augustsilverbear wrote:Thanks for your responses.
I have read about RERAs. Definition is fairly cryptic.
Respiratory Event Related Arousal... a sequence of breaths characterized by increasing respiratory effort leading to an arousal from sleep, but which does not meet criteria for an apnea or hypopnea.”
RERA Detection in the Respironics System One data..Respiratory effort-related arousal..defined as an arousal from sleep that follows a 10 second or longer sequence of breaths that are characterized by increasing respiratory effort, but which does not meet criteria for an apenea or hypopnea. Snoring, though usually associated with this condition need not be present. The RERA algorithm monitors for a sequence of breaths that exhibit both a subtle reduction in airflow and progressive flow limitation. If this breath sequence is terminated by a sudden increase in airflow along with the absence of flow limitation, and the event does not meet the conditions for an apnea or hypopnea, a RERA is indicated.
Other definitions I have read characterize RERAs as indications of events of increasing respiratory effort without an oxygen desaturation. So they are not like an obstructive apnea, nor like a hypopnea, but do cause arousals, change sleep levels, and sometimes cause awakenings.
Informally, it's easiest to think of RERAs as part of a continuum of sleep disordered breathing-type events. In a sleep lab, a RERA is scored under very particular circumstances, but it boils down to the airway is slightly compromised (so there is increasing respiratory effort), but the person has an EEG-detectable arousal and a return to normal sleep breathing
before the breathing has deteriorated to the point where a hypopnea or an obstructive apnea can be scored.
In a RERA, the arousal may occur before the 10 seconds needed to score a hypopnea have passed. Or it could be that the reduction in airflow is less than the 30-50% needed to score a hypopnea. (How much the airflow must decrease depends on which rules are used to score the hypopnea.) Or both.
So it's reasonable to think of a RERA as a "hypopnea wannabe"---you arouse (or wake up)
before the breathing deteriorates enough to be a hypopnea, but the breathing has started to deteriorate before you arouse just enough to get the airway fully opened back up.
My sleep is highly fragmented, due to having a RERA thirty+ times per night. Some of my arousals in conjunction with a RERA do result in an awakening. During my sleep study I had NO obstructive apneas, but did have 26 hypopneas.
Are we talking about RERAs scored on your PR DreamStation?
My recent pressure elevation (ordered by sleep doc) has lowered AHI from average of low teens to now around average of 4. Have only been at 8-12 pressure level since March 11; so a self initiated pressure change at this duration of a recent pressure increase would not be warranted. And, No, I do not know how to increase the pressure on my DreamStation device. I have a review appointment with sleep doc on March 23.
Personally, I can see why you want to wait for the review appointment. Yes, there are a lot of folks on this board who advocate self-treatment and changing your own pressures. But there is a lot to be said when you are new PAPer to be more patient and work with the doc when the doc is willing to work with you. If your pressures were changed on March 11 and you have an appointment on March 23 to review that data, it makes a lot of sense to just be patient until that March 23 meeting.
Can anyone advise if RERAs are indicative of some underlying condition about which I should be concerned?
Again, are you talking about RERAs scored by your PR DreamStation?
If so, my best guess is that the RERAs are just part of your overall sleep apnea. As some pressure is applied by the machine, the potential apneas often turn into hypopneas and the potential hypopneas turn into FL and RERAs. As more pressure is applied, the RERAs and FLs should start to disappear. In a "good" titration, the goal is to find a pressure level that is high enough to prevent the OAs, Hs, FLs, and RERAs, but low enough to not cause the patient any difficulty. (Too much pressure can lead to
spontaneous arousals, problems with aerophagia, and in rare cases problems with pressure-induced centrals.)
Since the only suggested remedy was crank up the pressure; I have to ask how would that address the issue? By its definition, these events are not associated with a narrowing, nor an occlusion, of the airway. So what would more pressure do for an irregular "subtle reduction in airflow along with the absence of flow limitation?"
No, you've got a misunderstanding: RERAs are caused by a very subtle narrowing of the airway. The narrowing is not enough to cause the significant reduction in airflow that is required to score a hypopnea, but the narrowing is enough to cause additional respiratory
effort: It takes more work to breathe during the flow limitation that precedes the arousal in a RERA. The arousal is caused by the increased respiratory effort, which is caused by the subtly narrowed airway.
There are some descriptions that describe the kind of increasing respiratory effort associated with a RERA as trying to breathe through a straw: The narrower the straw, the more you have to work on drawing the air in through the straw---even though the straw is not so narrow that you can't actually move enough air through the straw to stay properly oxygenated.
Additional pressure addresses the issue of RERAs by making it more difficult for the airway to become subtly compromised and slightly narrowed.
I believe the pressure increase prescribed for me on March 11 DID markedly lower my AHI; however, I am not experiencing a corresponding level of more restful and restorative sleep. My numbers of apneas is lower, but some are continuing to occur. My time in apnea has been around 11 minutes for a 7+ hours of sleep experience. Hypopnea are still higher than desired, and likely would be reduced further by more pressure. I will discuss pressure levels with the sleep doc next week, but believe he is likely to say give the new pressure level some time to work before he will change it again, given an 8 point drop overnight in AHI when the last increase was instituted.
First: For most CPAPers, the overnight AHI is seldom a 0.0 and there's not much point in chasing a 0.0 just for the sake of having a 0.0 AHI. The point of CPAP is to get the AHI low enough to allow you get normal, restful and restorative sleep. Which you're not yet getting. But CPAP is a process. It may take a few weeks to really settle in and learn how to sleep
well with the machine. There's a lot of sensory stuff coming from the machine that we have to grow accustomed in order to sleep
well with the machine. So yes, it is quite likely that your doc may suggest keeping the pressures at the new setting for a while longer when you talk to him/her on the 23rd.
Next, it's not clear to me that the total time in apnea will be something the doc will care about. The Encore software the doc is likely to use to analyze data from your machine does not compute that particular statistic. On the other hand, I don't want to suggest that it's not important at all. Its significance, however, may be more dependent on whether you are known to have serious O2 desats during apneas.
I was just hopeful someone could answer the questions in my above post, and give me some insight into how I might achieve more restful and less fragmented sleep. Thanks for any assistance you can provide.
augustsilverbear
1) Since you want to wait until you talk to the doc before possibly increasing the pressure, it's important to be a bit patient. And try hard to separate "how I feel?" each day from "how bad does the data look?" What I mean by this is don't automatically expect that you're going to feel awful if your RERA index is up a bit one day vs. another.
2) Prudent, watchful waiting is not a bad idea right now. Give yourself the time to really adjust to these settings before your appointment with the sleep doc.
3) Work on making sure that
non-OSA, non-RERA causes of fragmented sleep are addressed. If you are waking fully awake several times each night for any reason, that can cause the sleep to feel less than restful and restorative. So work on encouraging high quality sleep through good sleep hygiene practices.
