Lumbar Puncture

[neuronick]

I looked at a few books and searched online, but could not find the answer to this. I was asked today what the average opening pressure should be on a SEATED LP. Not lateral. decubitus. Also wanted to know what upper range pressure should be considered high in the seated position. Most places I look quoted the 20cm H2O mark and then stated "only valid in the lateral decubitus". Any ideas? Thanks for any help.

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[typhoonegator]

In the seated normal patient the opening pressure should rise to approximately the level of the foramen magnum. However, if you really care about the opening pressure, you should probably lay them down.

 

[AlternateSome1]

fluid density * acceleration of gravity * height of the fluid above the needle

 

[BlackFrancis33]

fluid density * acceleration of gravity * height of the fluid above the needle

Seated LPs are unreliable for opening pressure period. There is no proven or reliable formula for seated LPs. Get the needle in seated if needed, and then lie them on their side to measure the pressure. It is easier to just do it on their to start with.