6.9 Renal Replacement Therapy Flashcards
Q9 — Renal replacement therapy
a) What are the renal indications for starting renal replacement
therapy (RRT) in the intensive care setting (ICU)?
● Rapid increase in serum urea and creatinine.
● Uraemic encephalopathy.
● Hyperkalaemia resistant to medical treatment.
● Severe metabolic acidosis.
● Oliguria or anuria
b) What are the non-renal indications for starting RRT in the ICU?
● Fluid overload.
● Toxin clearance.
● Severe electrolyte abnormalities.
● Temperature regulation.
● In severe sepsis, to remove inflammatory mediators.
c) List the types of RRT available in intensive care.
● Intermittent haemodialysis (IHD).
● Continuous renal replacement therapy (CRRT):
- continuous veno-venous haemofiltration (CVVH);
- continuous veno-venous haemodialysis (CVVHD);
- continuous veno-venous haemodiafiltration (CVVHDF);
- slow continuous ultrafiltration (SCUF);
- hybrid therapies (IHD and CRRT).
d) Outline the principal mechanisms of solute and water removal
by filtration.
Transmebrane pressure gradient created by diaylsis circuit which has pores in it
These pores allow filtration of water molecules accross from a higher pressure to a lower pressure and removal of fluid
solute drag will also move some solute
● Convective process.
● Similar to the physiological filtration process in a nephron.
● Hydrostatic pressure gradients filter plasma,
water and solute across a membrane.
● Works on the principle of a ‘solute drag’ —
solute particles are dragged along with the
mass movement of solvent across a membrane.
● Dependent upon direction and
magnitude of transmembrane pressure.
e) Outline the principles of haemodialysis.
● The underlying principle is diffusion across a membrane.
● Dialysate is pumped in a counter-current
fashion to the blood flow.
● Diffusion across a membrane occurs
as per the concentration gradient.
● This leads to a rapid equilibration of solutes.
