I don't TRUST my PRS1's LCD: Am I missing something?

Ok folks,

I like to have overnight AHI numbers when I wake up and the PR S1 only gives seven day averages. And I know that resetting the data every day back to 0 should make the machine report a 1 day average in the morning which should be the overnight figure for me, right?

Well I must be doing something wrong because the last three mornings when I check the LCD, the therapy hours are listed as 4 hours and some odd minutes when the actual number of therapy hours ranges from 6 1/2 to 7 1/2 hours. Of course, the fact that the number of therapy hours is wrong makes the LCD's AHI also incorrect.

Putting the SD card into Encore Viewer shows that the SD card has the correct number of therapy hours on it. Hence I've got no reason to believe that the rest of the data on the SD card is incorrect. Indeed, the scatter prints of events, the AHI numbers, the leak data, etc all look consistent with how I've felt each of the days, given the head cold I've had the last two nights and the nasty migraine I woke up with during the night of Dec. 23---complete with a large cluster of events that night. In going through data these past several weeks, I'm beginning to suspect that apnea clusters may be a migraine trigger for me. But that's material for another post.

So I'm suspecting that either I'm missing a step in resetting the data and the numbers I'm looking at the morning are somehow two day averages OR there's some kind of a clock setting on the PR S1 that's set incorrectly and i'm rolling across "days", although that's not showing up in EncoreViewer's one primative Patterns of Use table, where you get to see an indication of what time of day the machine was running.

So, any ideas? And if anybody who regularly resets the data successfully on their PR could post the step-by-step instructions, I'd appreciate it. I really don't want to have to download the data every single morning once my spring semester starts and things get hectic again.

And a very Merry Christmas to all!

robysue

PS: And continuing the theme of time stamps---Is there any way at all of making Encore Viewer replace the vague horizontal axis labels of "0, 1, 2, 3, ..." etc with the more meaningul real time of night the machine was running? Thanks

I have a PR System One Auto and reset my data every evening. I do this because I often have a nap during the day (because of Rheumatoid Arthritis fatigue) and I don't want my nap data to be there. I get the card out in the morning and get my night's data. I tried just leaving the card out as I did when I napped when I used the M Series auto and that worked. I had no nap data on the card. It doesn't work the same way with the System One. I tried it, without resetting the data and no card in while napping (as I could do with the M Series) but the System One holds the data and puts it on the card as soon as you put the card in. I found out how to reset the data because of this.

To do this, I go into "setup mode" (holding the 2 buttons until it beeps twice).

Then I go into "Info". Scroll down to "reset data" and push the big button until it beeps. You can then check to see if things are at 0 to be sure it is reset to 0.

Ok,

I've started to double check myself on this. But this "therapy hours" being way, way too short and the machine's LCD AHI consequently being meaningless has now happened 2 out of the four nights I've owned the machine. So it's caught my eye and not in a good way.

I am 99% sure that I cleared the data correctly. But tonight I will double and triple check that the data is really cleared by checking to make sure they're all at 0.0 before I turn the mask on.

But here are some interesting things to ponder for troubleshooting the issue. If you have ideas about what's going on, please chime in.

In the clinician's Info menu, there are "blower hours" and "therapy hours". The "blower hours" correctly report the number of hours the machine was on last night and agree with the EncoreView report for how many hours the machine was on. "Therapy hours" gives the same incorrect figure that is shown in the patient's Info menu. Blower hours is not the same as machine hours which is the total number of hours the machine has been run in its lifetime, which can never be reset back to zero.

The clinician's and patient's Info menus both report the same (incorrect) AHI that I cannot figure out where it comes from or what it means.

Here's the actual data:

PR S1's LCD for night of 12/24 to 12/25:

• Therapy hours: 4:12
  Blower Hours: 6.4 (only on the Clinician's Info menu)
  Days > 4: 1 (Not a surprise since I cleared the data last night)
  AHI: 1.4

Data from Encore Viewer for 12/24 to 12/25:

• Usage (for this night) 6 hours, 22 minutes, 22 seconds (which works out to be about 6.4 hours)
  Blower time (for this night) 6 hours, 22 minutes, 22 seconds
  AHI: 1.6

Now the important thing to me is that I'm trying to track nights where I may have potential clusters of events so that I know that I need to download the data and take a good look-see. These are clusters of 7--10 events occurring in a one to two hour period. Now obviously, in order to have such a cluster, I have to have at least that many events.

Now if I just trusted the numbers from the patient's Info menu on the LCD woke up this morning, I would have written this down in my log of events:

(1.4 events per hour) *( 4.2 hours of sleep)= 5.8 = 5 or 6 events

But this is HIGHLY misleading (in my humble opinion as a mathematician) since the real numbers---from Encore---indicate that I had ALMOST TWICE that number of events---enough for some potential clustering:

(1.6 events per hour)*(6.4 hours of "sleep") = 10.24 events = 10 or 11 events over night

So what gives? What is my PR S1 counting as "therapy hours" vs. "blower hours"? It's not merely ramp time: I thought about that. But subtracting ramp time off the blower time still leaves a gap of over an hour: my ramp time is set to 30 minutes and it was hit twice last night. So there was a total of 60 minutes of ramp time. So that means we've got:

6:22 of blower time - 1:00 ramp time = 5:22 of therapy time?

but the LCD says 4:12 of therapy time. So either that's not the problem or that's not all of the problem.

Depending on how the machine was programed to compute weekly averages, they generally add up the last seven days, which will be zero's if all erased then it is divided by seven. With this method you will not have a good average until you get seven full days of data.So that for one days worth of data of 4.5 AHI you get (4.5+0+0+0+0+0+0)/7= 0.642. Because they say it is a seven day average you should not trust it for daily data.

When I wanted my data daily, I would remove the card every day and download the data in into the software. The daily wave report (someone correct on the report's name) is a great report and only available if you do the datacard download daily. You also have to make a special effort to save this report, the software doesn't do it automatically for you.

This report will give you tons of detailed data about your nightly sleep.

Its tedious and time consuming to have to do it this way, and because of that I stopped doing it months ago and gave up caring about having detailed data to analyze every day.

The lack of daily and more detailed data being available via readout on the LCD on the PRS1 is one of the things I detest about this machine, primarily because its something Respironics specifically and intentionally programmed the machine to keep from the user.

PhysicsBob wrote:

...So that for one days worth of data of 4.5 AHI you get (4.5+0+0+0+0+0+0)/7= 0.642. Because they say it is a seven day average you should not trust it for daily data.

It makes sense to think it would work that way, but it does not divide by 7. Nor does it divide by 7 or 30 in the week and month reporting windows for the hours data. The AHI after one night is the same (or at least within about .1, perhaps a rounding difference?) as is reported in the EncoreViewer data for the day.

robysue wrote:

...Blower Hours: 6.4 (only on the Clinician's Info menu)...

I'm not sure I understand, are you saying in the user's info menu it is not also "Blower Hours: 6.4"? But my user info always matches the duplicated sections in the clinician's info menu. In any case I'm baffled by the behavior of your machine.

You can do a search for "Respironics" and "Math" on the forum -- Respironics' math has always been considered unique by those who ran into it....

A rather wild thought about the difference between "blower hours" and "therapy hours" - and please bear in mind that I have no experience with this machine: Could the machine be subtracting time in "RERA" from "therapy hours" because it considers you awake?

O.