Flow Rate Data from Sleepy Head

Still not clear what this data means......Just trying to understand, every so often, the flow rate black graph, line will be narrow and tight thru the night.....But most of the time it is wider and more jagged......

The flow rate is simply the rate at which air flows into and out of your lungs. It is measured in liters per minute.

You can "hack" this yourself. Just after you start the machine, or just before you turn the machine off, do the following:

beginning with a "neutral" amount of air in your lungs:

pause breathing for a few seconds, don't allow any air into or out of your lungs
inhale slightly
pause a few seconds
inhale slightly some more

pause a few seconds
exhale slightly
pause a few seconds
exhale slightly some more

Repeat that entire sequence a few times.

When you examine your SleepyHead graphs, things will be quite obvious. When you pause you will see a zero flow rate. When you inhale you will see a positive flow rate. When you exhale you will see a negative flow rate.

The reason I tell you to pause is because it makes the pattern quite different from your normal breathing. So it will be easy to distinguish that experiment from your normal breathing.

In fact, if you have a DreamStation and you pause for long enough (about 10 seconds), you can feel the machine do a "pressure pulse" as it attempts to force a slight amount of extra air into your lungs. It does this to try to determine what type of apnea you are in. You can then see the corresponding Pressure Pulse tick on the graph.

Of course, the machine is continuously forcing a certain amount of air out of it and into the mask. It does this whether you are breathing or not. That background air "leaks" out the mask vents. That's the "leak rate" graph. The machine subtracts out that leakage before it reports the flow rate into and out of your lungs. That's how the DreamStation works, I think the way Resmed machines display this may be a little different.

Now as to why the actual waveforms are "narrow and tight" or "wider and more jagged", that's an indication of exactly how you are inhaling and exhaling for each breath. What does it mean? That's something you can discuss with a pulmonologist. (ha ha, good luck getting to see one if you're covered by a typical insurance plan).

So the machine plays doctor in place of a real MD. It tries to recognize various waveforms and whether they are good or bad. And if they are bad it tries to fix them. I have attached two pictures that show this.

The first picture shows how a machine analyzes a flow rate waveform to determine a "flow-limited breath". It then increases the pressure to make the waveform "prettier" (for lack of a better word). In other words, by analyzing the waveforms, the machine can correct typical breathing problems.

The second picture shows a form of disordered breathing called Cheyne-Stokes respiration. The machine recognizes and flags this pattern.

By the way, my personal breathing waveforms vary quite a lot from minute to minute and from day to day. I try not to worry about them too much as long as the machine doesn't report apneas or hypopneas or stuff like that. If you do get an MD to explain your waveforms to you, then come back and post here and let us all know!

The flow rate graph line doesn't really mean much of anything until you zoom in on the breath by breath details.
In most situations it involves so much time that the breaths are so squished together that we can't really see much of anything.
You have to zoom in and look at the breaths individually before the flow rate has much meaning.

rzw wrote: ↑

Sun Mar 25, 2018 3:42 am

Still not clear what this data means......Just trying to understand, every so often, the flow rate black graph, line will be narrow and tight thru the night.....But most of the time it is wider and more jagged......

Zoom in.

Snoringinoregan, thank you very much for that detailed post.......