amounts of dialysate, water and energy during the treatment. We studied in vivo the effects of three various Qd on the delivered dose of dialysis in 33 stable HDP. Hemodialysis was performed at Qd of 700 mL/mn, 500 mL/mn, and with AF, whereas specific dialysis prescriptions (treatment time, blood flow rate [Qb], and type and size of dialyzer) were kept constant. The results showed that increasing the dialysate flow rate more than the model of AF predicted had a small effect on the delivered dose of dialysis. The Kt/V (mean ± SD) was 1.52 ± 0.16 at Qd 700, 1.50 ± 0.16 at Qd 500, and 1.49 ± 0.15 with AF. The use of the AF function leads to a significant saving of dialysate fluid. The model predicts the appropriate AF factor that automatically adjusts the dialysate flow rate according to the effective blood flow rate of the patient to achieve an appreciable increase in dialysis dose at the lowest additional cost.

Pregnancy during hemodialysis: a single center experience.

Successful pregnancy outcome is an uncommon occurrence in women requiring chronic dialysis treatment. We reviewed the course and outcome of 9 pregnancies occurred in women on chronic hemodialysis in our center from 1999-2007; 5 of them ended with delivery of alive newborns, 2 with fetal deaths in-utero, and 2 with abortions. The average age of patients was 34 years. The etiology of the original kidney disease was unknown in 44.4% of the cases, and only 22.2% of the patients maintained diuresis. Dialysis started in 8 cases before the diagnosis of pregnancy. The average gestational age at diagnosis was 14 weeks. We modified the prescription of dialysis in 4 patients by increasing the frequency of the dialysis sessions to 6 per week and in 3 by increasing the duration of each session to 6 hours. Anemia was present in all the cases; 3 patients received erythropoietin and 4 patients required transfusion. The pregnancy was com-plicated in 44% of the cases by a polyhydramnios. The average time at delivery was 33 weeks and it was achieved in 80% of pregnancies through vaginal route. The average weight of newborns was to 2380 g. We conclude that pregnancy in women on hemodialysis is possible. The success of pregnancy may be influenced by the residual diuresis and early diagnosis to improve the quality of dialysis by increasing the dialysis dose.