Obstructive apnia looks like Central apnia on Oscar??

[tyrinryan]

I am a newbie and would like to say how extremely helpful it is to read all of the posts on the various issues. I am not particularly computer savy either. Somehow I managed to get Oscar loaded and I am trying to understand my Oscar graphs.

I notice that many of my Obstructive apnias look (to me) just like my Central ones from the standpoint that there usually doesn't seem to be significant or even any flow limitation at the time they are recorded. Do I need to recalculate these particular apnias as Central's in terms of trying to adjust the pressure to control AHI? How accurate should we take the Oscar (Resmed) coding/results/flow limitation graph to be?

Screenshot (3).png (94.18 KiB) Viewed 586 times

[Pugsy]

While the machine can make mistakes with the flag name....it's not common.
OSCAR or SleepyHead doesn't do the naming of the flags...that all comes from the machine.
The machine is calling them obstructive and it's right more times than it is wrong...especially ResMed machines.

Were you asleep when these events got flagged?

[tyrinryan]

I could very well have been awake or in that sleep/wake mode since it appears I experienced a large flow limitation and a RERA a couple of minutes before the screen shot. But what difference would that have made/ to Resmed/ to Oscar? They are still seeing the obvious stoppage in breathing but also still seeing an obvious absense of flow limitation. I took a look at last night's chart: I had 9 apnias; 8 Obstructive: 4 without flow limitation; 3 with very minimal flow limitation; 1 with a solid flow limitation approaching 50%; and 1 Central with obviously no flow limitation. The question is: should we take the coding by Oscar/Resmed or should we code it ourselves based on the flow limitation graph. Perhaps the flow limitation graph doesn't tell the whole story or isn't continuously accurate?

[Jay Aitchsee]

You do have a significant Flow Limitation around 06:48:45. Anything over .04 is significant in that it will cause the machine (ResMed) to increase pressure if not restricted by max settings. As Pugsy mentions, no doubt these events meet the machine's criteria to be classified as Obstructive. It is very difficult to eyeball the difference between CA and Obstructive. Both are the result of the machine not detecting a breath for 10 sec or more. The machine then determines whether it is Obstructive or Central by the phase shift of the FOT, not the presence of a Flow Limitation.
All of that said, given the time of night and the number of events in close proximity, my guess is that these are most likely Sleep-Wake Junk caused by transitioning between sleep and wakefulness and probably would not be counted in a lab setting. In the lab, it can be determined whether one is awake or asleep. Machines can't do that (yet) so they flag all events assuming one is asleep.

[Pugsy]

Nothing is perfect in terms of accuracy.
Nasal congestion can mess with the flow limitation graphs but we don't fix nasal congestion with more pressure. The machine will try though because all it knows is not as much air is moving like it expects to be moving.
The machine can't distinguish between awake events and sleep events.
Remember the machine only measures air flow...and not much of anything else.
Our awake/semi awake breathing is very irregular when compared to asleep breathing but again the machine can't distinguish what is causing the irregularity.
The machine just calls them like it sees them. Just remember it measures air flow only and it isn't necessarily perfect.
I have seen some hyponea flagging where I sit here scratching my head as to how it met criteria.

I do a combination of relying on the machine scoring and doing a bit of manual deciding about my results. So I take the best of both options. My AHI from last night was 1.67. I am currently playing with the settings to see if I need to raise the minimum a bit but when I looked at all the events up close...over half were obvious SWJ arousal/awake related flagged events. Some were flagged when we had a storm come through in the wee hours of the morning and it woke me up. I am not going to do anything for an AHI of less than 1.0 that is real asleep flagged events and last night qualifies.

My biggest factor though...not any of the numbers or graphs but instead I rely on how I slept and how I feel. Hours of sleep is a huge factor for me as well as how many times I might wake up during the night.
I have other health issues that mess with my sleep quality. I already know that I get more SWJ flagging than real asleep flags.
And I have had perfect 0.0 AHI nights and still feel like crap because I slept like crap.
There is so much more to getting good quality sleep than just apnea control or prevention.

[tyrinryan]

Sorry; I'm a newbie. What is FOT and additionally what is the phase shift (of FOT)? (I Itried google, please give me a hint.)

[Pugsy]

FOT is what ResMed does to help it distinguish between a central apnea and an obstructive apnea.

Forced Oscillation Technique
page 8 of the clinical manual
https://www.respshop.com/manuals/ResMed ... %20her.pdf

[palerider]

I notice that many of my Obstructive apnias look (to me) just like my Central ones from the standpoint that there usually doesn't seem to be significant or even any flow limitation at the time they are recorded.

Those look like obstructives to me, no airflow during the FOT, but a strong pressure response.

Please get rid of the calendar, and make sure you're on the detail tab on the left.

[palerider]

I could very well have been awake or in that sleep/wake mode since it appears I experienced a large flow limitation and a RERA a couple of minutes before the screen shot. But what difference would that have made/ to Resmed/ to Oscar? They are still seeing the obvious apnea but also still seeing an obvious absense of flow limitation.

So? You don't have to have a flow limitation to have an apnea.

[palerider]

Sorry; I'm a newbie. What is FOT and additionally what is the phase shift (of FOT)? (I Itried google, please give me a hint.)

https://www.youtube.com/watch?v=4GW97Xk06N8