Flow limitation and EPR

[danylam]

Why is there a relationship between Flow limitation decrease and EPR increase. Shouldn't it be the opposite?

[Lucky7]

Makes no sense to me as well, especially if the data is just based on one night or a handful of nights.

[Gideon]

Titration 101
Exhale pressure is what treats OA events. Increase pressure (Exhale pressure) until OA events are well managed. This is what provides the "splint"
Differential pressure, commonly called pressure support (PS) is the difference between exhale pressure (above) and inhale pressure which should be higher than exhale pressure is what best treats hypopnea, flow limitations, and RERAS/UARS by treating the underlying flow limitations. ROT is that exhale pressure should be held constant at the above-determined pressure.
With EPR the pressure setting may need to be increased to accommodate EPR by the amount of EPR. Many users are at a higher pressure than they need to just manage OA events so EPR is often just applied without adjustment and pressure is adjusted per the results as needed after EPR is used.

IMHO, once the airway is splinted open and OA events are managed the remaining hypopneas and flow limits are still restrictive events and the boost of higher pressure in inhale further opens the airway minimizing the resistance and smooths out the breathing.

Titration without EPR continues to increase pressure, there is no pressure relief, no EPR, just a constant pressure, until AHI/Obstructive events are minimized/managed.

[SarcasticDave94]

Agreed with Gideon. Flow limits are the beginning of that restricted airway. Next will be hypopnea. Finally a full Apnea.

You list as being on static pressure 7. If you're still getting flow limits, hypopnea, or Apnea, you can turn up the pressure until there's no events. However, you'll reach a point that comfort is lost. You can either back off of treatment pressure or add a differential, in this case EPR. EPR gives you the option to have both treatment and comfort.

EPR is a way to include a pressure relief and a differential, much the same as pressure support in a bilevel. EPR reduces to give the difference, PS adds to the pressure.

By the way my starting pressure was EPAP 7, the exhale pressure. IPAP max was at 25, which is the inhale pressure. I was using the ASV for Central Apnea. EPAP 7-12, PS 3-15, IPAP 10-25.

[Lucky7]

"IMHO, once the airway is splinted open and OA events are managed the remaining hypopneas and flow limits are still restrictive events and the boost of higher pressure in inhale further opens the airway minimizing the resistance and smooths out the breathing."

Conceptually I grok all the points above but. But.......If the airway is spinted open sufficiently to prevent full on obstructive events, then how can hypopnea's even occur? 

Thanks!

Afterthought: I've never seen ResMed or anyone else making therapeutic claims for EPR/Flex/Etc.

[Gideon]

I stayed OA events, these are apnea, full to near full restriction,

Can you kink a garden hose enough to get partial flow, but not totally stop it. It's the same concept

[gainerfull]

Well, you can solve flow limits in a number of ways ... the first being increasing pressure. Next, you can increase ventilation by adding EPR.

The important part to remember is EPR is subtractive, not additive and not true bi-level so many people turn on EPR when their minimum or constant pressure is just barely enough to control obstructive events and they end up working against themselves.

That being said, from my experience I will always add 3cmH20 to my minimum pressure or constant pressure then turn on EPR to account for the pressure drop and to make sure my airway stays open.

[CPAPfriend]

I think the concept is already well-explained here, but one other piece of food for thought I wish to leave on this trail is that what if the most effective arrangement is for us just to have different pressures for breathing in and breathing out? This is such a simple question, but I don't believe it has ever been properly addressed in the scientific literature. In other words, why a constant pressure by default and not two different pressures by default? Barry Krakow talks about this in his article on the site.

[Lucky7]

Titration 101
Exhale pressure is what treats OA events.  Increase pressure (Exhale pressure) until OA events are well managed.  This is what provides the "splint"
Differential pressure, commonly called pressure support (PS) is the difference between exhale pressure (above) and inhale pressure which should be higher than exhale pressure is what best treats hypopnea, flow limitations, and RERAS/UARS by treating the underlying flow limitations.  ROT is that exhale pressure should be held constant at the above-determined pressure.  
With EPR the pressure setting may need to be increased to accommodate EPR by the amount of EPR.  Many users are at a higher pressure than they need to just manage OA events so EPR is often just applied without adjustment and pressure is adjusted per the results as needed  after EPR is used.

IMHO, once the airway is splinted open and OA events are managed the remaining hypopneas and flow limits are still restrictive events and the boost of higher pressure in inhale further opens the airway minimizing the resistance and smooths out the breathing.

Titration without EPR continues to increase pressure, there is no pressure relief, no EPR, just a constant pressure, until AHI/Obstructive events are minimized/managed.

This is well worth watching. I marked a specific time, but the whole thing is enlightening. Specifically addresses the current titration protocols. As well as EPR, CFlex, and A-Flex.

https://youtu.be/EWTzFXNUIZU?t=2050

[Dog Slobber]

The benifits of EPR to treat flow limitations is *way* overstated, and has never been demonstrated empiracly.

I believe the history is based in the benifits of Pressure Support (PS) on Bilevels to improve Flow Limitations.

On a Bilevel, when one increases PS, one often reduces flow limitations because of the increased pressure, not just the pressure differential.

But then, many extrapulated that to; EPR is similar to PS, therefore increasing EPR should have the same benifits. The problem becomes, if one increases EPR, the net result is less pressure and FLs are not decreased.

For the most part, most people advise to increase EPR, because that's what they see others suggesting.

OSCAR tracks stats, including FLs, it also convienantly demarcs therapy points when adjustments are made. You know what has never been posted? An OSCAR statistics screen print demonstrating that increasing EPR and a resulting decrease in FLs.

There are countless posts where one can see minimum, maximum adjusted and the decreased AHI is demonstrated. There are counless posts where decreasing EPR reduces Centrals. 

Increasing EPR to treat FLs is unfounded is not supported by any evidence. 

Put please, post your OSCAR stats showing an increased EPR and a reduced FL. Or step up and start an expreiment. Post your stats today, increase your EPR, and let's look at your FL a month from now. 

Easy to demonstrate, yet has never been done.