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CVVHDF

This document discusses continuous veno-venous hemodiafiltration (CVVHDF), a treatment that filters waste and fluid from the blood. It explains that with CVVHDF, blood is removed from the patient and passed through a filter before being returned. Dirty dialysate fluid is removed from the filter at a higher rate than clean replacement fluid is added, allowing fluid removal from the patient. CVVHDF clears small molecules through diffusion and middle molecules through convection, but is less effective at clearing middle molecules than continuous veno-venous hemofiltration (CVVH) and requires lower blood flow rates.

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Tarek Ibrahim Alshihabi
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113 views1 page

CVVHDF

This document discusses continuous veno-venous hemodiafiltration (CVVHDF), a treatment that filters waste and fluid from the blood. It explains that with CVVHDF, blood is removed from the patient and passed through a filter before being returned. Dirty dialysate fluid is removed from the filter at a higher rate than clean replacement fluid is added, allowing fluid removal from the patient. CVVHDF clears small molecules through diffusion and middle molecules through convection, but is less effective at clearing middle molecules than continuous veno-venous hemofiltration (CVVH) and requires lower blood flow rates.

Uploaded by

Tarek Ibrahim Alshihabi
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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This document was created by Alex Yartsev (dr.alex.yartsev@gmail.

com); if I have used your data or images and forgot to reference you, please email me.

CVVHDF: Continuous Veno-Venous HemoDiaFiltration


Heparin
Replacement fluid

Venous
Blood Blood returns back
to the patient

Dirty dialysate: Clean dialysate:


2 litres 1 litre
- Typically in hemodialysis , the clean dialysate is pumped into the pt at the same rate as the dirty dialysate is pumped out: in
such a case, solute clearance is purely diffusional.
- If you want to have some fluid removal, you can change the dirty dialysate removal rate to be greater than the clean dialysate
influx rate. This will mean that more fluid is being removed from the filter than is being pumped into it. The excess fluid being
removed from the filter (say, 100ml per hr, or 200ml per hr) will be cleared convectively. This is ultrafiltrate, and will clear out
some of the middle molecules.
- So, one can have a setup where 2 litres of effluent are being pumped out with 1 litre of dialysate being pumped in, and 1 litre of
replacement fluid being added post-dilution. This would be hemodiafiltration, with equal contributions from hemodialysis and
hemofiltration

- Needs lower blood flow rates than CVVH


- Filter life is longer than CVVH
- Smaller molecules cleared better than pre-dilutional CVVH, but no better than post-dilution CVVH
- Only about half as good at clearing middle molecules as CVVH
For a definitive treatment of all of this, you ought to pay homage to the “Critical Care Nephrology” by Ronco Bellomo and Kellum (2009)

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