wildly jagged flow rate curves -- do you see this in your data?

[cathyf]

Over my years on therapy, one of the things I see throughout my data are periods of time during sleep where my flow rate curve gyrates wildly up and down within each inhale. It is so wild that it completely confuses my machine, and it records utterly ridiculous (and clearly wrong) respiration rates in the 30-50 bpm range during periods where the rate is a very even steady 14-15 bpm if you count the exhales and ignore inhales. Since this breathing pattern blows up the respiration rate statistics for the night, I can see the "big picture" of the overview page and see just how frequent this is for me over the whole seven years I've been on CPAP.
   https://www.dropbox.com/s/se4wfr9iw44ghk...w.png?dl=0

When I made a comment about this on my therapy thread, geer1 speculated that this is a showing of paradoxical breathing -- thoracoabdominal asynchrony (TAA) -- and is a sign of struggling against severe flow limits. He also pointed me towards a thread from elliotg http://www.apneaboard.com/forums/Thread-...ation-rate asking about this in his data.

I'm trying to figure out how common this is among us PAPers, and if we can figure out what it is by comparing experiences.

So I linked to my overview page with the respiration rate statistics graph in an exaggerated size. Just eyeballing it you can see that I have a LOT of nights where the machine has completely overmeasured my respiration rate. When you look at the daily graph these periods stick out like sore thumbs. Here's an example:
   https://www.dropbox.com/s/euxomhjseofd1p...l.png?dl=0
Ok, here's the money shot -- two zooms on that night:
   https://www.dropbox.com/s/2td8owlmbag9dw...m.png?dl=0
   https://www.dropbox.com/s/mt5vo6woj98fc8...2.png?dl=0

As you can see by counting the obvious real exhales, the respiration rate is not anything like what the machine reports -- the machine is counting all of the ups and downs in the inhales as separate breaths and is totally confused! Here's a different night where I had an EPR of 3
   https://www.dropbox.com/s/itx1pfxlhfzpft...m.png?dl=0
If you look at the mask pressure curve the machine is on a totally wild ride trying to raise and drop pressure following what it thinks are separate breaths -- total bedlam!

So now that I've shown you my pictures and explained how to look for this phenomenon, how many people see this in their data? (elliotg was clearly seeing it...) If there are enough of us, maybe we can figure out what this is? Is it the muscles of chest and abdomen getting out of sync? Is there some mechanical way that flow limits cause this wild ride? Is this something caused by the CPAP machine? Is it even real at all or is it some sort of mis-measurement from the machine's sensors?

This data is with my ResMed machine, and so I'm pretty sure that I know how to find this in ResMed data, but would be very curious to hear from someone with Respironics data who sees the wild jaggies in their flow rate curves. Is the Respironics algorithm also confused into goosing the respiration rate?


(I'm hoping that elliotg stops by, too...)

[Neelix]

Nothing like that on my charts that I've noticed, just a staged inhale and constant exhale for the most part. That being said, I'm wondering when was the last time you had a sleep test? It occurs to me that data from the band sensors they use to check abdominal and chest movements could help provide some of your answers if you can somehow obtain that data and correlate that with the flow rate data from your CPAP machine...

Does anyone here know exactly how those sensors work? I wonder if it would be somehow be possible to build a DIY rig to collect that type of movement data with an arduino based unit or something...

-Neelix

[2SleepBetta]

As posted in one of your threads, I've presented fairly similar flow rate waves.

A wild idea, maybe, but seeing this again here, I wondered if those ragged waves like ours could be our bodies' corrective ventilation responses performing similar to mucus clearance devices. Maybe the unusual pattern occurs in some of us having episodes of extra mucus build up, possibly arising from food, atmospheric load, drug other congestion causes. I don't recall those details, but have had episodes where mucus got to a level somewhere downstream from nasal passages where airflow would sound a bit like that from the tip of straw as we suck air with the bottom and last drops of a viscous drink.

Here are links to information and quotations from those sources touching on that. I do see (see below) that the frequency of oscillations for high frequency chest wall oscillator devices are far higher than our RM machines have indicated for us. Roughly, we show frequency in the neighborhood of 60 to 80 per minute, 3 to 5 between exhalations, as I recall (have not counted). Its not clear to me whether/how the device synchronizes a bursts of high frequency pulses with the RR and expirations.

I didn't see any info on chest excursion of the devices, but (battery drive-able) those can't be large at stated frequencies (where I think 13 hz was found to be good).

197151r1-HFCWO Airflow Whitepaper.pdf (hill-rom.com)

"HFCWO Operation and Action HFCWO therapy is administered via a vest-like garment that generates airflow oscillations sufficient to produce coughlike shear forces which may decrease secretion viscosity [13, 14, 21]. These effects assist patients in mobilizing secretions from smaller to larger airways where they can be more easily removed by expectoration or coughing. On inflation, pressure is exerted on the thorax, forcing the chest wall to compress and generate a short burst of expiratory flow. Pressure pulses are superimposed on a small positive pressure baseline. On deflation, the chest wall recoils to its resting position, causing inspiratory flow. HFCWO can generate volume changes and produce 300 to 1500 staccato coughs per minute [3, 20]. Repetitive cough induces significantly more mucus clearance than a single cough, and even more clearance with an increased frequency of repetitive cough or airflow oscillations [14]. HFCWO induces rapid air movement that mimics cough which enhances mucus mobility [14] ."
 

"The relationship between nonsymmetrical airflow and mucus mobilization has been evaluated over several decades by numerous research teams. They found, among other effects, that during HFCWO therapy, chest compression - induced oscillations create rapid air movement in and out of the lungs and that the magnitude of these effects may be measured at the mouth as mean oscillated volume. Increased mean oscillated volume increases mucus clearance from the peripheral and central airways in a cephalad direction [14, 22, 23]. HFCWO generates peak expiratory airflows sufficiently greater than peak inspiratory flows (VE/V1 > 1) resulting in mucus transport toward the airway opening. The increase in expiratory airflow bias is similar to that which occurs during a cough [23]." 

On second thought I deleted (as incompliant with AB rules) a link I had to a High Frequency Chest Wall Oscillator (HFCWO) vest device manufacturer's manual, but googling ought to turn it up.

[Sleeprider]

I have seen this kind of ragged respiratory flow before and really don't have a good explanation for it. As far as the machine response, I'd like you to try setting the Ti Min to 0.7. This will cause the machine to hold IPAP pressure rather than bouncing with every flow change.

[GuyScharf]

I have not seen this and I am not an sleep expert. Just looking at the graphs, I see that the frequency of the peaks is very regular, perhaps 80 per minute. That rate could be a heartbeat rate. Do you have any cardiac issues?

Given the magnitude of the blips, I'm not surprised the CPAP machine can't figure out your respiratory rate.

[cathyf]

I'd like you to try setting the Ti Min to 0.7. This will cause the machine to hold IPAP pressure rather than bouncing with every flow change.

To add some interesting information— I don’t breathe that way on the vauto. 

There are two concerns here: The first is that I don’t know if the vauto would be fooled into logging a silly respiration rate with the ragged breathing. If not, that  means that there is no telltale spike on the overview page or wild jaggy respiration rate visible on the whole-night view. The other question is whether the trigger in the vauto settings forces the pressure support to only react to real breaths where the autoset gamely tries to follow every little jig and jag with the EPR. 

Both of those mean that I can’t just look at the summary numbers to know when it happens. In order to be sure that those waveforms are not in the vauto data I have to expand to a 2-minute view of the first two minutes of the night, and then hold the right arrow and watch the entire night scroll by. For three months of data. Which I have done— and it doesn’t happen on vauto and happens all over the place on autoset. 

It’s all very intriguing!

[Geer1]

This is real, it occurs rarely (doesn't occur in most members data) and almost all instances I have seen so far have improved with increased EPR/PS indicating it is in some way related to flow restriction/breathing effort.

Imo the rapid, large amplitude nature cannot be replicated or explained by anything other than muscles out of sync/twitching. Imo the only other possibility is heart related as it does settle into a pattern roughly in line with a possible heart rate.

As I showed you in your other thread the one time I had breathing like this it was caused by the machine coming out of sync with my spontaneous breathing due to cardiogenic oscillations prematurely triggering IPAP. I believe that is a strong indicator of being an asynchronous issue and body fighting itself/machine and not being related to what my heart was doing.

The other reason I believe it is something along these lines is that I have video tapped myself enough times to see twitches etc during rem sleep that create similar ragged strange looking breathing (never as consistent as this though).

Yours occur commonly enough when using poor settings that if you really want to figure this out then use a camera to record movements and an oximeter to record heart rate, collect the data and then review it. I am guessing you will see what will looks like strange out of sync breathing movements.

[Geer1]

To add some interesting information— I don’t breathe that way on the vauto. 

I would bet you do if you set PS to 0.

[SarcasticDave94]

Nope, all my charts are perfectly flat. Until I get a new machine that is.

[cathyf]

Nope, all my charts are perfectly flat. Until I get a new machine that is.

Dave, have I told you recently that I love you?  

(Keep on truckin, dude!)