Haemodiafiltration (HDF) is a renal replacement treatment that combines convective and diffusive clearance. HDF eliminates more middle-molecular-weight solutes compared to regular haemodialysis. HDF has been linked to better clinical outcomes in certain trials, though not all, when appropriate convection volumes are attained.
What is Haemodiafiltration?
Haemodiafiltration is a therapy for kidney illness that is reported to be more successful than haemodialysis at removing waste and toxins from your blood. Kidney failure is a disorder in which your kidneys can no longer eliminate waste from your blood efficiently on their own. Diabetes and high blood pressure are frequently associated with it, and it raises the risk of a heart attack or stroke.
More water is eliminated from the blood during haemodialysis with haemodiafiltration than during regular dialysis. The procedure aids in the removal of bigger toxin particles that are not usually filtered out during regular dialysis. The haemodiafiltration machine removes the extra water and toxins, and then it replaces the water with a filtered electrolyte solution before returning the treated blood to the body.
For those with renal disease or kidney failure, haemodiafiltration or standard dialysis treatments are required. However, it isn’t the sole method of assisting dialysis patients in maintaining their quality of life. Haemodiafiltration compared to normal haemodialysis removes more middle-molecular-weight solutes.
HDF is known to give:
- Improved clinical results.
- Adequate convection volumes.
- Increased elimination of bigger pollutants.
How does Haemodiafiltration Work?
Haemofiltration
In haemofiltration solutes move over a semi-permeable membrane. The haemofiltration technique involves convection, rather than diffusion, in transporting solutes. Dialysate is not used in haemofiltration. Instead, water and solutes are forced through the filter membrane from the blood chamber to the filtrate compartment, where they are emptied. Small and big solutes are both drawn through the membrane at the same pace by the hydrostatic pressure-induced flow of water.
Methods of removing solutes from a solution.
There are three main methods of removing solutes from a solution:
Diffusive Removal
Diffusive removal relies on the formation of a gradient of concentration between two solutions separated by a partly (or semi-) permeable barrier that allows solutes to flow through. Solutes move through the membrane from the more concentrated to the less concentrated side. This method is most effective for removing tiny compounds (like urea, or potassium).
Convective Removal
Convective removal is based on the rate at which water flows through a membrane and is driven by the pressure differential (known as the hydrostatic pressure) between the membrane’s two sides. Water pushes through the membrane from the larger pressure side to the lower pressure side if the pressure in the blood compartment is higher or the dialysate side is lower. The water flow increases as the unopposed pressure increases. To understand the mechanism in practical terms, consider a garden hose with a permeable lining.
Adsorption
Plasma proteins, as well as any solutes attached to them, are primarily affected by adsorption. Membrane binding removes plasma proteins that attach to the membrane surface to varying degrees. Adsorption of protein-bound solutes is improved by high flux membranes over low flux membranes. Adsorption was widely overlooked until recently since it was an entirely uncontrolled element. However, with the ability to nanoengineer membranes, modification of protein-bound solutes is quickly becoming a potential development area in membrane biophysics.
While all dialysis procedures include all three processes, early haemodialysis was primarily a diffusive process with low-flux (low permeability) membranes in practice. As membranes became more high flux (leaky) and our capacity to maintain water purity and safety increased, dialysis gradually shifted its dependence on convective forces from diffusive clearance.
Online Haemodiafiltration Technique
HDF is far more difficult and sophisticated than regular haemodialysis. Online haemodiafiltration (HDF) is a technique in which the dialysis fluid is itself employed as the replacement solution. The dialysis machine generates the substitution fluid in online HDF, allowing for huge convection volumes. This is a new innovative treatment that has helped many individuals suffering from renal disease all around the world.
Benefits of Online Haemodiafiltration Technique
- Online HDF gives patients a higher chance of survival than traditional dialysis, which uses simply the concept of diffusion.
- It has been established that any patient tolerates haemodiafiltration far better than haemodialysis, with less hypotensive episodes.
- Toxins with intermediate molecular weights such as phosphorus, beta two microglobulin, and inflammatory cytokines are removed.
- Complications, such as dialysis-related amyloidosis, occur at a lower rate.
- Improved renal bone disease management.
How is Haemodiafiltration different from Conventional Dialysis?
Toxins are eliminated via diffusion and convection techniques in this approach. When compared to traditional dialysis, which relies only on the diffusion principle, patients have a higher chance of survival. The existence of ultrapure (injection quality) water is the most crucial criterion for haemodiafiltration. Many patients have reported that haemodiafiltration is far more tolerable than haemodialysis, with fewer bouts of hypertension.
Conclusion
Haemodiafiltration as a renal replacement treatment gives patients a higher chance of survival than traditional dialysis, which uses simply the concept of diffusion.Convective dialysis may lower cardiovascular mortality, but not all-cause mortality, and the effects on nonfatal cardiac events and hospitalisation are unclear. However, because of limitations in study methodologies and reporting, any therapeutic benefits of convective dialysis on any patient outcomes, including cardiovascular mortality, are suspect. Future research that examines the therapy effects of convection dosage on patient outcomes, such as mortality and cardiovascular events, will be useful.