Model CVVHD - Continuous Veno-Venous HemoDialysis
CVVHD allows to remove the substances that are the most commonly cleared by the kidneys such as water, urea, creatinine 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.
- Acute renal failure
- Lactic acidosis
It is a therapy that is usually performed continuously 24/24 until the renal function recovers, which may take from 2-3 days and up to 2-3 weeks.
In CVVHD, blood is passed through a dialyzer while dialysate is circulated on the other side of the semi-permeable membrane across which the concentration differences of small substances will tend to equilibrate which is named diffusion or osmosis. 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.