In anticipation of my BIPAP Re: New Thread

[Sleeprider]

I don't have any further changes to suggest, and the discussion above is very good. A mask needs to float to fit. Over-tightening is not the solution. I'm encouraged by the results of the second half of the night and would consider that a success if it holds. Even more important, is that there are no CA events and we can go higher on PS if needed.

[Plmnb]

ApneaQuestions    I will review as suggested.

While we wait for Sleeprider to comment:


I am still in the process of wrapping my head around a number of things of course,  but before I do review the clinicians literature, (I am sure this has already been covered in my threads), I'm just trying to solidify the info,... even though the AHI is low, you can have poor quality breaths that do not count in the AHI, correct? And this makes you have sucky sleep, right?

Plmnb

[slowriter]

even though the AHI is low, you can have poor quality breaths that do not count in the AHI, correct? And this makes you have sucky sleep, right?

Right. And your AHI isn't THAT low (notwithstanding what the medical industry says).

[Plmnb]

I don't have any further changes to suggest, and the discussion above is very good. A mask needs to float to fit. Over-tightening is not the solution.  I'm encouraged by the results of the second half of the night and would consider that a success if it holds.  Even more important, is that there are no CA events and we can go higher on PS if needed.

Hi Sleeprider...Very encouraging, thank you so much.

Just a couple of questions   And then I will try to leave you in peace for a while.

(I will work on the mask issue).

You mention no CA, yet there is a very low number listed in the summary box, .16.....is this inconsequential in the scheme of things?

You state that we can go higher on the PS.  If I change this tonight do you think that would be ok?

I do hit the ceiling on pressure quite a bit, will changing the PS help this?  Or may I adjust the max to a higher number?  Or should I just leave ALL the settings alone for a few days and see how it goes?

MOST respectfully,
Plmnb

[Sleeprider]

Plmnb, I'm going to drop some information here from JoeyWallaby's post I linked earlier. Some of these references refer to the Airway Suspension surgery you asked about in another thread, and other parts are related to the use of ASV in treating UARS. You might want to keep track of this in case we eventually go to your doctor to try to treat using this approach.

I've tried to set the Min EPAP to the point where my airway, consciously fully relaxing it, feels supported on exhale (and vice versa, Min PS so that airway feels supported on inhale). I found this quote from B. Tucker Woodson in the book "Sleep Apnea and Snoring" related to this...

Airway collapse during sleep is both dynamic and passive. Dynamic collapse occurs during inspiration. Passive collapse occurs during expiration. Both are the result of a combination of applied forces that collapse and dilate the airway. In a structurally small airway during sleep, when dilating forces that stabilize the airway are greater than the collapsing forces, the airway is obstructed.

Obstruction during sleep is the result of a complex cascade. During inspiration, upper (pharynx) and lower (chest wall and diaphragm) airway muscles are activated. The lower airway muscles create a negative intraluminal force balanced by upper airway muscles that stiffen and dilate the airway. Increases in negative airway pressure or loss of muscle dilation will obstruct the airway. In sleep-disordered breathing both occur. Increased upper airway resistance leads to more negative intraluminal pressure and activation of upper airway dilator muscles is delayed or decreased. During expiration, positive pressure forces dilate the airway, and upper airway muscle tone is reduced. If the balance is unfavorable and the effects of tissue mass are not compensated, collapse and obstruction occur.

The tipping point for apnea is poorly understood, but is likely initiated by passive expiratory collapse. It is this collapse that triggers the dynamic events during inspiration. Without passive airway collapse, the cascade of progressive inspiratory flow limitation, increased negative luminal pressure and increased upper airway resistance may be aborted. If adequate airway size is maintained during expiration, inspiratory obstruction is prevented.

Since during expiration the largest decreases in airway size occur in the hypopharynx, treatment of this segment may be critical for most if not all individuals with sleep-disordered breathing. The tongue suspension procedure was conceived as a means of providing an extraluminal dilating force to the lower pharyngeal airway in contrast to nasal Continuous Positive Airway Pressure (CPAP) which is an intraluminal dilating force. This is accomplished by passing a submucosal suture into the posterior midline tongue. The suture prevents passive collapse while not interfering with anterior and superior tongue movements which are involved with swallowing and speech. Placement is directed towards the level of the foramen cecum.

Also, this is apparently how ResMed ASVs determine respiratory cycle phase
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4629962/

And more info



If passive airway collapse on exhale is causing some of the inspiratory flow limitation, but not enough to cause apneas/hypopneas, the machine isn't going to increase EPAP but instead the PS (since it can't tell of course). Maybe I should try a higher Min EPAP and see if the required PS to achieve a good waveform is decreased?

More on inspiratory vs expiratory collapse/narrowing

Upper airway obstruction during sleep is characteristically attributed to inspiratory narrowing owing to a collapsing subatmospheric pressure against a hypotonic pharyngeal airway. However, several lines of evidence implicate expiratory narrowing as a possible mechanism of the initial narrowing. First, ventilatory motor output is an important determinant of upper airway patency. Oscillation of ventilatory motor output, during the characteristic periodic breathing of OSA, is associated with pharyngeal narrowing or obstruction at the nadir of the motor output, especially in individuals with a highly collapsible airway. Second, an obstructive apnea is often preceded by expiratory narrowing of the upper airway as evidenced by increased expiratory resistance or progressive expiratory narrowing, detected by fiberoptic imaging. Finally, although upper airway narrowing or occlusion occurs during a spontaneous or induced hypocapnic central apnea or induced hypocapnic hypopnea, pharyngeal narrowing during central hypopnea occurs during the expiratory phase only and is associated with increased expiratory upper airway compliance. Therefore upper airway obstruction may occur in either inspiration or expiration. Individuals with a high surrounding tissue pressure may be particularly susceptible to expiratory pharyngeal narrowing during such low ventilatory motor output and driving pressure.

From chapter "Anatomy and Physiology of Upper Airway Obstruction", in "Principles and Practice of Sleep Medicine 4th edition".

[slowriter]

You mention no CA, yet there is a very low number listed in the summary box, .16.....is this inconsequential in the scheme of things?

A few here and there is not a problem. When you have a problem, it will be obvious; the number will increase a lot.

[Plmnb]

even though the AHI is low, you can have poor quality breaths that do not count in the AHI, correct? And this makes you have sucky sleep, right?

Right. And your AHI isn't THAT low (notwithstanding what the medical industry says).

Good morning slowriter!

At this point what do you think would be a "low" enough AHI for me?  Or should I really not concern myself with this number as long as I can get a restful sleep? As per the esteemed Sleeprider I'm in pretty good shape as compared to what was going on...his assistance has been incredibly helpful...

Plmnb

[Plmnb]

  SLEEPRIDER, I appreciate all you have contributed.

I really want to make a donation, it won't be much but everyone deserves the assitance found here.

Plmnb

[slowriter]

You're in the range where it's "good" but I think that it probably varies by individual the relationship between AHI and how one feels subjectively.

In my case, for example (I have UARS, so super sensitive to nighttime arousals), good is close to 0.

I can imagine other people feel good if 1 or 2.

We'll have to see what works for you as you tackle the remaining issues (which SR is clearly hinting may ultimately require an ASV machine).

Long story short: right, don't worry about the number in the abstract too much.

[Plmnb]

GOD, I wish there was a LIKE or THANKS button, I feel like I'm being annoying with all my posts.


 Slowwriter, duly noted.

Plmnb