Dialysis and Transplantation

Question 1

What procedure is involved in renal replacement therapy?

Answer 1

Dialysis.

Question 2

List the types of dialysis.

Answer 2

1 - Peritoneal dialysis.

2 - Haemodialysis.

Question 3

List 4 functions of the kidney that are replaced by dialysis.

Answer 3

1 - Water homeostasis.

2 - Electrolyte homeostasis.

3 - Acid / base homeostasis.

4 - Excretion of waste products.

Question 4

Define dialysis.

Answer 4

An extracorporeal therapy where fluid and solutes are exchanged between a patient’s blood and dialysis fluid, which are separated by a semipermeable membrane.

Question 5

What GFR is achieved by dialysis?

Answer 5

<15ml / min.

Question 6

What is the average range of GFR in a healthy individual?

Answer 6

90 - 120ml/min.

Question 7

List 2 factors that determine permeability of a semipermeable membrane to a particular solute.

Answer 7

1 - Size.

2 - Charge.

Question 8

Define ultrafiltration.

Answer 8

• 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.

Question 9

Describe the procedure of a peritoneal dialysis.

Answer 9

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.

Question 10

List 5 molecules found in dialysis fluid used for a peritoneal dialysis.

What is the role of each of these molecules?

Answer 10

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.

Question 11

List 5 molecules that move into the dialysis fluid during a peritoneal dialysis.

Answer 11

1 - Water.

2 - Na+.

3 - K+.

4 - Urea.

5 - H+.

Question 12

Give an example of a risk of peritoneal dialysis.

Answer 12

Peritonitis (due to infection).

Question 13

Describe the procedure of haemodialysis.

What preparation is necessary for haemodialysis?

Answer 13

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.

Question 14

What drug is administered during haemodialysis?

What is the purpose of this drug?

Answer 14

• Heparin.

- To stop clotting.

Question 15

By which process are solutes exchanged across the dialysis filter during haemodialysis?

Answer 15

Ultrafiltration.

Question 16

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.

Answer 16

A central venous catheter into the jugular vein.

Question 17

Why is acid load not able to be removed by filtration alone?

Answer 17

Because the H+ concentration in the blood is low since most H+ freely diffuses into tissues.

Question 18

List 2 buffers that move into the blood during dialysis.

What are these molecules converted to when in the blood?

Answer 18

1 - Lactate.

2 - Acetate.

• They are converted to bicarbonate in the blood.
• Bicarbonate isn’t used in dialysis fluid because it tends to precipitate.

Question 19

List 4 factors which influence choice of dialysis type.

Answer 19

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.

Question 20

List 2 conditions in which dialysis is needed for patients with chronic kidney disease.

Answer 20

1 - When eGFR is <10ml/min.

2 - As prophylaxis.

Question 21

List 6 conditions in which dialysis is needed for patients with acute kidney injury.

Answer 21

1 - When creatinine >500um/L.

2 - Uraemic pericarditis.

3 - Uraemic encephalopathy.

4 - Hyperkalaemia.

5 - Pulmonary oedema.

6 - Metabolic acidosis.

Question 22

List 6 complications of dialysis.

Answer 22

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.

Question 23

What is the first choice treatment for stage 5 chronic kidney disease?

Answer 23

Kidney transplant.

Question 24

What is done with the diseased kidneys in a kidney transplant?

Answer 24

They aren’t removed from the body unless they are contributing to disease.

Question 25

Into which anatomical space are kidneys implanted?

Answer 25

The iliac fossa.

Question 26

List 2 absolute and 3 relative contraindications for kidney transplant in patients with stage 5 chronic kidney disease.

Answer 26

Absolute contraindications:

1 - Poor life expectancy.

2 - Active malignancy.

Relative contraindications:

1 - Coronary artery disease.

2 - Recurrent disease.

3 - Non-compliance.

Question 27

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.

Answer 27

• Galactose 1,3-alpha-galactose (alpha gal).
• Human leukocyte antigens must also be matched.
• Blood group is often also matched.

Question 28

List the genotypes of the human leukocyte antigen.

How many possible versions of each genotype exist?

Answer 28

1 - 59 possible A genotypes.

2 - 118 possible B genotypes.

3 - 124 possible DR genotypes.

Question 29

How many of each genotype of human leukocytes antigen exist on cell surfaces?

Answer 29

• 2 A genotypes.
• 2 B genotypes.
• 2 DR genotypes.