Haemodialysis and Renal Failure
What is Dialysis?
Dialysis is a method of treating kidney failure. Natural waste products build up in the body and the kidneys are supposed to excrete many of these toxins in the urine. When the kidneys fail, the toxin levels build up. Dialysis helps to remove these toxins.
Dialysis works on the principle of diffusion. Toxins move from an area of high concentration (the sick patient's body) to an area of low toxin concentration (the fluid supplied in the dialysis process).
A fistula access is created surgically by connecting an artery to a vein to strengthen the vein in the forearm, or sometimes the leg
A special site, called an access, must be surgically created in the arm, leg or near the collarbone of the haemodialysis patient. The access is where the needles are placed to remove blood from the body and return it to the body after it is filtered by the dialysis machine. Three types of accesses exist: natural fistula, artificial grafts, and jugular vein catheters.
Haemodialysis removes waste and excess fluid from the blood when the kidneys cannot do so sufficiently. The blood is drawn intravenously, sent through a machine called a dialyser, and returned to the body through a blood vessel. Inside the dialyser, the blood is passed over a membrane that filters waste and fluid into a dialysate solution. The dialysate is then pumped out to a disposal tank and new dialysate is pumped in.
Continuous Ambulatory Peritoneal Dialysis (CAPD)
Continuous Ambulatory Peritoneal dialysis (CAPD) uses a natural filter, the peritoneal membrane. Unlike haemodialysis, the patient does not need to travel to a dialysis centre. Instead, patients are trained to do dialysis at home, on their own schedule
What is Renal Failure
Renal failure refers to the kidneys and their ability to function adequately. Renal failure is divided into two forms; acute and chronic.
- Acute: a rapid lose of renal function typically characterised by a reduction in urine production (oliguria), electrolyte and body fluid disturbances. Once the underlying cause has been identified a short course of dialysis may be necessary to assist the kidneys until the cause has been rectified.
- Chronic: a progressive loss of kidney function over months or even years, with very few specific signs and symptoms the patient may just have a feeling of being unwell with a reduced appetite. Chronic renal failure will be identified from blood test results showing higher levels of creatinine which indicate a reduced filtration rate of blood through the kidneys (glomerular filtration rate). Chronic renal disease is classified in 5 levels, 1 being mild and 5 being a severe illness.
Functions of the Kidneys
The kidneys are responsible for a wide range of functions:
- Waste and water removal from blood
- Chemical balance
- Controlling blood pressure
- Releasing hormaones
- Production of vitamin D
- Helps ijn production of red blood cells
What Causes Kidney Disease
Kidneys lose their ability to filtrate blood when damage to the nephrons has occurred. This damage may have been quick as a result of illness or injury or a gradual onset over years.
Diabetes and High blood pressure (hypertension) are the two most common causes of kidney disease.
- High blood pressure damages the small blood vessels in the kidneys which reduce their ability to filtrate the blood as they're supposed to.
- Diabetic Nephropathy is caused by the increased levels of sugar in the blood. This sugar acts as a 'poison' and damages the nephrons if it stays in the blood instead of breaking down.