Hello Everybody!

I'd like to start a discussion about Sleep Strips, cause I see them tossed around a lot.  Never used them, never even seen one.  But I know a little bit about these types of devices and have some concerns.  I may be wrong, but invite enlightened debate here.  If I'm right, then people who use these things need to know these things too.

OK, so it's a stand alone device that monitors breathing during sleep.  You can find a picture of it if you surf, but I won't put up the link.  And it has an algorithm that quantifies the severity of SA you have.  Not OSA, just SA.  It can't tell a central from an obstructive, but that's picky.

And for that matter, it counts hypopneas as well as apneas:

"An apnea event is counted when respiration amplitude drops to under 12% of the average for more than 10 seconds. A hyponea event is counted if respiration amplitude drops to less than 50%, but more than 12%, of the average for more than 10 seconds. Respiratory events (apneas and hypopneas) are counted for the duration of the study. These values were selected for maximum correlation with polysomnographic results."

Which is odd, because you can't call a hypopnea as such unless there's also a desaturation and/or an arousal.  Or if you're using Medicare criteria, then a desaturation only. Well that's a problem, cause without an oximeter or EEG leads, you can't tell that.  OK, it's me being picky again.

Anyway, the algorithm calculates the severity of your SA:

"The final score represents five possible test outcomes based on sleep apnea severity level:

0 - no apnea: comparable to a sleep lab AHI of less than 14
  
1 – Mild: comparable to a sleep lab AHI between 15 and 24
  
2 – Moderate: comparable to a sleep lab AHI between 25 and 39
  
3 – Severe: comparable to a sleep lab AHI of more than 40
  
E – Error in measurement"

Now where did these values come from.  Even Medicare, with strict requirements, allow CPAP if your AHI is from 5 to 15 if you have symptoms.  And everybody I know says AHI 5-15 is mild sleep apnea.  And there's plenty of data that says even mild sleep apnea can cause all the same problems, including hypertension, that moderate to severe apnea can, so you should be treated.

But here's where I have real issues.  There are plenty of scenarios where the algorithm will give absolutely erroneous results.  For instance:

SA is usually more severe where you're on your back or in REM.  But one usually only spends 20% of the time in REM, and most people shift positions during the night.  But if they have severe SA in REM, or when supine, and are relatively normal in the other positions, and that sleep segment is say 20% of the night, you could have an AHI of 75 during those periods and this algorithm will say you have NO APNEA.  Not mild, not get a sleep study, NO APNEA.

OK, the desaturations.  We're very concerned about those, severe desaturations bump up your severity to moderate or severe.  For instance, AHI of 14 with desats to 40% would be very severe SA.  Normal again with the SS, and that's just dangerous.

PLMs occur in 10% of patients and can contribute to daytime sleepiness, and overall daytime sleepiness is caused by arousals, sleep stage changes and reduced levels of quality sleep.  You're still going to need PSG to evaluate these, and you're undoubtedly going to need it if you intend to have CPAP covered by insurance.

So here's the most important point:
A score of 0 can and will be misinterpreted.  It in no way can mean you have no apnea, it doesn't mean you don't have OSA and it absolutely cannot mean you don't have a problem.  Because if you have been have been screened properly, at least enough to get a SS, then you have some signs and symptoms of a sleep-related breathing disorder (SBD).  And after this test is done, you know what?  You still do.  And if a person unversed in the study of sleep is interpreting the results for you, that could very well be the end of the line in finding and treating your problems.

The medical support of this device is anecdotal at best, and only correlate AHI in the mild to moderate range.  With a 5 year history of its use, though, it's actually quite sparse.  Circumstantial arguement?  Maybe.

But until a see a study that looks at people who had complaints of SBD, used the SS, were rated 0, no apnea and then had follow-up studies to determine what their problems and their severity were, I would not even recommend using it.  Because I think that would really bring to light the dangers and limitations of this device, and consequently really educate potential users.

So what happened to the people with SS results?  There's 4 possibilities:

You had a positive result and had a PSG and/or now on CPAP.  OK, not bad.  Who had a positive SS and got a PSG anyway?  Did the SS really cost $40, or did you need 2 physician visits as well?

You had a positive result and did nothing about it.  Nuff said.

You had a negative result, but continued to follow-up and solve your problem.  Great.

You had a negative result and did nothing further.  What made you get a SS in the first place?  And knowing what you do now, are you still satisfied with the results?

My recommendation would be that a PSG is necessary in all of these situations.  Data from SS ranges from inaccurate to erroneous.  I believe many people are dangerously falling through the cracks when this device is used.  The information from the SS only has a remote chance of being accurately interpreted unless it is in the hands of a qualified sleep specialist, and I just don't see it becoming a part of their repertoire.  It just leaves too many questions unanswered.

Any and all responses are invited, especially those who had "normal" results and how their problem was finally solved or if it's still ongoing.
sleepydave



Last edited by sleepydave on Sat Aug 20, 2005 4:14 pm; edited 2 times in total

Dave

well said.  If someone is going to avoid doing a PSG, I tend to agree with Dr. Phillips, put em on CPAP and see if it gets better.  At least in that case they are getting some therapy.  Going cheap on diagnosing OSA or SBD is like buying discount life jackets, it might work, but who in their right mind would want to take that chance?

And lest anybody even think of using an SS on a child, don't-- no, non, nein, nyet.
Here's the range of abnormal values for OSA in children:

There aren't any.

There is general agreement among the pediatric community that anything over AHI 1.0 is abnormal, but after that, there's nothing concrete, but here's what we use, just to attach a name that puts the value into context:

AHI<1.0 Normal
AHI 1.0-5.0 Mild OSA
AHI 5.0-10.0 Moderate OSA
AHI >10.0 Severe OSA

At AHI 3.0, they're serious candidates for surgery, and adding in desaturations at any level is pretty much a trump.

And the SS didn't even report anything yet.

Here's some stuff that I put in the pedi section of the forum, yeah it's a child but illustrates the differences you can have between REM and NREM sleep.

And SS will report this out as (You guessed it!) 0, No Apnea

Here are 2 polysomnograms that show obstructive sleep apnea in a child.  I know there's a lot of stuff here, and most of it just looks like a bunch of squiggles (actually, it  is just a bunch of squiggles), but focus on the waveforms marked Thermistor, Chest and Abdomen.  The thermistor is registering breathing, in and out, in undulating fashion, while the other 2 channels are measuring effort at the chest and abdomen.  These are 5 minute blocks of time.  The first one shows normal breathing.  It is regular and uninterupted.

The next one shows obstructive apneas-- they're long, they cause severe desaturations (drops in oxygen level in the SAO2 channel), there's a lot of them and this kid needs to go to surgery.  Notice how that even though there's no airflow in the thermistor for long periods, the child is still struggling to breathe as evidenced by the movement seen in the chest and abdomen channels.

BTW I've downloaded the instructions and package insert from the website, and I see nowhere where it says that you shouldn't (or better yet, can't) use this on a child, or any mention of age limitation whatsoever.

sleepydave



Last edited by sleepydave on Mon Dec 03, 2007 9:42 am; edited 1 time in total

Are these the products developed at the Technion in Israel and sold by S.L.P., Ltd.?

Hi RK!
Yes, and Accutest in the U.S.
sleepydave

Dave,

My name is Noam Hadas and I’m the engineer who headed the team inventing and developing the SleepStrip at SLP, in collaboration with the Technion Sleep Medicine Center. Your arguments against the usage of the “SleepStrip� all target the “accuracy� of the device in the diagnosis of sleep apnea, which in our opinion completely misses the whole point of the device.

From your post I understand that you take your children to the hospital for a CT before you take their temperature at home. In your world there is only room for the best, and most expensive answers. Well, millions of undiagnosed apnea patients stand to show this approach in sleep medicine is very problematic.

We agree that a full night in a properly equipped sleep lab, with a well trained and attentive technician scoring the data, and an expert physician writing the report is the best way to diagnose SDB, but how many of the people who suffer from sleep apnea are studied in sleep clinics?

Based on the Wisconsin Cohort data, Dr. Terry Young estimated that no more than 15% of the patients “out there� were actually studied for sleep disorders. Thus, there are millions of people who are not aware of their sleep breathing disorders, and suffer cardiovascular damage night after night. There are many reasons for the disparity between the number of people with SDB and the number of studies actually performed. These include the limited number of available beds, the relatively small number of sleep specialists, the lack of awareness of the medical community and of the public at large of the clinical significance of breathing disorders in sleep and so on.

The purpose of the SleepStrip is NOT to provide a diagnosis of sleep apnea syndrome. Its purpose is to provide a simple, cost-effective screening of large numbers of people. A positive SleepStrip finding should be viewed as a ‘red flag’ signaling a high likelihood of breathing disorders in sleep that should be followed by a diagnostic test. We believe that the SleepStrip is an important tool particularly in younger people who, even if they have severe apneic events, are less symptomatic and “hateâ€� the idea to spend a night in the sleep laboratory connected to electrodes. For them, a positive SleepStrip finding should be a powerful incentive to seek a professional help and diagnostic sleep study.  

The SleepStrip is the only tool available that can allow these undiagnosed millions to test their likelihood of having sleep apnea. There is no way the health system can afford in-lab testing for all of them without some kind of proper screening, and there is no chance they will suddenly realize they need a study on their own. The SleepStrip is intended for screening the masses, identifying the moderate and severe patients (at least) at a very reasonable cost, and bringing them into the labs so people like you can help them.

During these years of marketing the SleepStrip I personally gave it to many people who were not happy about their sleep, but never thought of complaining to their physicians or getting tested. Following positive Strip findings many were later diagnosed and put on therapy. Are you so sure this is wrong?

Noam

Noam,

I am glad that there are quick ways to screen people, the spouse method is prolly the most accurate of them

Used as a screening tool only, then yes its great, but often it has been touted as being able to diagnose sleep apnea.  That could be a dangerous thing as someone could be having other issues such as severe o2 desats and might not see a positive response on the sleep strip, or a severe enough response.  

Used as a screening tool only, and following up with a full PSG to determine severity, wouldn't be a bad path, but I have a feeling that with the way its being advertised, people are going to think its an alternative to a PSG, instead of an adjunct.

All that said, I am glad that people are working on getting more people screened, as the current estimates are saying that there are MANY people that need to be treated.

Noam:
Thank you very much for your response, and I hope that you will understand my motivation in this discussion is to provide information to users and potential users of your device that will serve to allow for proper interpretation of the results that will result in identification, follow-up and effective treatment of OSA.
To digress immediately, I wish the picture you've painted of U.S. health care was true.  If you've read some of these posts, you'll see that affording proper health care here is a huge problem.  If there are ways to save money, trust me, people will jump on it.  However, they don't want only affordable quality care, they want quality care.  And that's what this discussion is really about.
I really need some direct response to my scenarios where patients with severe problems are told they have NO APNEA.  Am I not correct in how your algorithm and interpretation system works?  If so, then you are telling a lot of people who have significant disease that they are fine!  That they have NO APNEA!  Please review my examples, and if you can demonstrate how these people are not receiving at the least misleading, and at worse, erroneous information, I need to see that.  All of my examples show patients that absolutely need follow-up, and based on your analysis, they won't seek it.  Until that time, I remain firm in my conviction that you have to make it absolutely clear that the reporting of a "NO APNEA!" does not mean that, and that serious sleep-related breathing problems may still be present.
Secondly, I have deep concerns that the interpretation of this data will be left to people that may not or do not have the proper knowledge to do so.  If a patient were to use this on his own, or if his physician was not sleep-oriented and knew of the limitations of the device, there is no way that these people would not fall through the cracks.  If anything, it's much worse, now you have a patient that was tough to get anything done for to begin with, you have "hard" data that says he's fine, and a medical opinion that lends support to that.  How are we going to convince him he has a problem now?
Further, I am extremely concerned about the use of this device in children, again read my post about that, if there is anything in there whatsoever that you find to be untrue or inaccurate, let me know.  If not, I would strongly suggest that you include in your information sheets that this is NOT to be used in children for the reasons I have specified.
BTW, I did have the chance to meet the VP and General Manager of SLP last week at a conference, and presented my arguments and concerns to him as well.
I hope that you will view my arguments with a critical eye, and make appropriate changes where necessary to insure that quality and value can coexist.
Thanks again for your response.
Dave

I went back and read again these last three posts in this topic.  
To be honest, I hadn't read the earlier ones (I'm lazy, ok?).

It's weird, but when you read Noam's post and sleepydave's post, independently they both seem perfectly logical.

That's why the debate is so important, and why it is great you both brought up your concerns.

I do tend to agree with sleepydave in once sense.   (and keep in mind my basic ignorance of the subject)

If there were some simple blood test for sleep apnea like there are for other conditions, then there would likely be absolute or reasonable trust in the results.  Either you'd have sleep apnea or you didn't.  Same for major health conditions, such as diabetes and others.  This condition is not so simple.  And all too often medications for other or related health conditions muddy the situation.  I would hazard to guess they can mask or distort possible signs for the condition.  It is important to find that magic test that says aha! you've got sleep apnea of a certain severity and type, for I agree far too many sufferers are not being diagnosed.  But I feel we have to be careful, that it be accurate for both a positive and negative result.  So too, by the time most of us sleep apneacs are diagnosed, we have a host of other medical problems whether or not they were brought about by this condition.  These problems have to be treated and monitored along with sleep apnea.  Testing is vital, whether it's a sleep lab test, or testing for heart, lung, thyroid, or other ongoing conditions.  

I really don't understand what these sleep strips are all about, so I probably have no right voicing any thoughts.

Still, I thank you both for your thought-provoking discussion.  We all learn a little more from them.


Linda