Dialysis Flashcards
what is diffusion?
the process by which particles move from an area of high concentration to an area of low concentration, across a semi-permeable membrane
name two factors that affect diffusion
concentration gradient
molecular weight of solute
name four toxins that can be removed by dialysis
urea
creatinine
potassium
sodium
what can be infused during dialysis and how?
bicarbonate
concentration is higher in the dialysate than the blood so it diffuses
what flow rate is required for haemodialysis to be effective?
300-350 ml/min
what are the four vascular access options for haemodialysis?
arteriovenous fistula
arteriovenous graft
tunnelled central venous catheter
temporary venous catheter
what is another name for a temporary venous catheter?
vasacath
what vascular access would be used in someone requiring acute short term dialysis?
temporary venous catheter
at what rate is dialysate usually ran at in haemodialysis?
500ml/min
= around 120L in a four hour treatment
what does dialysate consist of?
pure water
electrolytes (Na, K, HCO3)
glucose
how is excess fluid removed from a patients blood during dialysis?
a pressure gradient is set up between blood and dialysate
this forces water and all of the solutes in it to leave the blood
what is the movement of water out of the blood in dialysis called?
the convective solute drag
what is the whole process of water loss and the solute drag in dialysis called?
ultrafiltration
what is the usual range set for ultrafiltration in a dialysis session?
1-3L
what is affected by adsorption?
plasma proteins
any solutes bound to them
what happens to plasma proteins in adosrption?
become stuck to the membrane of the dialysis kidney
removed by membrane binding
how is most solute removed in haemodialysis?
diffusion
how is most solute removed in hemodiafiltration?
convection
massive amounts of ultrafiltration
what defines high volume hemodiafiltration?
replacement volumes of >21 L
what can improve the efficiency of dialysis?
longer treatment times
what is the usual dialysis schedule?
four hours
three times a week
what four things need to be restricted in the diet if someone is on dialysis?
fluid
salt
potassium
phosphate
how much fluid can an anuric dialysis patient consume a day?
one litre
how much salt should a dialysis patient consume per day?
less than 2.3g
if the phosphate levels remain high in a dialysis patient, what do they need to take?
phosphate binders with meals
what is a tunnelled central venous catheter?
a catheter inserted into a large vein
what vein is often used for a TCVC?
internal jugular
what are the pros of TCVC?
easy to insert
can be used immediately
what is there high risk of in a TCVC?
infection
what is the most common cause of an infection of a TCVC?
staph aureus
what antibiotics should be given for an infected TCVC?
vancomycin and gentamicin
what is the gold standard for dialysis vascular access?
an arteriovenous fistula
what is an AVF?
when an artery and vein are surgically created for dialysis access
what are the three possible sites for an AVF?
radio cephalic
brachio cephalic
brachio basilic transposition
how is an AVF formed?
surgically
when can an AVF be used?
after a maturation period of 6-12 weeks
what is it called when an AVF limits blood flow to the distal arm?
steal syndrome
if a patient cannot have an AVF, what are the next best options?
arteriovenous graft
HeRo graft
what is a life threatening complication of an AVF?
rupture causing massive haemorrhage
what acts as the semi permeable membrane in peritoneal dialysis?
the peritoneum
how are solutes removed in peritoneal dialysis?
by diffusion of solutes across the peritoneal membrane
how is water removed in peritoneal dialysis?
osmosis driving by the high glucose concentration of the dialysate
what are the two types of peritoneal dialysis available?
continuous ambulatory peritoneal dialysis (CAPD)
automated peritoneal dialysis (APD)
which PD is done overnight?
automated PD
what are three possible complications of peritoneal dialysis?
infections
peritoneal membrane failure
hernias
what needs to be done if there is peritoneal membrane failure in someone on peritoneal dialysis?
switch to haemodialysis
