Gasping for air, but no events flagged

[boogiemoogie]

I've been trying out a BiPap to treat UARS and am hovering around the 5 EPAP and 7ish IPAP range for the past few weeks. I have great numbers, and barely any flow limitations or events, but will randomly wake up gasping for air. Outside of that, I do feel okay during the day so I think I am being treated, but any idea what would be causing this? Below are screenshots of what is happening right before I wake up.

[Julie]

Not trying to be funny, just passing on a little info if you never considered it... I am somewhat allergic to my cat, but won't let him go, so while most time is ok, I do get occasional problems when sleeping. I've chosen to not let it matter most of the time, but being aware that it's a factor at times helps me to not worry about every passing 'short' breath etc. My 'problem' but my choice to live with it. Not sure what I'd do if it got worse.

[robysue1]

Below are screenshots of what is happening right before I wake up.

To be honest, in my opinion there's nothing in these screen shots that shows anything is "unusual" in your breathing just before it appears that the machine is turned off when you wake up.

Also it's worth remembering that part of the arousal process is handing the control of the respiration back to the voluntary part of the nervous system and resetting the trigger for "inhale now" to a lower concentration of CO2 in the blood. Typically that means that we will take some deeper breaths just as we wake up. But this kind of normal arousal breathing shouldn't result in feeling like you are gasping for breath.

So, are you saying you're gasping for breath because of what you see in the flow rate curve? Or are you genuinely feeling like you're gasping for breath right when you first wake up?

Finally, I will also offer this: It's not uncommon for it to feel like the machine is not blowing as intensely when we wake up, even though it is still maintaining an appropriate pressure. (We become accustomed to what the pressure feels like while we're asleep.) And sometimes that causes people to wonder if the machine is still on when they wake up in the middle of the night, and for some people, that feeling like the machine is not blowing enough air into the mask can make them start breathing more deeply in an effort to inhale more air. If that might be the case, pulling the mask just a bit away from your face will make it quite clear that the machine is still on, and that can be just enough reassurance to keep the brain from fully arousing trying to figure out why it seems more difficult to breathe than it seemed at the beginning of the night when you first turned the machine on.

[boogiemoogie]

That is what is really confusing me - I will jolt awake in the middle of the night and feel my heart racing. But as you've mentioned, nothing really seems off in Oscar. I will say in the past I had experimented around with increasing PS and/or EPAP in .2 increments and the jolting awake would increase in frequency as that happened. I also have been trying different Trigger settings between Medium, High and Very High. While the higher trigger settings make it more comfortable, I wonder if it is messing with the CO2 levels.

[robysue1]

That is what is really confusing me - I will jolt awake in the middle of the night and feel my heart racing.

Any chance you're having some bad dreams?

It's not uncommon to have a wake at the end of each REM cycle. And if the dreams are disturbing, those wakes can feel like jolting awake with your heart racing.

And while your heart may feel like it's racing, the data in Oscar does not show you hyperventilating around the wakes that you've posted.

But as you've mentioned, nothing really seems off in Oscar. I will say in the past I had experimented around with increasing PS and/or EPAP in .2 increments and the jolting awake would increase in frequency as that happened. I also have been trying different Trigger settings between Medium, High and Very High. While the higher trigger settings make it more comfortable, I wonder if it is messing with the CO2 levels.

It sounds to me like you have been trying to dial wing in hopes to fix a problem that just might not be related to your OSA or CPAP.

If increasing PS and/or EPAP makes the problem worse, then don't do that. In other words, go back to the original PS and EPAP settings.

As for the Trigger (and Cycle) settings: I would suggest you set them where they feel most comfortable and use those settings for at least a week or two without changing the PS or EPAP settings either. Keep a sleep log to track the number of nights where you remember waking up in the middle of the night feeling like your heart is racing.

Then if you feel like you absolutely must change something, make one change at a time and use it for at least a week before concluding anything about whether it's working or not.

For what it's worth, I'm not sure how Trigger (or Cycle) would "mess" with your CO2 levels in a way that would cause the kind of wake you are describing

Both Trigger and Cycle are sensitivity settings based on the airflow into/out of of your lungs.

Trigger controls when the machine goes from EPAP to IPAP. A higher trigger level effectively delays the transition just a bit. A lower trigger level effectively makes the transition occur a bit earlier in the inhalation.

Cycle controls when the machine goes from IPAP to EPAP. A higher cycle level effectively makes the transition occur a bit earlier in the respiration cycle; a lower cycle level effectively makes the transition occur a bit later in the respiration cycle.

I suppose that since being at EPAP for a longer period of time might allow a person prone to central sleep apnea problems to "blow off too much CO2", and that might lead to a "CO2 overshoot/undershoot" cycle. But if that were happening, we would expect to see a lot of CAs in your data, but that's just not the case in the data that you posted.