how to interpret Flow Limitation graphs

[idamtnboy]

christinepi is and will receive more help than she can possibly use (yet this is the nature of forum discussion. Some responses and discussions may be of more interest to some than others), and you shouldn't say "no one knows" if what you really mean is "you don't know".

You're right, I shouldn't have said 'nobody'. As you know Resmed's FFL designation for FL means [F]uzzy FL. I admit that at times I'm inclined to be a bit fuzzy in my comments. When I wrote 'my first response' I was thinking in terms of my entire first post, not just my first sentence.

Just for interest I went back and reviewed the two different threads from back in November that were referenced in this one. I have to say it looks like you have been doing quite a bit of study since then on this issue because your comments above are more in-depth than your earlier ones. But still, my take on this whole subject after reading what you and SWS and others have presented is there still is no clear cut simple explanation, in layman's terms, what flow limitation really means to me as a patient using xPAP therapy. When I look at my Resscan graphs I don't see any obvious correlation between flow limitation and the other factors, except flow. But the value of the apparent correlation to flow is questionable because the flow graph shows many, many, fluctuations in flow greater when FL=0 than what is shown during the FL moments. When I look at apnea events over several different nights, every one occurs when the FL is 0 and I see no FL indicators preceeding an OA.

Would you mind giving us some indication what you do for a living, and/or what your background is? As I've read your posts over the past 4 months I've been left with mixed impressions as some of them indicate study and thoughtfulness, but others come across as a bit trite. Then when I see your somewhat trite entry for location in your signature info, and N/A for sex, I'm torn between recognizing you as being a knowledgeable contributor or as someone whose credibility is questionable.

[NotMuffy]

Would you mind giving us some indication what you do for a living, and/or what your background is? As I've read your posts over the past 4 months I've been left with mixed impressions as some of them indicate study and thoughtfulness, but others come across as a bit trite. Then when I see your somewhat trite entry for location in your signature info, and N/A for sex, I'm torn between recognizing you as being a knowledgeable contributor or as someone whose credibility is questionable.

Well, about 5 different responses came to mind, but I'll stick with the first one:

In a discussion re: credentials, this poster remarked:

Actually, SAG has been trying his best to lay low, but "somebody" keeps bringing those "letters" up!!

"IMHO", its not the letters anyway. Letters are not required to say something intelligent nor a guarantee that what will be said won't be stupid.

SAG

[SleepingUgly]

Muffy, since you've disabled PMs, I have to say publicly what I would ordinarily say to you privately. You've been remarkably restrained lately!! (Can I have some of whatever it is you're taking??)

[jnk]

According to my upcoming book, entitled "Muffy/NotMuffy--The Man, Myth, and Multiple Behind the Mutated Monikers and Playful Mayhem," the poster you ask about is, as I see him from his posts, a man with many interests, an entertaining sense of humor, an occasionally searing wit, and a long history of helping patients professionally and on message boards.

I have no idea what he is like in real life, but his posts here and elsewhere using many different names show him to be someone with keen insight into the inner workings of sleep medicine and respiratory medicine, as far as the science and the application of it, seems to me.

He appears to change names on a regular basis here in order to hide the number of his posts and to keep himself and others entertained. That is OK, though, because Rested Gal keeps links to many of the more important points made by him, and others, from posts made on this board, and elsewhere, in her subject-list of links.

Occasionally he even takes the risk of helping a patient directly on this board in a way that educates us all as he helps the patient navigate where to turn next for help. Some of them respond in a thankless way, which must be a slap to NotMuffy. Others appreciate the gesture and are glad to get the help in a way that educates and entertains others.

My conclusion from reading his posts in the few years I've been around, and in researching some of his past posts, is that he is fiercely protective of patients in that he attacks those he percieves as preying on others--especially those who attempt to pass themselves off as experienced professionals when they are not, those who are looking for easy marks with a questionable product, and those who say things that fly in the face of present medical science and that could be damaging to others. Some here have interpreted that to be some sort of turf-protecting on his part. I don't think that is the motive, though, since he could easily pick a name, do his thing, and develop a following, which he refuses to do on this board, as is easily seen by his humorous posts and off-topic shenanigans.

He most likely finds posts like this one by me to be highly irritating, by the way, but I have a feeling he'll let me slide, if it helps you to sift through his posts to learn from his experience and point of view.

When he keeps his language in check and doesn't get too off-color, I find his humorous posts some of the most entertaining stuff I've read anywhere, on or off the net. And I have learned a great deal about sleep-breathing from him here and expect to learn even more in the future. But I understand completely those who don't quite "get" his mindset.

I don't know if he is right about everything (who is?), but he is always relevant when being serious on serious topics, so don't discount his take without a good reason, I would say. At the same time, don't let your feelings get hurt by his playful, though sometimes rough, way of stating things.

Imagine the mind of an experienced administrative medical director who has the education and hands-on experience to actually know what techs/RTs/docs/patients do, but who is cursed with a wit that is a cross between Letterman and Dennis Miller, with a little House thrown in, but with more self-parody, and you may start to get his take and his humor both, or not.

Or, then, maybe I don't understand the guy at all.

Hey, I know, I'll call the book, "Muffins on Message Boards."

[SleepingUgly]

Wow, Jeff, that was very eloquent and insightful. Would you consider writing Muffy's eulogy when he dies? I already have dibs on -SWS writing mine.

[jnk]

Wow, Jeff, that was very eloquent and insightful. Would you consider writing Muffy's eulogy when he dies? I already have dibs on -SWS writing mine.

I suspect he'll outlive me. He'll still be running 1OKs when I'm long gone.

Though, most of those personas die before 1,000 posts, don't they?

[jnk]

Back to the scheduled program . . .

. . .There are no good explanations what FL really means. . .

I agree there are many ideas about what meaning should be attached to many things that are less than desaturating apneas, for the average person. However, still, the bottom line for me is what is expressed in the book Nonivasive Mechanical Ventilation: Theory, Equipment, and Clinical Applications, by Antonio Matías Esquinas (Nov 4, 2010), p. 101:

In patients with OSA, progressively higher CPAP levels applied during sleep turn obstructive apneas into hypopneas, hypopneas into continuous inspiratory flow limitation, with or without snoring, and flow limitation into unobstructed breathing. When breathing becomes unobstructed, "respiratory arousals" (i.e., arousals that may follow increased inspiratory efforts associated with obstructed breathing) are eliminated, while sleep becomes more stable and sleep cycles more regular, contributing to improvements in subjective sleep quality, daytime sleepiness, and quality of life usually observed after just a few nights of CPAP application. Also, relief of upper airway obstruction is associated with resolution of intermittent hypoxemia and hemodynamic swings that accompany obstructive events, with a consequent reduction in long-term cardiovascular morbidity and mortality.

The objective of CPAP treatment are elimination of symptoms and of cardiovascular and, possibly, metabolic risk related to OSA. Today, the best way to accomplish these aims is usually considered to fully eliminate all degrees of upper airway obstruction during sleep. The lowest CPAP that eliminates upper airway obstruction in all sleep stages and body postures in a patient is indicated as "optimal" CPAP.

Therefore, the question for an average OSA patient, in my opinion, is generally a matter of "more pressure or less?" rather than a question of "do those squigglies mean I have IFLs or not?" If you feel better with a higher pressure than what gets rid of apneas and hypopneas, then by all means, raise your pressure, if your doc doesn't mind, no matter what it is you are eliminating.

[NotMuffy]

Muffy, since you've disabled PMs, I have to say publicly what I would ordinarily say to you privately. You've been remarkably restrained lately!! (Can I have some of whatever it is you're taking??)

It's Lent.

[NotMuffy]

Wow, Jeff, that was very eloquent and insightful. Would you consider writing Muffy's eulogy when he dies?

I'll say. I'm actually quite disappointed to be alive still.

Where's an asteroid when you need one?

OTOH, it'll be a little tough handing out eulogies during the ELE.

Maybe texting would be a little more efficient:

HE WZ GRT!!

[Darkness]

[robysue]

Muffy, since you've disabled PMs, I have to say publicly what I would ordinarily say to you privately. You've been remarkably restrained lately!! (Can I have some of whatever it is you're taking??)

It's Lent.

[SleepingUgly]

Muffy, since you've disabled PMs, I have to say publicly what I would ordinarily say to you privately. You've been remarkably restrained lately!! (Can I have some of whatever it is you're taking??)

It's Lent.

What you're taking can't be had during Lent, or you gave up verbally eviscerating people for Lent? In any case, I don't celebrate Lent, so fork it over.

[idamtnboy]

I agree there are many ideas about what meaning should be attached to many things that are less than desaturating apneas, for the average person. However, still, the bottom line for me is what is expressed in the book Nonivasive Mechanical Ventilation: Theory, Equipment, and Clinical Applications, by Antonio Matías Esquinas (Nov 4, 2010), p. 101:

That's a new book, isn't it?

In patients with OSA, progressively higher CPAP levels applied during sleep turn obstructive apneas into hypopneas, hypopneas into continuous inspiratory flow limitation, with or without snoring, and flow limitation into unobstructed breathing.

This is one of clearest explanations I've seen about the purpose of xPAP therapy.

When breathing becomes unobstructed, "respiratory arousals" (i.e., arousals that may follow increased inspiratory efforts associated with obstructed breathing) are eliminated, while sleep becomes more stable and sleep cycles more regular, contributing to improvements in subjective sleep quality, daytime sleepiness, and quality of life usually observed after just a few nights of CPAP application.

So this author is saying the goal is no upper airway restrictions or disturbances at all. In other words the air passage should be clear and clean and slick as can be so air moves in and out with absolute freedom of movement, i.e., no OAs, no FLs, and a flow graph with uniform amplitude. I wonder, in light of the complexity of the human body and how it interacts with the environment it's in every day and night, how realistically needful or desirable this is.

Also, relief of upper airway obstruction is associated with resolution of intermittent hypoxemia and hemodynamic swings that accompany obstructive events, with a consequent reduction in long-term cardiovascular morbidity and mortality.

What the heck do those terms mean?

The objective of CPAP treatment are elimination of symptoms and of cardiovascular and, possibly, metabolic risk related to OSA. Today, the best way to accomplish these aims is usually considered to fully eliminate all degrees of upper airway obstruction during sleep. The lowest CPAP that eliminates upper airway obstruction in all sleep stages and body postures in a patient is indicated as "optimal" CPAP.

Therefore, the question for an average OSA patient, in my opinion, is generally a matter of "more pressure or less?" rather than a question of "do those squigglies mean I have IFLs or not?" If you feel better with a higher pressure than what gets rid of apneas and hypopneas, then by all means, raise your pressure, if your doc doesn't mind, no matter what it is you are eliminating.

But, as has been said many times on this forum, too high a pressure can prompt centrals. My sleep doc's assistant said too high a pressure can also cause OAs. How does the author address the conflicting results that may result from the pressure that eliminates "all degrees of upper airway obstruction?" but prompts CAs and possibly OAs?

[SleepingUgly]

When breathing becomes unobstructed, "respiratory arousals" (i.e., arousals that may follow increased inspiratory efforts associated with obstructed breathing) are eliminated, while sleep becomes more stable and sleep cycles more regular, contributing to improvements in subjective sleep quality, daytime sleepiness, and quality of life usually observed after just a few nights of CPAP application.

So this author is saying the goal is no upper airway restrictions or disturbances at all. In other words the air passage should be clear and clean and slick as can be so air moves in and out with absolute freedom of movement, i.e., no OAs, no FLs, and a flow graph with uniform amplitude.

The author didn't say no FLs, but rather respiratory AROUSALS.

I wonder, in light of the complexity of the human body and how it interacts with the environment it's in every day and night, how realistically needful or desirable this is.

Oh, it's desirable to eliminate arousals alright.

Also, relief of upper airway obstruction is associated with resolution of intermittent hypoxemia and hemodynamic swings that accompany obstructive events, with a consequent reduction in long-term cardiovascular morbidity and mortality.

What the heck do those terms mean?

It means oxygen desaturations and other bad stuff. BAD stuff.

Actually, I'm not sure there is evidence that arousals in the absence of hypoxemia and other "bad stuff" is really that bad for anything except the quality of one's life, which is of course, everything, but you know what I mean.

But, as has been said many times on this forum, too high a pressure can prompt centrals.

Right, that's why they said the minimum pressure necessary, without causing other BAD STUFF.

My sleep doc's assistant said too high a pressure can also cause OAs.

I have no idea if that's true, I just have no idea why that would be true. But he/she's the assistant, not me.

[idamtnboy]

The author didn't say no FLs, but rather respiratory AROUSALS.

Ok, what am I missing? In the first sentence jnk quotes above the author says

...progressively higher CPAP levels applied during sleep turn obstructive apneas into hypopneas,... and flow limitation into unobstructed breathing.

Then the author says

When breathing becomes unobstructed....

I read this as him saying eliminating flow limitations, the lowest level of the interferences with breathing, equals having unobstructed breathing. The progression that results from increasing CPAP pressure is: convert OAs into HAs, then convert those HAs into FLs, and then convert those FLs into unobstructed breathing. When you achieve unobstructed breathing you will have no arousals.

Oh, it's desirable to eliminate arousals alright.

But at what cost in terms of the complexity of the required therapy? How good a handle can we get on the extent to which therapy resources need to be expended?

But, as has been said many times on this forum, too high a pressure can prompt centrals.

Right, that's why they said the minimum pressure necessary, without causing other BAD STUFF.

That's not how I read the following

The lowest CPAP that eliminates upper airway obstruction in all sleep stages and body postures in a patient is indicated as "optimal" CPAP.

To my way of thinking all this balances out only if the CPAP level that eliminates upper airway obstruction is also less than the highest CPAP level that will not induce CAs or OAs. Is this in fact the case with all patients? In the portion of the book quoted above the author's focus is on eliminating upper airway obstruction. Jeff, how does he address the issue of CPAP level above that point, or does he? What does he say about centrals?

My sleep doc's assistant said too high a pressure can also cause OAs.

I have no idea if that's true, I just have no idea why that would be true. But he/she's the assistant, not me.

I was a bit surprised myself when she said that, but I have no basis to not accept it as valid.

[idamtnboy]

To NotMuffy:
After some PMs with another forum member, and going back and rereading your November posts about flow limitations, I have a sufficient understanding of who, or what, you are to not be concerned about your credibility. I apologize for questioning the efficacy of what you post, unless of course it happens to clearly be a pile of humorous BS, which you are known to occasionally cast upon us!

Thanks for your contributions.

idamtnboy