Dialysis Flashcards
describe the role of diffusion in the process of dialysis
allows removal of toxins from the blood(eg urea, potassium, sodium) and allows infusion of bicarbonate
why can a normal blood vessel not be used for dialysis to drain blood from the body
because the flow rate is 300-350ml/min which is too high
where does the blood need to be taken from for dialysis
arteriovenous fistula or graft, or failing that a catheter
what runs countercurrent to the blood being filtered in a dialysis machine and why
dialysate, in order to maintain the osmotic gradient
describe what convective solute drag in dialysis is
when a pressure gradient is made in order to allow movement of water and all its dissolved solutes across the semi-permeable border into the dialysate
what is the pressure gradient in dialysis called
ultrafiltration
describe the role of adsorption in dialysis
affects plasma proteins, which stick ti the membrane surface and are removed by membrane binding
what are the 3 main processes of solute removal in haemodialysis, in order of largest affect to least
diffusion, convection, adsorption
describe the convection of haemodiafiltration and its effect
it is increasingly convective in nature, the greater the convective force the greater the volume of pressure-driven ultrafiltrate
what are the most important influencers if the efficiency of the convective transport
water flux, membrane pore size, the pressure difference, fluid viscosity,
what is a key difference between haemodialysis(HD) and haemodiafiltration(HDF)
HDF involves the replacement of extra-convective ultrafiltrate throughout the dialysis period
what are the 3 main processes of solute removal in HDF, in order of largest affect to least
convection, diffusion, adsorption
what restrictions does dialysis put on the patient
fluid restriction, low salt diet, low potassium diet, low phosphate diet
what blood test results should dialysis be started on
resistant hyperkalaemia, eGFR <7, urea >40, unresponsive metabolic acidosis
what symptoms are associated with the need to start dialysis
nausea, anorexia, vomiting, profound fatigue, itch, unresponsive fluid overload
