Overview
Haemodialysis describes artificially performing the kidney’s roles in filtering by removing excess solutes and toxins from the blood.
Options for renal replacement therapy (RRT) include:
- Haemodialysis
- Peritoneal dialysis
- Renal transplant
Renal Replacement Therapy Indications
Acute indications
Acute indications for haemodialysis include complications of a severe acute kidney injury (AKI). These indications can be remembered using the mnemonic AEIOU:
- Acidosis that is severe and unresponsive to initial treatment
- Electrolyte abnormalities – hyperkalaemia that is severe and unresponsive to initial treatment
- Intoxication – overdose of certain drugs (such as aspirin, methanol, and ethylene glycol)
- Oedema – severe pulmonary oedema that is unresponsive to initial treatment
- Uraemia and its complications – uraemic pericarditis or uraemic encephalopathy
Chronic indications
NICE recommends considering starting dialysis if any of the following apply:
- The symptoms of uraemia affect activities of daily living
- Uncontrollable fluid overload
- Uncontrollable biochemical measures (e.g. electrolytes)
- Estimated glomerular filtration rate (eGFR) is around 5-7 mL/min/1.73 m2 if there are no symptoms
Haemodialysis
Overview
Haemodialysis involves passing blood through a dialysis machine out of the body in which the blood is surrounded by a fluid called the dialysate. The concentration of the dialysate is varied to ensure that excess products (such as urea and creatinine) diffuse out into the dialysate. Blood is then returned to the body.
Haemodialysis is often performed up to 5 hours a day 3 times a week.
Arteriovenous fistula
Haemodialysis requires good access to the blood. This can be attained by creating an arteriovenous (AV) fistula (an artificial connection between an artery and a vein).
This is performed around 8 weeks before the initiation of treatment and most AV fistulae are in the lower arm.
Complications
Some complications of haemodialysis include:
- Infection at the site of access
- Endocarditis
- Hypotension
- Air embolism
- Cardiac arrhythmia
- Nausea and vomiting
- Headaches
- Disequilibration syndrome – characterised by neurological symptoms including headaches, tremors, seizures, and coma
- Depression
Peritoneal Dialysis
Overview
Peritoneal dialysis uses the peritoneum as a filtration membrane. A dialysate is injected into the peritoneal cavity and blood flowing through peritoneal capillaries acts as a blood source. Excess and waste products diffuse across the peritoneal membrane into the dialysate which is then replaced.
Options for peritoneal dialysis include:
- Continuous ambulatory peritoneal dialysis:
- The dialysate is in the peritoneum at all times and changed throughout the day (e.g. 4 times a day)
- Automated dialysis
- A machine constantly replaces the dialysate in the abdomen overnight
- This takes up to 10 hours
Complications
Some complications of peritoneal dialysis include:
- Peritonitis
- Infection at the access site
- Fluid retention
- Back pain
- Weight gain
- Malnutrition
- Depression
