Can Itamar WatchPAT distinguish types of events?

[archangle]

I'm also looking forward to the answer to that question.

Saw the sleep doc yesterday. She seems convinced that I'm having obstructive events although she also says that WatchPAT can't tell what kind of event you're having. I told her that my concern is that this may be part of other neurological problems I am having; that the muscles I use for breathing are being affected and when I am asleep I can't compensate. I will just have to see how Sleep Study No. 4 goes.

It really sounds to me like you need a self administered SleepyHead/ASV/pulseox at home study.

[Darth Lady]

That will be next, for sure. I'm going to order the oximeter soon. Just waiting for the money to come in.

[Janknitz]

Does this answer your original question:



How WatchPAT Detects Apnea, Hypopnea, & RERA Events

WatchPAT utilizes Peripheral Arterial Tone (PAT), a special physiological signal that mirrors changes in the autonomic nervous system (ANS) caused by respiratory disturbances during sleep. The ANS regulates many of our basic functions and it does this without our conscious control. Among its activities are the regulation of blood vessel size and blood pressure, airflow in the lungs, and the heart’s electrical activity and ability to contract.

WatchPAT’s automatic algorithm analyzes the PAT signal amplitude along with the heart rate and oxygen saturation to identify breathing problems while you sleep. Using specific signal patterns, the algorithm provides two indices that allow a diagnosis of sleep apnea:


•AHI (Apnea/Hypopnea Index), which is an index used to calculate sleep apnea severity based on the total number of complete cessations (apneas) and partial obstructions (hypopneas) of breathing per hour of sleep.
•RDI (Respiratory Disturbance Index) is used to assess severity of sleep apnea by measuring respiratory efforts, or RERAs (Respiratory Effort Related Arousals). A RERA is an arousal from sleep that follows 10 seconds or more of increased respiratory effort but does not meet the criteria for apnea or hypopnea.

From: http://www.itamar-medical.com/itamar_mo ... ction.html

How WatchPAT Detects REM

REM (rapid eye movement) sleep, one of the two basic states of sleep, is notable for the presence of rapid eye movement, active brain activity, dreaming, and the absence of motor function. REM sleep is associated with considerable attenuation of the PAT signal and physiology coupled with specific variations in the PAT amplitude and rate. Based on this specific variability in the PAT and pulse rate signals, WatchPAT easily differentiates REM from NREM sleep.

How WatchPAT Detects Sleep Architecture

The cyclical pattern of NREM and REM sleep is detected by WatchPAT and recorded on its built-in actigraph. The propriety software’s automatic actigraph algorithm discriminates between sleep and wake states in normal subjects and patients with sleep apnea. This algorithm makes WatchPAT superior to any other actigraph devices because most are unable to detect sleep architecture in patients with sleep apnea.WatchPAT’s zzzPAT algorithm is based on 14 features extracted from two time series of PAT amplitudes and inter-pulse periods (IPP). Those features are then further processed to yield a prediction function that determines the likelihood of detecting a deep sleep epoch stage during Non-REM sleep periods.

See also:

Numerous validations studies demonstrated a high degree of correlation in RDI (Respiratory Disturbance Index) and AHI (Apnea-Hypopnea Index) between same-setting WatchPAT and polysomnography (PSG) sleep studies with R= 0.85- 0.96. Moreover, the RDI and AHI scores are highly reproducible, showing correlation between at-home and in-laboratory sleep studies.
•Bar A, Pillar G, Dvir I, Sheffy J, Schnall RP, Lavie P. Evaluation of a portable device based on arterial peripheral tonometry (PAT) for unattended home sleep studies. Chest, March 2003, 123(3): 695-703.
•Pittman DS, Ayas NT, MacDonald MM, Malhotra A, Fogel RB, White D. Using a Wrist-Worn Device Based on Peripheral Arterial Tonometry to DiagnoseObstructive SleepApnea: In-Laboratory and Ambulatory Validation. Sleep 2004, Vol.27 (5), 923-933.
•Ayas N. TA, Pittman S, MacDonald M, White D. Assessment of a Wrist-Worn Device in the Detection of Obstructive Sleep Apnea. Sleep Medicine 2003, Vol. 4, (5), 435-442.
•Zou D, Grote L, Peker Y, Lindblad U, Hedner J. Validation a Portable Monitoring Device for Sleep Apnea Diagnosis in a Population Base Cohort Using Synchronized Home Polysomnography. Sleep 2006: 29(3): 367-374.
•S.D. Pittman, G. Pillar, RB Berry, A Malhotra, MM MacDonald, DP White. Follow-Up Assessment of CPAP Efficacy in Patients with Obstructive Sleep Apnea Using an Ambulatory Device Based on Peripheral Arterial Tonometry. Sleep and Breathing, 2006.

I'm not really sure it can distinguish CA's.

[Darth Lady]

And I'm not sure whether it can tell that an event is obstructive at all. If you don't have enough oxygen you will arouse to deal with that and your peripheral arterial tonometry will change accordingly. Whether that goes into the AHI category or the RERA category seems to depend on how long it takes to arouse.

[Morbius]

Are you saying the ASV is reporting a nice low AHI because it's confusing the "nice regular waveform" that's being generated by the ASV's aggressive attacking of the central apneas with real normal breathing?

It only has to be "nice" enough to slip under the radar.

And the Watch PAT is not confused by the ASV-generated "nice regular waveform" because it's looking at different data?

Could be looking at PLMs for all we know.

And the Watch PAT can see that in spite of the ASV-triggered inhalations which smooth the waveform out, the desats are still happening?

Some desats. WP doesn't live on desats alone:

(1) PAT amplitude reduction occurred with an acceleration in the pulse rate or an increase in wrist activity, (2) PAT amplitude reduction occurred with a 3% or greater oxyhemoglobin desaturation, or (3) a 4% or greater oxyhemoglobin desaturation.

Also, if the desat is from 98% to 94%, maybe that's not much of a problem.

And a more general question for you: When is "ASV confusion" most likely to happen?

Non-chain centrals.

As a aside, the ASV might not even be set up properly. A review of posts show no data, no settings. Why do we think it's hypoventilation? Maybe the events are all obstructive and the machine can't drive through. Maybe the sleep is so poor (perimenpausal) they're all spontaneous arousals and post-centrals.

[Darth Lady]

Settings are:
Max pressure 25
EPAP min 10, max 15
BPM auto
PS min 0 max 15

Overall pressure hangs around 10-12 with occasional forays to as high as 18. So it's running toward the bottom of the prescribed range most of the time.

Yes I'm perimenopausal but arousing 22 times per hour is ridiculous. I'm worried about under breathing because either the machine isn't trying to knock anything out or believes it is succeeding in knocking everything out. There is periodicity in my breathing but I don't see evidence that the machine is failing to catch things.

Hopefully I can put up a couple of typical nights tomorrow evening when I have access to my regular computer.

[Blaifarm]

My doctor to me a watchpat could not tell what a person was experiencing. That it could only tell how many per hour.

[Morbius]

... arousing 22 times per hour is ridiculous.

An AI of 22 is about in the middle of "moderate". If you were having 22 "awakenings" per hour, that would be categorized as "ridiculous".

Also, event distribution needs to be considered (i.e., areas where AI is 60-90, etc.).

Do you have any cardiac arrhythmias? Stuff like afib can really mess that thing up. Any medications?

Hopefully I can put up a couple of typical nights tomorrow evening when I have access to my regular computer.

It might be easier if you just uploaded the file to dropbox.

[Darth Lady]

Somebody please help here, because I'm not sure how to export SleepyHead files. Use the CSV Export Wizard? How to set parameters in that?

At any rate, some answers to other questions: I don't have an arrhythmia. I take Neurontin, Glucophage, Amlodipine, Arixtra (anticoagulant), and Asmanex and albuterol for asthma. My liver knits glucose out of something all night, despite a very low carbohydrate diet, giving me high fasting blood sugars (between 115 and 125) and the going theory is that this is because of bad sleep quality and resulting stress on my body.

Here's SleepyHead from the night of the WatchPAT test: AHI was a big fat .13 according to the machine; a fairly typical night:


And here's a bit of, well, I won't call it periodic breathing, because it's not that extreme, but a periodic pattern that I seem to follow for large chunks of the night. The pressure compensations also show up, as well as the one hypopnea the machine flagged that night:


I'm no expert, but none of this would seem to support the horrible account that WatchPAT gave of that night.

[palerider]

Somebody please help here, because I'm not sure how to export SleepyHead files. Use the CSV Export Wizard? How to set parameters in that?

you can't export sleepyhead files.... the csv export is to export summary data in case you want to play with it externally.

you can copy the sleepyhead backup directory, or your sd card.

[Morbius]

I'm no expert, but none of this would seem to support the horrible account that WatchPAT gave of that night.

Of course it would.

You've got 20 attacks in 20 minutes giving locally an AI of 60:



as well as some SWJy stuff.

[Morbius]

Somebody please help here, because I'm not sure how to export SleepyHead files.

It's in

c:/Documents and Settings/YourName/MyDocuments/SleepyHeadData/Profiles/YourName

[Darth Lady]

I'm no expert, but none of this would seem to support the horrible account that WatchPAT gave of that night.

Of course it would.

You've got 20 attacks in 20 minutes giving locally an AI of 60:



as well as some SWJy stuff.

Thanks very much for looking at this.

I'm going in for Sleep Study No. 4 in a few days. Hopefully I will actually be able to sleep this time, unlike the titration study, where I got beyond Stage 2 for all of 4 minutes all night , and so they will be able to fix this problem. Somehow.

Question: With a full polysomnograph, is there going to be any way to tell what the root cause of this is (obstructive, central, something else)?

If anyone wants more info, I'll do my best to provide it. I really, really appreciate the help and advice I've gotten.

[Morbius]

Question: With a full polysomnograph, is there going to be any way to tell what the root cause of this is (obstructive, central, something else)?

It should.

If anyone wants more info, I'll do my best to provide it.

Sure, upload the SH file as above. Perhaps a breath-by-breath review will reveal some clues.

[Morbius]

EPAP trolling: