Crazy low Respiration Rates & high Centrals - sometimes...

[grubstake]

Hi, 

I've been on CPAP/APAP 13 years, new machine, some great improvement, but trying to figure out some really bad nights.

After a couple of weeks tweaking my new machine, with my AHI typically below 1.0 and feeling pretty dialed in, I'm concerned about times where my CAs and total time-in-apnea have zoomed and I am seeing my respiratory rate drop from my usual ~14 to ~7 for extended periods, sometimes when I think I was awake, sometimes when I think I was asleep. This happens sometimes when there are no apneas corresponding.  I wake feeling slammed and very tired the next day.



Opinions appreciated.  

Questions:

- Are my low respiration rates unusual?  From what I read that's half the normal respiration rate.

- Do my CAs look real or are they just “junk”? 

Last night (AHI 7.4) there were some rapid-fire long CAs/low RR for a significant period.  






Last night zoomed.  Note the event list - one CA over 30 seconds long.



More of this screen Overview 2  Overview 3



Looking back at earlier sessions, I have often seen drastically worse results after my common 3am wakeup returning to bed.  I also often but not always see my respiration rate low at beginning and end of night and during periods when I was sleepless with mask on.

A night with good AHI but big respiratory rate drop for about 2 hours (no CAs)




I have my 7 week-old Airsense 10 Auto dialed in pretty well with better results than my old machine, and have been watching the new data closely with Sleephyead.  I've ended up with enough variability in results to be focusing on sleep hygiene and positional issues. I haven't changed machine settings in 4 weeks. I've kept a sleep journal and my 'bad' nights have generally correlated with poor sleep hygiene (NOT the last to really bad nights.)



Background


I was diagnosed with OSA 13 years ago and have been on an auto-PAP since then. My sleep quality has been pretty variable, but vastly better than nothing. Having little useful support from sleep doc I've been actively lurking online and have had things dialed in for quite a while, not paying much attention but always compliant.  

I replaced my 2000 hr S8 Autoset 2 (8/14, EPR-3, with results AHI ~7.5, AI ~0.3, avg pressure 10.6, leak ~ 7-8 L/m.

My current settings: Pressure- 8-14, EPR ON - full time - 2, Response- soft, ramp- OFF.  I saw substantial improvement in the first few weeks enabling EPR and bumping up 1 to 2.  Similarly "soft" response had a big impact.



THANKS!



Tim

[DeepBreathing]

G'day Tim

The close-up plot looks like obstructive apnea rather than central. You can see at the end of each event there is a big recovery breath (basically gulping in air). Generally with central apnea you'll see a more gentle and progressive return to normal breathing. Because of the strong clustering I suspect there is a positional contribution - specifically tucking your chin to your chest which will close off the airway. It might be worth trying a soft cervical collar to avoid this.

Do you take any medications etc when you wake at 03:00? That might contribute to the low respiration rate.

[Gideon]

If you look at your detailed zoomed chart you see 2-3 breaths, then a pause that is the length of about 2-3 breaths effectively cutting your respiration rate in half.

They do look like positional apnea and a loose fitting soft cervical collar to keep your chin from tucking.

Fred

[grubstake]

Thanks for the reply DeepBreathing.

Centrals are all new to me as this is the first machine I have had that categorizes apneas as such.  You can see the event list at left that has these events under the category Clear Airwave.  I did not have any events classified as Obstructive that night.  Also my first exposure to sleep RR graphs.

No, I don't take any medication, I just pee, maybe a slurp of water. ;-)

I can see that I mistakenly posted the same image twice where I was trying to show another night with substantial low RR where there were no/few apneas:  



I often have difficulty falling asleep if I wake at this point.  The flattening of the flow rate from about 3:15-3:45 corresponds I see on many days where am wakeful, and the two subsequent interruptions in the data reflects my hitting the power switch which means "I'm still awake".  I suspect I was at least mostly awake from 2:45 - 5:00.  So a bad night...except for my AHI!

Regards,

Tim

[jaswilliams]

You may find that reducing your EPR back to 1 or 0 that you have just started using reduces the centrals.

[Sleeprider]

The lower respiration rate in the middle of the night may not be a problem. Take a look at the minute vent chart and see if it also sags. If not, then your respiration rate slows during a period of deeper slower breathing. There is nothing to really suggest a respiration rate in the 8 to 12 BPM range as shown on this chart is a problem.

[grubstake]

If you look at your detailed zoomed chart you see 2-3 breaths, then a pause that is the length of about 2-3 breaths effectively cutting your respiration rate in half.

They do look like positional apnea and a loose fitting soft cervical collar to keep your chin from tucking.  

Fred

Thanks, Fred. I get that it's expected that missing breaths reduces the resp. rate.  What's odd though is that I get the lowered resp rates at times I know I am awake, and also I get it at times when I know I am sleeping and I have NO apneas, like the middle section of the 0.7 AHI day in my original post.

I'm curious if others see significant periods of greatly reduced RR like this during PAP therapy.

Tim

[grubstake]

You may find that reducing your EPR back to 1 or 0 that you have just started using reduces the centrals.

Thanks for your thoughts. 

I ended up with EPR 2 slowly and I haven't changed any machine settings for 4 weeks, where until just recently I was averaging AHI below 1.5, commonly below 1.0.  

Having that period of consistent good results, I've purposely been avoiding fiddling with any settings until I can see if other factors like sleep hygiene or positional stuff might be the cause.  I will definitely test what you suggest if nothing else presents itself.

Regards,

Tim

[grubstake]

The lower respiration rate in the middle of the night may not be a problem. Take a look at the minute vent chart and see if it also sags. If not, then your respiration rate slows during a period of deeper slower breathing.  There is nothing to really suggest a respiration rate in the 8 to 12 BPM range as shown on this chart is a problem.

Thanks for your comments.  A cursory look shows the minute vent chart does not sag nearly as much, a little sometimes.  It does swing +/- a lot more during these periods along with flow rate etc.

Does the minute vent equate to total volume of air inhaled, i.e. would absence of a sag suggest little/no impact on blood oxygen saturation?  I've wondered because on days with a lot of this sort of thing I am often quite groggy the following day.

Regards,

Tim

[Sleeprider]

Tim, exactly that. The minute vent is the total air respired in one minute. What apparently happens is that as your respiration slows, you take larger breaths. That means a rise in tidal volume with the decrease in respiration rate resulting in an overall equal minute vent. In other words, minute vent is a function of tidal volume and respiration rate. I think your thoughtful, slow approach to making therapy changes is very good, and I'm in complete agreement with your process.