Slow low efficiency daily dialysis (SLED)

It is a CVVHDF modality, with a prescribed rate of ultrafiltrate fluid removal

  • Blood flow rate: ~ 100-300 ml/min
  • Dialysate flow rate: ~ 100-300 ml/min… typically 150
  • Runs over 6-12 hours

Those who cannot afford, or are unable to physically lift Critical Care Nephrology can find very helpful information in an older article by Mark Marshall et al (2001), or a more recent 2007 review by Tolwani et al.

Cardinal features which distinguish SLED from CRRT

Its neither IHD or CRRT; its a "hybrid" therapy.

  • Employs features of both IHD and CRRT
  • Runs for 6-12 hours
  • Blood flow rates 100-300ml/min
  • Dialysate does not come in pre-made bags: it is either generated from water that comes from a wall outlet, or it is mixed from pre-packaged electrolytes and sterile water.
  • "Single-pass" machines use a dialysate generated "on-line" from reverse osmosis purified water
  • "Batch" machines contain a huge tank ("batch") full of sterile water mixed with prepackaged salts.
  • The dialysate flow rate is usually about 300ml/min, particularly for shorter treatments.

Advantages of SLED

From basic principles, one can establish that

  • The sessions are shorter, and therefore the duration of exposure to anticoagulant is shorter.
  • The patient is off-circuit for a large portion of the day. In fact, most places perform nocturnal SLED so that the patient can be mobile and active during the day.
  • Haemodynamically, it is better tolerated than IHD.

Furthemore, a good pro-SLEDD review has reported several advantages of SLED over CRRT:

  • Its cheaper than CRRT - up to 8 times cheaper!
  • No need for any anticoagulation (much of the time saline flushes are sufficient)
  • Solute removal is equivalent to CRRT.

Disadvantages of SLED


For a definitive treatment of all of this, you ought to pay homage to the gigantic and all-encompassing "Critical Care Nephrology" by Ronco Bellomo and Kellum (2009).

The Gambro and Fresenius websites have also been an excellent source of information.