Dialysis and Renal transplant Flashcards
What is dialysis?
a method for performing the filtration tasks of the kidneys artificially in patients with end stage renal failure or complications of renal failure. It involves removing excess fluid, solutes and waste products.
(take over the normal process of kidneys)
Indications for acute dialysis:
AEIOU
A – Acidosis (severe and not responding to treatment)
E – Electrolyte abnormalities (severe and unresponsive hyperkalaemia)
I – Intoxication (overdose of certain medications where the only way to remove is dialysis)
O – Oedema (severe and unresponsive pulmonary oedema)
U – Uraemia symptoms such as seizures or reduced consciousness
long term:
- end stage renal failure (CKD stage 5) eGFR <15
- (any other acute indications)
options for maintenance dialysis
Continuous Ambulatory Peritoneal Dialysis
Automated Peritoneal Dialysis
Haemodialysis
decision is based on:
- Patient preference
- Lifestyle factors
- Co-morbidities
- Individual differences regarding risks
What is peritoneal dialysis?
uses the peritoneal membrane (the peritoneum in a persons abdomen) as a filtration membrane.
special dialysis solution containing dextrose is added to the peritoneal cavity.
ultrafiltration occurs across the blood (across peritoneal membrane) into the dialysis solution. this is replaced, taking away waste production.
Tenckhoff cather (plastic tube in peritoneal cavity) allows access to the peritoneal cavity. used for inserting and removing the dialysis solution.
continuous vs automated peritoneal dialysis:
Continuous Ambulatory Peritoneal Dialysis
This is where the dialysis solution is in the peritoneum at all times. There are various regimes for changing the solution. One example is where 2 litres of fluid is inserted into the peritoneum and changed four times a day.
Automated Dialysis
This involves peritoneal dialysis occurring overnight. A machine continuously replaces dialysis fluid in the abdomen overnight to optimise ultrafiltration. It takes 8-10 hours.
peritoneal dialysis complications:
- bacterial peritonitis (infusing solution of glucose so high risk of bacterial infections growing)
- peritoneal sclerosis (thickening and scarring of peritoneal membrane) (less effective over time)
- ultrafiltration failure. pt starts to absorb the dextrose. gradient is reduced so less effective
- weight gain (absorb carbs)
- psychosocial effect - having to change dialysis solution and sleep with a machine every night
haemodialysis
With haemodialysis, patients have their blood filtered by a haemodialysis machine. Regimes can vary but a typical regime might be 4 hours a day for 3 days a week.
They need good access to an abundant blood supply. The options for this are:
- Tunnelled cuffed catheter
- Arterio-venous fistula
tunnelled cuffed catheter
A tunnelled cuffed catheter is a tube inserted into the subclavian or jugular vein with a tip that sits in the superior vena cava or right atrium. It has two lumens, one where blood exits the body (red) and one where blood enters the body (blue).
There is a ring called a “Dacron cuff” that surrounds of the catheter. It promotes healing and adhesion of tissue to the cuff, making the catheter more permanent and providing a barrier to bacterial infection. These can stay in long term and be used for regular haemodialysis.
The main complications are infection and blood clots within the catheter.
A-V fistula
An A-V fistula is an artificial connection between an artery to a vein. It bypasses the capillary system and allows blood to flow under high pressure from the artery directly into the vein. This provides a permanent, large, easy access blood vessel with high pressure arterial blood flow.
Creating an A-V fistula requires a surgical operation and a 4 week to 4 month maturation period without use.
They are typically formed between an artery and vein in the patient’s forearm:
Radio-cephalic
Brachio-cephalic
Brachio-basilic (less common and more complex operation)
examining AV fistula
Skin integrity above fistula
Aneurysms
Palpable thrill (a fine vibration felt over the anastomosis)
Stereotypical “machinery murmur” on auscultation
AV fistula complications
Aneurysm Infection Thrombosis Stenosis STEAL syndrome High output heart failure
what is STEAL syndrome?
STEAL syndrome is where there is inadequate blood flow to the limb distal to the AV fistula. The AV fistula “steals” blood from the distal limb. The blood is diverted away from where is was supposed to supply and flows straight into the venous system. This causes distal ischaemia.
high output heart failure
Where there is an A-V fistula blood is flowing very quickly from the arterial to the venous system through the fistula. This means there is rapid return of blood to the heart. This increases the pre-load in the heart (how full the heart is before it pumps). This leads to hypertrophy of the heart muscle and heart failure.
never take blood from fistula!!!!!
Renal transplant
a kidney is transplanted into the patient with end stage renal failure. It typically adds 10 years to life compared with just using dialysis.
donor matching for renal transplant
human leukocyte antigen (HLA) type A, B and C on chromosome 6. They don’t have to fully match. Recipients can receive treatment to desensitise them to the donor HLA when there is a living donor. The less they match, the more likely the transplant is to fail.
