Haemodialysis - solute waste moves across a semi-permeable membrane down a concentration gradient. It's intermittent - can lead to rapid changes in plasma osmolality and volume, which can lead to haemodynamic instability in critically ill patients.
Haemofiltration - continuous convection of molecules across a permeable membrane
More effective in removing large quantities of fluid
Not as effective at clearing smaller molecules
Preferable in critically ill patients since the continuous process avoids sudden large fluid shifts
