EPR behavior not making sense during apnea event - Airsense 10 Auto

[PurchanceToDream]

I'm looking at my data in OSCAR and zooming in on events.

I have EPR turned on.

Looking at the "Mask Pressure", I see that during events it always sits at the reduced EPR pressure during the entire event.

This would lead me to think that the machine thinks I am ready/trying to exhale during that time. Why wouldn't it go to the "inhale pressure" level, especially during an obstructive event?

What is especially weird is looking at the "inspire time" chart, it is clear that during these events the inspire time is going up. This means the Airsense 10 "thinks" that I am trying to and/or should be inhaling, so again, why is it still on the EPR reduced pressure for exhaling?

Anybody else seen what I an talking about?

Below is an image of the relevant charts for one such event. I'd all or nearly all of my events look like this, whether OA or CA.

Notice about 4 seconds into the event, it starts the little pressure pulses to detect obstruction, but does not bother to bump up to the "inhale" pressure level. Notice the "Insp. time" chart rising during the event further indicating that the machine believes I should be inhaling, not exhaling.

One thing I'll note is that I'm pretty sure most of my OA's are nonetheless centrals (no effort), but the machine would not know that (or would it?). It could make sense for CAs, since there is no effort to breath and airway is open. Maybe the threshold for OA  is quite low, such that (perhaps) even if only briefly obstructed it gets classified as OA rather than CA, but during most of this event the airway was clear, no effort, therefore no boost to pressure?

What gives here? Seems like a defect in the Airsense programming to my quite possibly uninformed eyes (unless my above speculation is correct).

*** Moderator Note: Corrupted image removed. ***

[Sleeprider]

EPR and in fact, Vauto pressure support, rely on spontaneous effort for pressure to increase. During an apnea, and even severe flow limitation or hypopnea, the machine does not detect sufficient spontaneous effort to "trigger" IPAP. These machine follow your respiratory effort. The behavior you observed is normal for the Resmed CPAPs and spontaneous VPAPs. Only the ST, ASV and iVAPS have the capability to trigger IPAP and lead your respiratory effort.

[Gideon]

Is you EPR set to " full time" or "Ramp only"?
It should be full-time.
Try and repost your OSCAR screenshot as it did not come through.

[PurchanceToDream]

Is you EPR set to " full time" or "Ramp only"?
It should be full-time.
Try and repost your OSCAR screenshot as it did not come through

I pasted the image in, and the editor appeared to accept it just fine. Weird.

My EPR is full time. But as other answer mentioned, I guess it must fully detect inspiration effort in order to bump up to the higher pressure level, which of course cannot detect if you are having an event.

Seems like a bone-headed design choice, even if it not supposed to be ASV. After all, EPR is just supposed to be a relaxation of pressure for more comfortable exhale, NOT the default pressure setting, yes?

[PurchanceToDream]

Here is the image that did not go through before (hopefully)...

OK, so insert image only allows an url... but for some reason the forum editor allows you to past an image in and it looks like a perfectly good part of the message?

direct link

apparently inserting the image as a link is "broken"... it's just a plain jpg, that opens anywhere else...

[PurchanceToDream]

EPR and in fact, Vauto pressure support, rely on spontaneous effort for pressure to increase.  During an apnea, and even severe flow limitation or hypopnea, the machine does not detect sufficient spontaneous effort to "trigger" IPAP.  These machine follow your respiratory effort.  The behavior you observed is normal for the Resmed CPAPs and spontaneous VPAPs.  Only the ST, ASV and iVAPS have the capability to trigger IPAP and lead your respiratory effort.

I'm sure that is correct, but it makes not sense to design it that way. The machines don't have chest/diaphram sensors. The only way to detect "effort" is air fllows. So by definition an event -- the exact time you supposedly need the higher pressure -- is precisely the time when it does not supply the pressure?

Furthermore, I know that it will ramp the pressure if you have ramping turned on, but it won't revert from the (not default) lower EPR pressure that is there purely for "comfort" to the actual therapeutic pressure?

Makes absolutely no sense at all.

Here is direct link to chart image. The forum doesn't like it for some reason:  https://pasteboard.co/JKi4FLj.jpg

[Sleeprider]

The spontaneous machines do not predict or anticipate your respiration rate. The do sense inspiratory effort and follow it with the increase to IPAP or actually CPAP pressure once you begin, and continue inspiration. If inspiration is flow-limited, so is the transition from EPAP to IPAP. If total apnea occurs, there is no increase in pressure and you are stuck at EPAP until the next breath begins.

Philips machines use Flex and anticipate expiration and inspiration. Pressure relief is initiated as expiration begins, but pressure returns to CPAP pressure before expiration ends. This results in many people not enjoying a complete exhale, and having no pressure support for inhale. It's complicated to say the least, but the Resmed EPR works best for most people.

The hallmark of CPAP is that it does not increase pressure during an event. With EPR on a Resmed, you must be certain to have pressure high enough that the CPAP pressure keeps the airway patent with the EPR pressure reduction. Most people experience apnea at the end of expiration, or beginning of inspiration. If the airway is obstructed, the answer is to increase minimum pressure. In your graph, the EPAP pressure is at 4.0 cm, which is clearly not enough. Raise your minimum pressure so that exhale pressure, with the EPR you have selected is higher. For example, with a minimum pressure of 7.0 and EPR at 3, you will have 7.0/4.0 (IPAP//epap) pressure. Raise pressure to 8.0 to make that minimum pressure 8.0/5.0.

We have not yet seen a good graph that shows your settings or full-night therapy results. My signature links show how to organize your Oscar charts. Post the whole chart with settings.

[PurchanceToDream]

The spontaneous machines do not predict or anticipate your respiration rate.  The do sense inspiratory effort and follow it with the increase to IPAP or actually CPAP pressure once you begin, and continue inspiration.  If inspiration is flow-limited, so is the transition from EPAP to IPAP.  If total apnea occurs, there is no increase in pressure and you are stuck at EPAP until the next breath begins.

Philips machines use Flex and anticipate expiration and inspiration. Pressure relief is initiated as expiration begins, but pressure returns to CPAP pressure before expiration ends.  This results in many people not enjoying a complete exhale, and having no pressure support for inhale.  It's complicated to say the least, but the Resmed EPR works best for most people.

The hallmark of CPAP  is that it does not increase pressure during an event. With EPR on a Resmed, you must be certain to have pressure high enough that the CPAP pressure  keeps the airway patent with the EPR pressure reduction.  Most people experience apnea at the end of expiration, or beginning of inspiration.  If the airway is obstructed, the answer is to increase minimum pressure.  In your graph, the EPAP pressure is at 4.0 cm, which is clearly not enough.  Raise your minimum pressure so that exhale pressure, with the EPR you have selected is higher.  For example, with a minimum pressure of 7.0 and EPR at 3, you will have 7.0/4.0 (IPAP//epap) pressure.  Raise pressure to 8.0 to make that minimum pressure 8.0/5.0.

We have not yet seen a good graph that shows your settings or full-night therapy results.  My signature links show how to organize your Oscar charts.  Post the whole chart with settings.

(btw, if I seem[ed] argumentative, apologies)

For the present thread, I'm only discussing whether the EPR behavior makes sense. The charts I provided are those relevant to the question at hand, zoomed in on an example event. I have a fixed pressure with EPR full time at level 3 here. The only relevant setting not clear from the chart is that I'm using a fixed pressure setting (i.e. no autoset ramp up, min pressure=max pressure=6.6), although the fact it does not ramp during the event does show this indirectly.

Your answer helps make some sense of EPR behavior, if the idea is not to bump the pressure up until inspiration is detected in order to avoid discomfort.

But what about after 5, 10, 20, 30 seconds of zero airflow? As you said, if there is no effort or the airway is blocked, there is be no inflow so inspiration "effort' is not detected. Seems to me it should not need to detect inspiration if it is already detecting a long halt in breathing, although I suppose . The machine could integrate airflow for an estimate of how full the lungs are, and apply a rule like: if the lungs are (mostly) emptied (below average volume) and breathing has paused more than 5 seconds, then assume they need to inhale and stop using the low EPR exhalation pressure.

That it does not use a rule similar to the above is the thing that is perplexing to me.

At any rate, in this thread, I am not asking anyone to evaluate my full night therapy results nor for help figuring out the right pressure. I'm zeroing in on that, and I just had one of my best night with even lower pressure than the above (6 fixed, with EPR 2, for min of 4). AHI<2 which is a big improvement so far. I have good reason to think most of even my OAs are central. Half to two thirds of all my events are CA as it is. You can close off your throat or larynx while not making effort to breath so some or even all of the OAs might be central as well. So far, DIY EERS appears to do more to reduce my AHI so far than increasing pressure. Higher pressure seems to lead to leaks which defeat EERS. Multiple variables to contend with here, so I will be likely be trying higher pressures again at some point in effort to bring AHI down to zero.

At any rate, I might at some point start a separate thread seeking others thoughts on the nature of my apneas and what is seen in my charts, at which point I'll be sure to follow your guide for arranging the charts.

[SevereApnea]

@PurchanceToDream

It's complicated but very simple. (forgive my over-elaboration, you likely already know this but it might help others)

When I first got my machine (Autosense For Her) I was disappointed to find out that the pressure from the machine does not treat my existing Apnea event. Sad day, until I understood how it works.

Try this while awake, listen and watch what the machine does.

Settle in to a regular breathing rhythm, let the machine stabilise.

Then hold your breath (with closed airway obviously) to mimic an apnea. Hold this for as long as you can.

When I tried this I found that the machine ramped up the pressure internally, I could hear it ramping up. You might also hear the FOT.

But the "pressure" on the screen readout did not change...

...until after I released my fake obstruction. The machine then reset its Pressures (max and Min based on EPR) to where it was when my apnea was resolved. You can see the effect of this in OSCAR, see attached chart from real time sleep.

Same thing when you sleep. It then resets to a pressure close to where you yourself relieved your obstruction (due to arousal, wife slap on the head, changing sleeping position whatever). It waits for you to relieve the obstruction and then resets the pressure. That is how the Auto part of APAP works, as opposed to CPAP.

So, it does not Open your obstructed airways, but reacts to it retrospectively, in an attempt to reduce/prevent subsequent events. It resets the pressures to higher ones to prevent subsequent OSA's that might occur at similar pressures, for a period of time.

By having my EPAP close to where I would normally start most of my obstructions, my OSAs will be fewer and shorter.

My own OSA may start from 7 - 11 cmH20. Clearly I can't run at 12 cmH20 that would be over-treating.

But by running close to where most of my OSAs start I can reduce their number and duration.

The Resmed algorithm also reads flow limitations, and in anticipation of an impending OSA, it starts to up the pressure, but that is a different story.

(The problem, for me, with EPR is that it is subtractive, whereas PS is additive.

If my titrated therapy pressure is 7 and I use no EPR both my IPAP and my EPAP stay at 7 and I do OK.

If I dial in EPR 3 without changing my Pressure, my inspiratory pressures stays at 7 but my EPAP falls to 7 -3 =4. Too low to prevent any subsequent OSAs.)

This applies to how my Resmed Autosense For Her works, it is not a ventilator after all.

Once I got a handle on that, I felt less frustrated.

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On the attached chart: Flow Limitations occur at (1) as shown by Flow Rate and Flow Limit chart.
Pressure starts to go up at (2) but fails to prevent OSA at (3).
Note the FOT in the Flow Rate chart and the Mask Pressure chart.
At (4) after the OSA is released the machine holds that new pressure.
Only then does the Mask Pressure go up.

Cycle repeats at the next OSA.

I stand open to correction but at least that is my understanding of it all: others here may wish to elaborate.