Inspiration expiration ratio

[Jay Aitchsee]

Will have to wait until tomorrow to get some waveform...I totally screwed up my Encore reports from the 560 I am trialing...so I lost all wave form in Pro.
I don't have time to go looking for old stuff and I won't remember about sleeping well or not.

You give me a thought (no, probably not an orignal one). Why don't we all keep little diaries in which we record our opinions about quality of sleep, headaches etc every morning upon waking? The resulting data could then be analysed for association with AHI, pressures, CAs etc etc. If we somehow standardised the reporting we could pool our data and conduct a proper study!

Well I can dream can't I ....

Sleep Diaries are often recommended and encouraged. Here's a link to some examples

[Pneumophile]

Excellent. Maybe there's an app for that ...

[palerider]

Excellent. Maybe there's an app for that ...

the advantage of doing it in SH is that you've got your sleep data right there... but of course, you have to fire up sleepyhead.

[Jay Aitchsee]

This thread has been primarily about I:E ratios calculated from Sleepyhead Statistical Data gathered from a PR System One machine. I've spent some time on it and have asked one important question contained in the quotes below. I don't want the question to get lost, so I'm restating it here:

Are the data representing Inspiration and Expiration times for the System One machine reliable?

A reasonable question, I think, particularly in light of the discussion regarding event duration in the preceding posts.

Question:This thread began with a question about an abnormal (I.e., "Inverse") I:E ratio. The OP used SleepyHead to compare average Inspiration time to average Expiration time to arrive at an I:E ratio. The OP's machine is a PR System One REMStar 60 Auto CPAP (PR 560). Subsequently, a second poster, apparently using the same or similar machine, mentioned a possible abnormal I:E ratio as well. The "official" software to extract data from these machines would be some form of Encore.

I can find no mention of Encore presenting this data (specifically Inspiration and Expiration times) with these machines (doesn't mean that it doesn't).

My question is this: Is this data (Inspiration and Expiration times) as presented by Sleepyhead reliable for these machines, since I can find no reference that Phillips Respironics intended it to be extracted and used in this manner? Or, is this a construct by SleepyHead which may not accurately represent the data under all circumstances, particularly in the presence of Ballistocardiographic Artifacts?

OK Ron, here's the I:E for the two samples you put up. The measurements are by eyeball, but close enough for government work, I think.
As you can see, they are no where close to "Inverse."
Now, all you have to do is check these against what was reported by SleepyHead for IT and ET for this night (Aug 25) and times.

It occurs to me, though I think it unlikely, the detail statistics data labels of Sleepyhead for Inspiration and Expiration times for this machine type could be of reversed.

[rkl122]

..............

OK Ron, here's the I:E for the two samples you put up. The measurements are by eyeball, but close enough for government work, I think.
As you can see, they are no where close to "Inverse."
Now, all you have to do is check these against what was reported by SleepyHead for IT and ET for this night (Aug 25) and times.

It occurs to me, though I think it unlikely, the detail statistics data labels of Sleepyhead for Inspiration and Expiration times for this machine type could be of reversed.

Ok Jay, here you go: I'll give the I:E actual values for alignment of my cursor with each of your red lines.

For the first (00:46:30) strip: 1.82:2.14, 1.85:2.09, 2.00:2.00, // 2.18:2.21, 2.22:2.42, 1.96:2.25
For the second(5:57:00) strip: 3.64:1.04, 3.82:1.04, 3.71:1.10, // 3.04:1.00, 3.04:1.00, 2.90:1.00

So I'm afraid my readings don't match your measurements, but is this surprising? We've already concluded that there are timing/reporting issues in the Phillips Resperonics machines, not to mention the uncertainties associated with SH's representations. And as I think we speculated above, we don't really understand what these momentary I & E rates represent or whether two aligned numbers actually correspond to the same instant. FWIW, though, my ratios are in accord with an observation I think I made earlier: little or no inversion in the first hours of sleep, significant inversion in later hours.

Jay, you've put a lot into this thread, and I muchly appreciate it. Lots of reading links too. While I remain interested in the I:E ratio and what, if any, significance may be ascribed to inversion, I'm more concerned now with my flow chart at the breath by breath level. I'll be posting a new thread with a link to a video that exposes greater chunks of flow. I suspect you are correct to point out that my anomalous flow may be caused by something other than my OSA. I'm trying to prepare best I can for meeting with the sleep doc. Feel free to comment in the other thread if you see anything interesting.

by Pugsy on Tue Aug 30, 2016 7:16 pm
Without seeing the rest of the wave form it's kinda hard to come with what the irregularities are....

Pugsy, I'm starting a new thread, with a video link to show much more of the flow rate at the breath zoom level.

Big thanks to everyone who contributed to this thread. Much to think about and read.

-Ron

[Jay Aitchsee]

For the second(5:57:00) strip: 3.64:1.04, 3.82:1.04, 3.71:1.10, // 3.04:1.00, 3.04:1.00, 2.90:1.00

Thanks Ron, above are the times from the early morning (5:57:00). They show inspiration times of around 3 seconds and expiration times of around 1 sec. Looking at the actual waves, we can see that is WRONG. The Inspiration times (positive portion of the curve between red lines) are obviously about 1.5-2 seconds and the Expiration times are 2-3 seconds. (The hash marks on the time line are seconds)

I conclude either Sleepyhead or the machine is sensing the pulse (ballistocardiographic) artifacts and calculating the end of expiration in error, artificially shortening it. This would create, or tend to create, an "Inverted" I:E in error.

In the first set of waves above, the times reported are closer to what we can measure from the chart and the I:E would be more "normal". I think this is so because the pulse artifacts are not so pronounced. In other words, the artifacts become more pronounced later in the night leading to the false Inversion. Is this significant? I don't know.

So, it was a great exercise and we learned that, at least for this line of machines, reported timing related to breathing cycles and respiratory events are not reliable.

[Pneumophile]

Indeed. I must say the news from you guys is a great relief to this recent purchaser of a PR machine that gives I and E values. I've been holding my breath about my "inverse" ratios for some time now and have just this minute exhaled, now that I know at least two reasons why it's probably a bogus output.

Maybe that's why the software doesn't actually provide the ratio ..... (sarc.)

[Jay Aitchsee]

Maybe that's why the software doesn't actually provide the ratio ..... (sarc.)

Right, sarcasm aside, I don't think they saw a need to. As I mentioned somewhere above, these statistics are used in machines with more robust ventilator capabilities. And as far as I know, this line doesn't have any capabilities that we would normally associate with ventilators. That is, actually having the ability to control the timing and volume of individual breaths.

BTW, I did see a patent application for a method to filter the pulse artifacts from the flow wave to prevent exactly what appears to be happening above from occurring. It appeared that the method was for use in BIPAPs to accurately switch with the patients own breathing from IPAP to EPAP and not trigger or cycle prematurely. I don't know the company. I'll put up a link later in case somebody wants to have a look.

[Pneumophile]

Jay, as I age I become increasingly resistant to new knowledge yet you continue to penetrate the fog.

[Jay Aitchsee]

So, here's the patent application I referred to above: https://www.google.com/patents/US6318365
I think the inventors work for a subsidiary of ResMed.

From these excerpts, it looks as though it is method to correct issues similar to those we've discovered with the System One.

In the state of the art, usually the respiratory gas flow from and to the patient is measured and differentiated with respect to time (first derivative) for obtaining a more distinct transition between the inhalation and exhalation phases

...furthermore, influences of the patient's pulse may have an effect on the gas flow. This may result in an overshooting of the first differential function, wherein the threshold value for changing to the other breathing phase is achieved prior to the required time so that it is changed to the other pressure level and the patient's safety may be jeopardized. [emphasis added]

[Pneumophile]

Interesting. Reminds me of the good old days when I would trawl the patent literature for nuggets. You can learn a lot there but of course some of it is wrong or intentionally misleading. In this case it looks like you're on to something.