Dialysis

Question 1

Define diffusion

Answer 1

The process by which particles, atoms or molecules move from an area of high concentration to an area of low concentration across a semi-permeable membrane

Question 2

Name factors affecting diffusion

Answer 2

• concentration gradient

- molecular weight of solute

Question 3

Dialysis allows for the removal of what and the infusion of what?

Answer 3

• allows for removal of toxins which build up with ESKD; urea and creatinine, potassium, sodium
• allows for the infusion of bicarbonate

Question 4

Name different means of vascular access for haemodialysis

Answer 4

• arteriovenous fistula (AVF)
• arteriovenous graft (AVG)
• tunnelled central venous catheter (TCVC)
• temporary venous catheter (vascath)

Question 5

Describe the ‘artificial kidney’

Answer 5

• cylinder packed full of hollow filaments made up of semipermeable membranes
• flows in a countercurrent direct to the blood

Question 6

Describe ultrafiltration

Answer 6

The movement of water and all solutes dissolved in it known as convective solute drag across a semi-permeable membrane in response to a pressure gradient known as ‘ultrafiltration’ in dialysis

Question 7

Describe adsorption

Answer 7

• adsorption principally affects plasma proteins and any solutes that might be bound to them
• plasma proteins (especially those of low molecular weight) stick to the membrane surface and are removed by membrane binding
• high flux membranes absorb protein bond solutes better than low flux membranes

Question 8

The movement of molecules in haemodialysis is primarily through what process?

Answer 8

Diffusion