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Watch Pat Questions

PostPosted: Wed Feb 04, 2009 2:37 am
by sleep3
Does anybody have experience with the portable system called the Watch Pat?
What level device is it, type 3 or 4 for reimbursement?
What is the CPT code for the technical and the physician code?
How does the machine know when the patient is in NREM and REM?
Is it accurate for stages and AHI compared to a PSG?
I plan on testing the product, but would like your feed back.

I have the Apea link and question the accuracy. We have several patients that can not afford a formal PSG and this may fit the bill.
Thanks for your help.

PostPosted: Wed Feb 04, 2009 3:17 am
by Hypnagogic Hal
The WatchPat is a level 4 device. It does not measure sleep any more than an oximeter or actigraph measures sleep. It assumes sleep from changes in perfusion that commonly occur as a result of arousals (which also occur as a result of hiccups, however.) In severe apneics, the measured AHI from the WatchPat is comparable to that from a PSG. (In these patients, however, an oximeter can give you just as accurate an estimate of the AHI.) The units I tested (several dozen) were difficult to apply and prone to failure. Almost half the trials I attempted yielded no data whatsoever. The others correlated well with polysomnographic results, but the probes were way too expensive and I couldn't justify the cost for the small amount of information rendered. If all you want is to screen moderate to severe apneics, I suggest a good questionnaire and an overnight oximetry instead.

PostPosted: Wed Feb 04, 2009 3:19 am
by somnonaut
If you are AASM Accredited their guidelines call for use of similar parameter HST devices as the parameters used during the lab's PSGs. Meaning if you are NOT recording actigraphy and peripheral tone during the PSG, then an HST using these technologies would not be the right match for your lab. They want the same type of scoring and record review of the HST device as the PSG, so the Watchpat must afford direct event tagging and second by second raw record review.

PostPosted: Wed Feb 04, 2009 5:01 am
by sleep3
Thank you for your replies.
Do you happen to know the CPT codes for the portal test for level 3 and 4 technical and professional fee? or the link?
Do you have suggestions for cost efficient home testing devices besides the apnea link?
I have patients that simply will not come in for a PSG that most likely have severe apnea and several that do not have the means to pay for a PSG.
Thanks again for your input.

PostPosted: Wed Feb 04, 2009 6:19 am
by linuxgeek
It's hard to imagine that the Watch-PAT is any different than the Finger Pleth signal.

Finger Pleth is an interesting signal, but I don't think I'd like to base a diagnosis on it alone.

PostPosted: Wed Feb 04, 2009 1:41 pm
by somnonaut
I have boiled down my Accredited lab ability to perform HST to equipment such as:
Embla Embletta
Braebon Medibyte

And from there the other manufacturers (not that I have given it a total trial of every piece of equipment out there either) have things that I like or dislike.
There is:
Compumedics Somte
Grass Trek
Cadwell (never tried, not sure of name)
Clevemed Scout
Sandman Pocket
Respironics Stardust

All of these have varying numbers of PSG level parameter recording abilities, with either software to review and score second by second (Full disclosure), or allow for EDF to your present PSG system to score and report within one methodology.

I hope this helps.

I am sure I missed something it is early.

PostPosted: Wed Feb 04, 2009 6:59 pm
by Rick
The WatchPat is a level 4 device. I am curious about some responses to your question; Hypnagogic Hal, I don't think it is perfusion but the level of effect that the autonomous nervous system is having on the pleth signal from which they are trying to deduce sleep stages and arousals; it is yet in its infancy but may have some applicability in the future.

Back to the last of Sleep3s questions:
If you have patients who cannot afford formal PSG, will they be able to afford the cost of a CPAP machine and patient interface?

PostPosted: Wed Feb 04, 2009 8:29 pm
by Hypnagogic Hal

According to Wickipedia, a plethysmograph is: "An instrument for measuring changes in volume within an organ"; in this case, blood volume in a manual digit. Perfusion is "To force a fluid to flow over or through something, especially through an organ of the body." So I think we're splitting hairs here. The plethysmographic waveform measured by either an oximeter or the WatchPat is based upon pulsatile blood flow caused by cardiac contractions and is dependant on digital blood flow or perfusion. My point is that the WatchPat instrument determines an arousal from sleep based upon an increased blood flow rather than any measure of actual sleep or wakefulness. This increased blood flow can occur from any number of causes, and is not necessarily diagnostic of sleep apnea, although it will correlate with obstructed breathing in sufficiently impaired individuals. Then again, so will an audio tape recording. :P

PostPosted: Wed Feb 04, 2009 9:22 pm
by somnonaut
"...the WatchPat instrument determines an arousal from sleep based upon an increased blood flow rather than any measure of actual sleep or wakefulness."

"Actual sleep" how is that determined? Maybe this measure is a more subtle/true measure of actual sleep. No? It is all relative to what is being recorded.

PostPosted: Wed Feb 04, 2009 9:41 pm
by Hypnagogic Hal
Well, since 1967, sleep has been defined as a behavioral state that correlates with specific EEG changes (as well as eye movements and somatic tension), and can be quantified (i.e. measured) using a polysomnograph or EEG machine. This ability to quantify sleep is entirely lacking with a type 4 device, and any attempt to imply measurement of sleep with such a device is (in my not-so-humble opinion), misleading if not downright fraudulent. This is not to say the device has no place in sleep medicine diagnostics: I just don't like comparisons with these devices and actual polysomnography. And if you choose to use one for "screening", I feel you'll get more for your money with a decent pulse oximeter.

PostPosted: Wed Feb 04, 2009 9:51 pm
by somnonaut
As we constantly improve our technology, we must never loose sight of the ability to better peer into that which we call sleep.
One channel sleep/wake detminator is not fraudulent, since it is the fulfillment of the core basics of the rules of R&K in sleep/wake determination.

PostPosted: Wed Feb 04, 2009 11:27 pm
by Hypnagogic Hal
As long as that channel is a determinant of EEG (which Z-Ratio is), you are correct. Some day we may well define sleep in terms of other criteria, but for the present, any system that uses other parameters in lieu of the current standard is not measuring what we in the field call "sleep".

PostPosted: Wed Feb 04, 2009 11:30 pm
by sleep3

There are certain patients that simply refuse to come in for a formal PSG but may be willing to do the HST. The patients have told our board certified medical director. We realize it is no optimal or lucractive using HST. Our physician is almost positive the patient has OSA according to the consult. We work with several DME companies that provide used CPAP for minimal or no cost to patients if they do have OSA and have no other means. We are trying to help the community and receive more referrals from other physicians. Any help would be appreciated. I have sent an e-mail for more information on the embetta. Thank you for your responses.


PostPosted: Thu Feb 05, 2009 12:15 am
by Rick
In 1937 they were using EEG to determine stages of sleep ("Journal of Experimental Psychology", Vol 21, No. 2, August 1937). Please be open to new things, if one can measure the state of the autonomic nervous system without electrodes and wires does that mean the data gained from it is always going to be invalid because it is not based on direct measurement of EEG?

This reminds me of one time in my past when physicians refused to believe that oximeters showed the true saturation of the blood with oxygen; the data was thrown out because it had not come from a blood gas drawn directly from an artery.

I am not saying that the WatchPAT works (afterall they compete with my employer) and I used the term "Pleth" because it had been used before. I have been lucky to be part of some experimentation that truly amazed me with its results. At that time I said it would not be accepted by the Sleep Medicine community because it was so different from what people were used to seeing. And here we are, six years later discussing the possibility in an open forum.
As I said before, just try to be open to new possibilities.

PostPosted: Thu Feb 05, 2009 12:34 am
by Rick
I forgot to post the complete title of the paper it is "Cerebral States During Sleep, as Studied by Human Brain Potentials" by Alfred L. Loomis, E. Newton Harvey and Garret A. Hobart, III
It is a very interesting read, especially how they made their electrodes and the happiness at using an rolling drum for the paper and only have to change it every 3.5 hours.
I'll try to attach it.