Question

how the blood is purified in a uremic patients? explain the process.

Answer 1

Toxic levels of nitrogenous wastes like urea in the blood resulting from severe malfunction of the kidneys is called uraemia. If a person's kidneys are so impaired by disease or injury that is the kidneys are unable to function adequately, then blood must be cleansed artificially by dialysis, the separation of large solutes from smaller ones by diffusion through a selectively permeable membrane. An important method to treat uraemia is haemodialysis which is described as follows:

Haemodialysis directly filters the patient's blood by removing wastes and excess electrolytes and fluid and then returning the cleansed blood to the patient. The steps in haemodialysis are:

1. Blood removed from the body is delivered to a haemodialyzer or haemodialysis machine which is also called artificial kidney.
2. Inside the haemodialyzer, blood flows through a dialysis membrane, which contains pores large enough to permit the diffusion of small solutes based on a concentration gradient.
3. A special solution, called the dialysate, is pumped into the haemodialyzer so that it surrounds the dialysis membrane. The dialysate is specially formulated to maintain diffusion gradients that remove wastes from the blood, such as nitrogenous wastes like urea, creatinine, uric acid, etc., excess phosphate, potassium and sulphate ions; and add useful substances, such as glucose and bicarbonate ions to it.

4. The cleansed blood is passed through an air embolus detector to remove air and then returned to the body through the radial vein by adding anti-heparin.

An anticoagulant (heparin) is added to prevent blood from clotting in the haemodialyzer.