I'm trying to learn how to read OSCAR data - can you add insights?

[DustyDoozeer]

Good day,
I've now embarked on trying to get to understand OSCAR data, and I've been reading threads to see what these numbers mean.
I'd greatly appreciate if you could add your insights so I can focus on the right things.

Let's take one sample day where I had an AHI of 11.94 (only for study purposes)

I hope I formatted the image correctly - I read up on what charts you want to see.

Screen Shot 2020-02-21 at 10.20.41 AM.png (238.97 KiB) Viewed 8871 times

So here is my understanding:

a) AHI = CA + O + HI, where:
a.1) CA = Clear Airway Index, which means your airway inside you is clear, but you aren't breathing for >10s. I though CA=you are all clear and awesome. Yeesh.
a.2) O = Obstructive Apnea Index, which means there is some obstruction inside your airway which is resulting in you not creating for >10s
a.3) H = Hyponea Index, which means there is no obstruction inside your airway, but you are "shallow breathing" for some reason (i.e. not breathing normally)
a.4) All of these are indexes, that is total # of events per hour

b) As I understand, Flow Rate shows how much air is going in and out of my lungs with negative being exhalation and positive inhalation
b.1) It seems almost every spike (positive) maps to an obstructive apnea. I assume this means my lungs are trying to take in more air or does it mean the CPAP machine is trying to put in more air in those events? I don't see the pressure graph going up at that time

c) How do I correlate how the CPAP is trying to apply corrective measures doing OA events?

d) Is it correct to assume the CPAP cannot do anything for CA events?

e) How do I go about assessing REM and NREM hours by this graph? Any way?

f) I see "Vibratory Snore" events, but I can't map them to any flow rate events - what insight can I derive from VS?

g) I see the "pressure" graph mostly capping at 10 - I wonder if I need more pressure? Do I change this on my own, or do I ask a doctor?

h) What else would you do trying to analyze?

Bottom line, even in days when I get AHI < 3, I feel tired/confused after waking up and most of the day. Done all my tests/blood/MRI/whatever - all clean.

Thanks.

[Pugsy]

See if anything here helps with your understanding.
http://www.apneaboard.com/wiki/index.ph ... rpretation

Take a look at my SleepyHead tutorial in the Announcements section...OSCAR is based on SleepyHead so anything I explained about SleepyHead pertains to OSCAR.

a.3) H = Hyponea Index, which means there is no obstruction inside your airway, but you are "shallow breathing" for some reason (i.e. not breathing normally)

Actually this isn't correct. Hyponeas do usually come with some sort of airway obstruction. Not shallow breathing...if it was then people who are really shallow breathers would have a report chocked full of hyponeas that no amount of pressure would fix.
Hyponeas are by definition a reduction in the air flow of 40 to 79% because of the airway being partially blocked by airway tissues collapsing...it must last at least 10 seconds to earn a flag.
Obstructive apneas are by definition and 80 to 100% air flow reduction that last at least 10 seconds.
Think of hyponeas as obstructive apneas that haven't quite met the criteria for an OA flag.
Think about it....in terms of what a hyponea with a flow reduction of 75% might do to our sleep isn't really all that different from a flow reduction of 80%. There has to be a line in the sand somewhere but hyponeas can be just as bad for our sleep as OAs and that's why all the auto adjusting algorithms will increase the pressure to try to keep the airway open and prevent not only the OAs but the hyponeas as well.

d) Is it correct to assume the CPAP cannot do anything for CA events?

CPAP helps stent or hold the airway open so that it doesn't collapse. If the airway is already open there's nothing to stent.
So essentially yes...you are correct.
Centrals happen when you simply don't breathe because the brain hasn't sent the signal to breathe. Hold your breath for 10 seconds...that's essentially a 10 second central apnea. The area is open but you aren't making any effort to breathe.

CPAP machines don't force anything...they don't force you to breathe...they can't blow open a collapsed airway. They simply aren't able to push that much air pressure. Heck even at 20 cm it won't even blow up a balloon.

) How do I go about assessing REM and NREM hours by this graph? Any way?

No real accurate way of evaluating sleep stages with the data from the machine because the machine only measures flow rate (breathing). It has no way to know if you are asleep or not much less sleep stages.
Now sometimes you can evaluate the flow rate and spot some consistent changes that might point to REM sleep but not everyone can do it because the changes in the flow rate are too subtle. Best you can do is learn how to evaluate awake breathing from asleep breathing.
http://freecpapadvice.com/sleepyhead-free-software

b) As I understand, Flow Rate shows how much air is going in and out of my lungs with negative being exhalation and positive inhalation

correct...flow rate is just your respiration or breathing

b.1) It seems almost every spike (positive) maps to an obstructive apnea. I assume this means my lungs are trying to take in more air or does it mean the CPAP machine is trying to put in more air in those events? I don't see the pressure graph going up at that time

I don't understand this question. For normal breathing or flow rate the machine isn't expected to respond with more pressure.
It only is supposed to respond when there is either a reduction in air flow or a total flat line with no air flow.

NONE of the machine will do anything during the flagged apnea event. They all wait until after the airway is back open and then it evaluates things and decides whether or not a pressure increase is needed to better prevent the airway from collapsing.
For random rare lone events often the machine won't do a thing. You need something else going on along with it to get the auto adjusting algorithm to kick in with more pressure.

f) I see "Vibratory Snore" events, but I can't map them to any flow rate events - what insight can I derive from VS?

Snores are very early signs that the airway is trying to collapse...warning signs. They may or may not end up with the trying to collapse getting to the point of collapsing enough to earn a flag. Snores and flow limitations are part of what the auto adjusting algorithm is designed to try to prevent because they are the early warning signs that the airway is trying to collapse.

The whole idea with the auto adjusting algorithm is preventing the airway from collapsing in the first place...it not trying to blow past an obstruction. It's all about prevention and not so much fixing.

g) I see the "pressure" graph mostly capping at 10 - I wonder if I need more pressure? Do I change this on my own, or do I ask a doctor?

yes, the report above points to needing more pressure......you are in fixed cpap mode...it can't auto adjust the pressures. If you routinely get AHI less than 3 with this setting though then I would suspect the higher AHI on this report was from a lot of false positive event flagging because of a lot of awake time spent with mask and machine on.

You can change it yourself if you are comfortable doing it.
It's not hard but if you aren't comfortable doing it you can ask your doctor to order the change.

Bottom line, even in days when I get AHI < 3, I feel tired after waking up. Done all my tests/blood/MRI/whatever - all clean.

There's more to feeling the nice low numbers than just getting them. There's so much more to getting good restorative sleep than killing the apnea events.
Hours slept obviously...
Are those hours slept fragmented with lots of wake ups or arousals...
Medications taken...often a big cause of not feeling so great from the side effects which can mimic sleep apnea symptoms
Other health issues..
Insomnia issues maybe.

[Miss Emerita]

(I see that Pugsy just posted answers to your questions. I'll go ahead and post what I've written, but believe her!) It's good to see that you're trying to understand the data and take charge of your apnea therapy.

Hypopneas are events lasting 10 seconds or longer in which there is a partial limitation on your flow. They can be obstructive or central in nature.

If you zoom in on the areas where you see spikes, you may find that they are recovery breathing, that is, show you breathing deeply after an event.

You are right to suspect that you need to adjust your pressure settings. You are not allowing the machine to do its job with the pressure fixed at 10. I will defer to the experts, but I'd suggest you try making 10 your minimum and setting your maximum at 20, in auto. The pressure won't go any higher than it needs to go.

Your obstructive events show some clustering. That might be where you are sleeping on your back, or in REM, or tucking your chin toward your chest. A simple experiment is to try wearing a soft cervical collar or a "snore collar;" if you're chin-tucking, that should bust up the clusters.

I can sometimes tell I was in REM by seeing a period of higher respiration rate, but there's really no sure-fire method for tracking REM, or even sleep vs. awake, from these data.

[DustyDoozeer]

yes, the report above points to needing more pressure......you are in fixed cpap mode...it can't auto adjust the pressures. If you routinely get AHI less than 3 with this setting though then I would suspect the higher AHI on this report was from a lot of false positive event flagging because of a lot of awake time spent with mask and machine on.

Thanks Pugsy. Quick question on this point:

I have no problem in changing this setting myself. Questions:

a) Is it better that I change the CPAP to Auto mode in therapy and keep low of 5 and high of 20, or should I just change 10 to 20 in CPAP mode? My understanding is this is the "max pressure" anyway, so aren't they equivalent? (i.e. CPAP mode with pressure of 20 and Auto mode with min=5 and max=20)

b) I did read that setting CPAP at a high value has one risk: If there is leak (say from the mouth) the machine will not know and keep bumping up pressure to 20 which may not be good for you?


Thanks

[Pugsy]

b) I did read that setting CPAP at a high value has one risk: If there is leak (say from the mouth) the machine will not know and keep bumping up pressure to 20 which may not be good for you?

The machine NEVER increases the pressure to try to fix a leak. What it does is maybe increase the flow rate and flow rate and pressure aren't necessarily the same thing.
In fact the machines will often reduce pressure in an effort to bring a leak into control.
Palerider has a good example of that and maybe he will be along later and share it. I never saved it because I rely on him to post it.

Besides...even if you did need 20 cm for some reason...doesn't mean it isn't good for you. You need what you need and if you don't get it...that's what isn't good for you.
If you are thinking along the lines of the old wives tale that higher pressures cause centrals in everyone...that's not true.
Centrals can happen to a small minority of cpap users at ANY pressure...even as little as 5 or 6 cm. There are people using bilevel machines with pressures over 20 cm all night long and they don't get any more centrals than would be normal (it's normal to have an occasional central). All this panic over centrals is blown way out of proportion.

a) Is it better that I change the CPAP to Auto mode in therapy and keep low of 5 and high of 20, or should I just change 10 to 20 in CPAP mode? My understanding is this is the "max pressure" anyway, so aren't they equivalent? (i.e. CPAP mode with pressure of 20 and Auto mode with min=5 and max=20)

You can't have 10 to 20 in cpap mode...you only get one pressure in cpap mode and it's fixed and stays there all night long..it can't ever increase.

You would have to be using auto (apap) mode to make use of the auto adjusting algorithm where you get choices for minimum and maximum pressure settings.

You mentioned a night with AHI less than 3....that's a long way from the image posted above. Can you share that report image please?
It might help me decide if you might do better in apap mode with 5 minimum or 10 minimum or something in between.
If all your reports were like this one above...10 cm minimum but maybe it was a fluke or something and you could get by with less.

The maximum is just where the machine COULD go if it needed to go there. If it doesn't need to go there it won't. You want the maximum to be available IF needed. I use a 25 cm max because I use a bilevel machine but it rarely makes it to the mid teens. If the machine could be set to 100 cm...doesn't matter because the machine would still just rarely go to the mid teens.

[Dog Slobber]

a) Is it better that I change the CPAP to Auto mode in therapy and keep low of 5 and high of 20, or should I just change 10 to 20 in CPAP mode? My understanding is this is the "max pressure" anyway, so aren't they equivalent? (i.e. CPAP mode with pressure of 20 and Auto mode with min=5 and max=20)

No.

Auto adjusting machines take time to react and increase pressure. If their minimum is set well below what is typically needed they often do not react in time to address the apneas.

Setting a machine to 5 - 20, might be common during titration to establish what a good minimum should be.

b) I did read that setting CPAP at a high value has one risk: If there is leak (say from the mouth) the machine will not know and keep bumping up pressure to 20 which may not be good for you?

No.

When a leak is detected the machine (regardless of fixed or auto) will increase the volume, this does not result in increased pressure, but to maintain the existing pressure.

[DustyDoozeer]

You mentioned a night with AHI less than 3....that's a long way from the image posted above. Can you share that report image please?

Sure. I don't have that report with me right now, will post in the evening when I get home
But here is one day with 3.82

Even there, I see pressure going to 10 and capping.

[Pugsy]

Even there, I see pressure going to 10 and capping.

Well yes...that's because it is set for 10 cm...the going to part is just the ramp function you are seeing. It capped out because that is what it is set at.
If you didn't use ramp then it would start at 10 immediately. You wouldn't see that gradual increase over the 30 minutes or so that ramp is set to take.
The slightly less line below the 10...that is EPAP or exhale pressure and you are getting 2 lines because you are using Flex exhale relief.
Top line is inhale pressure (IPAP) and the bottom line reflects the exhale pressure (EPAP) because there is a slight drop from inhale because of the Flex exhale relief.

So....you have a rather big difference in results between the 2 nights both with the setting of fixed cpap at 10 cm.
Makes me wonder what changed to cause such different results....2 main suspects when we see wide changes in results...REM stage sleep or sleeping on your back.
And you have a little bit of clustering still yet....

You probably would be safe using auto mode with minimum of 10 and max of 20...see what happens.
You might get by with a little less minimum but I think a minimum of 5 will be too low. It takes too long to get from 5 cm to 10 cm to prevent those clusters. They would likely still happen and you very well would have a lot more of them.

My recommendation...auto mode....minimum of 10 or 9 (no lower as I think that you will find much lower not very comfortable since you have been using 10 for so long). I once used a minimum of 13 for a week and when I dropped it back to 10...it wasn't very comfortable. I felt like I was suffocating.
Maximum of 20...see where it wants to go....if it doesn't want to go much higher than 10...it simply won't go there.

I suspect that on the night with the AHI of 11....you were probably on your back a good part of the night.
The night with AHI around 3ish...you were probably on your side more.

The goal though is to figure out some settings that let you sleep however you want and still get good therapy.

[Pugsy]

Side note...on the Respironics machine when set to cpap mode...the Flow Limitation flagging is turned off.
So the absence of any FL flagging doesn't necessarily mean you didn't have any....just means the machine doesn't flag them.
Kind of stupid way of doing things since FLs are one of the things the machine will try to kill with more pressure in auto mode and it might be helpful to know if someone is having them....duh...

Anyway, should someone prefer a more fixed pressure like cpap what we do so that we can still monitor FLs is use auto mode but with the minimum to equal maximum. That way the machine will function like cpap mode but the FL flagging is turned on.

There is no reason to restrict the maximum unless where it is going to creates a problem. Deal with that bridge if/when we come to it.

[DustyDoozeer]

If it helps, here is the relevant portion of my sleep study that resulted in the fixed rate 10 pressure.

Some quick followups:
1. DogSledder above seems to indicate setting it to Auto mode results it the machine not being quick enough to adjust to avoid the apnea, unless I misunderstood the comment.

2. So in Fixed mode, the pressure will always stay at whatever X it was set to, irrespective of whether I need that much or not, correct? So the fact that the graph of pressure shows it capping at 10 doesn't mean much. It is not a maximum value - its a preset value.

3. Both you and Ms. Emeritta mentioned my OAs cluster. What does that indicate?

Thank you very much!

More questions will follow once I go through round 2 of analysis based on all your comments!

[Dog Slobber]

1. DogSledder above seems to indicate setting it to Auto mode results it the machine not being quick enough to adjust to avoid the apnea, unless I misunderstood the comment.

No, you misunderstood my comment.

I did not say simply, "setting it to Auto mode results it the machine not being quick enough to adjust to avoid the apnea"

I said:

Auto adjusting machines take time to react and increase pressure. If their minimum is set well below what is typically needed they often do not react in time to address the apneas.

The key part being: "If their minimum is set well below what is typically needed"

[DustyDoozeer]

The key part being: "If their minimum is set well below what is typically needed"

That sounds good - thanks for the note.

[rick blaine]

Hi DustyDoozeer,

A word or two about some key words.

The pre-fix hyper- means 'over, beyond, more than'.

So hyper-active – over-active. Hyper-tension – more than normal tension or pressure. Hyper-critical – excessively critical.

The pre-fix hypo- means 'under, less than'.

So hypo-dermic – under the skin. Hypo-glycemic – less than normal level of glucose in the blood. Hypo-thyroid – less than normally active thyroid.

Hypo-pnea – under, or less than, a full apnea – but still some reduction in air flow.

[Pugsy]

2. So in Fixed mode, the pressure will always stay at whatever X it was set to, irrespective of whether I need that much or not, correct? So the fact that the graph of pressure shows it capping at 10 doesn't mean much. It is not a maximum value - its a preset value.

Correct. Doesn't mean much. Fixed means it never goes up or down except for ramp time which is a separate thing or the minor variations when using Flex exhale relief.

3. Both you and Ms. Emeritta mentioned my OAs cluster. What does that indicate?

Several events either back to back or very close to each other in terms of a time frame. So several in a small group as opposed to a random lone event flagged here and there.

Your sleep study showed that at 10 cm pressure you still had a residual AHI of 5 ish....that's good enough for a sleep lab but not good enough IMHO for real life. It means every 12 minutes you average some sort of apnea event that can disrupt sleep. How rested would you be if I came over to your house and every 12 minutes all night long I poked you with a stick and woke you up?
They were happy with the residual AHI of 5...but that is actually the minimum number to qualify for the diagnosis of sleep apnea...so technically you were still having enough events to meet the diagnosis. Most of us shoot for less than 2 AHI before we are happy with it and some don't feel any improvement until the AHI is less than 1.0.

[DustyDoozeer]

See if anything here helps with your understanding.
http://www.apneaboard.com/wiki/index.ph ... rpretation

Fabulous link, Pugsy. Makes far more sense to use this as my "top" for the "top down" approach to understand the graphs. I'm doing several passes, one step at a time.

How rested would you be if I came over to your house and every 12 minutes all night long I poked you with a stick and woke you up?

Hah. Great way to put it.

Last 2 questions for today:

Air accumulates in my mouth even at 10cm. It does not create an issue, but when I open my mouth, its like I'm blowing out air that was sitting inside. I read this is normal, and unless it bothers my mouth, I should ignore it and this should not affect my venture to bump to auto 10-20 anyway, right?

Finally, are you in the medical business/equipment business in any way? If you represent/sell/consult in anyway, I'd like to know and patronize that service if possible and when needed. You seem to know a lot and are able to give simple explanations when questioned, something I consider an important marker to know if people really understand what they are saying.

Thanks.