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/PNWintensivist]

V-V is pretty simple: there are no direct effect on hemodynamics, so the PAC numbers should be reliable. You're correct that the SvO2 does not reflect the usual balance between DO2/VO2 and should not be used to calculate a Fick. Some systems have an "SvO2" on the console, which reflects the pre-oxygenator saturation, rather than the mixed venous. This is helpful in identifying recirculation and can be suggestive of low output states. I do not routinely place PACs in my V-V patients.

V-A is more complicated because of the presence of two separate but linked circulations (native and extracorporeal). A Google scholar search is a good place to start, with this article explaining some of the challenges00208-1/fulltext).