what keeps the airway open on expiration?

[tyrinryan]

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?

[jimbud]

Diaphragm rises.
Lungs compress.
Air moves out and vents through mask vents.
Pressure stays the same.
More or less.

I am no expert.
Others may show up and tell me I am wrong.
Happens to me every once and awhile.
Then I will learn something new just like you.
JPB

[Goofproof]

Sucking water through a hose tends to suck it closed, pushing pressure out of the hose tends to keep it open! Jim

[jimbud]

Sucking water through a hose tends to suck it closed, pushing pressure out of the hose tends to keep it open! Jim

See, I told you someone would show up and give us a better explanation.
Thank you my brother in the KISS principle.
JPB

[raisedfist]

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?

Are you talking about bi-level therapy? CPAP or EPAP is a constant pressure that keeps your airway open. Their isn't much work involved with exhalation - it doesn't involve muscle contraction and it's a passive process. Inhalation and exhalation are separate phases of a breathe cycle. You breathe in, gas exchange occurs, and then you exhale.

There isn't a usual EPAP pressure since everyone's needs vary. On normal machines the EPAP min starts at 3 or 4 because you have to flush the expired air so you don't re breathe a bunch of carbon dioxide and give yourself a nasty headache or early funeral.

[D.H.]

Machines equipped with exhalation relief (not BiPAPs), let up from zero to three points during exhalation. Thus, it does not go to zero. BiPAPs can have a larger differential, but I don't think that they go to zero either.

BTW, I found exhalation releif very annoying and turned it off.

[jimbud]

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?

Are you talking about bi-level therapy? CPAP or EPAP is a constant pressure that keeps your airway open. Their isn't much work involved with exhalation - it doesn't involve muscle contraction and it's a passive process. Inhalation and exhalation are separate phases of a breathe cycle. You breathe in, gas exchange occurs, and then you exhale.

There isn't a usual EPAP pressure since everyone's needs vary. On normal machines the EPAP min starts at 3 or 4 because you have to flush the expired air so you don't re breathe a bunch of carbon dioxide and give yourself a nasty headache or early funeral.

Machine: AirSense™ 10 AutoSet™ For Her CPAP Machine with HumidAir™ Heated Humidifier
EPR?
JPB

[Goofproof]

Their isn't much work involved with exhalation - it doesn't involve muscle contraction and it's a passive process. Inhalation and exhalation are separate phases of a breathe cycle. You breathe in, gas exchange occurs, and then you exhale.

There isn't a usual EPAP pressure since everyone's needs vary. On normal machines the EPAP min starts at 3 or 4 because you have to flush the expired air so you don't re breathe a bunch of carbon dioxide and give yourself a nasty headache or early funeral.

FALSE: It doesn't involve muscle contraction and it's a passive process.

It DOES involve muscle contraction! Don't believe it, take a breath open you mouth without breathing out with out (using your muscles, holding your hand up to your mouth. The air doesn't just jump out of your lungs, they aren't balloons, the diaphragm created the pressure change that fills and exhausts the air in the Lungs. It can be both be involuntary (Brain triggered) or voluntary (You think to do it and control it) Jim

[tyrinryan]

Thanks for your interest and replies. I'm a newbee and will probably look back in the future, on this post as shallow. None-the-less, persisting, I am trying to get a handle on how the "human" exhalation pressure/volume is affected by the incoming PAP pressure/volume? Some lucky people can take the mask and machine and just go forth. I'm starting from first principles. I can see how PAP works on inspiration. On expiration, what happens to the pressure and volume created by the PAP (machine).

[palerider]

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?

It's the expiration pressure, the pressure the machine creates *between breaths* that holds the airway open.

That's why EPR can cause more apneas. EPR drops pressure between inhalations, to make it easier to exhale.

For example, if you need 9 cm pressure to hold your airway open, and your machine is set to 10, you're great.

If you decide "it's too hard to exhale against that, I'm going to use EPR!" and you dial in 3 EPR, then your pressure is actually *7* in between inhalations, so, it's not enough to hold your airway open, your airway closes, and you can't take that breath that would cause the machine to go back up to 10cm pressure.

So, what you have to do in that case is raise your pressure by however much you dial in EPR... so instead of 10 EPR 3 giving a base pressure of 10, you'd need 13 EPR 3 giving a base pressure of 10.

Make sense?

[palerider]

On expiration, what happens to the pressure and volume created by the PAP (machine).

It goes out the vent. Air is always going out the vent to flush out the CO2 you exhale, so you don't re-breathe that.

[tyrinryan]

So when you finish inhaling-(there is a pause-very small pause perhaps but still a pause)-before exhaling; at that moment, is there not still the PAP pressure down the throat towards the lungs and if so, wouldn't that pressure be available to reduce the regular "human" pressure created by exhalation.

[tyrinryan]

Palerider wrote: "That's why EPR can cause more apneas"
I'm with Palerider on the whole EPR fiasco.
But assuming you don't get sucked into the "comfort" stuff or that you are correctly diagnosed as 10 cm for pause and exhalation apneas and set the machine accordingly---what happens with the pressures, if the tongue collapses into the throat on the pause between inhalation and exhalation? and what happens if the tongue collapses into the throat during the pause and into the start of the exhalation motion? and my question, what happens on a clear airway?
I've read that Resmed initiates the EPR on the pause and continues it until inspiration so you don't even have the full PAP to continue to keep the airway open on the pause. Probably, I guess, (PIG), this does not help the average soul.
Can the sleep study actually calculate the collapse of the airway as between inspiration/pause/expiration? Perhaps by calculating back from the apnea? Do you think?

[palerider]

So when you finish inhaling-(there is a pause-very small pause perhaps but still a pause)-before exhaling; at that moment, is there not still the PAP pressure down the throat towards the lungs and if so, wouldn't that pressure be available to reduce the regular "human" pressure created by exhalation.

Please rephrase what you're saying, because I'm not clear, and I don't want to guess.

[ChicagoGranny]

So when you finish inhaling-(there is a pause-very small pause perhaps but still a pause)-before exhaling; at that moment, is there not still the PAP pressure down the throat towards the lungs and if so, wouldn't that pressure be available to reduce the regular "human" pressure created by exhalation.

CPAP stands for Continuous Positive Airway Pressure.

The pressure splints the airway open throughout the breathing cycle. When there is a momentary pause between inhalation and exhalation, the machine's fan continues to run maintaining pressure on the airway.

A case in point, I don't use EPR. The pressure in my airway remains the same (roughly) at all points on a breath.

The theory of CPAP is proven in the sleep lab and in the home, by tens of millions of successful users. Are you overthinking something?