RRT - Dialysis

Question 1

What is the cardinal symptom of Chronic Renal Failure?

Answer 1

A syndrome known as uraemia. characterised by severe malaise and fatigue

Question 2

How does dialysis work?

Answer 2

The solute composition of Solution A (Blood) is altered by exposing it to Solution B (dialysate) through a semipermeable membrane.

Based on two principles:

• Diffusion
• Ultrafiltration

Question 3

How is blood exposed to the membrane in each type of dialysis?

Answer 3

Extra-corporeally in haemodialysis

Mesenteric circulation in Peritoneal

Question 4

What are the types of dialysis?

Answer 4

Haemodialysis (home, satellite or hospital)

Peritoneal (CAPD & APD)

Question 5

How do you gain blood access in haemodialysis?

Answer 5

Native AV fistula
AV prosthetic graft

Temporary access through a tunnelled or temporary venous catheter

Question 6

What are the types of peritoneal dialysis?

Answer 6

Continuous Ambulatory Peritoneal Dialysis:
- Patient changes their own fluid ~4x a day

Automated Peritoneal Dialysis
- Patient hooked to a machine which changes their fluid while they sleep

Question 7

What is used as a SPM in Peritoneal dialysis?

Answer 7

The peritoneal mesothelium

Question 8

Explain the difffusion principle?

Answer 8

Dialysate is designed with a solute composition that will equilibriate with that of the blood at the target solute conc.
E.g. it contains more bicarb so it diffuses into blood, less Na so some moves out the blood and no urea so lots of it is diffused out.

Question 9

Explain the ultrafiltration principle

Answer 9

The method by which excess fluid is drained out the blood.

In haemodialysis pressure is applied to the SPM to drain fluid from the blood

In PD osmotic agents (mainly glc) in the dialysate cause movement of water out the blood

Question 10

What indicates dialysis is appropriate?

Answer 10

Advanced Uraemia (<10ml/min GFR). Particularly when symptomatic

Severe acidosis (<10mmol/l Bicarb)

Hyperkalemia (>6mmol/l)

Fluid/Na retention uncontrolled by diuretics

Question 11

How is diet affected by dialysis?

Answer 11

Water soluble vit supplements
Phosphate restriction (+binders)
Na/K restriction
Calorie and protein restriction

Question 12

How is fluid gain measured during dialysis?

Answer 12

Measure body weight after dialysis and before the next treatment, tells you how much fluid to drain off

Question 13

How is fluid restricted in dialysis patients?

Answer 13

Haemo is strictly limited to their UO + insensible loss. (500-800ml/24 hrs depending on the patient)

PD is more liberal as continuous ultrafiltration is often achieved

Question 14

What meds would you put a dialysis patient on?

Answer 14

• Erythropoietin stimulating Agents (ESA)
• Calcitriol
• Phosphate binders with meals
• Water soluble vit supplement
• Fe supplements
• Anti-hypertensives/Lipid control as relevant

(Haemo gets heparin during treatments)

Question 15

Complications of Haemodialysis?

Answer 15

Coagulation issues:

• Clotting of vascular access point
• Heparin problems

CV:

• Arrythmias
• Hypotension & Cramps (excess fluid drained)

Allergic reaction to dialysis

Catastrophic Dialysis Accient

Question 16

Complications of Peritoneal dialysis?

Answer 16

PD Peritonitis
Exit site or tunnel infection
Ultrafiltration failure (Usually membrane damaged by infection, need to move them onto haemo)
Abdominal wall hernia
Tube problems
Encapsulating Peritoneal Sclerosis

Question 17

What organisms cause PD peritonitis?

Answer 17

Gram +ve if skin contaminant

Gram -ve if bowel origin

Question 18

Other than dialysis how else do we manage renal failure?

Answer 18

Transplant

Conservative Kidney Management (CKM) - Using meds to treat the symptoms of uraemia