Dreamstation 2 Variabile Breathing Events

[don600]

Hi,
After 4 years using the Dreamstation I am on my first week using the Dreamstation 2. My new machine provides information on Variable Breathing Events which is something new. I am interested in learning more about Variable Breathing metrics and their significant. Any tips on where to look would be appreciated.
Thanks,
Don

[don600]

Hi,

I've been unable to find useful information on this topic, but, after 40 days of use, I may have some useful observations to share. Thanks to OSCAR, I've carefully tracked and analyzed the variable breathing events on my Dreamstation 2.

From what I can tell, Variable Breathing occurs during REM sleep. It constitutes 18.5% of my sleep cycle, with a great deal of consistency; the standard deviation is a very low 3.7%. This percentage correlates well with my duration of REM sleep, and the time periods during which it shows up also correlates with periods that my Garmin fitness tracker classifies as REM sleep. This is plausible to me, since breathing is more disordered during REM sleep. 

Therefore, my current working hypothesis is that DS 2 Variable Breathing is a proxy for REM sleep. If so, this is likely to be a normal phenomenon and not a form of sleep dysfunction.

I am still open to learning more about this.

Don

[Lucid]

Hi, Don  Here's a reference I found via Google about how the Dreamstation uses this parameter:

http://www.apneaboard.com/wiki/index.php..._Breathing

When I google variable breathing and REM sleep, I get hits that indicate your hypothesis makes sense.  

I wonder how much variation is just normal REM sleep, and what level justifies treatment adjustments.

[Sleeprider]

I wrote the wiki article and my impression was that variable breathing simply paralyzes the auto CPAP algorithm, causing pressure to remain constant, when a higher pressure might overcome the flow limitation causing the VB flag.

[Lucid]

Hi, Sleeprider  Given that variable breathing is associated with REM sleep, is it possible that's intended to avoid disturbing REM sleep?

[Sleeprider]

I remember reading the patent language on VB and REM sleep was not mentioned. My recollection is that VB is interpreted as a breathing instability similar to periodic breathing, and it suspends the auto algorithm. I linked to the patent in the wiki and this is my interpretation:

The variable breathing algorithm seeks to develop a peak inspiratory flow trend on a 4 minute moving average, and measure the deviation above or below that trend. The system is designed to identify variable breathing and to turn over control of the pressure support system, from the auto CPAP controller to the Variable Breathing controller. Without figures, we don't know what that controller response is, but it seems if VB is detected while the pressure is steady, the VB controller will maintain that pressure, but if pressure was increasing before VB controller took control, the pressure is reduced up to 2-cm. Similarly if pressure was decreasing ahead of VB detection, the VB controller will in increase pressure up to 2-cm. The duration of VB controller action is 5 minutes unless VB is still detected.
If anyone else wants to take a shot at understanding it, I would be more than willing to expand the wiki to include further interpretation. In my experience, when the VB controller is active, the machine acts paralyzed and is ineffective at responding to events. Philips is the only machine I am aware of that suspends the auto CPAP controller when variable breathing is detected. I have seen many members that display erratic peak flow rates and I am yet to see where the VB control algorithm actually helps that.

[don600]

Thanks. In my particular case, I operate my CPAP in the "dumbest" mode possible: constant pressure. (It eliminates all my treatment-induced events.) I'd assume the Variable Breathing Mode still watches but does not intervene in the operation of my machine. I remain curious if the mode actually adds value. Eventually, if it does, I'd assume Philips will be bragging about it to their users.

I'll also ask my pulmonologist about it on my next annual visit, and post if I learn anything.

[Sleeprider]

As far as I know, you should not see the variable breathing algorithm in fixed pressure CPAP mode. If it is flagged, it has no auto-CPAP algorithm to override, so it's pretty meaningless other than it means your peak inspiratory flow varies on a 4-minute rolling average. I have no idea what the significance of that is because it is not even a clinical measurement. Why Philips saw fit to include it is beyond comprehension unless they tell us.

[Lucid]

Sleeprider, that was great research finding the Philips variable breathing algorithm patent and a great summary and analysis.  Thanks for all you do!

Don, here's a particularly ingenious study of REM sleep and breathing.  Some changes in breathing can be related to what's happening in the dream, at least in these lucid dreamers:

https://www.nature.com/articles/s41598-018-21067-9

There are a lot of other studies on this topic, e.g.:

https://jcsm.aasm.org/doi/10.5664/jcsm.8...EM%20sleep.