High OSA while on BiPAP

[lyankowy]

My baseline AHI was around 40. During my initial titration, my AHI was reduced to <5. However after a couple weeks of using CPAP, my AHI levels started to creep upward again. My dr had to increase my pressure 3x before deciding to have me do a BiLevel titration. The Bilevel titration showed that 11/6 dropped my AHI to <5. Again, the first couple of weeks I did fine, however my AHI started to creep up again, mostly all obstructive. My central apnea index was very low, seemingly non-existent. The dr. raised my bilevel pressures up 3x until finally we ended up at 14/10cm and my AHI was 83.7! (All obstructive)

Has anyone ever heard of this? For all intents and purposes, CPAP should have worked since I'm not having centrals. Why is my obstructive component so high?

[kaiasgram]

Is that 83.7 AHI reading from your machine's display or from software like SleepyHead?

[Pugsy]

What brand bilevel machine? ResMed or Respironics? and where are you getting the AHI number from?
If SleepyHead software...what version?

[Sclark08]

That is the same trouble I'm having. I have the same machine as you . I know I need a new masks but lady night leaks were not an issue and sleepyhead said I had 90 obstructive events. I felt pretty good this morning. I am really confused

[Sclark08]

My AHI was 22 by the way. It's never been that high

[lyankowy]

The readings were from my DME company via my modem.

[robysue]

My baseline AHI was around 40. During my initial titration, my AHI was reduced to <5. However after a couple weeks of using CPAP, my AHI levels started to creep upward again. My dr had to increase my pressure 3x before deciding to have me do a BiLevel titration. The Bilevel titration showed that 11/6 dropped my AHI to <5. Again, the first couple of weeks I did fine, however my AHI started to creep up again, mostly all obstructive. My central apnea index was very low, seemingly non-existent. The dr. raised my bilevel pressures up 3x until finally we ended up at 14/10cm and my AHI was 83.7! (All obstructive)

Has anyone ever heard of this? For all intents and purposes, CPAP should have worked since I'm not having centrals. Why is my obstructive component so high?

Something is fishy: Your treated AHI simply should not be twice as high as your baseline AHI was if there's been no increase in central apneas. But in order to try to figure out what's going on, somebody needs to look at more than just the summary AHI data. In other words, somebody needs to be looking at samples of your detailed daily data---the charts that show when the events are occurring, how long the events last, and what types of events are being scored.

Since you write

The readings were from my DME company via my modem.

I assume that it's the DME (or doc?) who told you that all the events are obstructive rather than central.

But here's the rub: While the central apnea detection algorithms are reasonably accurate for most people, it's also possible for real CAs to be mis-scored as OAs. (It's less likely that a real OA will be miscored as a CA)

And there's also a phenomenon called a mixed apnea: On an in-lab sleep test, a mixed apnea is scored when the apnea starts out looking like a central apnea---i.e. the airflow into the lungs drops to 0 L/min AND the belts show there's no effort being made to breath. But after a few seconds, the belts pick up an effort to breathe BUT no airflow starts going into the lungs in spite of the effort to breath---i.e. the apnea looks like an OA by the end of the apnea. The mixed apnea ends in the same way an OA typically does---there's frequently an EEG arousal where you wake up just enough to force the airway open and restart the breathing before immediately falling back asleep. The hypothesis about mixed apneas is that they are essentially central in nature, but just after the CA starts, the airway collapses and so when the brain once again remembers to send the signal to the lungs and diaphragm to inhale, no air can get into the lungs because of the collapsed airway.

Now think about the central apnea detection algorithm on your machine for a minute: After about 4-6 seconds of "no airflow into the lungs", the machine sends pulses of pressure down your airway to determine whether the airway is CLEAR (open) or OBSTRUCTED (blocked), and if the airway is OBSTRUCTED, the event is scored as an OA. But what that means is that if you are having a lot of mixed apneas, the fact that the airway collapses just after the mixed apnea starts means that most (or all) of these mixed apneas will likely be scored as OAs instead of CAs: although the cause of the apnea was the brain's "forgetting" to send the signal to breathe, the airway has collapse by the time the machine starts its CA/OA detection algorithm about 4-6 seconds after the apnea has begun.

And that's a problem because the mixed apnea's root cause is the same as a CA: Your brain is "forgetting" to send the signal to inhale on time. In other words, additional pressure is NOT likely to prevent mixed apneas getting started in the first place.

Now how likely is this to be the cause of your problems? I really don't know. But it's something that the doc ought to be considering at least as a possibility if the doc has looked at the detailed daily data instead of just a summary report of the overall AHI data sent via the DME.

So getting back to

The readings were from my DME company via my modem.

How often has the DME or doc told you what the readings say? And do you know whether they're looking at the daily detailed data on a regular basis or not?