ResMed Autoset LCD Reading

[atab]

I got switched from Elite II to Autoset for auto-titration. My earlier sleep lab titrated pressure was 6 and that wasn't working. I used to write down leak, AHI, AI after reading off LCD of elite and I do the same with autoset. On autoset "pressure" is also readable. Last night it read 11.8. Autoset is set to 6-12. So what exactly is the pressure reading here? Highest pressure during the night, average during apneas, or average through-out that night?

-atab

[jdm2857]

Your machine is displaying the 95 centile pressure. That is the pressure that the machine was at or below for 95% of the night. It was above that pressure for 5% of the night.

When you switch from day to week or month, etc. the machine desplays the median of the displayed values for the days in that period. The median is the value for which half of the days the data was below that value and half of the days the data was above that value. It is an average calculation that is less affected by extreme data (say a very bad day) than the mode (regular average).

If you have the AutoSet permanently, you should consider getting the ResScan software and a card reader.

[atab]

Thank you jdm.

So I did not understand something about autoset. My pressure is set to 6-12. I thought the pressure stays at 6, and when an apnea happens it goes up as necessary and then comes down after the apnea incident. If that is the case 95th percentile would be very close to 6. (Last night I had AHI 7.4 and AI 2.1, that is a very small fraction of night .) The reading of 11.8 says that I was near 12 all night. So is it the case that when the pressure goes up, it stays there? That explains why I had a hell of a problem with mask leaking. I think pressure of 12 is very different form 6.

Yes, I will buy software if I stay on autoset. At the moment it is a temporary machine for re-titration.

atab.

[Pugsy]

The reading of 11.8 says that I was near 12 all night. So is it the case that when the pressure goes up, it stays there?

Yep, it stays in that range because it needs to be there or it would fall back to 6 more often. The software will show you what it is responding to and it will become clearer to you.

[jdm2857]

The software responds to snores, flow limitations, and apneas (only at pressures less than 10). It increases pressure in response to events, and slowly decreases the pressure when there are no events. The fact that you pressure stayed up (at a pressure over 10) means that you must have been having either snores or flow limitations that kept the pressure up.

Unfortunately, ResMed software does not show snores or flow limitations, so it is hard to relate pressure changes to events.

[atab]

That clears up my understanding. Thanks all.

Last night I was waking up frequently with mask leaks. I now attribute this to higher pressure. I was on 6 with Elite. I use quattro FF. I guess the mask has to be looser for higher pressure. But how do I go to sleep at a pressure of 6 (starting pressure of APAP) ready for a pressure of 12?

atab

[jnk]

. . . My pressure is set to 6-12. I thought the pressure stays at 6, and when an apnea happens it goes up as necessary and then comes down after the apnea incident. . . .

An auto attempts to be at the lowest, yet still effective, pressure at any given moment for preventing events, as best it can tell. That's the idea, anyway, as I understand it.

. . . The reading of 11.8 says that I was near 12 all night. . . .

I don't think you can know that without software. The reading tells you only a number that you spent 95% of the night at OR BELOW. You MAY have spent much of the night WELL below. Then again, not. But it does seem your pressure did top out at the limit, though, at some point, so the upper-limit pressure may need to go higher.

. . . So is it the case that when the pressure goes up, it stays there? . . .

My understanding is that it comes down gradually if it senses nothing to make it stay there. It does so gradually so as not to disturb your sleep needlessly or cause events.

[atab]

I don't think you can know that without software. The reading tells you only a number that you spent 95% of the night at OR BELOW. You MAY have spent much of the night WELL below. Then again, not. But it does seem your pressure did top out at the limit, though, at some point, so the upper-limit pressure may need to go higher.

Good point. I am a little rusty on my statistics. Yes, 95th percentile can be well off of the mean (or even median). Thanks for pointing out.

atab.

[ricochetv1]

It slowly ramps down to the low pressure over a 20 min. period.

[joeydan]

I sometimes wake up and check my Resmed AutoSet 11 with my mask on and machine running. To my surprise the LCD shows a high pressure even though I'm awake and there is no flow limitation.I've watched for as long as 1 minute with no change in the pressure.Has anyone else noted this and should it take 20 minutes to drop to settling pressure?

[jdm2857]

I shouldn't take 20 minutes for the pressure to begin dropping, but it may not happen in a minute either. Because of conscious control, breathing when awake is less regular than when asleep, and that can confuse the algorithm. For example, holding your breath for 10 seconds can be scored an apnea, and shallow breaths can be scored hypopneas.

[ricochetv1]

And that is the exact reason I set a long settling time on mine.

[Slinky]

And a high leak rate can disrupt the accuracy of your data. Rule # 1, get your leak under control. It took a long time for forum members to get that to sink into my thick skull. The addition of a chin strap PROVED just how smart our forum members are!!! My sleep doctor and DME supplier's RT kept telling me these xPAPs can compensate quite nicely for leaks. And maybe they can - but those high leaks DO make the data unreliable.

Score: Forum Members 1, Sleep Profession 0

[ricochetv1]

Is a .18 L/s rate good?

[Slinky]

Since you are using a non-Resmed mask (or is the LIberty a Resmed mask???) - I don't know.

0.4 L/s or 24 L/M are the suggested limit of Leak. But since the Resmeds subtract the allowed vent rate for their own masks IF the correct Mask Selection has been set I can't say because I don't know if the Liberty is a Resmed mask or not nor do I know the Mask Selection being used and if it is the correct one for the Liberty if it is a Resmed mask.