Dialysis Flashcards
Define diffusion
- movement of solutes from high concentration to low concentration gradient across a semi-permeable membrane
Factors affecting diffusion
- concentration gradient
- molecular weight of solute
- properties of semi permeable membrane
In dialysis what is removed from patients blood
- urea and creatinine
- potassium
- sodium
What is infused into a patient in dialysis?
- bicarbonate
- glucose
What is the blood flow rate needed for haemodialysis?
- 300-350mls/min
What is the main vascular access used in haemodialysis?
- Arteriovenous fistula
What is the name of the fluid used in dialysis?
- dialysate
During dialysis what are patients treated with?
- heparin
What method is employed in dialysis to maximise gradient
- countercurrent flow of the dialysate and blood
What is the order from most prominent to least of the method of haemodialysis?
- diffusion
- convection
- adsorption
Explain convection
- pressure gradient created
- solute drag = ultra filtration
Explain adsorption
- plasma proteins stick to membrane surface
Difference of haemodiafiltration and haemodialysis
- HDF requires an extra-covective fluid replacement
- convection –> diffusion –> adsorption
Where is a arteriovenous fistula most commonly located?
- artery and vein in radio-cephalic
How often is a AVF scanned?
- every 6 months
Where is a TCVC placed?
- tunnelled central venous catheret
- internal jugular vein
Average dialysis prescription?
- 4 hrs
- 3 times weekly
Restrictions for a dialysis patient
- fluid
- salt
- potassium
- phosphae
What may occur if dialysis goes wrong?
- hypotension
- haemorrhage
- arrythmia
- cardiac arrest
When should dialysis be started?
- eGFR <7ml/min
- urea >40
- persistent hyperkalaemia
- unresponsive metabolic acidosis
Explain peritoneal dialysis?
- use of the peritoneal cavity as the semi-permeable membrane
2 types of peritoneal dialysis?
- continous
- automated
Risk in peritoneal dialysis
- infection
- membrane failure
- hernia
Why should initiating dialysis be done slowly?
- to reduce risk of disequilibrium syndrome