End-Stage Renal failure and Dialysis

Most persons with chronic kidney disease never progress to established renal failure (that is, Grade 5) also known as “End Stage Renal Failure”. However in those who do, renal replacement therapy (in the form of dialysis) is necessary for survival.

It is possible to predict when end-stage renal failure requiring dialysis will occur, as in most patients, renal function is lost at a constant rate and this can be predicted through measurement of serum creatinine.

The effects of renal failure are the same whatever the cause and the condition, which causes renal failure is not important unless it has other effects which give rise to functional effects.

Types of Dialysis

Dialysis (renal replacement therapy) takes over the function of the kidneys, that is, to remove toxins and excess fluid from the blood. Dialysis therapy is necessary for the rest of a person’s life unless a kidney transplant becomes available.

There are two types of dialysis, haemodialysis and peritoneal dialysis. Patients should be able to choose, which type of dialysis they would prefer. However, most patients will experience both types of dialysis, dependant on the personal choice and clinical suitability.

Haemodialysis means filtering of the blood and is a method of removing toxins and excess fluid from the blood using an “artificial kidney” or dialyser in a machine.

Peritoneal dialysis is a method of cleaning the blood without the blood leaving the body. A solution “dialysate fluid” is run through a tube into a person’s abdominal cavity. The dialysate fluid is left in a person’s abdominal cavity for several hours allowing toxins and excess fluid to pass from the blood into the dialysate fluid, this fluid is then drained out of the patient and replaced with fresh dialysate fluid.

• Haemodialysis
• Possible complications of Haemodialysis
• Peritoneal dialysis
• Possible complications of Peritoneal dialysis

1) Haemodialysis

Haemodialysis is used in three main situations:

• With sudden onset of acute renal failure (where renal function is expected to return to within a normal or acceptable range after treatment).
• For regular long term treatment of patients with irreversible renal failure. That is, when the kidneys can no longer remove waste products adequately, or when the person’s normal functional capacity is affected. This can be a permanent measure, and/or while the person is awaiting a renal transplant.
• For a one-off removal of toxic substances from the body (as in accidental or deliberate ingestion or overdose of certain drugs or poisons).

Therefore, it can provide short or long- term treatment.

A person will require minor surgery in preparation for haemodialysis. An artificial connection between a vein and an artery is made usually in the person's forearm. This is called an arterio-venous fistula. This causes the blood vessel to enlarge and allow easy and repeated insertion of two needles to access the person’s blood. Sometimes a synthetic tube (graft) may be used instead, and in a temporary situation access to the bloodstream in this case is through a large vein (usually near the neck) – by a central venous (CV) catheter.

Approximately 200 mls of blood at a time is taken out of the body and pumped by a machine into an artificial kidney (known as a dialyser).The blood is filtered of toxic substances, excess fluid and those compounds, which would normally be removed by a functioning kidney. After dialysis the blood is directed back into the body via the arterio-venous fistula in the forearm. The cleaning of blood is a continuous process and haemodialysis treatment can take 4 to 5 hours, 3 to 4 times a week, depending on the person’s clinical condition.

The blood is taken out of the body and pumped by a machine into an artificial kidney (known as a dialyser).The blood is filtered of toxic substances and those compounds which would normally be removed by a functioning kidney. After dialysis the blood is directed back into the body via the arterio-venous fistula in the forearm.

Blood is prevented from clotting in the tubes of the dialyser by the use of the anticoagulant, heparin, which is given as a continuous infusion. It is also kept warm while outside the body and maintained within a narrow temperature range not very different from normal body temperature.

Inside the dialyser, there is an artificial membrane which is porous. It allows the passage of fluids and metabolic waste products through, but not blood cells or large proteins. The haemodialysis machine can be set to remove an exact amount of fluid from the blood. This is dependant on a patient’s weight and clinical condition prior to haemodialysis.

Possible complications of Haemodialysis

• Infection (normally brought in at the site of insertion of the needle into the arterio-venous fistula) or site of the synthetic tube.
• Hypotension (low blood pressure) caused by too much fluid shift out of the bloodstream. This may make a person feel light - headed and nauseated.
• Cramp usually in the legs, caused by excess fluid and toxin removal.
• Bleeding - a side effect of heparin (see above). Prolonged bleeding – time, [following removal of needles from arterio-venous fistula]; or bruising.
• Allergy to substances or equipment used in the process - very rare.
• Air embolus (air entering the blood during the process) - extremely rare.
• Abnormal heart rhythms caused by a disturbance of potassium levels and other imbalances in the blood. (Merck Manual 2nd Edition)

However haemodialysis is effective to use, and is relatively user- friendly.

Patients dialyse either sitting in a reclining chair or lying on a bed. They are able to watch TV, read and can drink and eat snacks. Most haemodialysis treatment takes place in hospital as an out - patient, however some patients are able to have haemodialysis at home. Home haemodialysis requires the patient to take responsibility for their haemodialysis treatment with the assistance of a carer.

Being dependent on haemodialysis is just that, a lifelong dependency on machine for survival, and a huge change in lifestyle, affecting personal life, work (if applicable) transport considerations, etc.

Being dependent on haemodialysis has a huge impact on both the patient and the family.

2) Peritoneal Dialysis

The principles of peritoneal dialysis depend on the fact that the peritoneum (the lining that covers all the abdominal organs and the abdominal cavity itself) has a large surface area, a good blood supply, and also allows substances to pass through it. A catheter is surgically inserted through the abdominal wall into the peritoneal cavity, and this normally stays in place for a considerable time. Dialysis fluid, which is warmed to body temperature, is allowed to run into the abdominal cavity over a period of time, left there for a time to allow waste products and fluid from the blood to pass into the fluid, and then it is drained off, and thrown away, to be replaced with fresh dialysis fluid, which in turn is drained off. (The process is enhanced by the presence of sugar (dextrose or glucose) which helps “pull” the wastes into the abdominal cavity).

Connection and disconnection to the bags of dialysis fluid must be carried out using a meticulously aseptic (germ-free) technique to minimise the risk of peritonitis (infection of the peritoneal cavity).

The person performs the dialysis exchanges him/herself, and this type of dialysis allows the person to perform the dialysis at home and maintain much more independence.

The peritoneal exchanges can be performed manually (continuous ambulatory or CAPD) or by machine (automated or APD).

Continuous Ambulatory Peritoneal Dialysis (CAPD)

• In CAPD, typically 4 exchanges of 2 litres of fluid take place over a 24 hour period.
• Normally, 3 of these exchanges take place during the day, and one at night, when the dwell time (that is, the time the fluid stays in the abdominal cavity) is much longer, while the person sleeps.
• A machine is not needed, and the person can walk around during the process.

Automated Peritoneal Dialysis (APD) or Continuous Cycler- assisted Peritoneal Dialysis (CCPD)

Automated Peritoneal Dialysis is also known as Continuous Cycler- assisted Peritoneal Dialysis.

• This form of peritoneal dialysis is used in the frail, elderly and weak.
• In APD the machine makes a number of short exchanges during the night, (typically 3 to 5) with the option of (an) additional bag(s) during the day, without the cycler.
• Because of the number of short exchanges performed overnight, the need for exchanges during the day is reduced.

Intermittent Peritoneal Dialysis

• This process is normally used in acute renal failure. Short exchanges are performed every 1 to 2 hours, and the patient is required to stay in bed during treatment.

Possible complications of Peritoneal Dialysis

• Infection – peritonitis, which can be introduced through the catheter or the dialysis fluid, if a strict aseptic technique is not used.
• Blockage of the catheter
• Leakage of the catheter due to an inefficient seal of the catheter and the abdominal wall.
• Bleeding around the catheter or in the abdominal cavity
• Scarring of the peritoneum. Long- term changes may occur to the peritoneal membrane including encapsulating peritoneal sclerosis.
• High blood sugar level and poor diabetic control, caused by dialysate being high in sugar. Consequently, sugar control needs to be increased.
• Hernias (weakening of the abdominal wall) due to the mechanics of fluid continually expanding the abdominal cavity.

The treatment for a patient can vary between haemodialysis, peritoneal dialysis and transplant, and each method of treatment can be revisited more than once.

Click on the link for details of:

• Renal Dialysis - Deeming Provisions

Amended April 2008