Renal Replacement Therapy - Dialysis

Question 1

Name six function of the kidneys

Answer 1

• Excretion of nitrogenous waste products
• Maintenance of acid and electrolyte balance
• Control of blood pressure
• Drug metabolism and disposal
• Activation of vitamin D
• Production of erythropoietin

Question 2

What are the clinical features of advanced CKD?

Answer 2

• Until CKD stage 4 or 5 the patient may be asymptomatic
• The syndrome of advanced CKD is called uraemia (high urea)
• Uraemic symptoms can involve almost every organ system but the earliest and cardinal symptom is malaise and fatigue

Question 3

When is renal replacement therapy indicated?

Answer 3

To sustain life in patient suffering from end-stage renal disease

eGFR < 10ml/min (but can be variable between people)

Question 4

Name the different types of renal replacement therapy

Answer 4

• Renal transplant
• Haemodialysis
• Peritoneal dialysis
• Conservative kidney management

Question 5

What are the two types of peritoneal dialysis?

Answer 5

• Continuous ambulatory peritoneal dialysis (CAPD) - four times a day
• Intermittent peritoneal dialysis (IPD)

Question 6

What are the type types of haemodialysis?

Answer 6

• Home haemodialysis

* Satellite/hospital haemodialysis

Question 7

What is dialysis?

Answer 7

Dialysis is a process whereby the solute composition of a solution, A, is altered by exposing solutions A to a second solution, B, through a semi permeable membrane

Question 8

What are the principles of dialysis?

Answer 8

1. Diffusion
   Waste in blood moves towards dialyse (solution)
2. Ultrafiltration
   Flow of water and dissolved solute down a pressure gradient, removing excess fluid and waste from blood (increases volume of solution B and decrease volume of solution A to equilibrate pressure across membrane)

Question 9

What are the pre-requisites for dialysis?

Answer 9

• Semipermeable membrane (artifical kidney in haemodialysis or peritoneal membrane)
• Adequate blood exposure to the membrane (extracorporeal blood in haemodialysis, mesenteric circulation in PD)
• Dialysis Access (vascular in haemodialysis, peritoneal in PD)
• Anticoagulation in hemodialysis

Question 10

Describe the haemodialysis access routes

Answer 10

Permanent:
• Arteriovenous fistule
• AV prostethetic graft

Temporary
• Tunneled venous catheter
• Temporary venous catheter

Question 11

Describe the electrolyte loss in dialysis

Answer 11

• Some Na, K, Ca and little HCO3

* All of creatinine and urea

Question 12

What are the restriction for dialysis patients

Answer 12

Fluid restriction:
• Dictated by residual urine output
• Interdialytic weight gain

Dietary restriction:
• Potassium
• Sodium
• Phosphate

Question 13

Describe the process of haemodialysis

Answer 13

Blood travels through tubes from body into the dialysis machine. While blood is in the machine, it goes through a filter called a dialyser, which removes waste and extra fluid. Once it has been cleaned, the blood travels through tubes from the dialysis machine back into your body.

Used dialysate is continually removed from dialysed and fresh solution put back in.

Question 14

How is peritoneal dialysis performed?

Answer 14

A balanced dialysis solution is instilled into the peritoneal cavity via a tunnelled, cuffed catheter, using the peritoneal mesothelium as a dialysis membrane.

After a dwell time the fluid is drained out and fresh dialysate is instilled.

Question 15

What fluid is used in peritoneal dialysis?

Answer 15

The dialysate contains a balanced concentration of electrolytes. Glucose is the most common osmotic agent for ultrafiltration of fluid.

The peritoneal transport characteristics can vary from high transporter to low transporter
• Dwell times can be adjusted according to transport characteristics

Question 16

What is the difference between continuous ambulatory PD (CAPD) and automated PD (APD)?

Answer 16

ADP takes place at night, during sleep, over 8-10 hours.

CAPD is done four times a day.

Question 17

What are possible complications of peritoneal dialysis?

Answer 17

• Exit site infection
• Ultrafiltration failure
• Encapsulating peritoneal sclerosis

PD peritonitis:
• Gram positive – skin contaminant
• Gram negative – bowel origin
• Mixed – suspect complicated peritonitis eg perforation

Question 18

What are the indications for dialysis in ESRD?

Answer 18

• Advanced uraemia, (GFR 5-10 ml/min)
• Severe acidosis (bicarbonate < 10 mmol/l)
• Treatment resistant hyperkalaemia (K > 6.5 mmol/l)
• Treatment resistant fluid overload

Question 19

How is fluid balance maintained in haemodialysis patients?

Answer 19

Usually restricted to 500-800 ml/24 hours

• Intake allowed = urine output +insensible loss

Question 20

How is fluid balance maintained in peritoneal dialysis?

Answer 20

Usually more liberal than haemodialysis intake as continuous ultrafiltration is often achieved

Question 21

Name dialysis related drugs

Answer 21

Anaemia:
• Erythropoietin injections
• IV iron supplements

Renal Bone Disease
• Activated Vitamin D (eg calcitriol)
• Phosphate binders with meals (CaCo3)

• Heparin
• Water soluble vitamins

Question 22

What are complications of haemodialysis?

Answer 22

CVS:
• Intra-dialytic hypotension and cramps
• Arrythmias

Coagulation:
• Clotting of vascular access
• Heparin related problems

Other:
• Allergic reactions to dialyses and tubing
• Catastrophic dialysis accidents (rare)

Question 23

What are complications of peritoneal dialysis?

Answer 23

Infection:
• Exit site infection
• Tunnel infection
• Peritonitis

Mechanical:
• Tube malfunction
• Abdominal wall herniae

• Ultrafiltration problems

Question 24

How is the choice of dialysis modality made?

Answer 24

• Patient choice through education and shared decision making
• Perception of effectiveness

Question 25

Describe conservative kidney management for those not suitable for dialysis

Answer 25

Supportive care
• Priority for symptomatic management
• Holistic multi-professional approach
• Anticipatory care planning