The reduction in the ability of the kidneys to filter waste products from the blood and excrete them in the urine is called as renal failure. The regulation of the water balance, salt balance and control of blood pressure are impaired due to kidney failure. The kidney failure also leads to uraemia (a built up of urea and waste products) and other chemical disturbances in the blood and tissues. This leads to various disorders and symptoms.
Kidney failure can be acute (of sudden onset) or chronic (developing more gradually). In acute Kidney failure kidney function returns to normal once the causes have been discovered and treated. In chronic kidney failure the kidney function does not revive since it is caused by poor supply (flow) of blood, major illness, heart attack or pancreatitis. This damages the kidney tissue and its function. Heart transplantation is suggested for chronic type of failure.
Dialysis involves a technique used for removing waste products from the blood and excess fluid from the body as a treatment for kidney failure.
The kidneys filter approximately 1500 liters of blood daily. From this volume of blood, the kidney reabsorbs important elements such as sodium, potassium, calcium, amino acids, glucose and water. In people whose kidney have been damaged this process may fail either suddenly (in acute kidney failure) or gradually in chronic renal failure. Waste starts to accumulate in the blood, with harmful, sometimes even life threatening effects. In severe cases, the function must be taken over by artificial means of dialysis. Dialysis is called artificial kidney.
A kidney machine is a mechanical device through which a patient's blood passes. The blood leaves the body usually from an artery in the forearm and return to a nearby vein. Inside the machine the blood flows over or between membranes containing dissolved fluid (Dialysing fluid) and salt in concentrations normally found in blood. Solid constituents in the blood in excess of normal concentrations diffuse across the membrane into the dialyzing fluid. In this way waste like urea which accumulate in the body are extracted. Blood cells and protein remain in the blood. The process is called haemodialysis.
Two kinds of dialysis are performed in clinical medicine. They are haemodialysis and peritoneal dialysis.