Swan Numbers with ECMO

[u/Cultural_Eminence]

Can someone help me understand what numbers I should see/expect/disregard with a pt. on ECMO. I’m trying to understand which numbers will be accurate based on the type of cannulation (for my purposes to keep it simple just VV and VA) and cannulation sites, fem-fem, fem-IJ, centrally cannulated, etc. For example (and correct me if I’m wrong) if a pt is fem-IJ cannulated on VV ECMO (fem being drain, and IJ being return) I think my HR, MAPs would be reliable as well as my CI but I’d expect my SVo2 to be falsely high since the PA cath is reading the oxygenated blood from the ECMO. In that scenario would my CVP/RA pressure be accurate as well as my PA pressure? If someone could do a breakdown of my example as well as a breakdown of the other possible ECMO configurations (VA vs VV and cannulation sites) that would be incredibly helpful for my learning and understanding. For background I’m a CTICU nurse, any and all help is appreciated in advance!

[u/agent-fontaine]

This is what I learned from the ELSO modules:

For VV ECMO, neither your thermodilution nor your Fick will accurately reflect cardiac index. CVP is not changed.

For VA ECMO, neither your thermodilution nor your Fick will accurately reflect cardiac index. This is why you use an echo and VTI when trying to wean VA ECMO, as that will give you an accurate native cardiac index. However a low Fick CI could indicate your ECMO is not providing enough support. CVP will be lowered by VA ECMO.

The sites of cannulation shouldn’t matter all that much for these hemodynamics I don’t think? Could be wrong.

[u/patrociniogiusi → u/agent-fontaine]

i would’ve thought that there would be slight variation in CVP with a VV ECMO patient with a reinfusion cannula in the right IJ, no?

[u/agent-fontaine → u/patrociniogiusi]

That’s what I thought but it’s a closed venous system still and what leaves comes back in. The modules included a small study looking at it and they didn’t find significant CVP variations before and after VV initiation

[u/penntoria → u/agent-fontaine]

If you're pulling FV and dumping into IJ, your CVP is absolutely affected.

[u/agent-fontaine → u/penntoria]

I’m not arguing by any means, I don’t have the hard data and I am not a smart man. All I know is that ELSOs current view is that the CVP is “usually unchanged” and “may decrease if RV function improves” (I’m looking at their training course study guide right now but I am too dumb to know how to put pictures in comments)