Flow limitation

[Sleeprider]

I'm pretty sure I'm repeating myself. Flow limitation is treated with bilevel positive pressure therapy. Have I somehow failed to link this article? http://www.apneaboard.com/wiki/index.php..._and_BiPAP

[DanEm]

Sleeprider,

Sorry to have miss-red your comments.

I was wrongly under the impression you had backtrack on those comments.

I will check if I can get a Aircurve Vauto.

Until then I will keep the current settings.

[DanEm]

My first question is what can be the long term health effect of having a flow limitation higher than 0.1?
My question is based on the probability I would not be able to get a bi-level machine.

SCREENSHOT 1
Sessions 1 &2, pressure was set to 6/15.
When I woke up after session 2, I realized my mouth was open.
Not certain if the collar has shifted or not.
I then reset the pressure to 10/20 for session 3 and things got back to what I usually see.

My second question is can breathing through the mouth have an impact on the flow limitation.

SCREENSHOT 2
For the following night I kept the pressure settings to 10/20

I will try once more to set the pressure to 6/15 and see what happens.

[Sleeprider]

We don't have any health data on flow limitation, but since it is a form of obstruction, and is the root of respiratory effort related arousals, hypopnea and OA, it is logical to try to minimize its occurrence. A mouth-open condition reduces pressure in the airway and interferes with the feedback the machine requires to measure the flow rate. We often see higher flow limit during periods of high leaks. You should probably include a leak chart to see if these events correspond to loss of pressure by leaks. In the graphs above, you are attempting to draw a correlation between pressure settings and efficacy, but have other issues that may be obscuring those results.

I think many of us using the Vauto have dealt with denials from insurance or medical systems, and choose to purchase the higher level of therapy out of pocket. My current machine is now over 20K hours and was provided through insurnace, but with the transition to Medicare it seems unlikely that will continue. I have a backup Vauto I purchased several years ago out-of-pocket and it looks like that will be my future approach to getting a machine.

[DanEm]

To Sleeprider.

Thanks again for your patience with me.

I have always had weird health issues and test results.

For example, a normal person would take one or two regular Tylenols for a headache.
I took up to 5 (650mg each) with no significant pain reduction.
I did the same with different brands with the same results.
It seems painkillers don't work for me.

So I am most of the time in doubt about health issues and remedy.
This trying to explain why I would come back and ask more questions on the same subject.
Sorry for that.

SCREENSHOT 3
I have included the leak graph.
Leaks were a concern of my doctor in the past and I tried with the collar and mask tightening to reduce those. 
I was quite successful.
In this screenshot, I had the MAD, the rigid collar and added a chin strap over all.

When I woke up, the chin strap had gotten off. Maybe it explains the leak rate at the end, I don't know.

VAUTO
I have sent a request to my doctor to get the Vauto.  Waiting for her reply.

I have browsed internet to try and find a seller for the Vauto that do not require a prescription with no success.
I still have to search for a used one but I am not to comfortable with that solution since I would not get the warranty nor the support from my local provider.

Thanks again for your input.

[DanEm]

Here I am once more with questions about flow limitation.

I did get advice on the subject and my case seemed to require a change of my AirSense 11 for a BiPAP (Resmed AirCurve vAuto).

I found that it is almost impossible to get such machine without a prescription which means I have to convince my lung doctor to change her initial prescription.  So far I have not been successful.

I am thus trying to find more arguments to convince my doctor.

So, I took a different look at my results.
Almost all graphs out there are time based. Showing different events per hour.

I wanted to see if there is a relation between my AHI, my pressure and my flow limitation.

The graph I produced confirmed pretty much one information I got here that flow limitation under 0.1 is a good objective.
You can see on the graph that below the 0.1 value for flow limitation, I have no events occurring.  That is a clear indication for me.



Also shown on the graph is that higher the flow limitation is higher the AHI is also.

From WiKi:
Flow limitation may be inspiratory (during inhale) or expiratory (during exhale). It refers to any condition which impairs the flow rate of air through the respiratory tract.... 
Flow limitations can result from anatomical narrowing of the airway, airway obstruction, and positional obstruction where the airway is restricted due to an individual's sleep position resulting in occlusion of the airway (I am wearing a cervical collar). EFL may also result from intolerance to CPAP pressure during exhale. Both IFL and EFL seem to respond well to bilevel therapy where the exhale positive air pressure (EPAP) is a lower pressure than the inhale positive air pressure (IPAP).

So I conclude I do need to fight flow limitation which in my case sometimes goes up to 0.8.

I am thinking of presenting this argument to my lung doctor.

If you can improve/correct the above, please do so.

Thank you.

[DanEm]

The flow limitation index is calculated by dividing the total number of flow limitation events which occur by the number of hours over which events were recorded.

Oscar gives 4 values of flow limitation for:
Min
Med
95%
99.5%

I can understand the Min and Med values.

But what are the 95% and 99.5% values?  

Are those % representative of the hours or the number of events?

[Crimson Nape]

All these values are percentiles, not percents. The 95%-tile value means that this category was at this value, or lower, for 95% of the sleep session. The 99.5%-tile is reported to remove any stray artifacts, that would occur at either max value recorded or100%-tile.

- Red

[DanEm]

Thank you Crimson Nape.

Now the picture is clear. 

So, removing any stray artifacts (99.5%) gives the value of my total Flow Limitation for the sleep time.

It is important that I have the right figure because it will be used to convince my doctor to change her prescription for a BiPAP machine.
According to some studies I read online,

Inspiratory flow limitation can be observed in the polysomnography of normal individuals, with an influence of body weight on percentage of inspiratory flow limitation. However, only 5% of asymptomatic individuals will have more than 30% of total sleep time with inspiratory flow limitation. This suggests that only levels of inspiratory flow limitation > 30% be considered in the process of diagnosing obstructive sleep apnea in the absence of an apnea-hypopnea index > 5 and that < 30% of inspiratory flow limitation may be a normal finding in many patients.


CONCLUSIONS: BiPAP is better treatment modality compared to CPAP in patients with moderate to severe OSAS.

My 99.5% FL is 0.47 for the duration of my treatment and the 95% FL is 0.31 (so says Oscar).

[DanEm]

I went to WiKi and got a snapshot of the normal flow morphology.

Then I captured screens from my OSCAR and added them to the first one.

[attachment=44777]

The top waveform is normal flow from WiKi.

For the middle one,  OSCAR indicate I have more than 0.2 flow limitation for that stretch.

For the bottom one,  OSCAR indicate I have more than 0 flow limitation for that stretch.

To me, they seem mostly all the same.

Is there something to learn from this?