Hello Guest, Welcome to Apnea Board !
As a guest, you are limited to certain areas of the board and there are some features you can't use.
To post a message, you must create a free account using a valid email address.

or Create an Account


New Posts   Today's Posts

False events in SleepyHead
#1
Hi all

Last night's AHI on Sleepy Head was 4.23. On analysing the data in SH this was mainly caused by 22 hypopneas, 6 OAs and 4 RERAs. However, a lot of the events scored in SH do not appear to be genuine events.

Out of those 22 events, I'd say only 2 or 3 appear to be genuine hypopneas and the rest appear to be false events. The link is http://imgur.com/a/cu3hS and the link shows 2 typical hypopnea scored events along with a more genuine hypopnea.

Have other people experienced this in SH and how do you deal with them? Do you delete events or "un-score" them to get a more realistic AHI?

I feel pretty good this morning and better than a 4.23 AHI would suggest.

Thanks
Post Reply Post Reply
#2
(12-17-2016, 07:25 PM)marcus10 Wrote: Hi all

Last night's AHI on Sleepy Head was 4.23. On analysing the data in SH this was mainly caused by 22 hypopneas, 6 OAs and 4 RERAs. However, a lot of the events scored in SH do not appear to be genuine events.

Out of those 22 events, I'd say only 2 or 3 appear to be genuine hypopneas and the rest appear to be false events. The link is http://imgur.com/a/cu3hS and the link shows 2 typical hypopnea scored events along with a more genuine hypopnea.

Have other people experienced this in SH and how do you deal with them? Do you delete events or "un-score" them to get a more realistic AHI?

I feel pretty good this morning and better than a 4.23 AHI would suggest.

Thanks

SleepyHead does not manufacture data ... the basic raw data comes from your machine and is scored according to the criteria set by the manufacturer. And, while you can set reporting criteria, there does not appear to be any way to alter or filter the incoming data easily -- nor would you want to change a medical record.

I see much the same things, especially where I am convinced that there are false hypopneas in the data. Using the UF2 flag (custom event logging by flow restriction and duration) I am able to get a clearer picture of reality as produced by my particular machine. These custom events are not included in the AHI computation.

As for deleting that data which you believe is erroneous and rescoring the AHI is possible with a lot of effort, why bother? Individual data points are almost meaningless in the greater context of how you feel and how therapy is progressing.

When I was considering becoming a physician, my approach was conditioned by my experience in data processing. Some of the best advice came from my mentor, a rather well-known cardiologist. He said "don't treat the machine, treat the damn patient." Which he then proved by showing it is possible for a heart to display false information (PEA - pulseless electrical activity) where the patient has no pulse and is dying while an idiot looks at the monitor and not the patient. (BTW -- I did not become a physician because I could not divorce myself from the patient and the outcome.)

Use your data as indicative of a trend and keep trying to optimize your therapy using machine settings, not trying to improve your scores by manipulating data. It is what it is!

Best of luck with continued good numbers.

"The object in life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane." -- Marcus Aurelius
Post Reply Post Reply
#3
srlevine1 as a very good and accurate explanation. Sleepyhead does not create events, it transcribes them from the machine's data. The hypopnea you included in your data appear to be real. Notice the comparatively low amplitude inspiration, and it is easy to see how this may be 30% or more reduction from your running average minute vent. I see some flow limitation in those waveforms at the beginning of the segment, and recovery breathing in the middle. You are experiencing fairly significant leaks, just below the large leak threshold here, and that can certainly affect the accuracy of what the machine's sensors pick up.
Post Reply Post Reply


#4
(12-18-2016, 07:16 PM)Sleeprider Wrote: srlevine1 as a very good and accurate explanation. Sleepyhead does not create events, it transcribes them from the machine's data. The hypopnea you included in your data appear to be real. Notice the comparatively low amplitude inspiration, and it is easy to see how this may be 30% or more reduction from your running average minute vent. I see some flow limitation in those waveforms at the beginning of the segment, and recovery breathing in the middle. You are experiencing fairly significant leaks, just below the large leak threshold here, and that can certainly affect the accuracy of what the machine's sensors pick up.

Hi Sleeprider, thank for that. I hadn't considered those ones on the left of the image may be genuine hypopneoas.

So a narrowing of the amplitude of the waveform indicates hypopneoas as opposed to actually stopping breathing?

The pattern indicated there is pretty indicative of my general pattern over the night. A couple of further questions coming out of this:

- Leak rate. I'm using a trial N20. I can't say I actually notice any leakage other than the general vent port of the mask. I'd assumed this was the cause of the leak rate as the mask leak test and my own observations don't indicate any escaping air other than through the vent.

- Pressure. I'm therefore now thinking I need to increase my min pressure. My pressure settings are currently 6 - 12 with a 95% of usually around 8.7 but occasionally up to 9.5. I'm now thinking perhaps 8 to 12 - does that sound reasonable?
Post Reply Post Reply
#5
I'd increase minimum pressure by 1 cm and give it some time. Your machine is pretty responsive with any needed pressure increases, and starting at 7 will put you pretty close to your median pressure, and in range for the higher pressure needs.
Post Reply Post Reply
#6
(12-18-2016, 08:03 PM)marcus10 Wrote: - Leak rate. I'm using a trial N20. I can't say I actually notice any leakage other than the general vent port of the mask. I'd assumed this was the cause of the leak rate as the mask leak test and my own observations don't indicate any escaping air other than through the vent.

Check the timing of your leak rates against the times that you believe you are asleep.

You might find that leaks are a function of some level of mouth breathing and possibly positional changes that may occur throughout the night.

When examining the flow data, you may wish to look for sharp recovery breaths that may lead to mouth breathing and leakage.

I have observed that I hold my breath or disturb my mask seal when I turn over and thus create my own hypopnea event and a leak.

Again, it is all about how you feel and the trend line -- not the exact numbers on any given day.
"The object in life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane." -- Marcus Aurelius
Post Reply Post Reply




Possibly Related Threads...
Thread Author Replies Views Last Post
  Only O2 Sat matters, or OA False positives - Part Deux rbookman 7 236 Yesterday, 02:15 PM
Last Post: srlevine1
  OA - are the events ever false positive?? rbookman 2 120 10-17-2017, 10:46 AM
Last Post: Sleeprider
  Increase in Events per hour Dennisl27 3 146 10-10-2017, 08:32 PM
Last Post: Sleeprider
  Why is this not tagged? [CA events] mltam 6 179 10-05-2017, 06:49 PM
Last Post: Walla Walla
  Very Frustrated - Seeking Advise [about CA events] BlueJay22 6 281 09-27-2017, 01:46 PM
Last Post: Sleeprider
  Breathing Events Affect Sleep Onset Unison 9 307 09-10-2017, 02:55 AM
Last Post: SnoringInOregon
  How 'real' are events recorded by machine? nathanoj 4 342 08-31-2017, 09:23 PM
Last Post: nathanoj

Forum Jump:

New Posts   Today's Posts




About Apnea Board

Apnea Board is an educational web site designed to empower Sleep Apnea patients.

For any more information, please use our contact form.