Question about flow rate shapes

[yarrow]

I got about 9 hours of sleep last night -- very unrefreshing, alas. One thing I noticed was two half-hour periods with breaths like this:

where I seem to be breathing for a bit less than 2 seconds and pausing for a bit less than 3 seconds. That seems strange enough to be worth asking about. It is that anything to be worried about?

For reference, here is a flow limitation from the same night:


and a hypopnea:


and something maybe a little more normal:

[avi123]

Overall, the shape of your respiration waves show flatness on their tops instead of ideal rounded tops. It indicates some UARS (Upper Airway Resistance Syndrome). Most of SBD (Sleep Breathing Disorders) sufferers have it to some degree.

The S9 Autoset machine analyzes the shape of the wave and gives it a level of Flow Limitation, which you can see in a ResScan graph.

[yarrow]

Overall, the shape of your respiration waves show flatness on their tops instead of ideal rounded tops. It indicates some UARS (Upper Airway Resistance Syndrome). Most of SBD (Sleep Breathing Disorders) sufferers have it to some degree.

The S9 Autoset machine analyzes the shape of the wave and gives it a level of Flow Limitation, which you can see in a ResScan graph.

Yes. Though the little blips on the first graph are pretty round, and indeed the Flow Limitation graph is zero throughout. (Not just for that minute, but all through both half-hour periods with that respiration shape.)

[idamtnboy]

yarrow, how about changing the scale on the flow rate graphs to something like +/- 60 lpm to spread out the curve vertically. It'll give a better picture. It sure is an odd breathing pattern, to me anyway.

[yarrow]

yarrow, how about changing the scale on the flow rate graphs to something like +/- 60 lpm to spread out the curve vertically. It'll give a better picture. It sure is an odd breathing pattern, to me anyway.

SleepyHead seems to have a minimum scale (which varies day by day), that it won't let me go under. But here's that graph, as the only one on the page. I cut the top off but not the bottom, since that's where the time scale is:



(The minimum scale for leaks seems to be set so that every data point fits in the Y axis, which makes a certain amount of sense, though I really don't care how high a 2-second leak spike went. But the flow rate seems to be taking into account invisible data points or something.)

[NotLazyJustTired]

Just a guess, but by my eye that looks like only the inspiratory half of the curve is being shown. Could it be you are breathing in through your nose and exhaling through your mouth?

[yarrow]

Just a guess, but by my eye that looks like only the inspiratory half of the curve is being shown. Could it be you are breathing in through your nose and exhaling through your mouth?

Hmmmm... hadn't thought of that!

[idamtnboy]

yarrow, what mask do you have selected in the clinician's menu of the S9? Looking at the graph I think you have the wrong mask selected. Mathematically the area between the curve and the X axis should be equal on both sides, i.e. the volume of air, which is the area under the curve above the zero line, has to be equal to the volume of air exhaled, the area below the zero line. The zero line should be somewhat higher than it is. It must be displaced due the wrong mask being selected in the S9, or there is a problem with Sleepyhead. You do know the S9 subtracts the mask vent from the total flow to get the volume breathed, as well as leak rate, right? Respironics, and maybe others, do not.

What kind of leak rates are you having? How about looking at the data with Resscan? What does it show? In a case like this I would be inclined to trust Resscan to give a more accurate picture of what's happening.

Mouth breathing will show up as leak rate. It won't offset the flow rate graph.

[imfletch]

In through nose, out through mouth sounds like the perfect answer!
It would also mean you keep "releasing" the pressure which could lead to events and a crappy feeling in the morning. Are you waking with a dry mouth? Is the water in your tank running out or very nearly running out?
Do you use a chin strap?
3M makes "tape" which looks like a boomerang. It goes UNDER your lower lip and extends up to your cheeks on either side of your mouth. It makes opening your mouth much more difficult - still possible, but difficult. This is usually enough to remind your subconscious to keep the mouth shut and the lips sealed.
If you have a full face mask you might try that for a night or two, just to see if the waveforms change.

[yarrow]

yarrow, what mask do you have selected in the clinician's menu of the S9?

Away from the machine right now, so can't check -- but I have looked in the past and believe it to be correct.

Looking at the graph I think you have the wrong mask selected. Mathematically the area between the curve and the X axis should be equal on both sides, i.e. the volume of air, which is the area under the curve above the zero line, has to be equal to the volume of air exhaled, the area below the zero line. The zero line should be somewhat higher than it is. It must be displaced due the wrong mask being selected in the S9, or there is a problem with Sleepyhead.

I have a vague recollection of reading a post here that the weirdly-center graphs are a known flaw either of SleepyHead or the S9 itself.

You do know the S9 subtracts the mask vent from the total flow to get the volume breathed, as well as leak rate, right? Respironics, and maybe others, do not.

What kind of leak rates are you having? How about looking at the data with Resscan? What does it show? In a case like this I would be inclined to trust Resscan to give a more accurate picture of what's happening.

Mouth breathing will show up as leak rate. It won't offset the flow rate graph.

Yes, understood about S9 leak reports. For the period of these flow graphs, leak is low (for me, at least!): 5 to 8 L/min. I do have Resscan set up on a virtual machine -- will check tonight.

[yarrow]

In through nose, out through mouth sounds like the perfect answer!
It would also mean you keep "releasing" the pressure which could lead to events and a crappy feeling in the morning. Are you waking with a dry mouth? Is the water in your tank running out or very nearly running out?
Do you use a chin strap?
3M makes "tape" which looks like a boomerang. It goes UNDER your lower lip and extends up to your cheeks on either side of your mouth. It makes opening your mouth much more difficult - still possible, but difficult. This is usually enough to remind your subconscious to keep the mouth shut and the lips sealed.
If you have a full face mask you might try that for a night or two, just to see if the waveforms change.

I do use a chin strap (the Ultimate Chin Strap), though I'm never sure how much good it does. With the humidifier set on 5 I generally don't run out, though some nights I'm quite low in the morning. Don't have a full-face mask.

[idamtnboy]

I have a vague recollection of reading a post here that the weirdly-center graphs are a known flaw either of SleepyHead or the S9 itself.

That very well could be it, with SH that is. Resscan centers the graph correctly, at least for all the ones of mine I have looked at so I'm sure the S9 records it correctly.

What I'm thinking is that once we see your graphs properly centered the curve may not be as weird as it seems. I just took a quick look at one of my flow rate graphs, and even though I didn't see any portions that mimic yours, I did see that the exhalation time span in relation to the inhalation time span is somewhat the same ratio as yours. All of the graph I looked at, for one night only, show the exhalation times to be longer than the inhalation times, with quite a bit of flatness in the exhalation part of the curve. Apparently our diaphragm doesn't move up in an exact reverse pattern of when it moves down! I'll bet most all our muscles have a differing time/motion pattern during relaxation than during tightening.