I’m always glad for questions, because I think that it’s what forces everyone’s thinking to progress. So yesterday a couple of really good ones from Jonathan Cheung:
My 1st question: I am just curious if it is possible for a collapsible IVC and PW findings suggestive of venous congestion to coexist, say, for example, if the congestion actually leads to increased IAP (perhaps not to the extent of intra-abdominal hypertension) or even 3rd spacing to form ascites in a leaky patient.
This is a question that has come up a couple of times. My physiological answer would be that, in primary systemic congestion, the start point is the increased CVP, which leads to IVC distension, then hepatic vein distension, whose pressure transmits thru the hepatic to the portal circulation, and then pulsatility develops. So in these cases a plethoric IVC is an inherent part.
On the other hand, local phenomena, such as cirrhosis, organ-specific edema (ischemic bowel, renal capsular hematoma, etc) can lead to edema and congestive signs in the local circulation without central venous congestion.
This is an important delineation, because the therapy for localized inflammation and edema is not likely the same as for central venous hypertension.
My 2nd question is: does the physiological changes by pronation (e.g. variable change in transpulmonary pressure, slight “off loading” of the abdomen etc.) cause an observable change to the spectral findings? I often have this question in mind when I want to assess fluid status in a prone patient on whom doing an echo isn’t always possible.
First I would argue that the only trouble with prone and POCUS is for cardiac views – hence TEE. But for venous doppler, the kidneys are perfect, the PV and IVC are totally accessible laterally and the IVC even posteriorly.
Secondly, I think it’s important to remember that physiologically, venous congestion is venous congestion, no matter the cause, and that end organs can suffer similar consequences. At least initially, proning should drop the PAP and unload the RV, but this will likely change over a variable amount of time. Very tough to properly assess the physiology in my opinion.
I’ll try to get Korbin, Rory and Jon-Emile to chime in!
Cheers
Philippe
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