Dialysis Flashcards
what are indications for dialysis
resistant hyperkalaemia, eGFR <7ml/min, urea >40 mmol/l, unresponsive met acidosis
what is disequilibrium syndrome
too rapid removal of urea which causes neurological symptoms: oedema, confusion, seizures
what is the flow rate of haemodialysis
300ml/min
what type of membrane is used in haemodialysis
semipermeable
what does dialysis remove from the blood
toxins such as urea, potassium and sodium
what does dialysis add to the blood
water, HCO3, glucose (K and Na if needed)
how does water and electroyles travel across the membrane in dialysis
convection: there is a negative pressure created over the membrane which ‘sucks’ the water and filtrate out of the blood
what are the 3 principles of dialysis
diffusion, convection (and filtration) and adsorption
what does diffusion allow for in dialysis
removal of toxins and infusion of bicarbonate
what is convection in the context of dialysis
negative hydrostatic pressure across membrane causes movement of water and solutes across the membrane ‘sucked out’
how does haemodiaflitration (HDF) differ from haemodialysis
greater convection force in HDF which can replace more volume and is smoother than HD
what is adsorption in the context of dialysis
plasma proteins stick to the membrane and are then removed
what diet restrictions are required for effective dialysis
low fluid (1L/ day), low salt, low potassium, low phosphate
how long is dialysis usually carried out for each week
4 hours 3 times a week
what is a tunnelled venous catheter
catheter inserted into large vein usually internal jugular
what are pros of a tunnelled venous catheter
easy to insert and immediate access
what are cons of a tunnelled venous catheter
high risk of infection, can become blocked, can cause stenosis/ thrombosis
what infection can commonly arise from a tunnelled venous catheter and how would you treat it
endocarditis (staph) –> vanco + gent
what is a fistula
the gold standard - artery and vein surgically connected to create arteriovenous fistula (AVF)
where are fistulas normally created
both arms: radio-cephalic, brachiocephalic or brachio-basilic
what are pros of fistulas
good blood flow and unlikely to cause infection
what are cons of fistulas
requires surgery, need 6-12 weeks after surgery to use, can limit blood flow to distal arm (steal syndrome), thrombosis/ stenosis
what are complications of dialysis (6)
hypotension, haemorrhage, loss of vascular access, arrhythmia, cardiac arrest, acquired cysts (common with long term dialysis)
what is peritoneal dialysis
catheter is inserted into the peritoneal cavity
how does peritoneal dialysis work
peritoneum is used as a semi-permeable membrane, solute is removed by diffusion and water by osmosis
what is continuous ambulatory peritoneal dialysis
4x2L bags per day and waste fluid drains into a fresh different bag (lasts 2-30 mins each)
what is automates peritoneal dialysis
1 bag stays in all day and then is drained by a machine overnight (9-10 hours)
what are risks of PD
peritonitis, peritoneal membrane failures,, hernia
what are common organisms for peritonitis or exit site infection
contamination: staph, strep, diptheroids // GI bacteria: E. coli, klebsiella
what is peritoneal membrane failure
inability to remove enough water or solutes causing fluid overload or ureaemia
how do you manage peritoneal membrane failure
switch to HD
