Renal Replacement Therapy

Question 1

List the normal functions of the kidney [8]

Answer 1

1. regulation of total body water
2. waste excretion, e.g. urea/creatinine
3. regulation of body electrolytes
4. regulation of acid-base balance
5. mineral metabolism
6. production of renin
7. production of EPO
8. glucose metabolism

Question 2

What are the indications to commence renal replacement therapy? [5]

Answer 2

1. Medically resistant hyperkalaemia
2. Medically resistant pulmonary oedema
3. Medically resistant acidosis
4. Uraemic pericarditis
5. Uraemic encephalopathy

Question 3

What are the symptoms of clinical uraemia? [6]

Answer 3

1. anorexia
2. vomiting
3. itch
4. restless legs
5. weight loss
6. metallic taste

Question 4

At what eGFR level do patients who go for RRT normally have? [1]

Answer 4

generally eGFR between 5-10 ml/min/1.73m²

Question 5

What are the renal replacement therapy modalities for patients with establised disease? [3]

Answer 5

1. haemodialysis transplant
2. peritoneal dialysis
3. renal transplant

Question 6

Describe the mechanism by which haemodialysis replaces the functions of the kidney [5]

Answer 6

1. blood is taken out from the body by TCVC (tunnelled central venous catheter) or AVF access (arteriovenosus fistula)
2. solutes (such as potassium and urea) are removed from the blood by diffusion
3. fluid is removed from the blood by hydrostatic filtration
4. dialysate is discarded
5. “new” blood is pumped back in

Question 7

List the complications associated with haemodialysis [8]

Answer 7

1. “Crash” (acute hypotension)
2. Access problems
3. Cramps
4. Fatigue
5. Hypokalaemia
6. Blood loss
7. Dialysis disequilibrium
8. Air embolism

Question 8

Describe the mechanism by which peritoneal dialysis replaces the functions of the kidney [4]

Answer 8

1. uses the peritoneum as a semi-permeable membrane
2. a catheter is inserted into the peritoneal cavity and fluid is infused
3. solutes diffuse slowly across and ultrafiltration is achieved by adding osmotic agents (glucose/glucose polymers) to the fluid
4. it is a continous process with intermittent drainage and refilling of the peritoneal cavity, performed at home

Question 9

Describe the 2 types of peritoneal dialysis [2]

Answer 9

1. CAPD (continuous ambulatory peritoneal dialysis)
   
   • manual exchanges by patient
2. APD (automated peritoneal dialysis
   
   • machine performs automated changes while patient asleep

Question 10

List the complications associated with peritoneal dialysis [8]

Answer 10

1. infection - peritonitis
2. glucose load → could lead to development or worsening control of diabetes
3. mechanical
   
   • hernia
   • diaphragmatic leak
   • dislodged catheter
4. peritoneal membrane failure
5. hypoalbuminaemia
6. encapsulating peritoneal sclerosis

Question 11

List the pros [5] and cons [5] of renal transplantations

Answer 11

1. Pros
   
   • No dialysis
   • Better level of renal function
   • Can live much more independently
   • Better life expectancy
   • Fertility better
2. Cons
   
   • Immunosuppressive medication for duration of transplant
   • Increased cardiovascular risk
   • Increased infection
   • Post transplant diabetes
   • Skin malignancies and others