CVVH

SLED

IHD

            Mechanism of solute clearance

 Solvent removal occurs as a consequence of a pressure gradient across a semi permeable membrane. Solute removal occurs only by convection (solvent drag).

Solute removal occurs predominantly by diffusion down a concentration gradient created by dialysate fluid on the other side of the semi permeable membrane.

 Solute clearance by diffusion

            Advantages

Achieves better clearance of middle molecules (< 15 Kd) than CVVHD/IHD, fluid management easier and flexible, lesser hemodynamic instability as compared to IHD.

 Can be done at night so patient can be mobilized during the day. Period of anticoagulation reduced. Possible cost savings by using online water and ability for one
machine to deliver 2 treatment episodes per day.

shortest treatment time, anticoagulation often not required, cost  savings by using online water

            Limitations

 Patient immobilized , need for continuous anticoagulation  , higher nursing requirement

 inferior clearance of middle molecules, reduced fluid management flexibility. Higher risk of disequilibrium syndrome

 least clearance of middle molecules, least flexible fluid management, highest risk of disequilibrium syndrome. Possible greater

Good clearance of middle molecules

Well tolerated hemodynamically

Good control over fluid removal and solute exchange

Intermittent, thus less labour intensive;

Anticoagulation may not be required;

Intermittent, allowing periods of mobility for the patient

Well tolerated unless very unstable

Less labour intensive;

Anticoagulation may not be required;

Intermittent, allowing periods of mobility for the patient

Expensive

Requires anticoagulation

Prolonged immobilization

Poorly tolerated by very hemodynamically unstable patients;

Requires reverse osmosis facilities;

Poor fluid management

Limited clearance of middle molecules

Poorly tolerated by hemodynamically unstable patients;

and then there is the risk of disequilibrium syndrome.