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EPR or not EPR
#21
I'm a bit like Sleepster....ramp is not something I use (but my wife uses on hers and swears by).

For me, I personally like the EPR feature. You're still getting additional pressure to splint the airway open when you exhale, but I find it a little more comfy to not fight against as much pressure. It may be that I'm a little more sensitive to exhalation pressure as I am also an asthmatic....the pressure on inhalation assists with breathing (which is nice) but the full resistance on exhalation is more akin to what happens when I'm constricted (and is somewhat less plesant). AHI wise, it looks like my body could care less, but YMMV.
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#22
(06-27-2014, 10:10 AM)robysue Wrote: The big problem I see with the Fisher & Paykel SensAwake system is that the Icon has no EEG and hence it can't really tell when you are awake and when you are asleep.
Neither Resmed or Respironcis machine has EEG but both adamant that their machine can tell can tell obstructive apnea and central apnea apart

I,m not sure if this has been a good thing as many of us goes into panic mode whenever we see one or two central events scored by our machine
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#23
(06-27-2014, 04:23 PM)zonk Wrote: Neither Resmed or Respironcis machine has EEG but both adamant that their machine can tell can tell obstructive apnea and central apnea apart

I think this is where the puffs of air thing comes in, Zonk.

Boyle's law states that P1V1 = P2V2 = P3V3....increase the volume and the pressure will be less for a fixed number of molecules.

Many machines send out pulses of air (known pressure / volume) to try to identify centrals vs. obstructive events. If the airway is blocked due to an obstructive event, the resulting pressure would be higher than if it the airway was open and you have the full airway and lung volume. It's essentially "air pressure sonar" to see if the airway is open or blocked.

It is good to a point....but it isn't foolproof. I know if I'm trying to fall back asleep after being somewhat awake (i.e. stumble downstairs for a bathroom break, go up to yell at the neighbour's dog or wake up before the alarm and decide I'll snooze the last few minutes until it goes off), my breathing rate is slower and the machine will spit the occasional central out on me for it. Just something to be aware of and not stress over Wink
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#24
(06-27-2014, 04:36 PM)PsychoMike Wrote:
(06-27-2014, 04:23 PM)zonk Wrote: Neither Resmed or Respironcis machine has EEG but both adamant that their machine can tell can tell obstructive apnea and central apnea apart

I think this is where the puffs of air thing comes in, Zonk.

Boyle's law states that P1V1 = P2V2 = P3V3....increase the volume and the pressure will be less for a fixed number of molecules.
I forget to add, neither machines can tell whether you,re awake or asleep but score an apnea while you,re awake too

I know about Boyle's law Coffee

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#25
Re Centrals (and other events):

Yes, a lot of newbies get worried (even freaked out) because they see a central or two scored overnight. And they shouldn't. Of course, we also see newbiew who get worried (even freaked out) because they see an OA or two scored overnight ...

Fact is: Our machines are not perfect. But if you understand the limitations on the algorithms used for scoring the events, you do come to realize that our PAP machines really are technological wonders, and you do develop a real appreciation for the relative accuracy of most of the data they record.

For most of us, we ARE asleep MOST of the time we're using the PAP; and hence it's not an unreasonable for the manufacturers' algorithms to make the assumption that all breathing is "sleep breathing" and score apneas and hypopneas based on defined measurable decreases in airflow as compared to the running 5-10 minute baseline airflow. Two readily identifiable things can affect how the reported AHI and real AHI are related. Recall:
  • reported AHI = (number of scored events)/(run time)
  • real AHI = (number of real events)/(actual sleep time)
If the number of scored events is relatively close to the number of real events, then (lots of) wake time will tend to make the reported AHI look smaller than it should be because (run time) > (sleep time) implies:
  • reported AHI = (number of scored events)/(run time) < (number of scored events)/(actual sleep time)
But having lots of FALSE events, turns the inequality around:
  • reported AHI = (number of scored events)/(run time) > (number of real events)/(run time)
And so the reported AHI would be greater than the real AHI if run time and sleep time are roughly the same.

For people with "run time" roughly equal to "actual sleep time", the number of FALSE events caused by wake breathing is also likely to be low, and so the reported AHI and the real AHI will be in the same ballpark.

Likewise, MOST of the time the central/obstructive apnea detection algorithms works decently enough; although it's useful to remember that these algorithms are far more likely to misclassify a real CA as an "OA" than they are to misclassify a real OA as a "CA".

But I still think the PR RERA detection algorithm is not a reliable as the algorithms used for scoring OAs, CAs, and Hs. A real RERA requires an arousal, and while there are some clear earmarks as to what the flow rate trace of a RERA looks like, it's not at all clear if the PR RERA algorithm detects most RERAs (i.e. misses very few real RERAs) or scores lots of things as RERAs that aren't (i.e. scores a lot of non-RERA breathing as RERAs).

That's also my concern about the SensAwake algorithm on the F&P: Without the EEG, the machine is taking a (hopefully pretty good) statistical guess that you are are awake. And it lowers the pressure, perhaps substantially when it thinks you are awake. Now if the SensAwake algorithm is more prone to missing real wakes, all that leads to is a bit of middle of the night "potential" discomfort when the patient is awake. But if the SensAwake algorithm tends to score "false wakes"---i.e. if it thinks you are awake when you are really still asleep---then the fact that the machine lowers the pressure down might just be an issue.
Questions about SleepyHead?
See my Guide to SleepyHead
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#26
(06-27-2014, 05:56 PM)robysue Wrote: Yes, a lot of newbies get worried (even freaked out) because they see a central or two scored overnight.
Four years ago, i was one of those newbies but now, how many hours using the machine is the first thing i check in the morning
I,m happy with 7 hours, 8 hours is party time ... not long ago, was not even 4 hours
I suppose can say that because my AHI is quite low - below 0.5 most night, might freak out, had it been on the high end

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#27
(06-27-2014, 05:08 PM)zonk Wrote: I forget to add, neither machines can tell whether you,re awake or asleep but score an apnea while you,re awake too

I know about Boyle's law Coffee

That they certainly can do (and have done for me many a time).
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#28
My EPR works great for me.
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