Question about intra-abdominal pressures and its effects on respiration

[vanguard587]

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This relates to uworld questions 4600 and 4926, basically these questions hone in on the fact that elevating the trunk to 30 degrees or sitting up lowers the intra-abdominal pressure and thereby will help in respiration, and also in relieving neonatal GERD.

basically, what I don't understand, is why this occurs. Intuitively, I feel like it should be the other way around (meaning sitting should raise intra-abdominal pressure). And none of the sources I've searched really explains why. So now I am consulting SDN for help. Can anyone explain this concept for me?

Thanks!

 

[alpine37]

This relates to uworld questions 4600 and 4926, basically these questions hone in on the fact that elevating the trunk to 30 degrees or sitting up lowers the intra-abdominal pressure and thereby will help in respiration, and also in relieving neonatal GERD.

basically, what I don't understand, is why this occurs. Intuitively, I feel like it should be the other way around (meaning sitting should raise intra-abdominal pressure). And none of the sources I've searched really explains why. So now I am consulting SDN for help. Can anyone explain this concept for me?

Thanks!

I haven't researched this question out but I will add my two cents since no one has replied. I think that it might be somewhat related to the pressure of the viscera on the diaphragm when lying down.

When standing, the guts all pool down towards the bottom of the peritoneum unless they are tethered tightly to the abdominal by the peritoneum.

As you lie down the guts tend to spread out like a fluid and can press up against the diaphragm causing difficulty during inspiration as the diaphragm tries to contract against the force of the viscera.

During surgery reverse trendeleburg (feet down- head up) not only allows visualization of organs near the diaphragm- but will also allow the patient to breath easier if they aren't already on a vent.