Significance of 90% pressure number

[MikeSleeper]

Using encore viewer I see the 90% pressure reading displayed with major prominence, as if I should know what it means. I saw this answered partially in another post... you were at that pressure 90% or less of the time in that sleep session, which I get... but what I didn't see answered was "why is this such an important number?" (if answered elsewhere, sorry... for some reason if you put "90%" or even "90"in the search field on this forum site it rejects it, so cannot search for answers).

My thought is maybe it is the "statistically significant" high pressure reading during the night?

The real question is "how do you use this information?" Can you use it to adjust your APAP range settings more accurately somehow? Something else?

Thanks for any thoughts.

[ozij]

The real question is "how do you use this information?" Can you use it to adjust your APAP range settings more accurately somehow? Something else?

Hi Mike,
Read "Our Collective Wisdom" and "CPAP FAQ" both at about the top third of the main forum screen.

And then there's MileHighSleeper's blog:
http://www.smart-sleep-apnea.blogspot.com/

You'll learn a lot from all those sources.


O.

[NightHawkeye]

My thought is maybe it is the "statistically significant" high pressure reading during the night?

Nope. The 90% number is just a statistic, not much separating it from a thousand other statistics. The manufacturer could just as well have pulled out 95%, 85%, 75%, or 98% from ..., wherever it is they pull numbers from.

The real question is "how do you use this information?" Can you use it to adjust your APAP range settings more accurately somehow? Something else?

You could use it the way sleep labs have been reported to do and set your CPAP titration to that value and see what your residual AHI is. You might still have to make adjustments to lower the residual AHI though.

But, you're using your machine in APAP mode. So as long as your pressure range extends in both directions beyond the 90% pressure value, then it's merely one of about a dozen indicators available to you which provide some insight into your therapy.

Regards,
Bill

[DreamStalker]

Using encore viewer I see the 90% pressure reading displayed with major prominence, as if I should know what it means. I saw this answered partially in another post... you were at that pressure 90% or less of the time in that sleep session, which I get... but what I didn't see answered was "why is this such an important number?" (if answered elsewhere, sorry... for some reason if you put "90%" or even "90"in the search field on this forum site it rejects it, so cannot search for answers).

My thought is maybe it is the "statistically significant" high pressure reading during the night?

The real question is "how do you use this information?" Can you use it to adjust your APAP range settings more accurately somehow? Something else?

Thanks for any thoughts.

The 90 or 95 percentile may stem form the "it's good enough for government work protocol". In other words, the 90th percentile (or 95th for ResMed) should take care of 90% of your apnea/hypopnea events and if you were to set it to a single pressure CPAP mode, the 90% pressure value is the one you would want to use. Additionally, the 90% value can be used to as the min pressure setting in APAP mode (that's the way I have used it and this works well for me with a 0.3 average AHI).

[MikeSleeper]

Thanks all, v. good info, I appreciate it. (I originally tried the Collective Wisdom and FAQ but did not see it, could have missed it... maybe someone has a specific link).

Dreamstalker, you mentioned: "Additionally, the 90% value can be used to as the min pressure setting in APAP mode (that's the way I have used it and this works well for me with a 0.3 average AHI). "

That makes sense, I'll try that. Thanks.

Michael

[Guest]

Hey Dreamstalker, your remark about using your 90% pressure as your lower number in APAP mode caught my eye. I gave up on APAP and went back to CPAP. But certain forum friends are not real impressed with my reports when I send them to them.

Yeah, I'm mystified by the reports... I'm lame... Thank God I have friends here that love me...

Anyway, if the 90% is your bottom, what do you pick for your top number?

I might give APAP a try again.... Must keep trying everything...

Many thanks!
Babette

[Wulfman]

My take on the 90% is......"it depends".

It depends on:
How low your bottom pressure is.
What events are causing the pressure increases to reach it.....including:
Mask/mouth leakage.
Snoring.
Flow limitations/Apneas/hypopneas.

The 90% number can be a moving target.....or it can be fairly close.

Analyzing the software reports gives a better picture of whether it's usable number or not. I wouldn't trust that number from an LCD screen without corroborating data.


Den

[Wulfman]

Hey Dreamstalker, your remark about using your 90% pressure as your lower number in APAP mode caught my eye. I gave up on APAP and went back to CPAP. But certain forum friends are not real impressed with my reports when I send them to them.

Yeah, I'm mystified by the reports... I'm lame... Thank God I have friends here that love me...

Anyway, if the 90% is your bottom, what do you pick for your top number?

I might give APAP a try again.... Must keep trying everything...

Many thanks!
Babette

Similar logic should apply to the top number, too.

Den

[DreamStalker]

Hey Dreamstalker, your remark about using your 90% pressure as your lower number in APAP mode caught my eye. I gave up on APAP and went back to CPAP. But certain forum friends are not real impressed with my reports when I send them to them.

Yeah, I'm mystified by the reports... I'm lame... Thank God I have friends here that love me...

Anyway, if the 90% is your bottom, what do you pick for your top number?

I might give APAP a try again.... Must keep trying everything...

Many thanks!
Babette

Hey Babs,

I suppose you are already aware of the disclaimer … “everyone is different”.

As I learned to tweak my therapy early on, I discovered that my pressure needs were greater when sleeping on my back than when sleeping on my side. What I also observed about myself was that I toss and turn a lot when I sleep even though I would go to sleep on my side with the intention of staying on my side (that observation also helped me to choose the right hose routing method too).

So if I could stay put on my side, I would probably do just fine with fixed CPAP mode. Alternatively, I could just use a higher pressure in CPAP mode to cover back sleeping but then I get the stomach gas side-effect. The aerophagia side-effect is usually not real severe but why endure it if I don’t have to with the APAP option?

After many months of data and observation I have learned what my min pressure requirement is (90% value = 11 cm using AFLEX of 3) and that I need between 14 and 15 cm to cover those periods when I land on my back during the toss-n-turn sleep night (my max pressure or top number). So my APAP is running in a relatively short range to provide the safety of covering events when sleeping on my back … that’s my basic tweaking strategy. I must say it works well for me as I rarely have AHI nights over 0.4 and I get zero AHI readings at least 2 or 3 times a week. The SPO 7500 oximeter that I acquired a month or two ago confirms that I maintain between 96% and 97% O2 saturations for more than 99% of the time.

I decided to try the exhalation relief after following Dr. Krakow’s posts a few months back and I do like the AFLEX results and have stuck with that for the past couple of months. This however led to another recent discovery for me, that if I use exhalation relief, I need to shift both my min and max pressure up by about 2 cm when using an AFLEX setting of 3. I have learned to pay very close attention to my body not just with PAP treatment but also along my journey to healthier eating and exercise. Like Rested Gal, I too became aware that my apnea events initiate right at the end of exhalation and just before beginning the next inhalation … hence the correlation of having to shift my min and max pressure up a bit to compensate for exhalation relief.

For some reason that I have yet to figure out, CFLEX just does not work as well for me even though I can still achieve AHI of less than about 2.0 (I wake up with mild headaches, groggy, and more tired than usual) and I never got an AHI of zero using CFLEX like I can w/ AFLEX or no exhalation relief at all.

I should also note that my PSG sleep lab study showed no sensitivity to central apneas, so I do have the garden variety OSA condition.

[Guest]

Anyway, if the 90% is your bottom, what do you pick for your top number?

Similar logic should apply to the top number, too.
Den

Yeah, except I have fuzzy logic. I dont' remember PERFECTLY, but I think I was "bracketing" that 90% number when I gave APAP a whirl last summer. Like, if my 90% was 10, I was going 8-12, something like that.

So now, given today's posts, if my 90% was 10, I might go 10-14.

I was convinced I needed to set my pressure BELOW my 90% number, because 10% of the time I was utilizing pressures lower than the 90% number. Make sense?

LOL,
Babs

[DreamStalker]

Anyway, if the 90% is your bottom, what do you pick for your top number?

Similar logic should apply to the top number, too.
Den

Yeah, except I have fuzzy logic. I dont' remember PERFECTLY, but I think I was "bracketing" that 90% number when I gave APAP a whirl last summer. Like, if my 90% was 10, I was going 8-12, something like that.

So now, given today's posts, if my 90% was 10, I might go 10-14.

I was convinced I needed to set my pressure BELOW my 90% number, because 10% of the time I was utilizing pressures lower than the 90% number. Make sense?

LOL,
Babs

Uh no. 10% of the time you are using pressures ABOVE the 90% number.

[MikeSleeper]

Except in my case (just getting started with APAP), where as I slowly work my pressure up, my 90% number still = my max pressure. I Will keep raising max pressure a little at a time untill that is no longer the case (yes, I am watching leakage).

[DreamStalker]

Except in my case (just getting started with APAP), where as I slowly work my pressure up, my 90% number still = my max pressure. I Will keep raising max pressure a little at a time untill that is no longer the case (yes, I am watching leakage).

You also need to be careful about having central apneas listed on your sleep study as increased pressure may make them worse.

[MikeSleeper]

Thanks DreamStalker, Right. No Centrals on sleep study. Also, I notice that Currently most of my apnea events occur well below the max pressures (and so I am also raising minimum to try to better cover those events). If I see apneas show up at higher end will start to suspect centrals. (sound right? I am still very new at this)

Michael

[rested gal]

Currently most of my apnea events occur well below the max pressures (and so I am also raising minimum to try to better cover those events).l

What range is your autopap set for? Sounds like it is the minimum pressure that needs to be raised. Which is often the case for most people, if the minimum in the range has been set very low, like at 4 or 5.

If you were using CPAP instead of autopap, what was the single pressure suggested by your sleep study? In other words, if the doctor had prescribed "CPAP", what single pressure would he have put on the Rx?