I:E ratio and FL questions

[Dormeo]

First, my thanks to everyone here.  I'm 3 months in and have learned a huge amount by reading threads on the forum.

I was diagnosed via a home sleep study with an AHI of 23.2. Since starting treatment, my AHI has never gone above 0.8 and is usually below 0.5.  I'm very pleased with those numbers, and now I am looking for more information that might help me further improve my health and comfort.  I'd be grateful for thoughts on these two subjects:

1. Ratio of inspiration time to exhalation time.  Reading a recent thread, I learned that the I:E ratio should be about 1:2.  The SH data consistently say my I time is greater than my E time, which concerns me.  When I zoom in to look at breaths, I see pauses around the 0 line with little oscillations.  Could my I:E ratio actually be OK, with the oscillations accounting for the way the data are analyzed and reported?

2.  I consistently have flow limitations that drive the pressure up.  I'm fairly sure the FLs are due to the effects on my nasal passages of a dust-mite allergy.  I hope one day the allergy will be successfully treated, but until then, my question is whether it might make sense to experiment with a fixed max pressure of 7.0.  I suspect that will make me more comfortable both at night and during the day.  (The longer I'm at 8.0, the tighter my chest feels the next day.)  I like the full APR of 3, so I would prefer to go no lower than 7.  Does this idea for an experiment make sense?  Of course, if my AHI went up, I'd go back to 8.

Many thanks!

[Sleeprider]

Welcome to the forum. You've really done some homework and your AHI is very low...is zero even possible? Looking at the closeup on your chart, your I:E ratio is normal. This sample has a respiration rate of about 12 bpm (5-seconds/cycle). Inspiration time is much shorter than expiration, but the "bumps" are causing the machine to count the end of expiration as inspiration. Inhale does not really begin until the flow sharply rises from the zero line, and exhale begins the instant it drops below zero. I would estimate exhale is about 3-seconds in this series with inhale averaging 2-seconds. The breaths are all flow limited and the irregular flow bumps occur rhythmically through the entire cycle. This is often heartbeats translating to the CPAP pressure sensor. Most of us can see this from time to time during exhale as flow nears zero, but it does not usually appear so prevalent. If I count the bumps in a 10 second span I get about 64-66 per minute which is probably not far off your pulse.

Your pressure is at or near 8-cm most of the night, and with EPR at 3, that results in delivered pressure of 8/5. Given the residual flow limitation, I think you should have your pressure settings at 7-11 for a range of 7/4 to 10/7, and I would support fixed pressure if you prefer, but I would expect flow limitations to be nearly the same. Maybe you could increase the nasal pillow size and see if that clears up your perceived nasal restriction, and that might do it without the increase in pressure.

[Dormeo]

Sleeprider, this is so helpful, reassuring, and FAST!  Many, many thanks!

I did recently try going from M to L pillows, but the L is unfortunately too L to work for me.  I may have some follow-up questions about FL and pressure but need to review my earliest SH data first. (I started at a range of 4-20.)

Really appreciate your help!

[Dormeo]

I just wanted to follow up on the recommendation to increase the pressure range, given the FL activity.  Back in October, during my first week with my machine, the pressure range was 5 - 20.  Then, as now, the AHI numbers were good.  (See SH overview chart.)  Although the pressures then certainly ranged higher than the current max of 8, the FL numbers were not lower -- they were in the range of .09 to .11 for the 95% level, as they are now.  (See SH chart for 10/20/18.)  So I concluded that higher pressures wouldn't decrease the FLs. 

Does that sound right, or am I missing an angle?  If pressure increases wouldn't help, I'm pinning my hopes for FL reduction on effective treatment of dust-mite allergy and meanwhile looking for ways to sleep as comfortably as I can, hence my interest in experimenting with a fixed pressure of 7. 

Many thanks for any additional thoughts, Sleeprider -- your help via so many threads has been invaluable!

[Gideon]

I'm going to suggest perhaps another approach.
The ResMed Vauto. That would allow you to initiate PS (EPR) over 3 because of your Flow limitation. Low pressure, higher PS. Do you have a friendly Doctor?

[Sleeprider]

I'm going to suggest perhaps another approach.
The ResMed Vauto.  That would allow you to initiate PS (EPR) over 3 because of your Flow limitation.  Low pressure, higher PS.  Do you have a friendly Doctor,

or about $1000 to self fund?  

Before we go there, increase EPR to 3. Is pressure support that will deal with flow limits and hypopnea, and we might as well exercise the limits of your Airsense 10. I'd like to see minimum pressure at 7, EPR 3 and there is no need to change maximum pressure.

[Dormeo]

Bonjour and Sleeprider, I'm grateful to you both.  My current EPR is already 3, so that part of a possible experiment is in place.  I will first try raising the minimum pressure to 7; depending on how that goes, I will consider the Vauto experiment as well.  I'm very glad to be able to feel I have some grip on the issues and a couple of ideas to pursue.  Merci and thank you!

[Dormeo]

Just an update.  (I wanted to try making my pressure changes through my RT, who is very helpful, so it took a while.) 

I went down to 7.4 - 7.4, then 7.2 - 7.2, both with EPR of 3.  The FL data are the same as they were at 5-20 and 5-8, and AHI continues to look good (see attached).  My RT thinks it is weird to use an APAP machine this way, and I'm sure she's right, but I do feel my nights are now a bit less chaotic, with fewer wake-ups, so unless you advise some further adjustments, I'll probably stay with this for now.

Again, my thanks for all the help I get from posts on this site!

[Sleeprider]

Going back to the image you posted earlier, we can see that with EPR 3 and a pressure of 8.0 there is a prominent flow limitation with heartbeats showing in the wave-form.  If higher minimum pressure does not resolve the flow limits and you remain unrested, the Aircurve 10 Vauto can resolve the flattened inspiratory wave using pressure support rather than higher pressure.  Supplier #2 has a fantastic deal on the Resmed Aircurve 10 at $799, which is pretty hard to beat if you are self-financing.  Clearly, you have 0.0 AHI so your needs and objectives are not going to be well understood by the traditional sleep medicine people as you are already a success story by every measure they consider.

[Dormeo]

Many thanks, Sleeprider. I’ve done some reading to help me absorb your analysis and suggestions, and just now I’ve also read obob’s thread, which has been very helpful. Could you let me know if I have the right picture here? 

High IP can actually widen swollen nasal passages. That is the mechanism by which my FLs would be reduced: wider passages, less constriction of flow.  This would mean I wouldn’t have to work so hard during the night trying to overcome FLs as I inhale, and that would probably mean I would be able to sleep more deeply and experience fewer wake-ups and little arousals.  So sleep architecture would probably improve. Because my apnea is well treated at low pressures, there is no need for me to try to breathe against high EP.  So Vauto might be right for me, since I’d get reduced FLs while still having low EP. 

Am I understanding this correctly?  If so, there will probably be a Vauto in my future!  (I’m going to hold off until my doctor figures out why I’m having a sensation of harshness or rawness in my chest, but as soon as that’s resolved I will swing into action.) 

Again, I can’t thank you enough for thoughtful advice!