Related Experiment Video
Updated: Jul 8, 2026
10:19
Three-Dimensionally Printed Microfluidic Cross-flow System for Ultrafiltration/Nanofiltration Membrane Performance Testing
Published on: February 13, 2016
Increasing dialysate flow rate increases dialyzer urea mass transfer-area coefficients during clinical use
1Department of Medicine, Division of Nephrology, University of Louisville, Louisville, KY, USA.
Summary
Dialysate flow rate significantly impacts dialyzer mass transfer coefficient (K(o)A) during hemodialysis. Higher dialysate flow increases K(o)A, but blood flow and hematocrit also influence this crucial factor.
Area of Science:
- Nephrology
- Biomedical Engineering
- Mass Transfer
Background:
- Dialyzer clearance is vital for hemodialysis efficacy.
- The mass transfer coefficient (K(o)A) is typically assumed constant.
- Recent studies question the constancy of K(o)A under varying flow conditions.
Purpose of the Study:
- To investigate the hypothesis that K(o)A is dependent on blood and dialysate flow rates during clinical dialysis.
- To quantify the impact of these flow rates on urea K(o)A.
Main Methods:
- Urea clearances were measured in two dialyzers across four combinations of blood (300, 400 mL/min) and dialysate (500, 800 mL/min) flow rates.
- Urea K(o)A was calculated using standard countercurrent flow mass transfer equations.
- Analysis of variance assessed the effects of flow rates and hematocrit on K(o)A.
Main Results:
- Increasing dialysate flow rate significantly increased urea K(o)A (P=0.018).
- Increasing blood flow rate did not significantly increase K(o)A (P=0.083).
- K(o)A significantly decreased with increasing hematocrit (P=0.022).
Conclusions:
- This study confirms that increased dialysate flow rate enhances urea K(o)A during clinical hemodialysis.
- The observed increase in K(o)A in vivo was less pronounced than in vitro, likely due to blood-side resistance.
- Findings underscore the importance of optimizing dialysate flow for improved dialysis efficiency.
More Related Videos
Related Concept Videos
01:15Dialysis
Dialysis is a diffusion-based purification process that separates analyte molecules from a complex matrix. This is accomplished by allowing molecules in the solution to pass through a semipermeable membrane into a liquid on the other side. The membrane is usually made of cellulose acetate or cellulose nitrate, and the second liquid must be miscible with the solution. Ions (e.g., chloride or sodium) or organic molecules (e.g., glucose) can pass through the membrane pores, which generally have...
01:27Dialysis
Renal failure occurs when the kidneys lose their ability to filter waste products from the blood effectively. It can be classified into two types: acute renal failure (ARF) and chronic renal failure (CRF).
Acute kidney injury develops suddenly and can be caused by pre-renal causes (e.g., hypovolemia, shock), intrinsic renal causes (e.g., acute tubular necrosis), or post-renal causes (e.g., urinary obstruction). In contrast, chronic renal failure progresses gradually over time and is often...
Acute kidney injury develops suddenly and can be caused by pre-renal causes (e.g., hypovolemia, shock), intrinsic renal causes (e.g., acute tubular necrosis), or post-renal causes (e.g., urinary obstruction). In contrast, chronic renal failure progresses gradually over time and is often...
01:22Renal Drug Excretion: Effect of Urine pH, Flow Rate, and Drug pKa
The pH of urine, the drug's pKa, and the urine flow rate are vital parameters for drug reabsorption and excretion. Urinary pH varies between 4.6 and 8.0 and is influenced by diet, drug intake, and the patient's pathophysiology. It affects a drug's ionization state and reabsorption. For instance, carbohydrate-rich food produces alkaline urine promoting drug excretion, while proteins and certain medications like ascorbic acid lead to acidic urine enhancing reabsorption.
The pKa of a drug,...
The pKa of a drug,...
01:25Drug Dosing in Renal Diseases: Measurement of Glomerular Filtration Rate
The glomerular filtration rate (GFR) is a critical indicator of kidney health, reflecting how well the kidneys filter blood. Changes in GFR can signal potential kidney impairment, necessitating accurate measurement methods to monitor kidney function effectively.Various molecules can serve as markers for GFR measurement, with the ideal marker meeting several specific criteria. It must freely filter at the glomerulus, avoid reabsorption or secretion by the renal tubules, remain unmetabolized, not...
01:25Drug Dosing in Renal Diseases: Dose Adjustments Based on Drug Clearance and Elimination Rate Constant
In patients with renal disease, dosage adjustments are necessary to maintain therapeutic plasma drug concentrations and prevent toxicity or subtherapeutic exposure. Renal impairment alters drug pharmacokinetics, especially in conditions like uremia, where changes such as prolonged elimination half-life and altered apparent volume of distribution can significantly affect drug disposition. These changes require careful modification of the dosing regimen to achieve the desired clinical...
01:30Peritoneal Dialysis I: Introduction and Procedure
Peritoneal dialysis (PD) is a procedure that facilitates the exchange of solutes, waste products, electrolytes, and excess fluid between the blood in the peritoneal capillaries and a dialysis solution introduced into the peritoneal cavity.Principles of Peritoneal Dialysis (PD)Diffusion: Waste products such as urea and electrolytes move from high concentrations in the blood to low concentrations in the dialysate across the peritoneal membrane. This mechanism is driven by the concentration...