CVVH : Continuous Veno-Venous Hemofiltration

Description

This technique allows to remove all the substances that would normally be cleared by the kidneys such as water, urea, creatinin or salts, as well as medium size substances which result from an injury to body cells and are often nephrotoxic. This therapy is usually performed continuously 24/24 until the renal function recovers, which may take from 2-3 days up to 2-3 weeks.

HVHF : High Volume HemoFiltration is technically similar to CVVH but uses higher ultrafiltrate and blood flows thus allowing to perform treatment for some hours per day (i.e. 6-12) instead of continuously. HVHF may also provide clinical improvement in case of sepsis however this is still controversial.

Examples of application

Technical information

In CVVH, blood is passed through a hemofilter which allows water to be filtrated together with some other substances which are important in this case, such as salts, urea, creatinin or other medium size substances, the resulting fluid being named ultrafiltrate. Ultrafiltrate is removed at a rate which allows the necessary clearances of desired substances. As this rate is often too important for other substances a substitution fluid is injected in the blood to compensate for undesired losses, such as that of water.

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