Dialysis Flashcards
What is dialysis, and when is it used?
Dialysis is a method for artificially performing the filtration tasks of the kidneys. It is used in patients with end-stage renal failure or complications of acute kidney injury to remove excess fluid, solutes, and waste products.
What does the ‘AEIOU’ mnemonic stand for in the context of short-term dialysis indications?
A – Acidosis (severe and not responding to treatment)
E – Electrolyte abnormalities (especially treatment-resistant hyperkalaemia)
I – Intoxication (overdose of certain medications)
O – Oedema (severe and unresponsive pulmonary oedema)
U – Uraemia symptoms (seizures or reduced consciousness)
What is the main indication for long-term dialysis?
The main indication for long-term dialysis is end-stage renal failure (CKD stage 5).
What are the two options for long-term dialysis?
- Haemodialysis
- Peritoneal dialysis
How does haemodialysis work?
Blood is filtered through a dialysis machine, passing through semipermeable membranes. Waste, solutes, and excess water are removed by diffusion and ultrafiltration into a fluid called dialysate. The blood is returned to the body after filtration.
What are the types of access required for haemodialysis?
- Tunnelled cuffed catheter
- Arteriovenous (AV) fistula
What is a tunnelled cuffed catheter, and what are its complications?
A tunnelled cuffed catheter is a tube inserted into the subclavian or jugular vein, with a tip in the superior vena cava or right atrium. It has two lumens for blood removal and return. Complications include infection and blood clots within the catheter.
What is an arteriovenous (AV) fistula?
An AV fistula is an artificial connection between an artery and a vein, allowing high-pressure blood flow for haemodialysis. It requires surgery and a maturation period of 4-16 weeks before use.
What are the types of AV fistulas?
- Radiocephalic fistula (wrist)
- Brachiocephalic fistula (antecubital fossa)
- Brachiobasilic fistula (upper arm)
What are the AV fistula features to examine during an OSCE?
- Skin integrity
- Aneurysms
- Palpable thrill (fine vibration over the anastomosis)
- ‘Machinery murmur’ on auscultation
What are complications of an AV fistula?
- Aneurysm
- Infection
- Thrombosis
- Stenosis
- STEAL syndrome
- High-output heart failure
What is STEAL syndrome in relation to AV fistulas?
STEAL syndrome occurs when blood is diverted from the limb distal to the fistula, leading to ischaemia in that part of the limb.
What is high-output heart failure in the context of an AV fistula?
High-output heart failure results from the rapid blood return through the AV fistula, increasing pre-load and causing hypertrophy of the heart muscle, eventually leading to heart failure.
What is peritoneal dialysis, and how does it work?
Peritoneal dialysis uses the peritoneal membrane to filter the blood. A special dialysis solution is introduced into the peritoneal cavity, where ultrafiltration occurs across the membrane into the dialysis solution, which is then replaced to remove waste.
What is a Tenckhoff catheter?
A Tenckhoff catheter is a plastic tube inserted into the peritoneal cavity for peritoneal dialysis. It allows for the insertion and removal of dialysis solution.
What is continuous ambulatory peritoneal dialysis (CAPD)?
CAPD is a form of peritoneal dialysis where dialysis solution is constantly in the peritoneal cavity. It involves replacing the solution four times daily, typically two liters each time.
What is automated peritoneal dialysis?
Automated peritoneal dialysis involves a machine that automatically replaces the dialysis fluid for 8-10 hours overnight.
What are complications of peritoneal dialysis?
- Bacterial peritonitis (serious infection)
- Peritoneal sclerosis (thickening and scarring of the peritoneal membrane)
- Ultrafiltration failure (due to absorption of dextrose)
- Weight gain (from dextrose absorption)
- Psychosocial implications
