Why do PAP machines let you apnea?

[tierdal]

I am a bit confused. IVe been trying to figure out if im getting good therapy in another thread and it led me to the question - why are the machines letting you stop breathing? 

They providing constant air pressure so how are you getting apneas?

[pholynyk]

If the pressure is too low - on ramp, or default 4, or just too low - then the airway can still collapse. An auto-adjusting CPAP machine will detect that stoppage, and then raise the pressure a bit, repeating each time there is an apnea until the airway stays open.

Some machines use additional triggers for raising the pressure, but that's the basic principle.

[tierdal]

i see people with liek 4-6 AHI reported in oscar tho, why is that happening?

if i just set my preasure to 20 would i stop having events and sleep better?

[Sleeprider]

The CPAP machine can only splint the airway with positive pressure. If a person needs higher pressure or is in a body position that restricts their airway, then an obstructive apnea may occur. The machines don't breathe for us, and the amount of pressure used is limited by comfort, settings or health concerns.

[Sleepster]

I am a bit confused. IVe been trying to figure out if im getting good therapy in another thread and it led me to the question - why are the machines letting you stop breathing? 

They providing constant air pressure so how are you getting apneas?

You have to stop breathing for only 10 seconds to score an apnea. Asking for a perfect score of zero apneas is just not realistic. It's not the way the human body functions. If you have a AHI of less than 5 you are deemed "normal" and are not prescribed a CPAP machine.

[staceyburke]

It depends on the type of apnea. There are 2 main types: obstructive and clear airway or also called central.

A normal pap machine can only treat obstructive apnea. A central apnea takes a specialized pap machine and more expensive.

Of obstructive apnea they are Categorized as apnea, Hypopnea and flow limits. See my signature for how they are categorized.

If you have a flow limit or a Hypopnea - they could have been a full apnea but the machine got to it and made it a smaller event.

[SarcasticDave94]

Note that your other thread which you're dealing with a lot of leaks, where the leaks are high enough to prevent good therapy. And we don't expect all Apnea to be eliminated. That's not a realistic goal. In your example of just using 20 and trying to sleep, it just won't work for most. You state you have leaks above 7, and then you're not real comfortable now, imagine what 20 will do.

[clownbell]

If I understood the original question correctly, it was "why do PAP machines allow apnea to exist." I am no expert but my understanding is as follows.

PAP machines increase pressure in response to CLUSTERS of obstructive apneas, not in response to individual events. PAPs raise the pressure in response to obstructive apneas and hypopneas if TWO OR MORE events occur in a relatively small amount of time – which indicates that the current pressure may not be sufficient to prevent the airway from collapsing in the near future. Goal is to increase the pressure just enough to prevent more events from happening in next few minutes and allow the breathing to stabilize. Once the breathing is stable, the pressure decreases until there is evidence that the airway is again in danger of collapsing.

The experts may have different explanations, in which case I stand corrected and appreciate the lesson learned.

[archangle]

If you have a flow limit or a Hypopnea  - they could have been a full apnea but the machine got to it and made it a smaller event.

Maybe.   It's also possible you would have had the same hypopnea or flow limit without CPAP.