Is it weird that I dont like my pressure too low?

[avi123]

Treehorn, I am still studying your situation. One thing for sure is that since you need that hi pressure to overcome your flow limitation, you qualify for a BiPAP (=BiLevel) machine according to the American Association of Sleep Medicine (AASM) guidelines.
A BiPAP would let you set the inspiration and expiration pressures separately. In such case you could set your inspiration on 20 cm for example, and the expiration pressure at 8 cm for example. This will make it more comfortable to exhale. If you read in the link that I posted above about UARs you know how the sleep specialist Dr Barry Krakow (pronounced Kraiko) treats UARs with BiPAPS. Dr Krakow himself has problems with UARs and uses hi inhale pressures on his BiPAP.

Let me continue checking my data on FL treatment.

Currently I am checking this report from 2011:

http://www.chestnet.org/accp/pccsu/uppe ... e?page=0,3

[robysue]

I put the autoset in 4-20 range but hated the low when the machine started. I felt like I was starving for air. Kinda cloaustrophic.
I turned the pressure up to 6 and turned off the ramp and now I am much more happy.
It is weird that I prefer my pressure turned up, lol?
I guess whatever floats my boat.

As you know by now, lots of folks agree with you that 4cm (or even 6cm) ps too low for comfort.

The fact is that most of us get used to the pressure we use---if it's high enough to be therapeutic and low enough to not blow us up like a basketball or trigger massive leaks.

For me? I'm quit comfortable breathing at my starting pressures of IPAP=6 and EPAP=4. Most folks around here would find that hard to take---the need and are used to pressures that are quite a bit higher. But I find that at the modest CPAP pressure of 9cm I wake up feeling like I swallowed a basketball. And that's got a lot to do with why I have no problems breathing at my low pressures. And since the AHI is almost always below 2.5 in my current, tight, and low pressure Auto range, there's no real need for me to use a higher pressure range.

But I'm an outlier. Most people need more than 4-6cm to control the OSA and most people get used to breathing with pressures that feel like a jet engine to me. And it's really no great surprise that these folks are not comfortable breathing with pressure levels that feel fine to me.

[avi123]

[quote="robysue]
But I'm an outlier. Most people need more than 4-6cm to control the OSA and most people get used to breathing with pressures that feel like a jet engine to me. And it's really no great surprise that these folks are not comfortable breathing with pressure levels that feel fine to me.[/quote]


RobySue,

Thanks for the PM about the "Average Pressure" in SleepyHead. I don't know why Jedimark went the route of "weighted average"?

As to TreeHorn, notice that according to the following report by the famous UAR specilaist Prof Guilleminaul , TreeHorn does not have OSA [hardly any obstructive events ] but has UAR (Flow Limitation), which is a seperate disease according to Guilleminaul .

Link:

http://www.chestnet.org/accp/pccsu/uppe ... e?page=0,3

[robysue]

RobySue,

Thanks for the PM about the "Average Pressure" in SleepyHead. I don't know why Jedimark went the route of "weighted average"?

Because the usual mathematical meaning of the word "average" in the kind of data we're looking at in both leak data and pressure data is indeed a weighted average. And he wanted to get the mathematics right.

By the way, in SH 0.9.2 JediMark allows the user to choose between "average" and "median" for the "middle" calculations. Personally, I find the median pressure, leak, and snore numbers to be more useful and meaningful than the averages.

[avi123]

TreeHoren, after going over the following from Dr Barry Krakow:


Source:

viewtopic/t26622/UARS--A-Critical-Link- ... sults.html

Excerpt,


Is Bilevel the Answer?

Why bilevel works so well is still a puzzle. But, what’s so intriguing is that the subjective and objective findings match. That is, nearly all patients who switch from CPAP to bilevel state that it is easier (subjectively) to breathe out with bilevel. And, during their titrations, the ratty airflow signal disappears on expiration (objectively) and is replaced by a smooth and rounded curve indicating normal expiration.

Should you be able to produce the same results with CFLEX, APAP, etc? Presumably so, except for one “large” difference. You cannot generate the same gradient or gap between IPAP and EPAP with any of the other devices. And, in our clinical and research experience, we are using gaps of 4 to 12 cm of water in our patients. My personal bilevel settings are 21/12.5 for a gap of 8.5.

In our prescriptions for bilevel, I would venture that the average gap is in the 5 to 6 range with tremendous variation, including some with a gap of only 2 or 3. Those with a lower gap requirement would likely do as well on FLEX or APAP, but to repeat, the large majority of our patients have a gap of 4 or greater.

Still, it would be nice to have a respiratory physiologist explain to us why the larger gap is so effective. As an internist and sleep medicine physician, there are only two obvious theories that stand out. First, what if we’ve always assumed, mistakenly, that airway pressure had to be constant for both inspiration and expiration? I think it has already been proven by other researchers that you actually need higher pressure to keep the airway pinned open on inspiration and a lower pressure on expiration. If that’s so, then is bilevel the best system because it provides the exact pressure you need (not too much and not too little) during expiration.

The second idea relates more to the psychophysiological response to PAP therapy. Maybe the larger gradient simply gives the patient a distinctly more comfortable feeling, because the lower pressure creates a feeling so much closer to breathing normally (without PAP). If this theory were accurate, though, it would imply that over time as you get used to any sort of PAP therapy, then perhaps the gap would narrow and eventually you could use fixed CPAP again. If this were true, I would expect more people to eventually adapt to fixed CPAP pressure, and I don’t believe that’s occurring.

Notice that those "gaps" that Dr Krakow is talking about are between the settings of inspiration and expiration pressures. Dr Krakow's own setting on his BiPAP are 21/12.5. So he is inspiring with max pressure of 21 cm and exhaling with a pressure of 12.5 cm.

Let's try to duplicte it on the S9 Autoset that you use. I would try to set your S9 Autoset in APAP mode with a minimum pressure of 10 cm and a max pressure of 18 cm (or 20 cm), with NO RAMP, EPR =3 , full time, and see how you feel. Try to show ResScan graphs of Pressure, Snore, and Flow Limitation.

[Treehorn]

Like I said, cold is gone. A very stressfull week is behind me. Normal sleep has resumed. Im impressed that with the new mask and masine I have been able to get my AHI down to zero. Flow has improved but not sure how it compares to others flow. I read the article in the link. Very interesting. What do you think of the new data?

[avi123]

Hey TreeHorn it looks GREATE! I can't believe the "all zeros" in the AHIs, and it for 8 hours sleep!

[archangle]

It's always seemed weird to me that while sitting there with no CPAP (i.e. pressure =0), you feel fine, but put on CPAP at 4 cmH2O, and you feel you can't get air.

However, I do agree it feels that way.

[BigLou]

This is great stuff guys. Thanks from afar for the interesting links AVI. I mentioned UARS to my sleep doc last month and he just shook his head....ahh,dahh.

We must advocate for ourselves until the sleep docs get up to speed on the many faces of SDB. My 2 cents...... but I'm just an eye doc.

[Slartybartfast]

With the S9 Autoset, anytime I start getting more than two days in a row that show 0.0 AHI, I unplug the machine and let it rest during the day, then plug it in before going to bed. Something happens periodically to my machine, and I've heard others as well, that causes them to not record events. So when the data looks too good to be true, try resetting the machine and make sure you're not being lied to.

Re: your pressure range, I was looking at your pressure limits. I simply can't breathe at 6 cm. 8 cm is much more comfortable. My titration was for 11 cm, and after 2 years of fiddling around, I found I agree with the conventional wisdom on this board and set my lower limit 2 cm below my titrated pressure, at 9 cm. I leave the upper limit at 20 and have never seen the pressure go above 14 cm. The common recommendation to set an upper pressure limit I think might stem from a time when less sophisticated machines could run away with you, pressure-wise. I've never had that happen with either my S9 Autoset nor my Intellipap.

Returning to the low pressure limit, it looks like you've already discovered that it's important that the lower limit be set to a level that your pressure trace occasionally touches. If the low pressure limit is set too low, then when the machine detects and responds to an anomaly, it will take longer for the pressure to build to an effective level. Keeping the lower limit at a reasonably high level insures that your machine will respond quickly enough that your sleep won't be disturbed.

Below is a pressure trace that I recorded on a particularly placid night about one month into this adventure. I think I had the limits set at 8 and 13 then. I've since upped the low limit to 9 or 9.5 and 20 and everything's good.

[KEQ5]

My reasoning is a lot like Slarty's. I left things alone for the first 10 days (started at 4-20 with EPR 2), then started changing things so that I was 6-20. Looked at my graphs some more, got some more experience, then tweaked.

Most nights, my pressure bounces between 9-11, sometimes going up into the 12-13 range. So I now have my minimum set as 9cm with EPR of 3. But I did it gradually, going from 4 to 6 to 8 then 9 over the course of 4-6 weeks. I'm tempted to go back to an EPR of 2 but my AHI is almost always below 2.0 so I'm not inclined to fiddle.

I still like to set my top pressure at something less then 20cm. I have it set as 16 right now because:

- My mask leaks horribly at 17+ as I can't get a really good seal, but it's a wonderful mask at 15 and below.

- I get aerophagia at pressures above 16-ish.

- I've had the S9 Autoset take the pressure from 9.2 to 12.5 in the space of 30 seconds because it detected flow limitations and snoring. Another night it went from 9.2 to 15.2 in about 5 minutes.

Most of the time, I top out at around 12.5-13.5 on the graphs. So a maximum of 16 still leaves some headroom, given that I get the aerophagia and mask leaks above 16.

[avi123]

With the S9 Autoset, anytime I start getting more than two days in a row that show 0.0 AHI, I unplug the machine and let it rest during the day, then plug it in before going to bed. Something happens periodically to my machine, and I've heard others as well, that causes them to not record events. So when the data looks too good to be true, try resetting the machine and make sure you're not being lied to.

Re: your pressure range, I was looking at your pressure limits. I simply can't breathe at 6 cm. 8 cm is much more comfortable. My titration was for 11 cm, and after 2 years of fiddling around, I found I agree with the conventional wisdom on this board and set my lower limit 2 cm below my titrated pressure, at 9 cm. I leave the upper limit at 20 and have never seen the pressure go above 14 cm. The common recommendation to set an upper pressure limit I think might stem from a time when less sophisticated machines could run away with you, pressure-wise. I've never had that happen with either my S9 Autoset nor my Intellipap.

Returning to the low pressure limit, it looks like you've already discovered that it's important that the lower limit be set to a level that your pressure trace occasionally touches. If the low pressure limit is set too low, then when the machine detects and responds to an anomaly, it will take longer for the pressure to build to an effective level. Keeping the lower limit at a reasonably high level insures that your machine will respond quickly enough that your sleep won't be disturbed.

Below is a pressure trace that I recorded on a particularly placid night about one month into this adventure. I think I had the limits set at 8 and 13 then. I've since upped the low limit to 9 or 9.5 and 20 and everything's good.

Comment,

Starty, since I was prescribed a pressure of 13 cm in my last sleep steady being the most effective pressure for me ON CPASP, IMO it's not beneficial for me (given the damaging effects of higher pressures) to set my APAP on 20 cm, even if there would remain a couple of events untreated.

[Sir NoddinOff]

The first week I was on this forum, some well-meaning soul advised me to set my PR S1 Auto to 4cm Pmin to 20cm Pmax. That was probably the worst advice I've had in decades. I hated the low pressure almost more than I hated the high pressure ,which was zooming all over the place 'chasing leaks' all night long. Man, it was misery. Now I'm set at 8-12 and find that a good median setting for me, (Note: I'm not a sleep doc, therefore I'm not recommending this setting for others... go find your own best pressure!)

[Xney]

The idea of an "open" range of like 4-20 is so you can see where the pressure "needs" to be for a night or two. Then you want to tighten it down.

I would say most people probably want an eventual APAP range of about 4 to 5 cm from minimum to maximum.

[archangle]

The idea of an "open" range of like 4-20 is so you can see where the pressure "needs" to be for a night or two. Then you want to tighten it down.

Unfortunately, a lot of doctors, DMEs, and other "experts" think that's the only way to use an APAP.