Dialysis

Question 1

What are indications for dialysis?

Answer 1

1) Hyperkalaemia resistant to medical treatment (insulin dextrose) - can’t get rid of potassium in kidneys
2) Pulmonary oedema/fluid overload resistant to diuretics
3) Symptoms of uraemia (most common reason)
4) Acidosis

Question 2

What are uraemic symptoms (symptoms relating to toxins building up in the body, non specific)?

Answer 2

1) Poor appetite
2) Vomiting
3) Weight loss
4) Lethargy and fatigue
5) Itching (build up of phosphate)
6) Malaise

Question 3

What are the goals of dialysis?

Answer 3

1) Remove waste products (toxins, potassium)
2) Remove excess water
3) Maintain electrolyte and acid-base balance

Question 4

What are the two types of dialysis?

Answer 4

1) Haemodialysis

2) Peritoneal dialysis

Question 5

Describe haemodialysis

Answer 5

• Attached to a machine and blood is removed from the body
• It is put through a specific filter and then returned back to the body in a clean state
• The machine makes a fluid which runs in a countercurrent system with the blood across a semi-permeable membrane so need v pure water
• 3 times a week for 4 hours (what patient will tolerate, not medically best spacing of time)
• Need a fistula
• Flow of blood usually 200-300 ml/min
• Water requirement is 120L per session

Question 6

Where can haemodialysis take place?

Answer 6

1) Hospital
2) Satellite unit
3) Home - good bc can do overnight every day instead of coming in 3 times a week however need lots of pure water so need to special plumbing and water supply

Question 7

What do you need to put into the haemodialysis circuit tubing to prevent blood clotting?

Answer 7

Heparin

Question 8

Describe the AV fistula

Answer 8

• Connecting vein directly to artery to give blood at a pressure between artery and vein
• Don’t want vein to collapse
• Two needles in artery is bad bc continuous puncturing of arteries causes problems with bleeding due to high pressures
• e.g. radiocephalic, brachiocephalic, brachiobasilic
• Needs to mature for 4-8 weeks after it is constructed
• Benefit = all natural, no plastic

Question 9

What are potential complications of AV fistula?

Answer 9

1) Blows - blood leaks out of vein when needle goes in (instead of up needle) and moves to surrounding tissue causing bruising
2) Stenoses - narrowings form where joins have been made which can impinge on blood flow and where have lack of blood flow through the fistula it can clot or thrombose

Question 10

Describe use of a graft in haemodialysis

Answer 10

• If a patient doesn’t have good vessels, can put bit of plastic inside (PTFE) which connects a native artery and vein
• Can be used immediately
• Same complications
• Plus risk of infection

Question 11

Describe use of catheters in haemodialysis

Answer 11

• Used if patient doesn’t have weeks to wait and if high levels of toxins so can’t have anaesthetic (needed with graft)
• Instead dialyse them via a catheter until fistula has matured or graft is safe to do
• Inserted into big vein e.g. L/R internal jugular or femoral
• Can be temporary if someone needs emergency dialysis (high K, fluid overload) but after a week move on bc infection risk
• Use a tunnelled catheter which goes through skin tunnel reducing risk of it falling out and infection risk (gives time to spot it)
• Have two lumens - one for getting blood out and other for putting it back in

Question 12

Describe the contents of dialysate

Answer 12

• Low in potassium and phosphate (but still need to follow specific diet)
• Neutral sodium
• High in bicarbonate

Question 13

Why are dialysis patients usually restricted to 0.5L of fluid a day?

Answer 13

To avoid hypotension bc can’t remove more than 2-3L of water a session

Question 14

What are potential complications of dialysis?

Answer 14

1) Hypotension bc of fluid removal
2) Septicaemia
3) Bleeding
4) Clotting in fistula and line (can lose fistula)
5) Dialyser reaction - inflammation in blood
6) Air embolus - can mimic PE in lungs

Question 15

Describe peritoneal dialysis

Answer 15

• Home based done by patient
• Continuous ambulatory peritoneal dialysis
• Makes use of peritoneal membrane as semi-permeable membrane
• Creation of an osmotic gradient by addition of an osmotic agent (glucose)
• Fluid is removed by ultrafiltration caused by the osmotic gradient
• Solutes are transported by diffusion across a concentration gradient
• Membrane characteristics vary between patients
• Need to replace fluid and waste bags
• Should not be continued for > 5 years

Question 16

What are the benefits of peritoneal dialysis?

Answer 16

1) Done by patient at home/work
2) No need to attend hospital/dialysis centre
3) More likely to be able to lead a normal life/travel

Question 17

What are the requirements for peritoneal dialysis?

Answer 17

1) Physical → patient has to be able to lift 2kg bags
2) Storage space
3) Hygiene
4) Some residual kidney function

Question 18

What are potential complications of peritoneal dialysis?

Answer 18

1) Peritonitis
2) Compliance
3) Leak of fluid outside peritoneal cavity e.g. thoracic cavity, scrotum
4) Inadequate clearance
5) EPS → encapsulating sclerosing peritonitis