Increases in mass transfer-area coefficients and urea Kt/V with increasing dialysate flow rate are greater for high-flux dialyzers

2001 ◽  
Vol 38 (3) ◽  
pp. 575-579 ◽  
Author(s):  
John K. Leypoldt ◽  
Alfred K. Cheung
Keyword(s):  
Mass Transfer ◽  
Flow Rate ◽  
High Flux ◽  
Dialysate Flow ◽  
Dialysate Flow Rate

scholarly journals P1120QUANTIFICATION OF ACID-BASE TRANSPORT IN HEMODIALYZERS

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Pietribiasi Mauro ◽  
Jacek Waniewski ◽  
John (Ken) Leypoldt
Keyword(s):  
Mass Transfer ◽  
Flow Rate ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Bicarbonate Buffer ◽  
Flow Rates ◽  
Dialysate Flow ◽  
Plasma Bicarbonate ◽  
Dialysate Flow Rate ◽  
D Values

Abstract Background and Aims Quantification of bicarbonate and dissolved carbon dioxide (CO2) transport in hemodialyzers can be described by the product of a dialysance (D) and their respective concentration differences between dialysate and plasma. It is typically assumed that D values are constant for a given hemodialyzer and flow conditions; however, this approach neglects the chemical interconversion of bicarbonate and dissolved CO2 within blood. We assessed the validity of this approach by developing a comprehensive mathematical model of acid-base transport in hemodialyzers. Method Mass balance relationships in a hemodialyzer were defined using a one-dimensional model with counter-current flows of blood and dialysate. The molecular biochemistry of bicarbonate, dissolved CO2, and non-bicarbonate buffer in both plasma and erythrocytes, together with carbaminohemoglobins within erythrocytes, was assumed to be in equilibrium as described by Rees and Andreassen (Crit Rev Biomed Eng 2005). The model equations were solved numerically, and optimal mass transfer-area coefficients for bicarbonate and dissolved CO2 were determined by comparing model predictions with the data from Sombolos et al (Artif Organs 2005). The latter data included measured concentrations of bicarbonate and dissolved CO2 in plasma and dialysate inlet and outlet flows at a blood flow rate of 300 mL/min, dialysate flow rate of 700 mL/min, and dialysate bicarbonate concentration of 32.5 mEq/L. Base excess of blood was assumed as -5 mEq/L. Model simulations then evaluated the effect of the plasma bicarbonate concentration at the blood inlet (assuming constant mass transfer-area coefficients and flow rates) on D for both bicarbonate (Dbic) and dissolved CO2 (DCO2). D values were calculated as the loss of the molecule from the dialysate divided by the difference in inlet concentrations of dialysate and plasma. Results Optimal mass transfer-area coefficients for bicarbonate and dissolved CO2 were 396 and 1360 mL/min, respectively. Simulation results at different plasma bicarbonate concentrations at the blood inlet ([Bicarbonate]) as expected during a typical hemodialysis treatment are tabulated: Conclusion Quantification of acid-base transport in hemodialyzers requires dialysance values for bicarbonate and dissolved CO2 that are not constant but instead are dependent on the plasma bicarbonate concentration at the blood inlet for a given hemodialyzer at fixed blood and dialysate flow rates.

Does the Blood Pump Flow Rate have an Impact on the Dialysis Dose During Low Dialysate Flow Rate Hemodialysis?

2018 ◽  
Vol 46 (4) ◽  
pp. 279-285 ◽  
Author(s):  
Maxime Leclerc ◽  
Clémence Bechade ◽  
Patrick Henri ◽  
Elie Zagdoun ◽  
Erick Cardineau ◽  
...  
Keyword(s):  
Flow Rate ◽  
Blood Pump ◽  
Bivariate Analysis ◽  
Dialysis Dose ◽  
Dialysate Flow ◽  
Pump Flow ◽  
Dialysate Flow Rate ◽  
Pump Flow Rate ◽  
A Prospective Study ◽  
The Impact

We conducted a prospective study to assess the impact of the blood pump flow rate (BFR) on the dialysis dose with a low dialysate flow rate. Seventeen patients were observed for 3 short hemodialysis sessions in which only the BFR was altered (300,350 and 450 mL/min). Kt/V urea increased from 0.54 ± 0.10 to 0.58 ± 0.08 and 0.61 ± 0.09 for BFR of 300, 400 and 450 mL/min. For the same BFR variations, the reduction ratio (RR) of β2microglobulin increased from 0.40 ± 0.07 to 0.45 ± 0.06 and 0.48 ± 0.06 and the RR phosphorus increased from 0.46 ± 0.1 to 0.48 ± 0.08 and 0.49 ± 0.07. In bivariate analysis accounting for repeated observations, an increasing BFR resulted in an increase in spKt/V (0.048 per 100 mL/min increment in BPR [p < 0.05, 95% CI (0.03–0.06)]) and an increase in the RR β2m (5% per 100 mL/min increment in BPR [p < 0.05, 95% CI (0.03–0.07)]). An increasing BFR with low dialysate improves the removal of urea and β2m but with a potentially limited clinical impact.

Myoglobin Clearance during Continuous Veno-Venous Hemofiltration with or without Dialysis

1998 ◽  
Vol 21 (4) ◽  
pp. 205-209 ◽  
Author(s):  
D. Nicolau ◽  
Y.S. Feng ◽  
A.H.B. Wu ◽  
S.P. Bernstein ◽  
C.H. Nightingale
Keyword(s):  
Renal Failure ◽  
Animal Model ◽  
Flow Rate ◽  
Major Complication ◽  
Viable Option ◽  
Effective Technique ◽  
Dialysate Flow ◽  
Continuous Arteriovenous Hemofiltration ◽  
Pump Rate ◽  
Dialysate Flow Rate

The management of acute myoglobinuric renal failure, the major complication of rhab-domyolysis, continues to be a treatment dilemma for the clinician as limited therapeutic options are available. Previously, we have demonstrated that continuous arteriovenous hemofiltration (CAVH) is an effective technique for removing myoglobin in an animal model. In the present study, swine were administered four grams of equine myoglobin intravenously and underwent the continuous veno-venous hemofiltration (CVVH) procedure for six hours each. Animals were studied in each of the following groups: CVVH at a pump rate 100 ml/minute, CVVH at a pump rate 200 ml/minute and CVVH at a pump rate 100 ml/minute plus dialysis at a dialysate flow rate of one Liter/h. Once the filtering process was initiated there was a rapid and sustained production of ultrafiltrate in all groups. The amount of myoglobin excreted in the ultrafiltrate over the six-hour filtering period was 688, 948 and 570 mg which corresponded to 17, 24 and 14 percent of the administered dose, respectively, for the three treatments. In comparison to previous CAVH experiments, CVVH removed more circulating myoglobin and the addition of the dialysis component did not appear to improve removal. Based on these findings, it appears that the CVVH hemofiltration system is a viable option for the removal of systemic myoglobin.

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