What is meant by Dialysis
In medicine, Dialysis is a process for removing waste and excess water from the blood and is used primarily as an artificial replacement for lost kidney function in people with kidney failure. Dialysis may be used for those with an acute disturbance in kidney function or progressive but chronically worsening kidney function—a state known as chronic kidney disease . Indications for dialysis in the patient with acute kidney injury are summarized with the vowel acronym of "AEIOU".
1. Acidemia from metabolic acidosis in situations in which correction with sodium bicarbonate is impractical or may result in fluid overload.
2. Electrolyte abnormality, such as severe hyperkalaemia, especially when combined with AKI.
3. Intoxication, that is, acute poisoning with a dialyzable substance. These substances can be represented by the mnemonic SLIME: salicylic acid, lithium, isopropanol, magnesium-containing laxatives, and ethylene glycol.
4. Overload of fluid not expected to respond to treatment with diuretics
5. Uraemia complications, such as pericarditis, encephalopathy, or gastrointestinal bleeding.
Indications for chronic dialysis: Chronic dialysis may be indicated when a patient has symptomatic kidney failure and low glomerular filtration rate (GFR).
The kidneys have important roles in maintaining health. When healthy, the kidneys maintain the body's internal equilibrium of water and minerals (sodium, potassium, chloride, calcium, phosphorus, magnesium, sulphate). The acidic metabolism end-products that the body cannot get rid of via respiration are also excreted through the kidneys. The kidneys also function as a part of the endocrine system, producing erythropoietin and calcitriol. Erythropoietin is involved in the production of red blood cells and calcitriol plays a role in bone formation. Dialysis is an imperfect treatment to replace kidney function because it does not correct the compromised endocrine functions of the kidney. Dialysis treatments replace some of these functions through diffusion of solutes (waste removal) and ultrafiltration (fluid removal) of fluid across a semi-permeable membrane.
The two main types of dialysis, haemodialysis and peritoneal dialysis, remove wastes and excess water from the blood in different ways. Haemodialysis removes wastes and water by circulating blood outside the body through an external filter, called a dialyzer, that contains a semipermeable membrane. The blood flows in one direction and the dialysate flows in the opposite. The counter-current flow of the blood and dialysate maximizes the concentration gradient of solutes between the blood and dialysate, which helps to remove more urea and creatinine from the blood. In peritoneal dialysis, wastes and water are removed from the blood inside the body using the peritoneum as a natural semipermeable membrane. Wastes and excess water move from the blood, across the peritoneal membrane, and into a special dialysis solution, called dialysate, in the abdominal cavity.