Respiratory Rate of 7 on ASV - UARS x 13 years

Dear Sleep Apnea Board members:

I'm on ResMed Aircurve 10 ASV.

I've uploaded (attempted) screen captures from OSCAR, which shows two periods with perfect, almost machine-like, sinusoidal flow curves and no flow limitations at higher pressures. I've attached a zoomed view of the period around 7:20AM. The respiratory rate is 7 during these episodes. They happen 1-3 times per night (possibly N3).

If I take a Philips machine and set it to a fixed bi-level of 17/7, I get these same, perfect curves but centrals every 15-20 breaths. Otherwise the curves are perfect. I was advised by a very prominent sleep medicine doc that this is NOT good...all those centrals (even though I felt unusually good the next morning).

Been to MANY places (Stanford, Brigham, Mayo, Cleveland Clinic) with little relief, but those were before I tried ASV. I don't tolerate high pressures well and had 30,000 ectopic atrial beats/day for about 2 years on high pressures (20/15) that ceased when I lowered my pressure. Likely some issue with reduced atrial filling remodeling the atria and triggering the PACs. Long story and a LOT of suffering.

I'm new to ASV and no one seems to be able to explain these zen-like periods at higher pressure support (around 10) levels. The Resmed device dose not allow a PS min of greater than 6, otherwise I think it would eliminate the flow limitations while preventing centrals if I could set it to 10.

I did read that HRV is greatest at a RR of about 6-7, so this may be a GOOD thing, but clearly the literature considers any RR below 10-12 to be bradypnea.

I've taped my mouth for years and have no leaks. Use Bleep and/or Dreamware nasal cushions.

I get a status error (failed to move uploaded files) ...if the pics don't come through. I've tried .png .pdf and .jpg w/o success. Maybe I need the moderator's approval.

Will email the screen captures to anyone that wants to have a look.

I'm a physician, but not a sleep medicine boarded one. So any insights would be greatly appreciated.

Warm regards,

MRI_Doc

A constant fixed minimum PS of 10 is pretty much guaranteed to cause more centrals.
It is better to have a nice regular/normal PS with the ASV machine and then if/when centrals happen the machine will increase the PS to help you deal with the centrals for a breath or two...then it reduces back down to the nice normal level until another central happens.

PS of more than 6 (actually it can happen at any PS but not as common as when we start using more than 6 PS) can cause some unstable breathing or washing out of needed carbon dioxide in the blood levels. When this happens the carbon dioxide levels don't get high enough to trigger the brain to send the "breathe" signal to the body and you don't breathe and a central apnea occurs.
PS of 10 with every breath (like when using a regular bilevel machine) is going to wash out the carbon dioxide really quickly and you will just have a lot more centrals.
That's why you had so many centrals when you were on the bilevel at 7 exhale and 17 inhale. Pretty much guaranteed recipe for centrals in abundance.

You are going to have to sort of ignore the flow limitation graphs on the ASV because for some reason the ASV makes some really big mountains out of really little mole hills. I have seen in on my own graphs when comparing regular machine FL graphs to ASV graphs.

Your images didn't come through...not sure why unless the file is too large. There is a 1 MB limitation to file size.

If your files are too large you can host the screen shots on imgur.com.

I've seen the same slow metronome breathing occasionally on my ASV machines. From memory the Resmed ASV operates at the patient's own breathing rate until that falls below 8 bpm, at which stage the backup rate kicks in. What I suspect is happening is that your breathing has got down below the 8 bpm so the machine intervenes. However your spontaneous breathing hasn't picked up so the machine just keeps going at the backup rate - it is effectively acting as a ventilator.

That's my suspicion - I've never really investigated further, but I probably should.

Thanks for the replies, everyone. I have now compressed the files further in JPEG and uploaded them successfully. I was not aware of the 1MB size limitation. Note the periods where the RR drops to 7. I've zoomed in on one of those segments to show the machine-like, perfectly regular sinusoidal flow curves. Weird!

What I'm most interested to learn:

1. Does suddenly dropping from a RR of around 12 to 7 on ASV (with metronome-like, sinusoidal flow tracings) indicate any sort of pathology. I know the left ventricle has an "escape" heart rate of about 40 BPM, which kicks in if there's a total block of electrical activity to the LV. I'm wondering if this RR of 7 is a similar phenomenon. Otherwise, as my minute ventilation is maintained (via gigantic tidal volumes), this seems like some really deep, zen-like sleep (likely N3). An extensive literature search yielded nothing, other than HRV peaks at a RR of about 6-7 (which seems like a good thing). Any thoughts?

2. What ASV settings has the most effect on hyperventilation and centrals ? Is it Max PS or Max pressure or EP? I'm thinking Max PS is likely the most impactful. Again, an extensive literature search yielded nothing. But I'm sure this is respiratory therapy 101.

Thanks for any and all input!

Warm regards.

MRI_Doc wrote: ↑

Sat Apr 23, 2022 8:12 pm

1. Does suddenly dropping from a RR of around 12 to 7 on ASV (with metronome-like, sinusoidal flow tracings) indicate any sort of pathology. ...

I'd be interested in the answer to this. As I said, I have seen the same thing in my traces and it doesn't seem to cause any specific problems. I had a very thorough heart health work-up a couple of years ago and it was sound as a bell, so I don't think it's associated with any heart issues. Central apnea can be largely a neurological problem but again I've had no specific symptoms in that regard.

2. What ASV settings has the most effect on hyperventilation and centrals ? Is it Max PS or Max pressure or EP? I'm thinking Max PS is likely the most impactful. Again, an extensive literature search yielded nothing. But I'm sure this is respiratory therapy 101.

My understanding is that EPAP primarily controls obstructive events and pressure support helps with central apnea. I read something on the Resmed site a few years ago to the effect that if your PS is high enough (they recommend PSmax = 15) then all central apneas are eliminated and any events that do occur can be regarded as obstructive. Therefore EPAP should be set high enough to reduce the number of obstructives. In my case I have EPAPmin at 5 with PSmin = 3. This gives me the equivalent of P = 8 with EPR = 3 on a conventional CPAP, and that is a comfortable place for me. EPAPmax and PSmax are both at 15, giving a potential IPAPmax of 30 if the stars align, though I don't think it's ever got that high.

Can you load a zoom screen shot of the first episode? The expiratory times don't line up.

That's a weird sleep period.

Feel like uploading the whole SD card to dropbox for dissecting?

Conceivably could be REM-related.

Got an oximeter to simulmonitor with the ASV?

Rubicon wrote: ↑

Sun Apr 24, 2022 5:35 am

Feel like uploading the whole SD card to dropbox for dissecting?

Cause your breathing pattern seems to be able to allow you to sneak by the ability of ASV to make a classic attack, and it's choosing to make a PS attack instead. One wonders if what you got shouldn't be getting ASVed.

MRI_Doc wrote: ↑

Sat Apr 23, 2022 8:12 pm

HRV peaks

What means that?

MRI_Doc wrote: ↑

Wed Apr 20, 2022 9:25 pm

I've uploaded (attempted) screen captures from OSCAR, which shows two periods with perfect, almost machine-like, sinusoidal flow curves and no flow limitations at higher pressures.

Without *seeing them* (try using imgur.com to upload and display your images here, Instructions: https://www.cpaptalk.com/wiki/index.php/Oscar:organize ) I'm not sure, but normally sinusoidal flow curves are *awake* breathing whereas asleep breathing typically has a different curve with a more abrupt exhalation and then a pause before the next breath.

MRI_Doc wrote: ↑

Sat Apr 23, 2022 8:12 pm

I've zoomed in on one of those segments to show the machine-like, perfectly regular sinusoidal flow curves. Weird!

Ok, that shot shows classic sleep breathing, very nice patterns, but they are *not* sinusoidal,

This is sinusoidal:


and that's more characteristic of *awake* breathing.

For my asv charts, 12 bpm or a little higher would mean asleep, and 7 bpm would mean not asleep. Rough troughs at 7bpm in the respiratory rate chart come with recollections of awakening, smooth troughs at 7bpm come with no recollections of awakenings. It took awhile to figure out the awakenings were due to loud noises like the fire engine going by or the cell phone left on and a call received. I'm sure acid reflux causes awakenings, too, as well as other physical discomforts.

palerider wrote: ↑

Sun Apr 24, 2022 3:25 pm

MRI_Doc wrote: ↑

Sat Apr 23, 2022 8:12 pm

I've zoomed in on one of those segments to show the machine-like, perfectly regular sinusoidal flow curves. Weird!

Ok, that shot shows classic sleep breathing, very nice patterns, but they are *not* sinusoidal,

This is sinusoidal:


and that's more characteristic of *awake* breathing.

Technically you are correct, but I wasn't explicitly meaning a true sinusoid. Rather, perfect flow cycles (on the inspiratory and expiratory phases), which most closely approximate a sinusoid. Contrast that with flow limitations that deviate from smooth, sinusoidal-like curves (e.g. flat tops at peak inspiration).

In other words, my flow curves are perfect (textbook with no inspiratory or expiratory flow limitation) and stable (no periodicity) during these low RR periods and unlike any I have ever seen in me, looking at my OSCAR (SleepyHead) data daily for many years. I'll respond to your other replies and greatly appreciate you taking a look!

Pugsy wrote: ↑

Wed Apr 20, 2022 9:54 pm

A constant fixed minimum PS of 10 is pretty much guaranteed to cause more centrals.
It is better to have a nice regular/normal PS with the ASV machine and then if/when centrals happen the machine will increase the PS to help you deal with the centrals for a breath or two...then it reduces back down to the nice normal level until another central happens.

PS of more than 6 (actually it can happen at any PS but not as common as when we start using more than 6 PS) can cause some unstable breathing or washing out of needed carbon dioxide in the blood levels. When this happens the carbon dioxide levels don't get high enough to trigger the brain to send the "breathe" signal to the body and you don't breathe and a central apnea occurs.
PS of 10 with every breath (like when using a regular bilevel machine) is going to wash out the carbon dioxide really quickly and you will just have a lot more centrals.
That's why you had so many centrals when you were on the bilevel at 7 exhale and 17 inhale. Pretty much guaranteed recipe for centrals in abundance.

You are going to have to sort of ignore the flow limitation graphs on the ASV because for some reason the ASV makes some really big mountains out of really little mole hills. I have seen in on my own graphs when comparing regular machine FL graphs to ASV graphs.

Your images didn't come through...not sure why unless the file is too large. There is a 1 MB limitation to file size.

Thanks, Pugsy! It is interesting that with BIPAP 17/7 I get the same, perfect, regular flow curves at RR=7 (never seen in my 12 years since PAP initiated and showing up for first time after switching to ASV) that I get when my ASV adjusts UP to 17/7 spontaneously, yet there are NEVER any centrals on ASV at these pressures during these same periods. You'll note that the ASV stays at 17/7 but no centrals, yet BIPAP at 17/7 produces LONG centrals every10-20 breaths?

Respirator99 wrote: ↑

Thu Apr 21, 2022 12:35 am

I've seen the same slow metronome breathing occasionally on my ASV machines. From memory the Resmed ASV operates at the patient's own breathing rate until that falls below 8 bpm, at which stage the backup rate kicks in. What I suspect is happening is that your breathing has got down below the 8 bpm so the machine intervenes. However your spontaneous breathing hasn't picked up so the machine just keeps going at the backup rate - it is effectively acting as a ventilator.

That's my suspicion - I've never really investigated further, but I probably should.

I'm thinking it MAY be something like this, as the RR is so perfectly regular w/o any period breathing and perfect flow curves.

I wear Apple Watch at night and so far no obvious desaturations happening (although it measures every 30 minutes...suspect next version will check more frequently...battery life issue).