Cough & False Hypopneas

[Ralph437]

So my wife has had this persistent cough for the past several weeks. She will cough once or twice then not cough again for many minutes, it does not seem to awaken her.
Last night I observed her cough (while sleeping) at 11:17.
Here is her flow plot from last night at about that time.


So, two questions
Is this flow at 23:16:50 indicative of her cough and
does the flow rate (during the cough) distort her average flow rate so as to cause the reported hypopnea?

[ChicagoGranny]

Why not treat the cough and quit worrying about the flow chart?

[Ralph437]

Is there something that I said that makes you assume that the cough is NOT being treated?

[ChicagoGranny]

Is there something that I said that makes you assume that the cough is NOT being treated?

Then let me rephrase my question.

"Why not treat the cough and wait for it to be cured? Why worry about an occasional short-duration hypopnea that doesn't seem to disturb the CPAPer?"

The goal is to feel good all day, not have flawless charts.

[ChicagoGranny]

And don't forget what your wife has told you.

The other factor that I haven't mentioned yet is that she tells me that she had a good night, slept well and is alert all day ...

viewtopic/t187486/Possible-incorrect-Ev ... lysis.html

[Ralph437]

That was three months ago.

Either you have answer to the question or not, but if you don't, just stifle.

[Tec5]

Is this flow at 23:16:50 indicative of her cough and
does the flow rate (during the cough) distort her average flow rate so as to cause the reported hypopnea?

Yes that is probably the cough you observed.

Did the flow rate increase (caused by the cough) result in a false positive hypopnea, it would depend on if the Resmed algorithm to determine the baseline included the “cough breath”. IMO, that’s what happened and the resultant hypopnea is probably a false-positive.

So my question to you would be, how many of these (coughs followed by a suspect H) are occurring during her sleep sessions?

[Ralph437]

Last night she had approximately 35 of these solitary coughs (based on the flow rate shape) that were followed by a marked hypopnea.
Her AHI was 4.0 and her HI was 4.0

[Miss Emerita]

In the snippet you posted, we see a larger-than-usual inhalation, then a sharp-ish and deep-ish exhalation. Although my own coughs look a little different, this looks plausible to me as a cough.

After deeper breathing, it's common to see a pause, which will be flagged as a CA if it lasts 10 seconds or longer, or an hypopnea (or just some shallower breathing that isn't flag-worthy). It isn't clear exactly what mechanism causes this phenomenon. It might be changing levels of CO2, or it might be signaling that originates in sensors in the rib cage.

If your wife is concerned about the hypopneas, she might try using a recording oximeter during the night. But in her place I wouldn't worry about it.

I hope she gets over the cough soon.

[Ralph437]

In the snippet you posted, we see a larger-than-usual inhalation, then a sharp-ish and deep-ish exhalation. Although my own coughs look a little different, this looks plausible to me as a cough.

After deeper breathing, it's common to see a pause, which will be flagged as a CA if it lasts 10 seconds or longer, or an hypopnea (or just some shallower breathing that isn't flag-worthy). It isn't clear exactly what mechanism causes this phenomenon. It might be changing levels of CO2, or it might be signaling that originates in sensors in the rib cage.

If your wife is concerned about the hypopneas, she might try using a recording oximeter during the night. But in her place I wouldn't worry about it.

I hope she gets over the cough soon.

Thanks, she certainly is anxious to get over it, but it's been hanging on for weeks.
Yes, I'm certain that it was a cough, as I personally witnessed it and noted the time. Interesting that your coughs look a little different, but I suppose that there is no universal cough "signature".
What I'd like to get a better handle on is if the hypopnea is real or a false positive. I've no doubt that mathematically the 10 sec segment marked as a hypopnea is actually % reduction in peak flow from some comparison segment. But the question is this: What is the comparison segment? Is it prior 10 seconds, prior 20 seconds, or something else.

If the comparison segment contains an anomaly (such as the cough), then the immediately following "hypopnea" is probably also an anomaly or what we would call a false-positive.

The significance is (in my wife's case) that 98-99% of her AHI are Hypopneas.
If one were to disregard those cough/hypopneas (treat them as false-positives) her last light AHI would drop from 4ish to zero-ish.

She will be meeting with her (new) sleep doc in a couple of weeks and I'd like to make the case that her "numbers" (in the 4-6 region) are more likely significantly better than what the cpap reports. I would make my argument based on what I think are these false-positives. What I'm looking for at the forum is some assurance that I'm justified in my assumption that these "events" as I shown above are likely false-positives.

[Ralph437]

OH, forgot to add that her recording oximeter just hangs in all night in the 93-95 range.

[ChicagoGranny]

I would make my argument based on what I think are these false-positives.

News flash: Your doctor is not going to give a crap and will be annoyed by being pestered by someone who is obsessed with reports and hovers over his wife's therapy.

[Ralph437]

Granny, apparently you do NOT know her sleep Dr. In setting up her appointment he asked US to bring OSCAR reports and any questions we have.

I'm simply trying to get the sense of the cpaptalk community if it's reasonable to follow-up on these hypopneas if they are clinically valid.

[ozij]

The following article contains information about the algorithms.
https://www.tandfonline.com/doi/full/10 ... DER.S70062

She will be meeting with her (new) sleep doc in a couple of weeks and I'd like to make the case that her "numbers" (in the 4-6 region) are more likely significantly better than what the cpap reports

The CPAP reports she is not breathing smoothly.
So do you,
The CPAP doesn't know if it's sleep that disrupts her breathing, or something else.
It's not a "false positive". What you're thinking of is "an artifact" caused by the way the system measures things.

A word about a persistent cough:
I knew two women who developed a persistent cough in response to a cholesterol lowering drug. The cough disappeared when their medication was switched. Maybe your wife should check her meds and their side effects.

[Ralph437]

Thanks for the article, I'll work on digesting it over night.
Although one caution I see is that the article was written in 2015, and I've no idea if the Airsense 11 used the S-10 algorithms. (but for sake of discussion lets say that S-10 algorithm is employed in the Airsense 11)

Are you in agreement that the "cough" (apparently represented by the Inspiration/exhalation at 23:16:52) is real and not an artifact?

So my thought is that the "cough" (being a unusually large volume as well as peak flow) potentially influences the detection of the subsequent hypopnea. So, how can that be? This is what I'm thinking: if that "cough" breath is a major contributer to the RMS average that is the used to compare for the purposes of detecting a %age reduction, that single breath has an outsized influence.

Think of it this way, if the root mean squared average used for the comparison were measured over a 60 second interval, that one "cough" breath would have minimal impact on the % reduction. On the other hand if the root mean squared average used for comparison is over a 20 second interval, that one "cough" breath has a much greater impact on the percent reduction. What we don't know is what time period constitutes the baseline or comparison value being used.

Unfortunately the article that you shared doesn't really clarify that. The article does say:

A moving short time period (eg, one breath or 2 seconds) can be compared to a moving longer period (eg, 5 minutes) to evaluate for apnea or hypopnea.Citation18

.
I'll have to see if citation #18 is more specific.

Lastly, there was another thing that caught me eye:

Peak flow can be a poor measure of breath volume, which can lead to over- or underestimation of an apnea or hypopnea.

I've seen other discussions among members on the Cpaptalk forum that have insisted that the "peak" flow is what counts, not the volume of air.