What is Hemodialysis

Currently, more and more patients with kidney disease choose to take dialysis in the whole world, among which is hemodialysis. However, few patients know what hemodialysis is and how hemodialysis functions, even they have taken hemodialysis.

In clinic, hemodialysis means that some wastes in blood are moved out through semi-permeable membrane. It is one of the blood purification methods, which is safe, easy and used widely. Dialysis means that solute move from high concentrations to low ones through semi-permeable. Hemodialysis includes the movement of solute and water, that is, blood and dialysate exchange material in dialyzer (artificial kidney) with the help of semi-permeable membrane contact and concentration gradient. Then metabolic wastes and excessive electrolyte in blood move into dialysate and calcium and basic group in dialysate move into blood. If the mixture of albumin and urea are put into the dialyzer and soaked out of tube, urea in dialysis tube will move into water through artificial kidney pore.

Albumin molecule is larger, so it can’t get through the pore. The phenomenon that small molecules can get through semi-permeable membrane while large ones can’t is called dispersion. In clinic, the basic principle of hemodialysis is to purify the blood so that it can achieve the purpose of purification based on the phenomenon of dispersion.

The thickness of semi-permeable membrane in hemodialysis is 10~20 microns and the average size of membrane pore is 3nm. Therefore, small molecules with molecular weight of less than 15000 and part of medium molecules can get through the membrane, while large molecules of 35000 can’t. Protein, pyrogens, viruses, bacteria and blood cells can’t be disclosed. There is more water in urine, so if kidneys are replaced by artificial kidneys, quantities of water must be discharged from blood. Artificial can remove excessive water by osmotic pressure and ultrafiltration pressure. All of the hemodialysis have these functions mentioned above, which can regulate the quality and quantity of blood, approaching to physiological conditions.

Hope what mentioned above can help you know about hemodialysis. If you want to understand hemodialysis further, you can send email to renalhealth@hotmail.com.