Renal Therapeutics III: Renal Replacement Flashcards
What is the aim of renal dialysis?
For patients with GFR
What are the 2 general techniques of renal dialysis?
Haemodialysis
Peritoneal dialysis
Which 2 processes does dialysis try to mimic?
Ultra-filtration followed by reabsorption
How is ultra-filtration carried out in haemodialysis?
Artificial membrane
Fast cycles of fresh dialysis fluid = more effective than peritoneal dialysis
How is ultra-filtration carried out in peritoneal dialysis?
Patient’s own peritoneal membrane
Dialysis reaches equilibrium before fluid change
When is dialysis used?
ARF (in oliguric phase)
CRF
Drug overdose
Poisoning
What is required in order to mimic ultra-filtration?
Membrane similar to glomerular basement membrane
Differs in pore size
How is water removed in haemodialysis?
By hydrostatic force
How is water removed in peritoneal dialysis?
By osmotic pressure (between blood and dialysis fluid)
How is waste removed during dialysis?
Blood is exposed (through a membrane) to a solution with a low concentration of substances to be removed
How is conservation of useful substances mimicked?
Tubular reabsorption does not exist
Replacement dietary supplementation oradding substances to dialysis fluid = transfer to patient
Why is heparin added to the blood during dialysis?
Anticoagulant
To prevent thrombosis in the blood circuit of the dialysis machine
Prevents air bubbles in blood getting into body
What does the dialysis fluid remove from the blood?
Urea Creatinine Potassium Calcium (also in) Sodium (also in) Plasma water
What does the blood take up from the dialysis fluid?
Calcium (also out)
HCO3-
Sodium (also in)
Name the 4 haemodialysis techniques
Conventional haemodialysis
Haemofiltration
High-flux haemodialysis
Haemodiafiltration
What is conventional haemodialysis?
Low-flux membranes allow diffusive, but little convective solute removal
Middle molecule clearing is poor