Hemodialysis is commonly used for patients with stage 5 Chronic Kidney
Disease. Although many people who have lost all most their renal function have
undergone hemodialysis, they do not know how the dialysis machine works for
them, that is to say they do not know the principle of hemodialysis.
Hemodialysis is a safe, easy and widely used blood purification method.
Dialysis means through semipermeable membrane, solute move to the side of low
concentration from the side of high concentration. Hemodialysis includes the
movement of solute and water, which means that with the help of semipermeable
membrane and concentration gradient, blood and dislysate do the interchange of
material. While patients undergo hemodialysis, excessive electrolyte and waste
products move to the side of dislysate and meanwhile, calcium ion, basic group
and other substances shift to the blood.
If we put the mixed liquid of albumin and urea into the dialysis machine, and
the other side we fill water, we can observe that urea get through the hole of
dialysis machine and move into the water. However, as for albumin, because it is
macromolecular substances, it can not get through the hole. The phenomenon that
micromolecule can get through the semipermeable membrane, but macromolecule can
not is called diffusion. In clinic, people use diffusion to separate blood, so
as to achieve the purpose of blood purification.
The thickness of semipermeable membrane used in hemodialysis is ten to twenty
micros. The aperture in membrane is three nanometer and it only allow
micromolecule and some middle molecular substance which have molecular weight
less than thirty five thousand to get through. Therefore, patients should not
worry about that the nutrient substances in their body such as protein, pyrogen,
virus, bacterium and blood cell will be lost while they are undergoing
hemodialysis.
Apart from hemodialysis, peritoneal dialysis is also can be used in clinic to
help patients purify their blood. However, they just help to purify blood, and
they can not help patients restore their renal function. Thereby, if patients
avoid dialysis, they should receive treatment as soon as possible.
