We know that Renal Failure patients usually take Hemodialysis, which can clean their blood. However, it cannot remove all the poisoning substances. There is another method named Hemofiltration, which usually is mistaken as Hemodialysis. So what is the difference between them?
The Difference between Hemodialysis and Hemofiltration |
First, their principles are different. Hemodialysis involves diffusion of solutes across a semipermeable membrane. By concentration gradient and hydrostatic pressure across the membrane, excessive water, urea and other waste products are removed from blood to dialysate. Although Hemofiltration also achieves movement of solutes across a semi-permeable membrane, solute movement with Hemofiltration is governed by convection rather than by diffusion. Without dialysate, only a positive hydrostatic pressure drives water out and solutes get dragged through the membrane along with the flow of water at a similar rate.
Second, removed substances are different between Hemodialysis and Hemofiltration. As diffusion is used in Hemodialysis, only small substances can pass through the semi-permeable membrane, such as urea, potassium, and phosphate, but the large molecular weight solutes can not be removed. With the help of a positive hydrostatic pressure coursed by convection, it is better than Hemodialysis in moderate molecular and macro-molecular substances removal. Hemofiltration is more similar to glomeruli in the function of filtration.
Third, Hemofiltration is more suitable than Hemodialysis to some symptoms, such as Resistant Hypertension, Water Retention, Hypetension, Heart Failure caused by high blood volume, Uremic Pericardditis, Acut Renal Failure and Hepatic Coma. However, Hemofiltration also have disadvantages. Its price is higher than Hemodialysis due to the need of plentiful placement fluid. Blood pressure during Hemofiltration is not easy to control and low pressure and high pressure may occur if the volume is in imbalance. The small products may be not removed as effectively as Hemodialysis.
Therefore, which dialysis to choose depends on each patient’s individul condition instead of the disadvantages of those two dialyses.