Dialysis Flashcards

1
Q

What are the 3 concepts of Dialysis?

A

Diffusion

Convection

Adsorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is meant by diffusion?

A

Movement of solutes from high to low concentration

Gradient to equilibriate on both sides of a semi permeable membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Dialysis removes which toxins that build up in ESRD?

A

Urea
Potassium
Sodium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What compound is infused when on dialysis?

A

Bicarbonate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a normal blood flow rate on haemodialysis?

A

~ 300-350 mls/min depending on site

Tunnelled Catheter is lower at around 300 mls/min
Fistula = larger => can extend to 350/400 mls/min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is dialysate?

A

Purified water

Na, HCO3, K and Glucose can be added to in order to suit the patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is meant by convection?

A

movement of water (and solutes dissolved in it) across a semi-permeable membrane in response to a pressure gradient
Also known as “ULTRAFILTRATION”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does haemodialysis promote the removal of water?

A

Sets up a pressure gradient where the blood is higher than the dialysate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the main function of the microfilaments in the dialysis equipment which acts as an external kidney?

A

The increase the surface area available for exchange of water
Dialysate runs upwards as blood runs downwards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Adsorption affects what component of blood?

A
  • Plasma proteins and solutes bound to them

- Plasma proteins of low molecular weight stick to the membrane surface and are removed by membrane binding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

High flux membranes adsorb protein-bound solutes better than low flux membranes. TRUE/FALSE?

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the difference between haemodialysis and haemodiafiltration?

A

HD uses diffusion

HDF uses convection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Longer treatment times = better efficiency in haemodialysis. TRUE/FALSE?

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What must patients be warned if they choose to decrease their dialysis time?

A

Increased risk of death - 1% for every 30 mins less

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How often is a patient usually on dialysis and for how long are they on the machine at a time?

A

4 hours

3 days a week

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What restrictions do dialysis patients have to put on their diets?

A

Fluid (including foods which metabolise to H2O)
Salt
Potassium (avoid Banana, chocolate, potato, avocado)
Phosphate (or phosphate binders with meals)

17
Q

What options are there for vascular access in dialysis?

A
Arteriovenous Fistula (AVF = Scribner Shunt)
Tunnelled Catheter
18
Q

What vein is a tunnelled catheter usually inserted into?

A

Internal jugular

19
Q

What are the potential complications of a tunnelled catheter?

A
  • infection
  • blockage
  • damage (stenosis/ thrombosis) to central veins can make future line insertion difficult
20
Q

What are the main complications of arteriovenous fistulae?

A
  • Require surgery

- Usually requires maturation of 6 – 12 weeks before can be used

21
Q

What sites are used to establish arteriovenous fistulae?

A

Radio-Cephalic (RC AVF)
Brachio-Cephalic (BC AVF)
Brachio-Basilic transposition (BB AVF)

22
Q

What types of graft can be used in dialysis?

A

Arteriovenous graft
=> between Cephalic vein and Brachial artery

HeRO Graft (Hemodialysis Reliable Outflow Graft)
=> either into Right Atrium OR Left subclavian
23
Q

What can potentially go wrong in dialysis?

A
  • Hypotension (can mimic cardiac arrest)
  • Haemorrhage
  • Loss of vascular access
  • Arrhythmia /Cardiac arrest
24
Q

Why does dialysis cause hypotension and myocardial stunning?

A

Removing large volumes of H20 3x per week
rather than continuously with normal kidneys
=> Leads to under-filling of the intravascular space and low BP

25
How does peritoneal dialysis work?
Solute removal by diffusion across the peritoneal membrane Water removal by osmosis - driven by high glucose concentration in dialysate fluid
26
How often does Continuous Ambulatory Peritoneal dialysis need changing?
4 x 2L bag exchanges per day PD dialysate drained then fresh bag instilled Takes 20-30 mins to exchange
27
How often is Automated Peritoneal Dialysis changed?
1 bag of fluid stays in all day Overnight APD machine controls fluid drainage in and out for ~ 9-10 hours per night
28
What are the main complication of peritoneal dialysis?
Peritoneal Exit site infection Peritoneal membrane failure Hernias
29
What blood tests would prompt starting dialysis?
- Resistant hyperkalaemia - eGFR < 7 ml/min - Urea > 40 mmol/L - Unresponsive metabolic acidosis
30
How long should the first session of dialysis last in order to build up to the 4 hours?
90-120 minutes
31
What is Disequilibrium syndrome?
- Too-rapid a correction of uraemic toxin levels - Cerebral oedema - possible confusion - seizures - occasionally death
32
How long do patients need to train to administer peritoneal dialysis ?
3-6 weeks after PD catheter insertion
33
For what reasons may dialysis be withdrawn?
- Haemodynamic instability - Progressive dementia (pull out catheter etc) - Inability to remain on therapy for full duration due to agitation - Cardiovascular event - Terminal cancer