Can someone explain 90% pressure?

[ChicagoGranny]

but this particular person is pretty take charge (i.e. she needs to be the expert)

[palerider]

I'm curious as to why machines aren't designed to respond with appropriate pressure period. Just a flat minimum setting, then bring on the needed pressure as high as it may take. Done.

everybody is different, that's why machines go from 3 to 30cm of pressure. and there are 14 different resmed s9 machines, 8 airsense/aircurve 10 machines, and 7 or 8 different respironics machines.

the minimum pressure YOU need isn't going to be what I need, or Granny needs, or Pugsy needs. that's why the machines have settings, and (hopefully) provide data.

stop faffing about, download sleepyhead, stop GUESSING and SET a minimum pressure that's appropriate to YOU.

[wm_hess]

Everybody thinks it means that your pressure was at that level for 90% of the time. What it really means is that your pressure was AT OR BELOW that number for 90% of the time. So if you're running a range of 10-15, let's say, and you spend most of the night at 12 but your pressure spikes briefly to 15, your reported 90% figure will be 15, when you actually spent most of your night at a pressure lower than that.

I wish they'd stop using the 90% figure (or 95% in some cases), as it's confusing to everyone.

HTH

Hi just wanted to get clarification on something in this post.

If you spend most of the night at 12, with only a brief pressure spike to 15 wouldn't your 90% be at 12 not 15? Yes they might have jumped to 15 but the majority of the time it would have been 12 (or below). The way I see it the 10% is a cushion to eliminate the transient spikes in pressure

Thanks!

-Bill

[Wulfman...]

Everybody thinks it means that your pressure was at that level for 90% of the time. What it really means is that your pressure was AT OR BELOW that number for 90% of the time. So if you're running a range of 10-15, let's say, and you spend most of the night at 12 but your pressure spikes briefly to 15, your reported 90% figure will be 15, when you actually spent most of your night at a pressure lower than that.

I wish they'd stop using the 90% figure (or 95% in some cases), as it's confusing to everyone.

HTH

Hi just wanted to get clarification on something in this post.

If you spend most of the night at 12, with only a brief pressure spike to 15 wouldn't your 90% be at 12 not 15? Yes they might have jumped to 15 but the majority of the time it would have been 12 (or below). The way I see it the 10% is a cushion to eliminate the transient spikes in pressure

Thanks!

-Bill

It all depends on what the definition of "brief" is. ( to paraphrase WJC )
May be one or the other or somewhere in-between. It's whatever the machine calculates it to be.


Den

.

[ChicagoGranny]

Post was incorrect.

[wm_hess]

wouldn't your 90% be at 12 not 15

Does it help if you think of the inverse? If your 90% pressure is 12, that means that 10% of the time the machine ran at a pressure higher than 12.

I understand and agree with you. BB, in her post said if he had a brief period of time at 15 with the majority of the night around 12, his 90% would be 15. I thought it would report it around 12.

[palerider]

wouldn't your 90% be at 12 not 15

Does it help if you think of the inverse? If your 90% pressure is 12, that means that 10% of the time the machine ran at a pressure higher than 12.

not necessarily. it could have spent 0% of the time above 12.

[palerider]

wouldn't your 90% be at 12 not 15

Does it help if you think of the inverse? If your 90% pressure is 12, that means that 10% of the time the machine ran at a pressure higher than 12.

I understand and agree with you. BB, in her post said if he had a brief period of time at 15 with the majority of the night around 12, his 90% would be 15. I thought it would report it around 12.

again, as explained better here: http://adventures-in-hosehead-land.blog ... de-to.html 90% pressure has nothing to do with how much of the night anything was at anything... it's simply the specific number that happened when you arrange all the readings from the night in order, smallest to largest, and then take the one that happens to be 90% of the way along that list.

[ChicagoGranny]

not necessarily. it could have spent 0% of the time above 12.

I stand corrected.

Does anyone know how often a pressure data point is recorded?

[palerider]

not necessarily. it could have spent 0% of the time above 12.

I stand corrected.

Does anyone know how often a pressure data point is recorded?

depends on the machine.
resmed s9 as/ac10, record pressure twice a second.

[wm_hess]

wouldn't your 90% be at 12 not 15

Does it help if you think of the inverse? If your 90% pressure is 12, that means that 10% of the time the machine ran at a pressure higher than 12.

I understand and agree with you. BB, in her post said if he had a brief period of time at 15 with the majority of the night around 12, his 90% would be 15. I thought it would report it around 12.

again, as explained better here: http://adventures-in-hosehead-land.blog ... de-to.html 90% pressure has nothing to do with how much of the night anything was at anything... it's simply the specific number that happened when you arrange all the readings from the night in order, smallest to largest, and then take the one that happens to be 90% of the way along that list.

Thank you PaleRider. I have read the blog by RobySue and copy this from her blog (APAPS in auto mode section)

The 90% pressure is 11 cm H2O. This means that for 90% of the night, your pressure was AT or BELOW 11 cm H2O and for 10% of the night your pressure was AT or ABOVE 11 cm H2O.

I only quoted the posting that I had a question about, and said I was getting clarification on that post. In that posting that I originally replied to the poster used an example that for most of the night you were at 12, but briefly at 15. Depends on your interpretation of briefly I guess. I viewed it as something like 10 to 20 minutes out of an 8 hour night. The poster though said your 90% would be 15. 10 to 20 minutes out of 480 minutes (8 hours) is no where near 10% From the example information I assumed the balance of the night was around 12. Data would have around 465 minutes at 12 and 15 minutes at 15. Since 10% of the 480 minutes would be 48 minutes that 90% mark would be in the 12 range.

It's not that important to me, and has absolutely nothing to do with the OP (sorry for the hijack). I just thought the example given might be faulty.

Have a good day!

-Bill

[SewTired]

I find myself just ignoring the 95 percent thing because I'm not sure of its usefulness to me on a day to day basis. I look at my graph, and most of the night, I'm under 9.5. It only goes higher during REM or a major leak. So 80 percent of the night I'm under 9.5, but the 95 percent says 11.25.

To a doctor, it probably is useful as compared to another patient it's not say 15. Or, if they looked at the history, there is an obvious trend. A static number probably helps in this case.

I did notice though that the 95 percent I was getting was much lower on the used s9 that I had in May than on my current Airsense For Her. I noticed that on my loaner Respironics 560 as well but put it down to variations between manufacturers. Did anybody else notice a big variance (2 cm) between your old s9 and your new Airsense?

[Jay Aitchsee]

I only quoted the posting that I had a question about, and said I was getting clarification on that post. In that posting that I originally replied to the poster used an example that for most of the night you were at 12, but briefly at 15. Depends on your interpretation of briefly I guess. I viewed it as something like 10 to 20 minutes out of an 8 hour night. The poster though said your 90% would be 15. 10 to 20 minutes out of 480 minutes (8 hours) is no where near 10% From the example information I assumed the balance of the night was around 12. Data would have around 465 minutes at 12 and 15 minutes at 15. Since 10% of the 480 minutes would be 48 minutes that 90% mark would be in the 12 range.

I agree with you, Bill. I think that post was a little misleading. The 90% result may or may not be 15, depending on the total number of data points collected and the number collected at 15 or higher.

Example: 2 sets of 10 pressure data points arranged low to high. The 90th percentile is the 9nth number in each set.

10 10 10 10 10 11 12 15 15 15 (90th percentile = 15)

10 10 10 10 10 11 12 12 12 15 (90th percentile = 12)

[ChicagoGranny]

resmed s9 as/ac10, record pressure twice a second.

Well then, in that case ...

Example: 2 sets of pressure data points arranged low to high

10 10 10 10 10 10 11 12 15 15 15 (90th percentile = 15)

10 10 10 10 10 10 11 12 12 12 15 (90th percentile = 12)

... tiny data sets like this are very misleading.

[Jay Aitchsee]

... tiny data sets like this are very misleading.

Perhaps, but easier than typing 57600 example data points for an 8 hour night