How to interpret my data?

[Pugsy]

Mark,
We haven't commented on the obvious OSA events because until we know for sure the status of the CA events, it isn't in your best interest.

Some people have what we called pressure induced CA events. No history on the PSG test but show up on the cpap reports. Sometimes they go away after time, sometimes they don't.

Some people have a mixture of OSA and CA events. There are machines different from a cpap or auto cpap for dealing with that scenario.

This is why we suggested to get with the doctor. We didn't want to offer any ideas that might make things worse.

If we only saw the OA and Hyponea events (plain old garden variety OSA) then yes, we could have offered an opinion but with the amount of CA events, we can't offer ideas to increase pressure. It could make things worse.

There are times when it is prudent to wait and discuss these findings with a physician and your case is one of them.

Best we could do was to educate you on what was showing on the reports and advise follow up with doctor.
please keep us posted on what happens. We just couldn't offer anything else because we didn't want to complicate things more than they are.

[Mark NJ]

Hi All,
Back from doc.
Got my two previous sleep studies and titration. Here are the points I take to be important:

Study 1:Mild OSA, AHI=14.3 but supine AHI=55.5, O2 nadir 80%, <90% for 2.3% of total sleep time

Study 2: Moderate OSA, AHI=22.5 but supine AHI=62.1, O2 nadir 75%, <90% 5.2%

Titration: 7 Cm was "best tolerated" including supine but mild snoring persisted. On 8 Cm sept 23.2 min including REM in lateral position. AHI was 0, arousal index 10.4. At > 8 Cm CA appeared. No evidence of Cheyne Stokes pattern. O2 nadir 94% at 8 Cm, <90% 0.0 of total sleep time. Few clusters of periodic limb movements, PLMS mildly elevated at 20 and PLMS arousal index 1.0.

I brought 3 sets of xPAP data reports, doc wasn't interested in looking at them.

Doc didn't express any interest in changing my pressure from 8 Cm; I'm resuming 8 Cm in light of above.

Doc didn't express any interest in pursuing the possibility of CA; seemed to rely on the titration which showed no CA at titrated pressure of 8 Cm and only 1 instance above 8 Cm.

Doc didn't express any interest in finding a Respironics flow setting to correspond to my non-Respironics mask.

Doc had me book another appointment in 3 months and said he would discuss more then.


So, major accomplishment is that I have my hands on the two formal studies and the lab titration. These confirm that I really do have OSA but seem to refute the possibility of CA. Apparently, 7 Cm is almost enough and 8 Cm is enough pressure; so, there seems no formal evidence of merit in an increase in pressure. (Nor is there any informal evidence from my xPAP data that an increase of pressure helps.) Moreover, there is one observation of CA at higher pressure contraindicating higher pressure.

I'm puzzled by the difference between my 0 AHA figure from the titration vs. my AHIs of 6 - 10 from my xPAP data.

One possible explanation might be that my CA data from my xPAP machine is completely unreliable. If that were so, then I should discount my xPAP AHI and only look at OA+H data which ranges form 2.7 to 6.2. (I'm omitting one night's higher figures which seem to be an anomaly.) Yet, even then, my OA+H data is markedly higher than 0 observed in my titration.

My hypothesis now is that the ultimate objective is to see that my O2 remains above 90%. I'm expecting my recording O2 meter in a week or two. That meter will introduce a new data quality question. My expectation is that it is apt to error on recording values that are too low due to a disruption in the sensor's ability to accurately read the LED light. However, it's error on the high side is not likely. Therefore, if my CPAP at 8 Cm is keeping my O2 > 90% according to the recording O2 sensor, then, I imagine that I can assume - with confidence - that my CPAP at 8 Cm is keeping my breathing going sufficiently to keep my O2 at a safe level.

I can't infer much from such a hoped-for record of O2 concerning my apneas. Yet, the apneas are important (so far as I understand) only insofar as they interfere with my breathing which can drop my O2 to dangerous levels.

Now, then, if the foregoing O2 hypothesis is true, I won't need to concern myself with my raw AHI or CA data. That data might, for example, hang around 4 or 6. I might interpret such values as error due to oversensitivity on the par of my CPAP machine. If they stay at that level it might be fine. If they rise - and the rise is confirmed by a fall in O2 - then that would be a matter of concern to be reported to the doc.

Does this view strike the readers of the forum as reasonable? Or, can you refine my understanding of O2 and xPAP data?

Thanks
Mark

[Pugsy]

Does this view strike the readers of the forum as reasonable?

Very reasonable.

It is common for the titration study done at whatever pressure to end up with near perfect results because the tech is watching and tweaking as things develop. The cpap or apap machines we use don't have that luxury and we also have leaks that will mess with things somewhat.

At least we now know that your centrals/clear airway events are pressure induced. It is possible as time goes by that these will decrease. Also it is likely that as time goes by that 8 cm pressure will reduce the OA and H events without changing anything. The machines aren't supposed to be a diagnostic tool, they are a treatment tool. While we look at data to see if treatment is optimal we cannot expect to mimic the sleep study exactly.

So your use of 8cm pressure is what is best for you. Watch leaks should they occur and let the machine deal with the events to the best of its ability. Will it ever be "perfect"? Not likely but as long as it prevents dramatic desats and limits those severe events, it will be acceptable.

Also since the bulk of your events happens in the supine position, if you can spend more time on your side the machine won't have as big of a war to battle.

Good luck and please keep us posted on how things are going with you. I think you have a good grasp on all this and how it relates to you.

Oh, forgot. I am not at all surprised that the doctor didn't care about the reports. This is common unfortunately.

[mayondair]

I agree with Pugsy, seems like a good approach, things will settle as you get used to the leaf blower You really have a lot of events on your back, it would be good to know what happens with 02 while supine if you can work that out. To bad your doc is a jerk, lots like him out there. I wouldn't worry about the mask setting, I never noticed much difference, I forget to change it when going from pillows to full face all the time. You are off to a great start! Kathy

[Mark NJ]

Thanks everyone for your input.

I'm not convinced that my CAs are pressure-induced. Let's review what we know of my case.

My titration indicates one CA event associated with a higher-than-prescribed pressure. Clearly, that event could have been pressure-induced; or, it might have been a rare event which happened to coincide with a period of higher pressure. Can't be sure; even so, it makes sense to assume that it was pressure induced and that I might be relatively free of CA events but would have them if I used higher pressure than 8 Cm.

My CPAP data at 8 Cm show some CA. My CPAP data at 10 and 12 Cm show some CA; but, not clearly higher than the CAs at 8 Cm. One can't reliably conclude that the CAs at 10 and 12 Cm were pressure-induced whereas those at 8 Cm were not-pressure-induced. Perhaps all the CA data generated by my CPAP machine are all invalid. Or, perhaps some of them are valid and I have a CA problem which didn't seem to appear on my titration nor in my 2 sleep studies. If my CA problem (such as it might exist) is spuradic it's concivable that all 3 formal tests pretty well missed my CA (making just 1 observation) whereas my numerous nights of APAP and CPAP data are registering some valid CA events along with a lot of invalid CA events.

Most of the time I sleep on my sides; only minority of time is spent on my back. Not a lot I can do about this. I think I have to rely on my CPAP machine to keep me breathing when I'm on my back as well as when I'm on my sides.

I'm going to watch my CPAP data with a more casual attitude for a while and hope that my AHI goes down. I need to monitor the data for leaks anyway. I think I'm managing my leakage well enough, but I need to watch for rare events and keep actively manageing leakage.

I'm going to pay attantion to my O2 as soon as I get my recording meter.

I don't regard Doc2 as a "jerk". A more even-handed view would be that offered elsewhere. That is that our medical system isn't capable of providing to the patient a reasonable summary of what the Doc knows about the patient's case. That simply isn't going to change without making medical care more expensive than it is or a change in culture.

I can also imagine that a doc would prefer not to become concious of any apocraphal data. If he were to look at my reports he couldn't be sure that some memory of what he saw wouldn't register and eventually influance his conclusions. His view may be - legitimately - that he can't give any credence to my CPAP-generated data when he has no reason to beleive there is any quality control over that data. He may conclude that he is better off relying exclusively on the formal data gathered in the lab where he knows that there is some measure of quality control over that data.

Regards,
Mark

[robysue]

And another thing to keep in mind about that "perfect" reading at the "prescribed" pressure in the titration study: You were most likely NOT at that pressure setting for most of the entire night: Rather, that's the pressure at which (for that night) all events disappeared for however long you were at that pressure, and you may not have been at the given pressure for a substantial fraction of the night. For example, on my first titration study, I was prescribed a pressure of 9cm based on 17 minutes of sleep with no events. I'd been a 7cm for most of the night with an AHI of significantly less than 3.0 (can't actually recall how low it was), but because of two events occurring close together about 18 minutes before LIGHTS ON, the tech increased the pressure by 2cm and I had no more events for the rest of the night. Hence AHI at 9cm was 0.0.

[Mark NJ]

. . . You were most likely NOT at that pressure setting for most of the entire night: Rather, that's the pressure at which (for that night) all events disappeared for however long you were at that pressure, and you may not have been at the given pressure for a substantial fraction of the night.

For example, . . . I'd been a 7cm for most of the night with an AHI of significantly less than 3.0. . . but because of two events occurring close together about 18 minutes before LIGHTS ON, the tech increased the pressure by 2cm and I had no more events for the rest of the night. Hence AHI at 9cm was 0.0.

Hi robysue,
Thanks, that casts a new light on things.

So, I surmise that if I got 1 CA at a higher pressure than my prescribed 8 cm, my scenario might have been:

7 cm for a long time with some AHI and snoring, so they tried
8 cm for a while and that seemed to work with 0 AHI, so they tried
10? cm for a while and got a CA hit, so they went back to 8 and continued to get 0 AHI.


If so, the period on 7 cm might have been for quite a whiie. That left some time for a period on 8. Then some time at 10 to get the 1 CA hit. And some more at 8.

No guarantee that my time at 8 was long enough to be quite sure that it is precisely high enough but not too high.

I suppose I could ask for more details as to how long I was at various pressures. Yet, I still might not learn much from that additional knowledge. My sweet spot might really be at 8; but it might be at 8.5 or at 9, maybe 9.5. I wouldn't know unless I had enough hours of data to be really meaningful.

I could spend a month in a sleep lab; but that's not going to be cost effective. My impression of my data from my CPAP machine is that it is too "noisy" with false positives to reveal my sweet spot. (Perhaps I'm too skeptical now.)

Maybe my O2 data will prove more reliable. I think I'll try to get a good base-line at 8 cm and see how much time I spend below 90%. Then, I'll try 8.5 cm for a while and see if the O2<90% gets better or worse. If worse, maybe I'll try 7.5 cm. If 8.5 seems better I'll try 9 cm.

Anyway, I take it from my initial periods of tinkering that I need longer periods at a steady pressure to accumulate enough observations to be meaningful. And, I can see how my O2 data corrilates with my CPAP data. If both sources suggest an improvement/deterioration then I'll have greater confidence in the indication. If they disagree, I'll be more puzzeled.

Regards,
Mark

[idamtnboy]

I suppose I could ask for more details as to how long I was at various pressures. Yet, I still might not learn much from that additional knowledge. My sweet spot might really be at 8; but it might be at 8.5 or at 9, maybe 9.5. I wouldn't know unless I had enough hours of data to be really meaningful.

Be careful, be VERY careful about what correlation you place on OAs and CAs vs pressure. Increasing pressure too much can cause increases in CA, but my sleep doc (actually his right hand assistant, an NP) told me today that too high a pressure can induce OAs as well. So let's take it as a given that CAs will increase with a pressure increase above some threshold. BUT, that's as far as we can go with the pressure/CA correlation. Why, because the specific number of CAs in a given night is NOT a function of pressure. I can tabulate the numbers if you want, but here's what I have in my data. I have been in CPAP mode all the time for the past 5 months with the pressure set at 9 cm, and never changing. For the month of February I have had a CA almost every night. My CAs vary in number from 0 to 6 for a CAI from 0.0 to 0.7. OAs vary from 0 to 11 for an OAI of 0.0 to 1.8. My leak rate has been zero almost every night during this time. Obviously some other factor is influencing the specific number of CAs, and OAs, in a given night.

Anyway, I take it from my initial periods of tinkering that I need longer periods at a steady pressure to accumulate enough observations to be meaningful.

You've got that right. The big question is how long a period. The smaller the change the longer the time will need to be to reliably see a correlation.