420E Run Question ???

pjwalman · Post by **pjwalman** » Sat May 24, 2008 3:39 pm

Thank you for explaining things to me, -SWS. Sorry to be asking so many questions. I just Googled silent acid reflux disease, and it certainly makes sense of many things, things linked both to SARD and GERD: The cloggy feeling in the throat, wanting to clear it all the time, the congestion before bed, the body arming itself against the acid it knows is coming, waking up coughing and not knowing why. Guess I figured, since I was able to eat most anything now while taking the Prilosec daily, that meant I'd licked the problem. Obviously not.

I will try not to be a baby during the exam, but I make no promises.

I very much appreciate your patience with me!!

Peggy

NightHawkeye · Post by **NightHawkeye** » Sun May 25, 2008 6:11 pm

I promised myself I was gonna dig into the Puritan-Bennett patents in more detail. I did that this morning and prepared a write-up on it. As I was nearing completion of the first write-up, the beta version of Firefox 3 I was using crashed on me. Herewith is my 2nd attempt at this ...

Gruenke & Trimble Auto-PAP patents based on snoring detection - assigned to Puritan-Bennett:
5134995 (1992) fundamental patent
5259373 (1993) derivative
5549106 (1996) derivative

Other Puritan-Bennett patents - I suspect both apply to PB420E
5443075 (1995) Flow Measuring Apparatus
6134106 (2000) CPAP Pressure and Flow Transducer

Rapoport's Auto-PAP patents dealing with flow-limitations - the fundamental patent plus derivative patents:
5335654 (1994) assigned to NYU - the fundamental flow-limitation technique
5490502 (1996) assigned to NYU
5535739 (1996) assigned to NYU & Puritan-Bennett
5546933 (1996) assigned to NYU
5803066 (1998) assigned to NYU - includes cardiac sensing CA technique
6299581 (2001) assigned to NYU & Puritan-Bennett
6488634 (2002) assigned to NYU
6793629 (2004) assigned to NYU & Puritan-Bennett

New Rapoport CPAP patents dealing with "sleep-state".
6988994 (2006) assigned to NYU
7186221 (2007) assigned to NYU

These last two Rapoport patents utilize breathing patterns to categorize the patient into one of the following four states:
1. regular breathing state
2. sleep-disorder breathing state
3. REM sleep state
4) troubled wakefulness state

After looking through Rapoport's patents I came to the inescapable conclusion that Rapoport's technique, given human to human variations, attempts to extract more precision from breathing patterns than those breathing patterns support. An example of what I mean comes from the claims in one of his more recent flow-limitation patents, No. 6488634 (2002).

patent 6488634 (2002) wrote:3. An apparatus for optimizing the positive pressure in an airway of a patient, comprising: means for providing positive pressure of a breathing gas to an airway of a patient; means for generating a signal corresponding to a waveform contour of an inspiratory flow of breathing gas to the patient; means for utilizing the wave form contour signal to detect a flow limitation in the airway of the patient; and means for increasing the positive airway pressure when the means for utilizing detects a flow limitation in the airway of the patient.

4. The apparatus of claim 3, further including means for decreasing the positive airway pressure when the means for utilizing does not detect a flow limitation in the airway of the patient.

5. The apparatus of claim 4, wherein the means for utilizing is configured to generate data values representative of the signal corresponding to the inspiratory flow, to correlate the data values with a pure sine wave to determine a first index, to compare a regression fit of the data values with a regression fit of a pure sine wave to determine a second index, to compare a peak value of the data values with a peak value of a derivative of the data values to determine a third index, and to compare a peak value of the data values with an average of a plurality of peak flow values for flow limited breaths and with an average of a plurality of peak flow values for non-flow limited breaths to determine a fourth index.

6. The apparatus of claim 5, wherein the means for utilizing is further configured to determine a fifth index as a function of the first index, the second index, the third index and the fourth index, wherein each index includes a weighted coefficient.

...

19. The method of claim 17, wherein determining whether the signal indicates a flow limitation in the airway of the patient further includes calculating a fifth index as a function of the first index, the second index, the third index and the fourth index, wherein the fifth index indicates the presence of flow limitation in the patient.

20. The method of claim 17, wherein determining whether the signal indicates a flow limitation in the airway of the patient further includes calculating a fifth index as a function of the first index, the second index, the third index and the fourth index, wherein the function includes a weighted coefficient for each of the first, second, third and fourth indexes.

Claim 6 above is the part which appears over-reaching. (It is restated on claim 20.) That fifth index is what is often referred to in technical circles as a "fudge factor". That itself wouldn't be so bad, except that all the inputs to it also each include their own "fudge factors". Garbage-in, Garbage-out, or "you can't get blood from a turnip".

So that's my take on why so many folks find it necessary to turn OFF the flow-limitation algorithm in the PB420E. Having come to this conclusion, it's now kinda hard for me to read much into the flow-limitation runs which are showing up in so many different people's data.

Regards,
Bill (open to hearing contrary opinions ... )

NightHawkeye · Post by **NightHawkeye** » Sun May 25, 2008 7:08 pm

ozij wrote:Bill
I'm having trouble keeping track on your setup / evnets / aerohpahgia /runs combination.

Could you create chart of that?

I'm not sure how to make a single chart, Ozij, but I'll offer up the data.

Here's where my settings have been for the past month:

Biggest change is that range has narrowed. That narrowing cut AHI to about one-third of what it had been. It was running over 5.0 a month ago and now runs under 2.0 (at last week's settings). Initial pressure was lowered within the past week.

Here are the current statistics where I lowered the Initial Pressure to 8.0 from 9.5 cm showing AHI=2,2:

Here are last week's stats with Initial Pressure at 9.5 cm showing AHI=1.7:

Here are the stats from a month ago when I had a much wider APAP range showing AHI=5.5:

As for aerophagia, it's kinda up and down. I'm tolerating greater average pressures, but still have some nights which are troublesome. Yesterday, was a problem, but today isn't. Funny thing is, the charts for last night and the night before are very similar as shown below:

Regards,
Bill

-SWS · Post by **-SWS** » Sun May 25, 2008 11:42 pm

NightHawkeye wrote:Claim 6 above is the part which appears over-reaching. (It is restated on claim 20.) That fifth index is what is often referred to in technical circles as a "fudge factor". That itself wouldn't be so bad, except that all the inputs to it also each include their own "fudge factors". Garbage-in, Garbage-out, or "you can't get blood from a turnip".

Claim 6 and Claim 20 refer to that fifth index. I personally didn't find that fifth index to be inherently over-reaching. My take was that index five is a highly typical method of dismissing artifacts: if prior cycles were also found to be flow limited, then index five carries a low-probability weighting toward final, sum-total p; if prior cycles were normal, then index five carries a high-probability weighting toward that final, sum-total p (probabilities weighted toward 0, w/ 0=FL or weighted toward 1, w/1=non-FL).

So in my view index 1 through index 4 collectively assess four unique wave shape characteristics of a single inspiratory cycle, presently receiving calculation for a semi-final probability p. Then index five steps in with its context/temporal sensitive factorization toward weeding out artifacts.

But I do agree with your high-level assessment, Bill: I very strongly suspect the 420e carries a low specificity for FL detection. In other words I also happen to suspect the 420e is generating quite a few false positives for FL---much more so for certain patients possessing the right characteristics for FL false positive readings on the 420e.

Regardless, I think the 420e is accurately measuring something---perhaps a variety of conditions across the patient population---when it does accurately detect inspiratory wave shapes that significantly deviate from that sinusoidal reference. The question in my mind is how many different conditions in physiology might be capable of generating these FL false positives on the 420e? How many are benign? How many are SDB related? And how many are potentially problematic with respect to health?

Peggy, I just saw one of your threads where you mentioned morning naps were returning higher than usual AHI. Were those morning naps after the consumption of food and/or beverage? If so, then perhaps GERD played a role there as well.

pjwalman · Post by **pjwalman** » Mon May 26, 2008 1:08 am

-SWS, I think you just solved the mystery of the naps. I foolishly ate some deep-fried mozzarella sticks tonight before bed while out bowling with my family, and here I am at almost midnight because I am so full of air, I can hardly stand it. I was lying there, almost asleep, and all of a sudden this weird sound startled me, and it was danged air leaking out of me. Not a burp, just a weird gurgle of air. Then I totally freaked out, and now I am wide awake, burping like crazy after having thrown up, and I'm going to look to find SnoreDog's suggested lower pressures 'cause my guts just can't handle the higher ones tonight, apneas or not. Thought I was going to be a copycat there for a minute and end up in the emergency room because of the pressure in my chest, but it's easing up as I'm sitting up. Obviously I am going to have to either deal with my primary doctor or find a new one soon to get this looked at. I'm just a ridiculous mess all of a sudden, and I'm no longer seeing the humor in it.

Okay. On to the search for those suggested lower pressures that he says I missed. Thanks again for explaining the higher nap numbers. I do eat during those first two hours of work before I go back to bed, and I'm sure you're right about what is going on.

Peggy

EDIT: Miserable night despite lowered pressures. Now I'm thinking none of the "aerophagia" has much to do with the pressures but rather just the CPAP air, at any pressure, aggravating the esophagus apparently. I went from acid under control, I thought, with Prilosec OTC every morning to back to "bubble", throwing up, miserable in just about six weeks of CPAP, so apparently there's some connection to the air but probably no machine or setting is going to improve things until I address the GERD I didn't realize I still had, just masked well until now. So I'm a moron. What can I say?

NightHawkeye · Post by **NightHawkeye** » Mon May 26, 2008 7:33 am

-SWS wrote:I personally didn't find that fifth index to be inherently over-reaching. My take was that index five is a highly typical method of dismissing artifacts: if prior cycles were also found to be flow limited, then index five carries a low-probability weighting toward final, sum-total p; if prior cycles were normal, then index five carries a high-probability weighting toward that final, sum-total p (probabilities weighted toward 0, w/ 0=FL or weighted toward 1, w/1=non-FL).

So in my view index 1 through index 4 collectively assess four unique wave shape characteristics of a single inspiratory cycle, presently receiving calculation for a semi-final probability p. Then index five steps in with its context/temporal sensitive factorization toward weeding out artifacts.

To be honest, -SWS, after skimming through a bunch of very similar patents, most with similar claims, I suddenly keyed in on that fifth index because it just looked loosey-goosey. Since I didn't elaborate earlier, let me elaborate now.

Patent 5335654:
This is the fundamental patent. Regarding flow-limitations it says:

Patent 5335654 wrote:9. The apparatus of claim 7, wherein said signal processor further comprises means for determining the presence of patient airway obstruction when the contour of said waveform corresponding to inspiration includes a plateau.
10. The apparatus of claim 7, wherein said signal processor further comprises means for determining the presence of patient airway obstruction when a portion of the contour of said waveform corresponding to inspiration is flattened.
11. The apparatus of claim 7, wherein said signal processor further comprises means for determining the presence of patient airway obstruction when the contour of said waveform corresponding to inspiration deviates from a substantially sinusoidal shape.

These three claims are the only qualifying details provided which describe waveshape processing. Otherwise, the claims are very nebulous and extremely broad. Don't get me wrong though, Rapoport was crystal clear in the description of his invention about what he was proposing. In the claims he backed that up by stating his processing was looking for a "flattened" waveshape. So far, so good.

I see this morning that patent 5490502 is where Rapoport introduced the five indices which are front and center stage here, beginning with the very first claim:

Patent 5490502 wrote:What is claimed is:
1. A method for optimizing the positive airway pressure to a patient, comprising the steps of:
a) applying an initial level of positive airway pressure of a breathing gas to a patient;
b) detecting the onset of an inspiratory flow of breathing gas to the patient;
c) storing data values representative of the inspiratory flow of breathing gas to the patient;
d) determining whether the stored data values indicate a flow limitation in the patient; and
e) increasing the positive airway pressure when the stored data values indicate a flow limitation in the patient.
2. The method of claim 1, further comprising the step of decreasing the positive airway pressure when the stored data values do not indicate a flow limitation in the patient.
3. The method of claim 1, wherein step d) includes comparing the stored data values with a sinusoidal contour.
4. The method of claim 3, wherein step d) includes correlating the stored data values with a pure sine wave.
5. The method of claim 1, wherein step d) includes analyzing the stored data values for flatness.
6. The method of claim 5, wherein step d) includes comparing a regression fit of the stored data values with a regression fit of a pure sine wave.
7. The method of claim 1, wherein step d) includes analyzing the stored data values for respiratory effort.
8. The method of claim 7, wherein step d) includes comparing a peak value of the stored data values with a peak value of a derivative of the stored data values.
9. The method of claim 1, wherein step d) includes analyzing the stored data values for relative flow magnitude.
10. The method of claim 9, further comprising repeating steps b) through d) for a plurality of patient inspirations to create a plurality of peak flow values for flow limited breaths and to create a plurality of peak flow values for non-flow limited breaths, and comparing a peak value of the stored data values with an average of the plurality of peak flow values for flow limited breaths and with an average of the plurality of peak flow values for non-flow limited breaths.
11. The method of claim 1, further comprising the steps of:
f) repeating steps b) through d) for a plurality of patient inspirations to create a plurality of peak flow values for flow limited breaths and to create a plurality of peak flow values for non-flow limited breaths;
g) correlating the stored data values with a pure sine wave to create a first index;
h) comparing a regression fit of the stored data values with a regression fit of a pure sine wave to create a second index;
i) comparing a peak value of the stored data values with a peak value of a derivative of the stored data values to create a third index; and
j) comparing a peak value of the stored data values with an average of the plurality of peak flow values for flow limited breaths and with an average of the plurality of peak flow values for non-flow limited breaths to create a fourth index.
12. The method of claim 11, wherein step d) further includes the step of calculating a fifth index as a function of the first index, the second index, the third index and the fourth index, wherein the fifth index indicates the presence of flow limitation in the patient.
13. The method of claim 12, wherein step d) further includes the step of calculating a fifth index as a mathematical function of the first index, the second index, the third index and the fourth index, wherein each index includes a weighted coefficient having a range including a value of zero.

Patent 535739 adds nothing on flow limitation, but is an interesting patent which goes off in the direction of a mini sleep-lab, including a position sensor, oximeter, and expiratory airflow measurement. For example:

Patent 535739 wrote:2. The device of claim 1, further comprising a position sensor configured to generate third data values representative of the physical position of the patient, wherein said computer memory is further configured to store the third data values.
3. The breathing device of claim 1, further comprising an oximeter configured to generate fourth data values representative of the oxyhemoglobin saturation level of the blood of the patient, wherein said computer memory is further configured to store the fourth data values.
4. The device of claim 1, wherein said flow sensor is further configured to generate fifth data values representative of an expiratory flow of ambient air from the patient, and said computer memory is further configured to store the fifth data values.

Patent 5546933 simply adds expiratory flow to the mix:

Patent 5546933 wrote:What is claimed is:
1. A method for detecting flow limitations in the airway of a patient, comprising the steps of:
a) providing a nasal fitting in fluid communication with the airway of a patient, the nasal fitting having means for measuring the inspiratory flow of air to the patient;
b) measuring the inspiratory flow of air to the airway of the patient;
c) generating a curve of data values representative of the inspiratory flow of air to the patient for each breathing cycle;
d) processing such data values to generate a plurality of indices each independently descriptive of the shape of each such curve; and
e) combining such indices to determine whether a flow limitation in the patient is indicated.
2. The method of claim 1, further comprising the step of measuring the expiratory flow of ambient air from the patient, and generating second data values representative of the expiratory flow.

In Patent 5803066, Rapoport uses six indices by adding the area of the inspiratory waveform to the mix. It seems obvious here that Rapoport needs additional discriminators to accurately identify flow-limitation. No doubt flow-limitation detection has presented itself as a more difficult problem than he first imagined. This is also the patent where cardiac sensing was introduced to determine airway patency.

Patent 5803066 wrote:What is claimed is:
1. A method for optimizing the positive airway pressure to a patient, comprising the steps of:
a) applying an initial level of positive airway pressure of a breathing gas to a patient;
b) detecting the onset of an inspiratory flow of breathing gas to the patient;
c) storing data values representative of the inspiratory flow of breathing gas to the patient;
d) determining whether the stored data values indicate a flow limitation in the patient by calculating the ratio of the area of the inspiratory waveform to the area of a pure sine wave to create a first index; and
e) increasing the positive airway pressure when the stored data values indicate a flow limitation in the patient.

In Patent 6299581, Rapoport goes back to the mini sleep lab thing:

Patent 6299581 wrote:1. A method for detecting flow limitation in an airway of a patient breathing air in an unassisted manner, comprising the steps of:
...
2. The method of claim 1 wherein said patient is in a physical position, further comprising the steps of:
generating with a position sensor a third set of data values representative of the physical position of the patient; and
...
3. The method of claim 1 wherein blood circulating within said patient has an oxyhemoglobin saturation level, further comprising the steps of:
generating with an oximeter a fourth set of data values representative of the oxyhemoglobin saturation level of the blood of the patient ...

Patent 6793629 doesn't seem to add anything new to the flow-limitation arena. I'm not quite sure what the point of this patent was, although some of the wording seems to suggest a diagnostic slant rather than a treatment regimen.

-SWS wrote:But I do agree with your high-level assessment, Bill: I very strongly suspect the 420e carries a low specificity for FL detection. In other words I also happen to suspect the 420e is generating quite a few false positives for FL---much more so for certain patients possessing the right characteristics for FL false positive readings on the 420e.

Yeah, it's those false positives which kept Rapoport busy trying to find a solution.

-SWS wrote:Regardless, I think the 420e is accurately measuring something---perhaps a variety of conditions across the patient population---when it does accurately detect inspiratory wave shapes that significantly deviate from that sinusoidal reference. The question in my mind is how many different conditions in physiology might be capable of generating these FL false positives on the 420e? How many are benign? How many are SDB related? And how many are potentially problematic with respect to health?

Agreed! The 420E is measuring something. For many folks flow-limitation detection apparently works but, if ozij's poll is an indication, there are just as many folks for whom flow-limitation detection doesn't work, or at least not for the intended purpose.

Flow-limitation detection seems simple enough, doesn't it? Rapoport apparently thought so, too, back around 1992 when his patent was filed. His more recent patents which analyze breathing to determine the "patient's state" suggest that the complexities of breathing patterns have drawn him into considerably further analysis of this seemingly simple area.

Regards,
Bill (who still has a few comments to make regarding his own apnea in relation to GERD ... )

ozij · Post by **ozij** » Mon May 26, 2008 8:34 am

Bill,
If I had your results I'd try one of the following:

I would try min =8.5 or 9, initial=10, max 12. You don't have any pressure induced (or other) apneas at 10.5 (in this last data...) so I'd try max. pressure for command on apnea at 11 - or even 12 ;- it won't go there unless it has to - and it won't raise your pressure for central apnea no matter where you are, so I think it's a safe setting based on what I see. If you find it bothersome drop it in .5 steps. The important thing though is giving the machine leeway to go down for your comfort, and to respond quickly on the way up.

I think those amplitude reduced hypopneas in a row -culminating in flow reduced ones and apneas mean your min. is still too low (hour 87, 90(mild) and 91), and the response is too slow because initial=min.

O.

NightHawkeye · Post by **NightHawkeye** » Mon May 26, 2008 9:06 am

ozij wrote:Bill,
If I had your results I'd try one of the following:

I would try min =8.5 or 9, initial=10, max 12.

Raising the minimum pressure is something I've approached very cautiously, ozij. However, given that the latest data shows that I've tolerated higher pressures for nearly all night the past couple of nights anyway ... Of course, two nights ago resulted in way too much aerophagia.

I'm inclined to agree on increasing the max pressure, as well as command on apnea. Snoredog thought that appropriate, too. Biggest concern I have is that the machine occasionally maxes out at top pressure and stays there for no apparent reason. I'm not sure there's enough data to say for sure what will happen if I raise both command on apnea and max limit at the same time. Maybe I'll compromise at 11 cm for both and see how that goes. I've already got a week's worth of data with the current settings. Being averse to pain and having experienced excruciating aerophagia/insufflation before, I'd really like to avoid that.

ozij wrote:I think those amplitude reduced hypopneas in a row -culminating in flow reduced ones and apneas mean your min. is still too low (hour 87, 90(mild) and 91), and the response is too slow because initial=min.

I agree that the response is too slow. I forget now why I backed the Initial Pressure down. It does seem like things were a little better the prior week. For sure, AHI was lower.

Here's what I think I'll try:
Initial Pressure - 9.5 cm
Min Pressure - 8 cm (call me a wimp ... )
Max Pressure - 12 cm
Max command on Apnea - 11 cm (just to be different from max pressure)

Regards,
Bill (wondering how close to joining the AHI under 1.0 club he can get ... and, considering aerophagia, whether he wants to join ... )

ozij · Post by **ozij** » Mon May 26, 2008 9:26 am

I can understand why you're being careful... . Lets see how it goes...

O.

-SWS · Post by **-SWS** » Mon May 26, 2008 11:54 am

Peggy, I agree that you need to see a doctor ASAP. You can get a referral to a GI specialist at any immediate health care center (you know---those little 7-11 or Circle-K convenience establishments of emergency medicine). Or you can wait for a referral from your primary physician. But don't wait very long. And if you're extremely uncomfortable, a trip to the ordinary ER is entirely reasonable.

You might want to research a possible GERD comorbidity known as a "hiatal hernia". And if you have to sleep without CPAP, consider doing so more or less upright in a recliner. Hang in there, ma'am! And just remember that you're on the home stretch toward getting one big and fairly common health problem under control.

So hang in there! Positive attitude counts for BIG points toward improved health IMHO!!! Good luck!!!

.

NightHawkeye · Post by **NightHawkeye** » Mon May 26, 2008 12:06 pm

I attempted to respond a couple of times to the acid-reflux/apnea/flow-limitation connection, but never could compose anything with the least bit of intelligence to it, so I discarded the prior attempts and continued thinking about it. (Cogitating instead of agitating, maybe?) Like many things involving physiology, I just didn't see enough pieces to put them together. My own experience with Protonix for a year was inconclusive and Protonix certainly didn't resolve apnea for me. Protonix, like other PPI's, was intended for and studied for short-term use.

This morning's data (when I finally got around to downloading it) is different enough from my prior postings to offer some possibilities in this area:

Here's what I see in the data:
- Like the other days I've gone golfing, minimal pressure was needed all night (although I only walked nine holes).
- I was enough of a glutton with snacks (chocolate and other stuff) yesterday to have stomach discomfort at bedtime. Amazingly, the first several hours were devoid of apneas, and had (for me) a remarkably low number of flow-limitation runs. Even so, after a little over three hours, the machine registered a cycle-state crash which preceded my waking up with heart racing, heavy breathing and a "burning" esophagus (which hasn't happened recently). It also seems significant that flow-limitation runs preceded the cycle-state crash. I'm thinking perhaps the LES remained closed for those several hours, but then finally relaxed allowing acid out. The lack of hypopneas and apneas at this time suggests to me the possibility of the vagal nerve being implicated here. I am prone to bradycardia and vagal nerve stimulation is known to prompt bradycardia. I was sleeping with my upper body elevated considerably so I don't think the vocal chords are implicated.

Anyway, after getting up in the middle of the night, I took my usual supplements which calm things down and went right back to sleep, whereupon the machine began recording the usual high number of flow-limitation runs as has been the pattern.

As an aside to the above, now that my AHI is lower than it's been, I'm noticing that I'm consistently getting hit with a few apneas/CAs/hypopneas at about the 6th hour of sleep which I normally respond to by waking up and going about the day.

That's about all I've got for now. Thanks for listening.

Regards,
Bill

-SWS · Post by **-SWS** » Mon May 26, 2008 1:20 pm

Bill, right about now I'm leaning toward thinking your 420e FL runs are probably nothing to worry about. Your AHI looks great and your central apneas are so sparse that they don't seem problematic. People without SDB can have sparse incidental central apneas at that rate.

However, many problems in physiology tend to be inherently episodic or flare-up oriented. So I guess keeping an eye your your 420e data toward A or H flareups may some day reveal something. I hope not.

Also just a general reminder to readers that we can feel unrested for an entire variety of reasons unrelated to SDB. I happen to know that harsh physiology lesson first hand because of trigeminal neuralgia. And lastly, a reminder that untreated or under-treated acid reflux disease can really exacerbate SDB symptoms in some cases (Peggy's may be just such a case). Of course, the upside to that point is that getting acid reflux disease under control can drastically improve SDB symptoms in some cases.

Much earlier in this thread I wrote:Well, I think the 420e may be scoring FL runs and H events as if they were separate occurrences with separate scoring criteria. I think lesser amplitude reductions (not meeting H amplitude-reduction criteria) are probably what the 420e includes among its FL scoring criteria (clinics never double-score H as FL, but they do differentiate obstructive H from central H---see my next post).

Ooops! Sorry for forgetting about that intended "next post".

That side discussion related to how FL wave shape sitting directly on top of hypopneic amplitude reduction can be combined toward differentiating obstructive hypopneas. Here's a link discussing how sleep clinics employ that wave shape distinction toward differentiation of obstructive versus central hypopneas:
http://www.sleepreviewmag.com/issues/ar ... -04_07.asp

pjwalman · Post by **pjwalman** » Mon May 26, 2008 1:30 pm

Thank you for getting me to see the problem, -SWS!! I've got the fax ready to send to my primary physician asking for the referral. If she doesn't see the need, then I've got the sleep doc as a second option or the emergency clinics, as you mentioned. I know I don't want to keep up this way! You'd think I'd be losing weight at least, but no such luck!

I really appreciate the guidance, and I will do more research as you suggested so maybe I can be smarter about what I'm taking into my body in the interim until I can see the specialist.

Take care!

Peggy

NightHawkeye · Post by **NightHawkeye** » Mon May 26, 2008 4:17 pm

-SWS wrote:Bill, right about now I'm leaning toward thinking your 420e FL runs are probably nothing to worry about.

Well, I think you missed my drift, -SWS. The FL runs, per se, have never been as much a concern as an indicator. But, an indicator of what? Hence, the questioning title of this thread.

Rapoport apparently missed the boat a little in terms of applying flow-limitation to the general apnea population, but I suspect that for many people, yourself apparently included, the 420E with its flow-limitation algorithm provides noticeably better treatment than ResMed or Respironics machines can. While I might wish that I were included in that population, I will gladly settle for what information the flow-limitation sensing algorithms can provide.

I kinda like to connect the dots anyway. It's something I do in my own work and the approach has served me well over the past few years; not just in regards to my own apnea treatment but also understanding my own unique health care needs.

Yes, I am pleased with my AHI right now and certainly feeling the better for it; but also wanting even more. I would surely like to get better sleep and more of it. I kinda feel like I'm on the verge of making additional improvement there. (Not to mention that I'd like to improve my overall health some but, hey, I'm working on that too! ) This whole discussion thread, like so many here at cpaptalk, has offered some real possibilities; while some play out, some pan out. It just takes one or two to make the whole process immensely worthwhile.

Regards,
Bill

-SWS · Post by **-SWS** » Mon May 26, 2008 6:44 pm

Well, Bill, there's certainly no reason not to continue exploring this topic IMHO.

I'll try to put some more thoughts in regarding how elusive I think correlations can be with respect to pathosphysiology in general---and how I suspect that very phenomenon of intermittent cause/effect or intermittent stimulus/response just may be playing an illusory role here.