Respironics Data Tutorial

The Philips Respironics System One Auto PAP with A-Flex that I use is a great machine.   It’s whisper quiet, comfortable, and easy to use.  The biggest complaint I have is that the LED screen gives very little data, and it’s hard to read.  The only useful data you can get from the screen is 7 and 30 day averages for AHI’s, and because they are averages, these readings aren’t really that useful at all.

I wasn’t too happy about having to spend $100 out of pocket to buy the Encore Viewer 2.0 software that is required to read the data card, and I’m green with envy for the people who have Resmed S9 machines that show so much data on an easy to read, colorful, LED screen right on the machine.  It’s cumbersome to remove the data card from my machine, plug a card reader (fortunately, the PR S1’s use a standard SD card that can be read by any SD card reader), fire up Encore Viewer, upload the data to my computer, then generate a report (zzzzzzzzzzzzzzzz) that takes time and gives a buttload of data for a week at a time.  Cumbersome!

Nevertheless, the process makes up for itself in that you get a lot of useful data.  When I was having problems with waking in the middle of the night, I could see the graphic representation of exactly why, and understanding what was going on allowed me to fix the problem instead of complaining about it.

Each Encore Viewer report is about 13 or 14 pages right now.  I think these reports will go ever longer, since the software does not allow the user to select any parameters for data except choosing the week for daily details.  The first few pages show compliance information, pressure trends, long-term sleep therapy trends, and patterns of use that always default to starting from the very beginning of CPAP usage to the present time.  Currently it is taking 2 pages to show patterns of use–I suspect that this will take up more and more pages as time goes on.  I’m not quite sure what the point of that is, because this is information for me, the patient (hello, remember me?), NOT a clinician.  I know how much I use it and when.  I could care less about a graphic representation that takes up so much bandwidth.

Finally, on page 6 now, I get to the first page of “Daily Details”.  That is the meat–this shows me exactly what happened during a particular night on my machine.  That’s the useful data.

(To steal a phrase from my favorite knit blogger, click on a graph to “enbiggen”)

Let’s look at leak data first:

The green line at the top of the graph means “Normal Mask Fit”.  So why is the graph shoing leaks around 25-28 LPM?  Every mask has an “acceptable leak rate” depending on the pressure.  If not, no air would come out the CO2 vent.  You can find a chart showing the acceptable leak rate for your mask by looking in the information booklet that came with your mask or looking it up online.  In this case, I was using the Swfit FX mask, and you can see a copy of the chart here (see chart on page 5 called “Pressure Flow Curve”)

Resmed machines show the leak rate as 0 if the leaks are within the acceptable leak rate, but PR’s show the actual leak rate.  In this case, the average leak rate was 26.0 LPM, well within the masks range for the pressures I was using this night.

If you notice a break in data, that’s because I was watching t.v. in the evening and–realizing I was probably going to fall asleep–I put my CPAP on.  When I woke off, I turned it off and got ready for bed, and then put my mask back on for a real sleep.

Pressure data is what I look at next:

My pressure range is 9 to 15 cm H20.  This was a good night, and my pressures stayed fairly low.  Here’s an example of a different night:

It’s very rare for me to bump up against the top pressure like that now that it’s set at 15.  I was having a lot of nasal congestion.  Despite all that, my machine did a great job–my AHI was only 0.2.

Here’s my best night ever:

AHI was 0.0.  July 4, 2010  No fireworks while I slept ;o)  I went to bed around 11:30 (O on the graph) and between 2:30 and 4:30 a.m. (hours 3 to 5 on the graph) I was probably in deep REM sleep.  You can see that the machine handled it beautifully to stop any OA’s CA’s or hypopneas from occurring.

Then I look at the Daily Events Per Hour:

This chart isn’t particularly useful for me at this point in time, but it could be very useful if you are having problems.  For example, someone who is having a lot of central apneas (also called “clear airway” apneas) can look to see if they are being induced at a particular pressure.  Or, if the pressure is too low, it might show increased obstructive apneas and hypopneas a the lower pressures.

Next, there are “Sleep Therapy Flags”:

This chart can be useful to show “cluster” events.  For example, some people may have clusters of OA’s, CA’s, or Hypopneas during REM sleep.  It’s possible to have a fairly low AHI, but if the events are all clustered at a particular time of the night, that can be useful to determine what might be going on if you are not feeling the benefit of your therapy.

Finally, when there’s a problem, it’s helpful to look at the entire page of Daily Details. 

Mine is not particularly useful because since I have such good therapy there’s nothing much to see, but if you look at all three of the top graphs together they can tell you a lot.  For example, if your leaks go up on the leak chart, you might expect to see increases in the events recorded on the Sleep Therapy Flags chart at the same corresponding time, or wild pressure increases.  Or, if you have a sudden and prolonged apnic event, you can expect to see big changes in the pressure to combat it.

If I were to run my machine in straight CPAP mode, the pressure data would be reflected as a flat line, unless I used the ramping feature.

Take a look at your data (you DO have a data capable machine, don’t you????) and see what you can learn.  It’s very useful information.