Dialysis

Question 1

what are indications for dialysis

Answer 1

resistant hyperkalaemia, eGFR <7ml/min, urea >40 mmol/l, unresponsive met acidosis

Question 2

what is disequilibrium syndrome

Answer 2

too rapid removal of urea which causes neurological symptoms: oedema, confusion, seizures

Question 3

what is the flow rate of haemodialysis

Answer 3

300ml/min

Question 4

what type of membrane is used in haemodialysis

Answer 4

semipermeable

Question 5

what does dialysis remove from the blood

Answer 5

toxins such as urea, potassium and sodium

Question 6

what does dialysis add to the blood

Answer 6

water, HCO3, glucose (K and Na if needed)

Question 7

how does water and electroyles travel across the membrane in dialysis

Answer 7

convection: there is a negative pressure created over the membrane which ‘sucks’ the water and filtrate out of the blood

Question 8

what are the 3 principles of dialysis

Answer 8

diffusion, convection (and filtration) and adsorption

Question 9

what does diffusion allow for in dialysis

Answer 9

removal of toxins and infusion of bicarbonate

Question 10

what is convection in the context of dialysis

Answer 10

negative hydrostatic pressure across membrane causes movement of water and solutes across the membrane ‘sucked out’

Question 11

how does haemodiaflitration (HDF) differ from haemodialysis

Answer 11

greater convection force in HDF which can replace more volume and is smoother than HD

Question 12

what is adsorption in the context of dialysis

Answer 12

plasma proteins stick to the membrane and are then removed

Question 13

what diet restrictions are required for effective dialysis

Answer 13

low fluid (1L/ day), low salt, low potassium, low phosphate

Question 14

how long is dialysis usually carried out for each week

Answer 14

4 hours 3 times a week

Question 15

what is a tunnelled venous catheter

Answer 15

catheter inserted into large vein usually internal jugular

Question 16

what are pros of a tunnelled venous catheter

Answer 16

easy to insert and immediate access

Question 17

what are cons of a tunnelled venous catheter

Answer 17

high risk of infection, can become blocked, can cause stenosis/ thrombosis

Question 18

what infection can commonly arise from a tunnelled venous catheter and how would you treat it

Answer 18

endocarditis (staph) –> vanco + gent

Question 19

what is a fistula

Answer 19

the gold standard - artery and vein surgically connected to create arteriovenous fistula (AVF)

Question 20

where are fistulas normally created

Answer 20

both arms: radio-cephalic, brachiocephalic or brachio-basilic

Question 21

what are pros of fistulas

Answer 21

good blood flow and unlikely to cause infection

Question 22

what are cons of fistulas

Answer 22

requires surgery, need 6-12 weeks after surgery to use, can limit blood flow to distal arm (steal syndrome), thrombosis/ stenosis

Question 23

what are complications of dialysis (6)

Answer 23

hypotension, haemorrhage, loss of vascular access, arrhythmia, cardiac arrest, acquired cysts (common with long term dialysis)

Question 24

what is peritoneal dialysis

Answer 24

catheter is inserted into the peritoneal cavity

Question 25

how does peritoneal dialysis work

Answer 25

peritoneum is used as a semi-permeable membrane, solute is removed by diffusion and water by osmosis

Question 26

what is continuous ambulatory peritoneal dialysis

Answer 26

4x2L bags per day and waste fluid drains into a fresh different bag (lasts 2-30 mins each)

Question 27

what is automates peritoneal dialysis

Answer 27

1 bag stays in all day and then is drained by a machine overnight (9-10 hours)

Question 28

what are risks of PD

Answer 28

peritonitis, peritoneal membrane failures,, hernia

Question 29

what are common organisms for peritonitis or exit site infection

Answer 29

contamination: staph, strep, diptheroids // GI bacteria: E. coli, klebsiella

Question 30

what is peritoneal membrane failure

Answer 30

inability to remove enough water or solutes causing fluid overload or ureaemia

Question 31

how do you manage peritoneal membrane failure

Answer 31

switch to HD