Question about ResMed 10 AirSense pressures

[GuyScharf]

Bodies re different, so I can understand not all people responding in the same way. Is blood pressure related? I could imagine that higher blood pressure might cause greater expansion of vessels.

[Ratchick]

Maybe FOT around 6:35:20.

Yeah, the part circled in red is definitely FOT, IMO.

I have seen some cardiac artefacts on at least some of my central apneas, but only if I stretch the chart to make it super obvious. That said, I'm awful at spotting subtle changes.

[Geer1]

Bodies re different, so I can understand not all people responding in the same way. Is blood pressure related? I could imagine that higher blood pressure might cause greater expansion of vessels.

If it is related to blood pressure mine must be different when sleeping as mine is in normal ranges.

I read one thing that said it is more common in people with more dynamic circulation. I think it is just an indication of more obvious pulses of blood flow rather than smoother more continuous flow. Not sure exactly what would cause that if true. 

I did have a holter monitor test over a year ago and it found nothing abnormal so if it is something to do with heart operation must be considered a normal action or within normal limits.

[Ratchick]

I would guess it's probably as much down to normal anatomic variance, TBH. Considering how close all those major blood vessels are to the lungs and trachea, and how small the measurements are, it's usually just "noise" in the background.

I also have had (repeated) tests including 24hr at home monitors and several-day inpatient monitoring. Aside from a minor 1st-degree heart block (which can be a normal variation) and sinus tachycardia (again, just a regular fast pulse) caused by my neurological issues, I don't have anything that would make my heart beat harder or raise my blood pressure. If anything, the opposite, I'm on medication to boost my blood pressure and keep it at a healthy level.

[Jadazu]

So far as the cardiogenic fluctuations go, I have them show in the flow graphs more often then not; having them show up about 2/3 of the times to compared to 1/3 of the times not having them.

My measured blood pressure is in the healthy range. Probably the reason for the cardiac pulse effect on my mask pressure is physiological (morphological). I am rather barrel chested, and when resting i can usually feel my heart beating, as chest 'pulses'. i can usually count my heart pulses with out having to palpate an artery...

As an aside, when I look at long apneas in my flow charts, it is my guess that when I can still see the cardiac pulses in the flow chart and mask pressure chart, those occasions are clear airway apneas (similar to Ratchick's remark about seeing the pulses during central apneas).

Thank you, everyone

[Geer1]

Your comment about being able to feel your heart beat is interesting as I am the same way and similarly have obvious cardiogenic oscillations the majority of the time.

Yeah if you can see cardiogenic oscillations during an apnea then that would mean the machine is picking up pressure changes all the way from lungs so there must not be an obstruction. That is how the Resmed forced oscillation technique works for determining if an apnea is obstructive or central (and these may even be what you think are cardiogenic oscillations during apnea). For more info see this post with insight on the matter.

http://www.apneaboard.com/forums/Thread-...#pid395779

[Jadazu]

Geer1,

Thank you.

Yes, I saw that post. And I think the posts in this thread are insightful, too,  http://www.apneaboard.com/forums/Thread-...t=ratchick  ,
as my problem or complaint is hypoxia when I'm sleeping.  

My (very!) naive guess about the ResMed FOT measurements is that it is looking for harmonic resonance, and that the resonant frequency of a typical person's upper airway and PAP hose is about 4 Hz.

In the attached image, I think (maybe imagine) I can see the difference between the two events where the relatively high-ish frequency pulsations are being applied. The OA event seems to have a greater amplitude than the CA event. That they are being correctly flagged seems so, as the cardio pulses seem to be apparent in the CA event but not in the OA event. (This relative difference seems typical, for me.)  

   

FWIW, I've only been recording treatment data for about three weeks; I only recently realized I need to take my treatment partly into my own hands. I have a very high level of frustration with sleep doctors. As an example, I unknowingly encountered the chin-tuck issue. When I used a nasal cannula mask, I needed to sleep with a pillow stuffed tightly under my chin to keep my mouth closed. When I told this to my sleep doctor, he actually laughed at me and dismissively said that there was a much better solution to the problem of keepimg my mouth closed, 'It's called a chin strap'. So I tried a chin strap and my oximetery was much worse, and I went back to the pillow under my chin. When I next saw the doctor, I brought him a few pages of oximetery reports to show him the different results between the chin strap and the pillow-under-my-chin methods. The doc looked at a couple of the pages for a few seconds, and then handed then back to me and said "Oh, a home science experiment..."

I'm grateful that there is a thousand times more concern than that here, on this forum...

Thank you,
Jim

ETA:

This
   

vs this
   

It looks to me like there is a difference in regularity, that a harmonic filter could differentiate the two.

[Geer1]

Is that your data? If so you have a lot more going on. Central apnea might be part of the picture or those might be transitional central apneas after arousal caused by the obstructive apnea. Post some screen shots showing full days of recent data so we can give better advice. Make sure to show the pressure and flow limitation graphs.

I don't think FOT is looking for harmonic resonance, I think they impart frequency and look at the resulting amplitude of the pressure spikes imparted. Higher resulting pressure amplitude means obstructive in nature because there is less air to be compressed (hose and upper airway vs hose, upper airway and lungs).

Chin strap vs pillow results could be due to effects on some sort of positional apnea but too hard to tell without seeing apnea/SPO2 data side by side.

[Jadazu]

Yes, that is my some of my data. I think that I do have a lot going on. Thank you for being concerned. I will start another thread about my treatment, rather than posting that on this thread.

What I mentioned about chin straps and pillows was with regard to positional problems. Using a soft cervical collar was the first advice I received here. and it is working well! It is frustrating that the 'specialist' I was going to for treatment evidently did not know about the 'chin tuck' problem.

Thanks,
Jim