Question on PAD and wedge (& Gasparis)

Specialties CCU

Published

Hi there,

On Gasparis' DVD she talks about a number of situations in which the PAD is not an accurate indicator of LVEDP - such as mitral stenosis/regurg, aortic stenosis, RBBB, etc. She goes on to tell the story of how a doc was angry that she wedged her swan, but she said she had to because the PAD wasn't accurate since the pt. had mitral stenosis. How does the wedge work that it can give you useful information that the PAD can't?

TL;DR: when is wedging indicated, and what is the physical reason that it can be helpful in some cases when the PAD is not?

Thanks!

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Specializes in Critical Care.

Laura Gasparis' educational programs are well packaged and many nurses find them to be useful, one issue I've found though is that the information it's based on is not always up to date or well-rounded.

At one time, Swan lines and routine wedge pressures were all the rage for a relatively large proportion of critically ill patients. Over time though we learned that routine wedge pressure readings make absolutely no difference for most of the patients we were using them for, and at the same time the risk of injury to the patient from wedging is obscenely high. It's for this reason that Physicians often have "do not wedge" orders on their patients.

While Laura's rationale is correct, mitral valve dysfunction (as well as a very long list of other factors) can alter how PAD relates to PWP, the more important question which she fails to ask herself is "does it matter"?, and the answer to that is no, so why is she doing a wedge?

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Thank you for your reply. I agree about her material. Definitely can't trust blindly, but I enjoy her presentation.

I am still curious though, just to understand how it all works together - what about mitral stenosis will alter the PAD but *not* affect the wedge? What is her rationale for wedging? Wouldn't it also be affected by mitral stenosis?

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Specializes in SICU.

The wedge wouldn't be accurate with mitral stenosis either, so yeah I don't know why she did that. In order for a wedge pressure to accurately be a measure of LVEDP, equal pressure across the system must be present. In other words, the pressure has to be equalized across the capillaries, pulmonary veins, left atrium, and left ventricle during diastole or else your number isn't accurate. During mitral stenosis, blood backs up and increases left atrial pressure. Therefore, during diastole (when the mitral valve is open), there isn't enough time for pressure to be equalized. So your wedge never has a chance to be accurate.

Better question, as pointed out, is why wedge? Ever?

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