Phosphorus kinetics during hemodiafiltration: analysis using a pseudo-one-compartment model.
John K Leypoldt1, Baris U Agar, Alp Akonur
1Medical Products (Renal), Baxter Healthcare Corporation, Deerfield, IL 60015, USA. ken_leypoldt@baxter.com
Blood Purification
|March 8, 2013
Summary
On-line hemodiafiltration (HDF) increases phosphorus removal compared to hemodialysis (HD). This enhanced extracorporeal clearance likely explains lower predialysis serum phosphorus levels observed with HDF therapy.
Area of Science:
- Nephrology
- Renal Replacement Therapy
- Biomedical Engineering
Background:
- On-line hemodiafiltration (HDF) shows modest reductions in predialysis serum phosphorus compared to hemodialysis (HD).
- Phosphorus kinetics during HDF and HD require further elucidation.
- Understanding phosphorus removal mechanisms is crucial for managing hyperphosphatemia in dialysis patients.
Purpose of the Study:
- To analyze phosphorus kinetics during on-line hemodiafiltration (HDF) and conventional hemodialysis (HD).
- To compare phosphorus mobilization clearance (KM) and dialyzer phosphorus clearance (Kd) between HDF and HD.
Main Methods:
- Utilized a pseudo-one-compartment kinetic model to analyze existing phosphorus kinetic data from HDF and HD.
- Estimated KM and dialyzer phosphorus clearance (Kd) using predialysis and postdialysis serum phosphorus concentrations and total phosphorus removed.
- Data from previously published studies were retrospectively analyzed.
Main Results:
- Phosphorus mobilization clearance (KM) did not significantly differ between HDF (105 ± 34 ml/min) and HD (112 ± 44 ml/min).
- Dialyzer phosphorus clearance (Kd) was significantly higher during HDF (175 ± 23 ml/min) compared to HD (160 ± 14 ml/min).
- Individual KM values ranged from 53 to 173 ml/min across patients.
Conclusions:
- A pseudo-one-compartment kinetic model effectively analyzes phosphorus kinetics in HDF.
- Higher extracorporeal phosphorus clearance during HDF contributes to lower predialysis serum phosphorus concentrations.
- HDF demonstrates superior phosphorus removal capacity compared to conventional HD.
Related Concept Videos
01:09One-Compartment Model: IV Infusion
Intravenous (IV) infusion is often utilized when continuous and controlled drug delivery is necessary, such as during surgery or in the treatment of chronic diseases. This method offers numerous advantages, including immediate drug action, precise control over dosage, and bypassing the first-pass metabolism.
The one-compartment model for IV infusion uses mathematical equations to describe the rate of change in drug quantity in the body. At steady-state or infusion equilibrium, the drug input...
The one-compartment model for IV infusion uses mathematical equations to describe the rate of change in drug quantity in the body. At steady-state or infusion equilibrium, the drug input...
01:26Pharmacokinetic Models: Comparison and Selection Criterion
Physiological and compartmental models are valuable tools used in studying biological systems. These models rely on differential equations to maintain mass balance within the system, ensuring an accurate representation of the dynamic processes at play.
Physiological models take a detailed approach by considering specific molecular processes. They can predict drug distribution, metabolism, and elimination changes, providing a comprehensive understanding of how drugs interact with the body.
Physiological models take a detailed approach by considering specific molecular processes. They can predict drug distribution, metabolism, and elimination changes, providing a comprehensive understanding of how drugs interact with the body.
01:19One-Compartment Open Model for IV Bolus Administration: General Considerations
The one-compartment model is a pharmacokinetic tool that models the body as a single, uniform compartment, facilitating the understanding of drug distribution and elimination. This model is particularly beneficial for intravenous (IV) bolus administration, where the drug rapidly circulates throughout the body.
The drug's presence in the body is defined by an equation representing the difference between the rates of drug entry and exit. Key parameters—elimination rate constant, half-life,...
The drug's presence in the body is defined by an equation representing the difference between the rates of drug entry and exit. Key parameters—elimination rate constant, half-life,...
01:13Physiological Pharmacokinetic Models: Assumption with Protein Binding
Physiological models with protein binding in pharmacokinetics offer a sophisticated approach to understanding drug disposition. These models consider drug-protein interactions, enabling them to effectively predict drug concentrations in different organs and tissues. This precision aids in accurate drug dosing, providing a significant advantage over conventional models. A key process within these models is equilibration, which ensures that drug concentrations achieve a steady state within the...
00:57Physiological Pharmacokinetic Models: Blood Flow-Limited Versus Diffusion-Limited Models
Physiological pharmacokinetic models, often called flow-limited or perfusion models, typically assume a swift drug distribution between tissue and venous blood, creating a rapid drug equilibrium. This premise is based on the idea that drug diffusion is extremely fast, and the cell membrane presents no barrier to drug permeation. In this scenario, where no drug binding occurs, the drug concentration in the tissue equals that of the venous blood leaving the tissue. This greatly simplifies the...
01:11One-Compartment Open Model: Urinary Excretion Data and Determination of k
The one-compartment open model leverages urinary excretion data to estimate renal clearance, which gauges the kidney's capacity to expel a drug. This method offers several benefits, including directly measuring drug elimination and assessing the kidney's contribution to overall drug clearance. However, this approach has limitations. It assumes sole renal excretion of the drug, which is not true for all drugs. Accurate urinary excretion and plasma drug concentration measurement can also be...