Help me understand individual breaths

[Rick007]

It would appear that Sleepyhead subtracts "Intentional Leak", which, in ResScan, is already accounted for.

That may be the reason. In SleepyHead there is an option to select the mask type, along with a note saying "Leak Profiles Currently Does Not Work Yet". I can't see any options in Rescan to select the mask type at all, but maybe it automatically determines the mask type from the internal S9 settings.

However I think that ignoring the intentional link would just offset the graph above the zero mark. For example the pauses between breaths would show as 10 LPM rather than zero. The actual swings with each breath would still rise and fall by the same amounts.

[Sludge]

Well this is a drag!

The new ResScan v4.xx xml cannot be edited to allow tidal volume, adding numerical values to Flow Limitation, colors such as fuchsia, etc. (without causing to program to malfunction).

Some people have no sense of humor!!

[robysue]

It would appear that Sleepyhead subtracts "Intentional Leak", which, in ResScan, is already accounted for.

That may be the reason. In SleepyHead there is an option to select the mask type, along with a note saying "Leak Profiles Currently Does Not Work Yet". I can't see any options in Rescan to select the mask type at all, but maybe it automatically determines the mask type from the internal S9 settings.

However I think that ignoring the intentional link would just offset the graph above the zero mark. For example the pauses between breaths would show as 10 LPM rather than zero. The actual swings with each breath would still rise and fall by the same amounts.

Perhaps the recorded data for the wave flow data is "actual flow rate - intentional leak rate" and Sleepy head shows the recorded data while ResScan adds the intentional leak rate back to the recorded data before displaying the wave form graph.

Why Resmed would choose to record "actual flow rate - intentional leak rate" for the wave flow graphs is a puzzle to me, but this would account for the negative shift in the SleepyHead wave flow graph.

[Pugsy]

Code: Select all

Why Resmed would choose to record "actual flow rate - intentional leak rate" for the wave flow graphs is a puzzle to me, but this would account for the negative shift in the SleepyHead wave flow graph.

My SleepyHead 0.9.3 version shows the flow rate in the negative...below 0
My SleepyHead 0.9.4 unstable version show the flow rate in the positive...above 0

If I was wanting to evaluate the flow rate exactly...I would use ResScan.

[Rick007]

Perhaps the recorded data for the wave flow data is "actual flow rate - intentional leak rate" and Sleepy head shows the recorded data while ResScan adds the intentional leak rate back to the recorded data before displaying the wave form graph.

The question is, does a xPAP machine always produce positive airflow.
1)- I know it does when I inhale.
2)- I know it does when I am holding my breath due to the intentional mask leaks.
3)- I don't know what happens when I exhale. Do I actually reverse the flow of air in the tube?

Regardless of the answer to number 3, I expect 90% of the flow should be positive. I assume Rescan is correcting for the intentional leaks because they show the area between breaths on the zero line rather than positive which we know it has to be. If the Rescan graph is correct then we actually do reverse the flow of air in the tube when we exhale.

Since SleepyHead shows everything below zero, I have no idea what it means, but at least the shape of the waveform matches the Rescan graphs, so it still provides useful information.

[Sludge]

The question is, does a xPAP machine always produce positive airflow.

Unless there's an aggressive exhalation, I would say generally not, and I suppose one could hook up the TSI 4040 and get a readout that's significantly more accurate than the CPAP Flow and know precisely, but in the big scheme of things, what difference does it make...

[Rick007]

The question is, does a xPAP machine always produce positive airflow.

Unless there's an aggressive exhalation, I would say generally not, and I suppose one could hook up the TSI 4040 and get a readout that's significantly more accurate than the CPAP Flow and know precisely, but in the big scheme of things, what difference does it make...

Sorry, not sure that I am understanding your answer. Are you saying there is generally not always positive airflow from the xPAP machine unless there is an aggressive exhalation? How does an aggressive exhalation produce positive airflow?. Wouldn't that be the most likely scenario to produce negative air flow.

With regards to what difference it makes, I think the discussion began because some of us where confused why Rescan and SleepyHead produced substantially different graphs. As I mentioned in a previous post I don't think the actual numbers in the flow pattern are important to me as a layman, as long as the patterns are correct. However I am trying to determine which software is representing the data correctly so that I can learn to trust or distrust that software with the monitoring of my nighttime breathing.

[Goofproof]

The only thing that concerns me is when I see Flatlines!

[Sludge]

Sorry, not sure that I am understanding your answer.

Because it's confusing and contradictory.

The premise should be:

An xPAP machine always produces positive airflow unless there's an aggressive exhalation. The exhalation pressure generated would need to exceed the set pressure of the machine.

[Sludge]

OK, so if the Leak Rate of an Eson mask at 8 cmH2O is about 26 LPM, and your peak expiration is about 40+ LPM:





if you have -0- unintentional leaks, then it appears (albeit briefly) that there will be some negative flow.

[DeadlySleep]

Nothing to sneeze at.

[Setj]

Hi, OP back again.

Very interesting information. I also refer to this thread - viewtopic/t95558/ADVICE-NEEDED-ON-GRAPH ... yhead.html

Let me summarize my situation. I started CPAP for the first time on 12/16/2013. Right away I got good leak control and reduced a severe level AHI to 2.0 most nights. 100% compliant. I am sure my life expectancy is being significantly extended by CPAP.

Let me add that while CPAP has made me feel much better, I still feel something is not quite right with my daily energy level, endurance and alertness.

So, is my therapy good enough? I have moved on from a concern about AHI to a concern about the shape of my flow curve.

Here is a typical flow curve when I am sleeping well:



Here's a guide to waveform shapes posted by Mellabella in the other thread:




Now my waveform certainly does not look like #1 which is "THE" healthy waveform shape.

Is our goal with CPAP to achieve #1 waveform shape? Or are we just satisfied with low AHI?

Thanks for any help!

[Rick007]

So, is my therapy good enough? I have moved on from a concern about AHI to a concern about the shape of my flow curve.

Here is a typical flow curve when I am sleeping well:

Seth, I think you need to zoom in closer to see the details of your flow graph. You can go into the Rescan Tools menu, and then select Options. On the preferences tab, select Detailed Graph Ranges (in the bottom section) . Select the flow graph from the drop down menu, and then set it for -40 and +40 to see the details in your waveform. This will show much more detail than the -250 to +250 setting you currently have. You might even try getting a little closer if you want to experiment. I also suggest selecting a 30 second window, rather than the 1 minute window you currently have.

Remember that you are just trying to compare the inhalation part of the waveform to the reference waveforms. That is just the area above the red line in Rescan.

[Setj]

Thanks Rick.

Here is a closer look at just the inspiratory portion of typical relaxed breaths while asleep and using CPAP.




I feel totally unqualified to evaluate.

My questions are still,

Now my waveform certainly does not look like #1 which is "THE" healthy waveform shape.

Is our goal with CPAP to achieve #1 waveform shape? Or are we just satisfied with low AHI?

Thanks!

[Rick007]

Here is a closer look at just the inspiratory portion of typical relaxed breaths while asleep and using CPAP.




I feel totally unqualified to evaluate.

I am certainly not qualified either, just another person suffering from OSA. So why we are waiting for a qualified answer, here is my opinion.

In my layman's opinion, your breathing most closely resembles class #4 from the chart you previously posted. The notes for that class state "Initial opening indicates effective phasic upper airway dilation". I don't know what most of that means, but "effective" sounds like a good thing to me.