Filling Pressures

Why do docs use the term "filling pressures" for PA pressures? I know this is probably a silly question, but I am a new grad and new in the ICU, as well. For some weird reason, I like to know the why's of things and this term seems backwards to me b/c the blood is leaving the heart and heading to the lungs when they're in the pulmonary artery.

Hello,

I'm 5 months new to SICU as well but I'll give it a try. If I'm not mistaken the docs are referring to when the balloon is inflated and wedged in one of the branches in the Pulm artery and the blood is backing up secondary to the occlusion, therefore allowing the chambers to fill more readily, hence "filling pressures".

Wanting to know the "whys" about things is a good way to learn in the ICU. I am the same way and often do a lot of reading and picking the attendings brains to find these anwsers.

Anyone with more experience and better interpretation please feel free to add on.

PCWP (wedge pressure) measures the underlying LVEDP ie: left ventric filling pressure

Thanks, guys. I really appreciate your help.