apnea on exhale

[tyrinryan]

I read on the forum somewhere that there are more apneas on exhale than inhale. What are the stats? proof?

[JDS74]

Interesting thought.
My understanding of an apnea was a cessation of breathing in, OSA's are inhale, Hypopneas are inhale, and CSA's are no air movement in or out.
Is there an RT who can clarify if this is correct?
Edit: a couple of typos.

[palerider]

I read on the forum somewhere that there are more apneas on exhale than inhale. What are the stats? proof?

And, where did you read that?

You can find all sorts of garbage, but was it refuted? Was it credible?

[Patriot Partner]

My 2 cents

This is why a lot of cpap people should be on bipa
Even if they're showing compliant

[palerider]

My 2 cents

This is why a lot of cpap people should be on bipa
Even if they're showing compliant

And why is that?

[zonker]

My 2 cents

This is why a lot of cpap people should be on bipa
Even if they're showing compliant

please define "a lot".

[ChicagoGranny]

My understanding of an apnea was a cessation of breathing in

An apnea is a cessation of breathing, period.

[ChicagoGranny]

My 2 cents

This is why a lot of cpap people should be on bipa
Even if they're showing compliant

If there were more apneas on exhale, then some should use a "reverse bilevel" - more pressure on exhale/less pressure on inhale.

[ChicagoGranny]

I read on the forum somewhere that there are more apneas on exhale than inhale. What are the stats? proof?

Interesting thought.
My understanding of an apnea was a cessation of breathing in, OSA's are inhale, Hypopneas are inhale, and CSA's are not air movement in or out.
Is there and RT who can clarify if this is correct?

Are you guys thinking that an obstructive apnea just begins "boom" at a single point in time? All the trace flows of apneas show a somewhat gradual decline of stability in the airway leading to a complete, or nearly complete, cessation of breathing.

[Janknitz]

Exhalation is a passive relaxation of the diaphragm muscle, and generally has sufficient pressure to push through any obstruction in the airway. That's why exhalation pressure relief works--you don't have to hold the airway open much if at all for exhalation in most cases.

I've seen a few people here say that their apneas are on exhalation and they perceive them even while awake. I don't really understand this enough to comment. However there is an interesting article about expiratory apnea here: https://doctorstevenpark.com/expiratory ... ral-apneas

Inspiration requires respiratory effort--the flattening of the diaphragm to pull air in, and may not be strong enough to push through an obstruction because the airway is more relaxed during sleep.

[tyrinryan]

I thought that this was a known generalization (all apneas are on exhale) and I was sure I read it straight-up on this forum or somewhere else. It seemed a little counterintuitive. I was looking for confirmation and proof from the Forum members. However, without prompting, my DME sleep tech said it to me too, just the other day-"all apneas are on exhale". I am a newbie and I of course nodded with agreement! When I looked at an Oscar chart for one night, I could not see any clear or dramatic evidence of this concept. Could the question could be better phrased: do all apneas start with an airway closure (or even almost closure) during expiration? If this were so, it would seem to me to important when choosing a CPAP machine with one of the EPR/C Flex algorithms. I read somewhere, that without positive pressure, the "regular" pressure is lowest at the end-expiration point. Would that not mean that EPR should stop and regular PAP pressure should begin at the end of expiration instead of the start of inspiration. I read somewhere that that was the difference in the algorithms of Phillips and Resmed. Would this then be a reason to choose Phillips over Resmed? It is hard to believe that Resmed overlooked this. I look forward to your comments.

[palerider]

I thought that this was a known generalization (all apneas are on exhale)

You're seem to be quite confused about this.
Apneas don't happen *on exhale* typically, the throat closes *after exhale* and *before inhale*... preventing the inhalation from happening. Now, there is a thing called 'palatial prolapse' where your soft palate can get in the way of exhaling, but it's very unusual.

and I was sure I read it straight-up on this forum or somewhere else. It seemed a little counterintuitive. I was looking for confirmation and proof from the Forum members. However, without prompting, my DME sleep tech said it to me too, just the other day-"all apneas are on exhale".

Either they don't know what they're talking about, or they just poorly phrased things.

Could the question could be better phrased: do all apneas start with an airway closure (or even almost closure) during expiration?

No. If they did, you'd see a sudden cessation of exhalation flow, as opposed to the normal tapering off you see in almost every instance.

If this were so, it would seem to me to important when choosing a CPAP machine with one of the EPR/C Flex algorithms.

I'm not aware of any modern machines that don't have some form of exhale relief, so that's a non-sequitur.

I read somewhere, that without positive pressure, the "regular" pressure is lowest at the end-expiration point.

I have no idea what you're reading, but CPAPs *always* have positive pressure, that's what the CONTINUOUS means.

Would that not mean that EPR should stop and regular PAP pressure should begin at the end of expiration instead of the start of inspiration.

Then it would be like *flex, which does exactly that, and confuses many people into thinking that the machine is trying to rush their breathing.

I read somewhere that that was the difference in the algorithms of Phillips and Resmed.

Yes.

pressure-relief.png

It seems a majority of people prefer the way Resmed does it.

Would this then be a reason to choose Phillips over Resmed?

Quite the opposite.

It is hard to believe that Resmed overlooked this.

"overlooked" that they have a superior system? pretty sure they didn't.

I look forward to your comments.

Well, you have 'em.

[tyrinryan]

Thanks pale rider That chart is terrific

[tyrinryan]

What does the grey line shown in the graphs shown by Palerider represent?

[palerider]

What does the grey line shown in the graphs shown by Palerider represent?

Respiratory flow.