Dialysis Flashcards
What does dialysis involve?
Diffusion of urea, potassium, sodium and creatinine across a semi-permeable membrane into the dialysate
Bicarbonate will diffuse into the blood from the dialysate
Why is sodium present in the dialysate?
To prevent excess loss during dialysis
This means only true excess will be lost as the gradient is controlled
What is haemodiafiltration?
A form of renal replacement therapy that utilises convective in combination with diffusive clearance, which is used in standard hemodialysis
Which factors can affect the efficiency of convective transport of a molecule across a permeable membrane?
Water flux
Membrane pore size
Pressure difference
Charge of molecule
What is the minimum time required for adequate dialysis?
4 hours 3 times per week
If a patient cannot pass urine at all (anuric), whay must happen to their fluid intake?
Limited to around 1 litre per day
When a patient is on dialysis, they require _____ salt, _____ potassium and _____ phosphate in thier diet?
When a patient is on dialysis, they require low salt, low potassium and low phosphate in thier diet?
What is the gold standard for dialysis access?
Fistula
What is a fistula?
An artery and vein are joined to make an enlarged thick walled arteriovenous fistula
What are the benefits to creating a fistula?
Good blood flow
Lower infection risk
What are the downsides to a fistula?
Surgery
Required up to 12 weeks before use
Can thrombose or stenose
May limit blood flow to distal arm
What is a common alternative to a fistula?
Tunneled venous catheter?
What is a tunneled venous catheter/
Catheter inserted into a large vein such as femoral vein or internal jugular vein
What are the main concerns with a tunneled venous catheter?
Staph aureus infection (endocarditis, discitis, death)
What may go wrong with dialysis?
Hypotension
Blood leaks
Loss of vascular access
Hyperkalaemia and cardiac arrest
How does peritoneal dialysis work?
Diffusion of solutes across the peritoneal membrane
How is water removed in perironeal dialysis?
Osmosis driven by high glucose concntration in dialysate
What are the two types of peritoneal dialsysis?
Continuous peritoneal dialsysis
Automated peritoneal dialysis
What can go wrong with peritoneal dialysis?
Peritonitis (contamination - staph, strep, diptheroids; gut bacteria translocation:, E.coli, kelbsiella)
Inability tp remove enough water, or solutes
Hernias
Why is dialysis started slowly?
Disequilibrium syndrome
