Dialysis and Transplantation Flashcards
What procedure is involved in renal replacement therapy?
Dialysis.
List the types of dialysis.
1 - Peritoneal dialysis.
2 - Haemodialysis.
List 4 functions of the kidney that are replaced by dialysis.
1 - Water homeostasis.
2 - Electrolyte homeostasis.
3 - Acid / base homeostasis.
4 - Excretion of waste products.
Define dialysis.
An extracorporeal therapy where fluid and solutes are exchanged between a patient’s blood and dialysis fluid, which are separated by a semipermeable membrane.
What GFR is achieved by dialysis?
<15ml / min.
What is the average range of GFR in a healthy individual?
90 - 120ml/min.
List 2 factors that determine permeability of a semipermeable membrane to a particular solute.
1 - Size.
2 - Charge.
Define ultrafiltration.
- The movement of an isosmotic solvent across a semipermeable membrane due to the exertion of a physical pressure.
- There is no overall change in concentration, rather a mass movement of the solvent containing an isosmotic concentration of the solute.
Describe the procedure of a peritoneal dialysis.
1 - A catheter is placed at the midline below the umbilicus into the abdominal wall.
2 - Dialysis fluid is injected into the peritoneal space.
3 - After 4 hours, the peritoneal fluid is drained.
4 - Steps 2 and 3 are repeated 4-5 times per day.
List 5 molecules found in dialysis fluid used for a peritoneal dialysis.
What is the role of each of these molecules?
1 - Glucose to change the osmolality.
2 - Dextrose to change the osmolality.
3 - Na+ to reduce irritability of the dialysis fluid.
4 - K+ to reduce irritability of the dialysis fluid.
5 - HCO3-, which moves into the blood to provide an acid / base buffer.
List 5 molecules that move into the dialysis fluid during a peritoneal dialysis.
1 - Water.
2 - Na+.
3 - K+.
4 - Urea.
5 - H+.
Give an example of a risk of peritoneal dialysis.
Peritonitis (due to infection).
Describe the procedure of haemodialysis.
What preparation is necessary for haemodialysis?
1 - Blood is removed from the patient.
2 - The blood is then passed across a semipermeable membrane (a dialysis filter) in countercurrent.
3 - Blood is returned to the patient.
- In preparation for haemodialysis, patients undergo surgery to create an arteriovenous fistula between an artery and a vein in the arm.
What drug is administered during haemodialysis?
What is the purpose of this drug?
- Heparin.
- To stop clotting.
By which process are solutes exchanged across the dialysis filter during haemodialysis?
Ultrafiltration.
Give an example of an alternative method of harvesting and returning blood in a patient undergoing dialysis who is unable to undergo surgery to form an arteriovenous fistula.
A central venous catheter into the jugular vein.
Why is acid load not able to be removed by filtration alone?
Because the H+ concentration in the blood is low since most H+ freely diffuses into tissues.
List 2 buffers that move into the blood during dialysis.
What are these molecules converted to when in the blood?
1 - Lactate.
2 - Acetate.
- They are converted to bicarbonate in the blood.
- Bicarbonate isn’t used in dialysis fluid because it tends to precipitate.
List 4 factors which influence choice of dialysis type.
1 - Lifestyle factors.
2 - Peritoneal dialysis is contraindicated with previous major abdominal surgery.
3 - Peritoneal dialysis might be better in severe heart disease.
4 - Peritoneal dialysis might be better in young patients or older patients with carers.
List 2 conditions in which dialysis is needed for patients with chronic kidney disease.
1 - When eGFR is <10ml/min.
2 - As prophylaxis.
List 6 conditions in which dialysis is needed for patients with acute kidney injury.
1 - When creatinine >500um/L.
2 - Uraemic pericarditis.
3 - Uraemic encephalopathy.
4 - Hyperkalaemia.
5 - Pulmonary oedema.
6 - Metabolic acidosis.
List 6 complications of dialysis.
1 - Infection.
2 - Left ventricular hypertrophy due to hypertension, anaemia (due to low EPO) and fluid overload.
3 - Calcification of arteries.
4 - Anaemia.
5 - Bone disease.
6 - Malnutrition due to dietary requirements for dialysis.
What is the first choice treatment for stage 5 chronic kidney disease?
Kidney transplant.
What is done with the diseased kidneys in a kidney transplant?
They aren’t removed from the body unless they are contributing to disease.
Into which anatomical space are kidneys implanted?
The iliac fossa.
List 2 absolute and 3 relative contraindications for kidney transplant in patients with stage 5 chronic kidney disease.
Absolute contraindications:
1 - Poor life expectancy.
2 - Active malignancy.
Relative contraindications:
1 - Coronary artery disease.
2 - Recurrent disease.
3 - Non-compliance.
Give an example of an antigen that must be matched between a donor and a recipient when assigning a kidney for transplantation.
List 2 other factors that should also be matched between recipient and donor.
- Galactose 1,3-alpha-galactose (alpha gal).
- Human leukocyte antigens must also be matched.
- Blood group is often also matched.
List the genotypes of the human leukocyte antigen.
How many possible versions of each genotype exist?
1 - 59 possible A genotypes.
2 - 118 possible B genotypes.
3 - 124 possible DR genotypes.
How many of each genotype of human leukocytes antigen exist on cell surfaces?
- 2 A genotypes.
- 2 B genotypes.
- 2 DR genotypes.
