Dialysis Flashcards
end stage renal disease can be caused by
stage 5 chronic kidney disease or failure of recovery from an AKI
without renal replacement therapy end stage renal disease will cause
death very quickly
what is the best form of renal replacement therapy
transplant however, because of the shortage of organs most people have to be started on dialysis while they wait
dialysis is used to prevent
life threatening hyperkalaemia, metabolic acidosis and pulmonary oedema
modern renal replacement uses dialysis to remove
unwanted solutes by filtration and remove water by haemofiltration which carries with it unwanted soluble substances
the principle of dialysis
if blood is separated from a fluid by a semi-permeable membrane then electrolytes and other substances diffuse across the membrane until equilibrium is achieved in haemodialysis a synthetic membrane is used while in peritoneal dialysis the persons own peritoneum is used
principle of haemo-filtration
similar to glomerular filtration, if blood is pumped at a higher hydrostatic pressure than the fluid on the other side of the semi-permeable membrane then the water in the blood is forced through the membrane by ultrafiltration and carries with it dissolved electrolytes
practical aspects of haemodialysis
in haemodialysis blood is pumped past one side of a semi-permeable membrane while the dialysate is pumped past the other side in the opposite direction
the amount of fluid removed by ultra-filtration can be controlled by
controlling the hydrostatic pressure of the blood in comparison with the dialysate
the dialyse fluid is composed of
essentail component of the plasma, sodium, potassium, chloride, glucose, magnesium, glucose and a buffer such as bicarboante
the plasma concentration can be controlled by
altering the composition of the dialyse i.e. there is less potassium in the dialyse to promote the movement of potassium from the blood into the dialysate
what else is in the dialyse
heparin to prevent clotting
access for dialysis
arteriovenous fistula but this takes a surgery and a few months to form therefore if access required urgently central census catheter
acute complications of dialysis
- overaggressiveness can cause hypovoalemia and dialysis disequilibrium syndrome
- dialysis disequilibrium syndrome caused by osmotic changes in the brain as plasm urea follows
- cramps can occur and an itch caused by a ild allergic reaction to the semi-permeable membrane
chronic complications of dialysis
- fistula, thrombosis, aneurysm formation, infection
- patients have to limit there fluid intake between dialysis sessions
- patients should reduce sodium intake to reduce thirst
peritoneal dialysis
dialysate is infused into the peritoneal cavity through a tube and water and solutes then diffuse across the peritoneal membrane
in peritoneal dialysis
water moves by osmosis because the dialyse contains glucose which also causes solutes to move via diffusion
continuers ambulatory peritoneal dialysis requires
the patient to change there 2 litre bag every 4 hours
complications of peritoneal dialysis
infection is the most common complication and is most commonly caused by staph epidermis
repeated peritonitis in people with peritoneal dialysis can
reduce the permeability of the semi-permeable membrane
continous haemofiltratioen
venous bloos is pumped at a high pressure onto a highly permeable membrane producing large volumes of unltrafiltrate which is then discarded and replaced by an appropriate volume of balaned electrolyte solution which is added back to the blood
continuous haemofiltration
is a continuous process and is slower than dialysis s is more suitably for crticillay ill or haemodynamically unstable as it avoids rapid changes in solute concentraiotn
