what keeps the airway open on expiration?

Janknitz · Post by **Janknitz** » Fri Jul 05, 2019 1:16 pm

Goofproof said

It DOES involve muscle contraction!

I think, that a muscle contraction is required for inspiration--the diaphragm contracts and the lungs expand, causing a pressure gradient that brings air into the lungs. But exhalation is RELAXATION of the diaphragm (no agonist muscle that must contract to expel a reasonable volume of the air from the lungs although we have accessory muscles that can push it out with great force if we want to consciously--that's how you blow up a balloon, whistle, or talk). So unless there's a significant obstruction, as the diaphragm relaxes, air is pushed out of the lungs with a degree of force, like the bowstring analogy. There is stored energy, but not muscle contraction, required for exhalation.

I may be wrong . . .

jimbud · Post by **jimbud** » Fri Jul 05, 2019 1:25 pm

what keeps the airway open on expiration?
Post by tyrinryan » Thu Jul 04, 2019 9:17 am

One has the PAP pressure (say 10cm's) and you have the expiration pressure (I guess). Do they cancel out leaving the expiration pressure to do all the work of the "expiring" and keeping the airway open. How high is the usual expiration pressure? How does all this work---- on expiration?

_________________
Machine: AirSense™ 10 AutoSet™ For Her CPAP Machine with HumidAir™ Heated Humidifier

Here is the original post.
Anyone have an answer?

I did not think so.
You are all too shallow.

JPB

palerider · Post by **palerider** » Fri Jul 05, 2019 2:15 pm

ChicagoGranny wrote: ↑
Fri Jul 05, 2019 7:04 am

palerider wrote: ↑
Thu Jul 04, 2019 11:55 pm
Or maybe "relax" means 'works harder' in their perverse twist on the English language.
You are always talking about that balloon that can't be blown up with CPAP pressure. Do you think you can blow it up with your breath just by relaxing some muscles?

There is quite a difference in normal expiration, which happens normally when you breathe, which has very little, if anything to do with forced exhalation.

Don't be absurdly obtuse. You're smarter than that.

palerider · Post by **palerider** » Fri Jul 05, 2019 2:18 pm

Janknitz wrote: ↑
Fri Jul 05, 2019 1:16 pm
Goofproof said
It DOES involve muscle contraction!
I think, that a muscle contraction is required for inspiration--the diaphragm contracts and the lungs expand, causing a pressure gradient that brings air into the lungs. But exhalation is RELAXATION of the diaphragm (no agonist muscle that must contract to expel a reasonable volume of the air from the lungs although we have accessory muscles that can push it out with great force if we want to consciously--that's how you blow up a balloon, whistle, or talk). So unless there's a significant obstruction, as the diaphragm relaxes, air is pushed out of the lungs with a degree of force, like the bowstring analogy. There is stored energy, but not muscle contraction, required for exhalation.

I may be wrong . . .

You're not wrong.

zonker · Post by **zonker** » Fri Jul 05, 2019 2:19 pm

jimbud wrote: ↑
Fri Jul 05, 2019 1:25 pm
You are all too shallow.
JPB

get-out.gif

palerider · Post by **palerider** » Fri Jul 05, 2019 2:20 pm

jimbud wrote: ↑
Fri Jul 05, 2019 1:25 pm
what keeps the airway open on expiration?
Post by tyrinryan » Thu Jul 04, 2019 9:17 am

One has the PAP pressure (say 10cm's) and you have the expiration pressure (I guess). Do they cancel out leaving the expiration pressure to do all the work of the "expiring" and keeping the airway open. How high is the usual expiration pressure? How does all this work---- on expiration?

_________________
Machine: AirSense™ 10 AutoSet™ For Her CPAP Machine with HumidAir™ Heated Humidifier

Here is the original post.
Anyone have an answer?

I did not think so.
You are all too shallow.
JPB

I didn't understand what the op was trying to ask,because of the way the question was phrased, I believe the phrasing is based on a faulty understanding of how CPAP works.

jimbud · Post by **jimbud** » Fri Jul 05, 2019 2:33 pm

palerider wrote: ↑
Fri Jul 05, 2019 2:20 pm

I didn't understand what the op was trying to ask,because of the way the question was phrased, I believe the phrasing is based on a faulty understanding of how CPAP works.

[/quote]

jimbud writes:

My thoughts exactly.
How can you answer a question seriously when it was not phrased cognizantly.
So we all fall back on another question and answer that.
One we understand.
Or move on to another post.
See if we can help them.
JPB

palerider · Post by **palerider** » Fri Jul 05, 2019 2:49 pm

jimbud wrote: ↑
Fri Jul 05, 2019 2:33 pm

palerider wrote: ↑
Fri Jul 05, 2019 2:20 pm
I didn't understand what the op was trying to ask,because of the way the question was phrased, I believe the phrasing is based on a faulty understanding of how CPAP works.

My thoughts exactly.
How can you answer a question seriously when it was not phrased cognizantly.
So we all fall back on another question and answer that.
One we understand.
Or move on to another post.
See if we can help them.
JPB

That's why I usually ask for the person to restate the question, instead of just .along a guess about what they mean and answering that... I've seen too many people (not just here with CPAP) over the years that didn't even know enough about the subject to ask a coherent question... So you have to back up and figure out what they're actually talking about, then move forward, often in a completely different direction.

jimbud · Post by **jimbud** » Fri Jul 05, 2019 3:14 pm

palerider wrote: ↑
Fri Jul 05, 2019 2:49 pm

jimbud wrote: ↑
Fri Jul 05, 2019 2:33 pm

palerider wrote: ↑
Fri Jul 05, 2019 2:20 pm
I didn't understand what the op was trying to ask,because of the way the question was phrased, I believe the phrasing is based on a faulty understanding of how CPAP works.

My thoughts exactly.
How can you answer a question seriously when it was not phrased cognizantly.
So we all fall back on another question and answer that.
One we understand.
Or move on to another post.
See if we can help them.
JPB
That's why I usually ask for the person to restate the question, instead of just .along a guess about what they mean and answering that... I've seen too many people (not just here with CPAP) over the years that didn't even know enough about the subject to ask a coherent question... So you have to back up and figure out what they're actually talking about, then move forward, often in a completely different direction.

Well, you are obviously better at this than I.
I am not known for my patience (actually I am hardly known at all).
I am trying to help some people within my wellhouse of knowledge and experience. [ And having some fun in the process.]
Which is limited in this APAP field, but I am learning almost every day.
If I live long enough maybe I will achieve adequacy.

Just felt like typing,
JPB

palerider · Post by **palerider** » Fri Jul 05, 2019 3:26 pm

jimbud wrote: ↑
Fri Jul 05, 2019 3:14 pm
Well, you are obviously better at this than I.

I don't know if I'd go that far...

But I did spend many years in a very technical field, and got asked many questions that made no sense at all... Many like "how do I do x",when it turned out that instead of going over hill and dale, through the dark forest, and the land of monsters, the really just n|ded to turn left at the next intersection, and they'd be where they wanted to end up... They just didn't know the ahortcut existed.

Janknitz · Post by **Janknitz** » Fri Jul 05, 2019 6:41 pm

I thought the question was pretty clear, even if it's not "technical" enough to satisfy some of you.

The OP was asking--if we need pressure to splint the airway open during inhalation, but there's pressure relief on expiration, how does the airway stay open to let air OUT?

My non technical understanding is the passive (caused by relaxation of the diaphragm, not by muscular force to exhale) exhalation has enough pressure in most cases to pass mild, mechanical obstruction like a floppy airway. Kind of like letting the air out of a balloon but holding the balloon neck so air comes out through a narrower opening.

jimbud · Post by **jimbud** » Fri Jul 05, 2019 7:20 pm

Janknitz wrote: ↑
Fri Jul 05, 2019 6:41 pm
I thought the question was pretty clear, even if it's not "technical" enough to satisfy some of you.

The OP was asking--if we need pressure to splint the airway open during inhalation, but there's pressure relief on expiration, how does the airway stay open to let air OUT?

My non technical understanding is the passive (caused by relaxation of the diaphragm, not by muscular force to exhale) exhalation has enough pressure in most cases to pass mild, mechanical obstruction like a floppy airway. Kind of like letting the air out of a balloon but holding the balloon neck so air comes out through a narrower opening.

You got all that from this:

what keeps the airway open on expiration?
Post by tyrinryan » Thu Jul 04, 2019 8:17 am

One has the PAP pressure (say 10cm's) and you have the expiration pressure (I guess). Do they cancel out leaving the expiration pressure to do all the work of the "expiring" and keeping the airway open. How high is the usual expiration pressure? How does all this work---- on expiration?

Wish I had second sight.
JPB

palerider · Post by **palerider** » Fri Jul 05, 2019 7:25 pm

Janknitz wrote: ↑
Fri Jul 05, 2019 6:41 pm
I thought the question was pretty clear, even if it's not "technical" enough to satisfy some of you.

The OP was asking--if we need pressure to splint the airway open during inhalation, but there's pressure relief on expiration, how does the airway stay open to let air OUT?

My non technical understanding is the passive (caused by relaxation of the diaphragm, not by muscular force to exhale) exhalation has enough pressure in most cases to pass mild, mechanical obstruction like a floppy airway. Kind of like letting the air out of a balloon but holding the balloon neck so air comes out through a narrower opening.

I could *guess* that's what the OP meant, but, considering "One has the PAP pressure (say 10cm's) and you have the expiration pressure (I guess). Do they cancel out leaving the expiration pressure to do all the work of the "expiring" and keeping the airway open. How high is the usual expiration pressure? How does all this work---- on expiration?" I'm not sure.

It sounds *to me* like OP doesn't understand how exhalation relief works... but I could be wrong.

ChicagoGranny · Post by **ChicagoGranny** » Sat Jul 06, 2019 5:05 am

Janknitz wrote: ↑
Fri Jul 05, 2019 6:41 pm
My non technical understanding is the passive (caused by relaxation of the diaphragm, not by muscular force to exhale) exhalation has enough pressure in most cases to pass mild, mechanical obstruction like a floppy airway.

Have you seen a setting where the exhalation pressure is zero? There's never been one discussed here. This is because pressure support on exhalation is required to maintain airway patency.

Judging by how the OP titled his thread,

what keeps the airway open on expiration?

the simple answer is that CPAP maintains positive pressure on the airway during exhalation. This is true even when exhalation relief or bilevel is used.

palerider · Post by **palerider** » Sat Jul 06, 2019 11:11 am

ChicagoGranny wrote: ↑
Sat Jul 06, 2019 5:05 am

Janknitz wrote: ↑
Fri Jul 05, 2019 6:41 pm
My non technical understanding is the passive (caused by relaxation of the diaphragm, not by muscular force to exhale) exhalation has enough pressure in most cases to pass mild, mechanical obstruction like a floppy airway.
Have you seen a setting where the exhalation pressure is zero? There's never been one discussed here. This is because pressure support on exhalation is required to maintain airway patency.

Judging by how the OP titled his thread,

what keeps the airway open on expiration?
the simple answer is that CPAP maintains positive pressure on the airway during exhalation. This is true even when exhalation relief or bilevel is used.

The lowest possible exhalation pressure I've ever seen on a machine is 3cmH2O.

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