Who needs a dialysis?

Emobileclinic Trending Topic: ABOUT DIALYSIS

a dialysis machine in the renal unit of a hospital

Emobileclinic Specialist

Dialysis is a process of removing waste and excess water from the blood. It is primarily use as an artificial replacement for lost kidney function in people with renal failure ( Pendse et al., 2008). 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 stage 5 or end stage renal disease. Dialysis is regarded as a holding measure until a renal transplant can be performed, or sometimes as the only supportive measure for those who will not undergo kidney transplant (Pendse et al., 2008).
The kidneys play important roles in maintaining health. Kidneys maintain the body’s internal equilibrium of water and minerals (sodium, potassium, chloride, calcium, phosphorus, magnesium, sulfate). 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. Kidney also regulates acid base balance (Hall, 2013).
Dialysis is an imperfect treatment to replace kidney function because it does not correct the compromised endocrine functions of the kidney but replace some of these functions through diffusion and ultrafiltration .

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Dialysis operate base on principle of diffusion and ultrafiltration
Diffusion is the movement of substances from an area of high concentration to an area of low concentration. Blood flows by one side of a semi-permeable membrane, and a dialysate or special dialysis fluid flows by the opposite side. A semipermeable membrane is a thin layer of material that contains holes of various sizes, or pores. Smaller solutes and fluid pass through the membrane but the membrane blocks the passage of larger substances (for example, red blood cells, large proteins). This replicates the filtering process that takes place in the kidneys when the blood enters the kidneys and the larger substances are separated from the smaller ones in the glomerulus (Mosby, 2006) .

There are two main types of dialysis, hemodialysis and peritoneal dialysis. The other types are hemofiltration and intestinal dialysis.

Hemodialysis 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. The concentrations of solutes (for example potassium, phosphorus, and urea) are undesirably high in the blood, but low or absent in the dialysis solution, and constant replacement of the dialysate ensures that the concentration of undesired solutes is kept low on this side of the membrane.

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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 ( Kallenbach, 2005) .

Hemofiltration is a similar to hemodialysis, but it makes use of a different principle. The blood is pumped through a dialyzer or hemofilter as in dialysis, but no dialysate is used. A pressure gradient is applied as a result of the pressure water moves across the very permeable membrane rapidly, dragging along with it many dissolved substances, including ones with large molecular weights, which are not cleared as well by hemodialysis. Salts and water lost from the blood during this process are replaced with a substitution fluid that is infused into the extracorporeal circuit during the treatment. Hemodiafiltration is the combining of hemodialysis and hemofiltration in one process.

Intestinal dialysis is the transfer of toxic substances from the blood system of the intestine to the decaying waste matter passing through the intestine and out of the body. This process is assisted by the presence of microorganism and soluble fiber in the gut.


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Mosby’s Dictionary of Medicine, Nursing, & Health Professions. 7th ed. St. Louis, MO; Mosby: 2006
Papadakis MA (2007). Current medical diagnosis and treatment McGraw-Hill.pp. 934–935. ISBN 0-07-147247-9.
Pendse S, Singh A, Zawada E. Initiation of Dialysis. In: Handbook of Dialysis. 4th ed. New York, NY; 2008:14–21
Kallenbach J.Z. In: Review of hemodialysis for nurses and dialysis personnel. 7th ed. St. Louis, Missouri:Elsevier Mosby; 2005.

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