#3064 Adequacy of urea and middle molecules clearance with online hemodiafiltration (HDF) for dialysate flow rates of 300 vs 500 ml/min
Authors: Barril Guillermina , Sobrino Pedro , Núñez Almudena , Giorgi Martin , Mojica Tatiana Carolina Niño , Cabrera Alicia , Pascual Natalia , Sanz Pilar , Sanchez Ana , Montes Nuria 
Published: May 2024

Abstract

Background and Aims
Trial cross design to determine non-inferiority in the adequacy of urea and middle molecules (B2 microglobulin, myoglobin and prolactin) clearance with 300 ml/min vs 500 ml/min of dialysate flow rate

Method
We have evaluated 2542 online HDF sessions (over 3 × 3 months trial cross design) in 50 patients in online HDF with sessions three times a week lasting 4 hours each.
The online data from the DDM module of the Nikkiso DBB-EXA monitor were crossed, measuring urea in the dialysate effluent every 20 seconds by absorptiometry with UV light with age, sex, dialyzer, DM, BMI. In the laboratory, urea and B2 microglobulin, prolactin and mioglobin were measured at 300 and 500 ml/min, calculating the reduction rates of these toxins.
We analyzed the data of 50 patients, in 25 patients, the first 3 months involved a dialysate flow rate 300 ml/min, followed by subsequent three months at 500 ml/min and vice versa for the remaining patients. They used the same dialyzer during the 3 × 3 months of the study as well as card programming.
To study whether the change in dialysate flow influenced the effectiveness of dialysis, “generalized models with repeated measurements over time correcting the temporal autocorrelation with the covariance matrix AR1” were used the following parameters: kt/v, eKt/V and URR

Results
23 men, 27 women, average age 70 years
Kt/V.- The variables that are related to the Kt/v values throughout the sessions are:
The effect of dialysate Flow 500 ml is statistically non-significant and positive (beta = 0.01, 95% CI (−0.06, 0.08),p0.707
The effective gender (female) is statistically significant and positive (beta = 0.26, 95% CI (0.15, 0.38) p &lt; 0.001
The effect of DM is statistically non-significant and negative (beta = −0.1, 95% CI (−0.22, 0.01) p = 0.081
The effect of period 2 is statistically non-significant and negative (beta = −0.02, 95% CI (−0.08, 0.03) p = 0.37
eKt/V.-
The effect of dialysate Flow 500 ml is statistically non-significant and positive (beta = 0.05, 95% CI (−0.02, 0.12),p0.138
The effect gender (female) is statistically significant and positive (beta = 0.22, 95% CI (0.11, 0.33) p &lt; 0.001
The effect of DM is statistically non-significant and negative (beta = −0.10, 95% CI (−0.20, 0.01) p = 0.082
The effect of period 2 is statistically non-significant and negative (beta = −2.44e.03, 95% CI (−0.06, 0.05) p = 0.930
URR.-
The effect of dialysate Flow 500 ml is statistically non-significant and positive (beta=1.19, 95% CI (−0.22, 2.60),p0.098
The effect of gender (female) is statistically significant and positive (beta=5.52, 95% CI (3.48, 7.56) p &lt; 0.001
Didn´t found significant difference between mean of RRb2 microglobulin, RRProlactin and RRMioglobin with dialysate flow 300 vs 500 ml/min

Conclusion
Urea and B2 microglobulin, myoglobin and prolactin depuration is adequate at both dialysate flow rate 500 ml/min and 300 ml/min in the evaluated patients.