What do we think about really long events?

[cathyf]

One of the characteristics of my relationship with the Air11 is that I'm getting some really long apneas, which are associated with deep desaturations. I've noticed events longer than 50 seconds. Since it's only one event that doesn't count any more than a 10-second event, so from an AHI point of view it's trivial. This was last night -- 53-second apnea, sent my saturation to 78%.


Here's from a month ago, my first night on the new Airsense11:

Other times that this has happened I felt pretty crappy the next day, while last night's deep dive didn't seem to bother me much at all.

Also the cpap algorithm didn't really react by raising pressure much, and when it's an isolated event I guess pressure isn't going to help.

I'm curious about whether these were going on over the last 7-1/2 years with either the Air10 or the vauto, but I don't see that OSCAR flags unusually long apneas (other than putting the time in seconds in parentheses after the event timestamp in the events list). So I would need to look through the event lists day by day.

Anyway, do other people with experiences of very long apneas have thoughts?

[GuyScharf]

In both cases, all of the graphs agree you weren't breathing for about a minute--flow graph, mask pressure, dropping SpO2, respiratory rate, etc. It looks to me in both charts like there is an arousal before the apnea. Which makes me wonder if you were changing positions; we often hold our breath for a while when rolling over.

Do you have many of these long apneas during the night, and are they all preceded by some irregularity in your breathing pattern?

Have you ever tried video recording your sleep? If you did, you could see if anything else was happening at that time. Sleep stage might also be interesting, but I don't know how to deduce that reliably from an OSCAR graph.

[mesenteria]

It looks like an arousal evinced by the more jagged verticals just prior to the stoppage.  You turned, or just adjusted, whatever, and you sagged back into sleep quickly.  But, you were probably just experiencing Ye Olde Sleep Onsette Centralle Apnea.  Yes, it was long, and yes, you desatted pretty darned solid, but it seems to have been a one off, or maybe twice a night, so no biggie. Your AHI record sez you're being well handled.  I would worry about these more when you gasp yourself awake, and that's it for at least an hour of blinking at the lights coming through the blinds.  You don't want to be awakened.

[Dormeo]

Both events are flagged as obstructive rather than central, and both are preceded by exhalation, rather than the inhalation that would be typical for breath-holding. That said, I'm not sure what to make of the arousal-type breathing just before the events, or, for that matter, the recovery breathing afterwards.

Given how infrequent these events are, I guess the big question is whether the desats are harmful. Can you run that question by your doctor?

[cathyf]

To focus on my Airsense11 first night, I'm thinking I'm not buying a 59-second "hold my breath while moving" scenario. A minute is a freaking long time to be not breathing! Here's another view of the same event, a little more zoomed out (20 minutes rather than 17), and taken on the big monitor so it shows more graphs.



Without the tooltip you can see that it starts on the exhale not inhale. That was well into the night. Here's how I started -- about two hours in, here are the first 21 events:

I put the event list in the left sidebar to show the lengths. This is a totally typical massive cluster of positional apnea. I dumped the data out into a spreadsheet, and showed time breathing vs time in apnea:

Code:

    Obstructive    10s
breathing    24s
Obstructive    43s
breathing    23s
Obstructive    54s
breathing    31s
Obstructive    38s
breathing    18s
Obstructive    25s
breathing    24s
Obstructive    14s
breathing    20s
Obstructive    14s
breathing    4s
Obstructive    15s
breathing    32s
Obstructive    13s
breathing    30s
Obstructive    25s
breathing    35s
Obstructive    20s
breathing    28s
Obstructive    16s
breathing    19s
Obstructive    38s
breathing    26s
Obstructive    16s
breathing    18s
Obstructive    32s
breathing    26s
Obstructive    32s
breathing    24s
Obstructive    13s
breathing    0ms
Obstructive    11s
breathing    23s
Obstructive    43s
breathing    45s
   RERA    0ms
breathing    8s
Obstructive    25s
breathing    11s
Obstructive    12s

grand totals -- 7 minutes 49 seconds breathing, 8 minutes 29 seconds in obstructive apnea!

I see the movement before and the movement afterwards as being me moving into the position where my airway is kinked and then me moving out of that position.

I think that the singleton later in the night was ALSO positional apnea, just that it's a "cluster of one" where I got into the position, had a minute-long apnea caused by chin tucking, and then I untucked my chin.

I think that I was asleep through all of it, with just microarousals at the movement. I'm even pretty dubious about the single scored RERA -- it doesn't really look any more awake than any of the other recovery breathing.

[Dormeo]

Yes, I meant to be differing with Guy Scharf about holding your breath and with Mesenteria about central apneas.

Apologies: I didn't notice that you had O2 graphs included in your screen shots. Given the amount of time you were in apnea during that 16-minute period, your desats look surprisingly modest.

I can't think how this might be related to the ResMed 11 machine. What I do wonder is whether you are doing some chin-tucking or back-sleeping that is producing clusters like this one. Have you tried a soft cervical collar? Good entry on that subject in the wiki.

[cathyf]

I was looking at another article on apnea, followed a reference, and came upon this article:
https://journals.lww.com/md-journal/Full...ot.29.aspx

To determine which polysomnography parameters are associated with severity of hypertension.

This retrospective study collected data on all patients admitted to our urban, academic center in Beijing with hypertension who had undergone polysomnograms (PSG) and were diagnosed with obstructive sleep apnea (OSA) (apnea–hyponea index [AHI] ≥5/hour). We then compared polysomnographic parameters (AHI, oxygen desaturation index [ODI], lowest oxygen saturation [LOS], and mean apnea–hypopnea duration [MAD]) by hypertension severity in this cohort.

There were 596 subjects who met entry criteria. Age, sex distribution, body mass index (BMI), history of current smoking and alcohol were similar among groups. Subjects with longer MAD suffered from more severe hypertension (P = 0.011). There were no relationship between AHI, ODI, and LOS and hypertension in our cohort. There were no significant differences in age, sex, BMI, history of current smoking and alcohol use between hypertension groups. MAD had a small but significant independent association (odds ratio [OR] = 1.072, 95% confidence interval [CI] 1.019–1.128, P = 0.007) with moderate to severe hypertension, using logistic regression analysis that accounted for age, sex, BMI, history of current smoking and alcohol, AHI, and LOS.

Chinese inpatients with longer MAD by PSG face higher odds of moderate to severe hypertension. The mechanism of these effects may be due to aggravated nocturnal hypoxaemia and hypercapnia, as well as disturbed sleep architecture. These results suggest that additional information available in the polysomnogram, such as MAD, should be considered when evaluating OSA patients.

So now I have a name for the phenomenon "mean apnea–hypopnea duration [MAD]"

Interestingly, my blood pressure has been rising a bit over the last few years. I have a history of low BP, and it's gotten more average recently.

Oh, and I can report on what Dr. Jackass had to say at my 3-month followup compliance check for the new machine. I reported that I was having these long apneas, and that even a single event above 40 seconds would result in me waking up with vertigo and then progressing to a splitting headache for the rest of the day. His response?

"The machine isn't going to do anything for that."

I was pretty gobsmacked -- I mean I already had a really low opinion of this jerk and I've been putting up with it in order to get insurance to pay for the new machine. I should note that according to his CV, Dr. Jackass is a neurologist. I report neurological symptoms impacting my life pretty negatively, and he completely blew me off -- didn't even put it in the notes.

Given what I've seen of the "data" that he shows me on the "reports" that he prints out, I'm pretty sure that the durations of events don't get sent back to the ResMed servers when the machine phones home. It's not something that OSCAR focuses on, either. This just might give me the incentive to dive into the OSCAR source code and see if I can come up with some way to parameterize this. This discussion in the paper, where they are focusing on the mean duration, I think misses the mark -- especially a night where there's a couple of short apneas and low AHI combined with one whopper of an apnea. My experience is that a dozen 10-15 second events over a night (which is an AHI of 2ish) is really no big deal, but a single 60-second event will wreck my entire next day. And in a night with a dozen 12-second events and one 60-second event, the whopper event only raises the average from 12 seconds to 15.7 seconds. It sounds pretty trivial, but it's pretty ugly for me.

...anyway, now that I have a name for it, I'm off to do some more research!

[Dormeo]

I’ll be interested to know what you come up with. As for Dr. JA, I’m blowing a great big raspberry at him right now.

[pholynyk]

It's not the OSCAR code you want to look at, it's the EVE.edf files that tell us about events.

However, you may find that to be easier if you add some debugging statements to the LoadEVE routine in resmed_loader.cpp.

I think the difficulty - for the ResMed programmers - is that the hypopnea is defined as X% drop from the average of some number of previous minutes (or breaths?). I've not seen a definition of 'when it ends'... assuming it would be 'when it rises back to y % of the previous average' you would have to keep track of that previous value in addition to the current value...

I thank that never occurred to them. So OSCAR never gets a duration for hypopneas.

[coolbranch]

Hard to see, but looking at the charts, it seems that the machine did not respond by increasing pressure until the end of the apnea. My Airsense 11 did this last night after a 38 second OA.