CVVHD: Continuous VenoVenous HemoDialysis :
CVVHD allows to remove the substances that are the most commonly cleared by the kidneys such as water, urea, creatinin or salts. It has also some ability to remove the medium size substances which result from an injury to body cells however with less efficiency than CVVH.
It is a therapy that is usually performed continuously 24/24 until the renal function recovers, which may take from 2-3 days up to 2-3 weeks.
An alternative to CVVHD is SLEDD, an acronym for Slow Extended Daily Dialysis. As HVHF to CVVH, SLEDD is technically similar to CVVHD however with higher dialysate and blood flows allowing to avoid the 24/24 schedule and reduce it to a daily 6-12/24 hours treatment.
Examples of application
- Acute renal failure
- Lactic acidosis
In CVVHD, blood is passed through a DIALYSER while dialysate is circulated on the other side of the semi-permeable membrane across which the concentration of different small substances will tend to equilibrate by DIFFUSION. In particular the substances to be removed from blood will migrate into the dialysate and the drained dialysate will take them away. The removal of water is added to the diffusion process by extracting more drained dialysate than the quantity of fresh dialysate injected, the difference of volume being water removed from the blood by filtration.