Two noob questions that I should know the answers to

[old dude]

But don't, since I've coasted along fine for the last few years thinking everything was just fine. But since a recent move and new bed, it's like I'm starting all over again, so here goes:

1. Which of the three pressure metrics do you pay the most attention to, and why? I'm talking about max pressure, 95% pressure and median pressure. Maybe it depends on what you're going to use the pressure to inform you about?

2. In SH there is what appears to be an hourly AHI chart. If your overall AHI for the entire night is acceptable (say under 2.0), how much do you worry about bursts through the night where it goes much higher, say 10-15 for various periods?

Thanks for opinions.

[palerider]

But don't, since I've coasted along fine for the last few years thinking everything was just fine. But since a recent move and new bed, it's like I'm starting all over again, so here goes:

1. Which of the three pressure metrics do you pay the most attention to, and why? I'm talking about max pressure, 95% pressure and median pressure. Maybe it depends on what you're going to use the pressure to inform you about?

None of them. they're all just curiosity statistics. What matters is the way the pressure curve behaves during the night.

2. In SH there is what appears to be an hourly AHI chart. If your overall AHI for the entire night is acceptable (say under 2.0), how much do you worry about bursts through the night where it goes much higher, say 10-15 for various periods?

As far as I'm concerned, the AHI chart is useless. All it's good for is saying "oh, look, you had several events around this time", which you can easily see just by glancing at the flags chart.

[zoocrewphoto]

I agree with palerider.

I never look at those pressure numbers. I look at the pressure graph. I like to see a graph that is mostly boring, with maybe a few spikes. But not constantly up and down. If it goes up and down a lot, then I raise the minimum until the graph looks fairly boring. The minimum pressure should be high enough to prevent most events, and it should only need to go up as your need goes up, such as sleeping on your back and/or REM sleep.

The ahi per hour doesn't help either. There are two many goals with ahi. Low for the night, and not too many clusters. It also helps to know if the events are long and get rid of those, but that doesn't show up in the numbers.

[palerider]

I agree with palerider.

I never look at those pressure numbers. I look at the pressure graph. I like to see a graph that is mostly boring, with maybe a few spikes. But not constantly up and down. If it goes up and down a lot, then I raise the minimum until the graph looks fairly boring. The minimum pressure should be high enough to prevent most events, and it should only need to go up as your need goes up, such as sleeping on your back and/or REM sleep.

that's what I look for too.

[old dude]

I agree with palerider.

I never look at those pressure numbers. I look at the pressure graph. I like to see a graph that is mostly boring, with maybe a few spikes. But not constantly up and down. If it goes up and down a lot, then I raise the minimum until the graph looks fairly boring. The minimum pressure should be high enough to prevent most events, and it should only need to go up as your need goes up, such as sleeping on your back and/or REM sleep.

The ahi per hour doesn't help either. There are two many goals with ahi. Low for the night, and not too many clusters. It also helps to know if the events are long and get rid of those, but that doesn't show up in the numbers.

Is there any way to reliably identify REM sleep from a SH chart? I've always considered a higher pressure plateau that occurs at appx. 90 minutes after sleep onset to be REM, but I could be reaching here.

[Pugsy]

No real accurate way to identify REM with the data available from the machine.

But...your 90 minute idea..that's fairly commonplace. First REM is normally around 90 minutes after sleep onset.
If you google "sleep stages" and then look at some nice normal hypnograms then you can get and idea when REM usually happens (assuming we don't have major wake ups in the middle to mess with the cycles) and get a fairly decent idea when you are having REM.
The first is typically about 90 minutes after sleep onset is not very prolonged...the rest of them start coming on more frequently and lasting longer as the night progresses.
The greatest amount of REM occurs in those wee hours of the morning.

[Jay Aitchsee]

Is there any way to reliably identify REM sleep from a SH chart? I've always considered a higher pressure plateau that occurs at appx. 90 minutes after sleep onset to be REM, but I could be reaching here.

viewtopic.php?t=175444&p=1299718#p1299718

Have a look at this: viewtopic/t158359/Tracking-sleep-stages.html#p1218669 A comparison to SleepyHead and a ResMed S+ sleep tracker, reproduced below.

Generally, one might expect fluctuations in Respirartory Rate during REM. In the comparison graphics below, one can see that REM periods identified by the S+ Tracker roughly correspond to periods of increased fluctuations in Respiratory Rate (Which could also represent awake periods).



The example below shows a very strong correlation between what the S+ tracker thinks is REM and more erratic Respiration Rate, where S+ sleep stages are represented by: Red=Wake, Gold=REM, Blue=Deep, and Green=Light

splus.JPG

As stated, the only way to know for sure what sleep stage one is in is through lab analysis, although many OTC trackers claim to be able to accurately report them.

My "pressure plateaus" roughly correspond to these periods of more erratic respiration rates as well.

[Jay Aitchsee]

Is there any way to reliably identify REM sleep from a SH chart? I've always considered a higher pressure plateau that occurs at appx. 90 minutes after sleep onset to be REM, but I could be reaching here.

So below I've added the pressure graphic to the above example. I think it shows a very strong correlation between increased pressure and what the S+ has identified as REM (gold bars)

spluspssr.JPG