Dialysis

Question 1

Role of kidneys

Answer 1

SWEAT

• salt removal
• water removal
• electrolyte balance
• acid base balance
• toxin removal
• make EPO
• 1-alpha hydroxylate vitamin D

Question 2

What does dialysis do?

Answer 2

Same as kidney roles

Question 3

3 types of dialysis

Answer 3

1) haemodialysis (home or in centre)
2) peritoneal (home based, CAPD and APD)
3) continuous veno-venous haemofiltration (CVVH) (inpatient treatment in critical care setting)

Question 4

Haemodialysis

Answer 4

• blood filtered across membrane using machine
• at home but usually in haemodialysis units in hospital
• min. 4 hours 3 x a week

Question 5

How does haemodialysis work?

Answer 5

• blood exposed to dialysate across biocompatible membrane
• small molecules through pores large cannot
• diffusion conc. gradient across membrane so waste removed and desirable ions replaced
• water driven through membrane by hydrostatic force
• ultrafiltration can clear solutes via convection
• requires vascular access and anticoagulation

Question 6

What vascular access is there is haemodialysis?

Answer 6

AV fistula
AV graft
Tunnelled catheter

Question 7

Complications of haemodialysis

Answer 7

ACCESS

• thrombosis
• infection
• failure of access
• aneurysm
• distal ischaemia
• central venous stenosis
• hypotension
• reactions to dialysis (cramps, headache)
• inadequate dialysis dose

Question 8

Peritoneal dialysis

Answer 8

• at home by patient/carer/healthcare worker
• patient autonomy and self care focus
• every day
• infuse dialysate and drain via catheter surgically placed in peritoneal cavity
• peritoneal membrane = filter, semi permemable, lines abdom cavity covering viscera
• ultrafiltration (removal of fluid) via osmosis
• steady state of toxin clearance and fluid management achieved

Question 9

CAPD

Answer 9

• 4-5 exchanges a day
• fluid in peritoneal cavity
• DRAIN = through closed system fluid drained by gravity
• FLUSH = small amount into drain bag to clear line
• FILL = new fluid run in peritoneal cavity via closed system
• DWELL = 4-6 hours

Question 10

APD

Answer 10

• alternative to CAPD
• patient has cycler machine
• over night 8 hours
• better for someone that works

Question 11

Complications of peritoneal dialysis

Answer 11

• infection
• catheter dysfunction/malposition
• peritoneal leak
• pain
• membrane failure
• inadequate dialysis
• encapsulating peritoneal sclerosis

Question 12

Supportive care > dialysis?

Answer 12

If

• heart disease
• terminal diagnosis with short prognosis
• frailty
• QoL
• patient choice
• medications instead
• multi-disciplinary approach