Hemodialysis is one of the renal replacement therapy in patients with acute and chronic renal failure. So you know what the hemodialysis principle is? What is hemodialysis?
Hemodialysis refers to the drainage of blood out of the body, with an extracorporeal circulation device with a dialyzer, blood and dialysate through the semipermeable membrane for water and solute exchange, blood and uremia toxins in the blood, including creatinine, urea, potassium, etc. into Dialysate was removed.
The dialysate in the base and calcium into the blood, so as to remove water and urine toxins, water, electrolyte and acid-base balance purposes. The specific method is through a plastic tube to the body's blood drainage to the dialyzer to be purified, the purified blood through another plastic pipe back to the body.
Hemodialysis often need to be performed 2 to 3 times a week, each about 3 to 5 hours. As the general vein is not thick enough, the wall is not thick enough to meet the hemodialysis treatment of blood flow requirements, so before permanent hemodialysis surgery must establish a permanent vascular access, the most common is to do forearm arteriovenous fistula .
What is the principle of hemodialysis?
Hemodialysis is a mature artificial kidney support system. The principle of its treatment is based on the principle of membrane balance, that is, when both sides of the semipermeable membrane solution ion concentration and (or) there is a difference in pressure, ions and moisture can occur through the semipermeable membrane exchange.
In hemodialysis, the semipermeable membrane on one side of the blood, dialysis fluid on the other side, due to the presence of more uremic toxins in the blood, and no toxins in the dialysate, toxins from the blood side of the dialysis fluid to a Side, thereby clearing toxins, while by increasing the dialysis fluid osmotic pressure or the use of a negative pressure, you can make the water flow from the blood to the dialysate and be cleared.
The dialyzer used during hemodialysis is made of a hollow fiber membrane with semipermeable membrane function. Hollow fiber flow is the blood, fiber flow is dialysate. According to the solute and water through the semipermeable membrane can be pided into diffuse, infiltration, convection and ultrafiltration.
Specifically, according to the principle of membrane balance, the gradient difference of the solute concentration contained in the liquid on both sides of the semipermeable membrane and the different osmotic concentrations formed by the semipermeable membrane enable the solutes such as sodium and potassium ions to pass from the high concentration side to the concentration The low side moves. Moisture moves from the lower permeate side to the higher permeate side until it reaches equilibrium.
Therefore, when the blood enters the dialyzer, metabolites such as urea, creatinine and excessive electrolytes such as potassium can diffuse into the dialysate through the dialysis membrane, while substances in the dialysate such as bicarbonate or acetate Can also be dispersed into the blood, in order to achieve the purpose of clearing the body's metabolic waste and correct the balance of water, electrolytes and acid-base treatment.