CPAPtalk.com

rested gal wrote:My hypothetical question was (and still is)... is increasing the pressure from a cpap by one or two cms while the back of a relaxed tongue is obstructing the airway be more likely to shove the tongue into blocking the airway a bit more tightly? Or would increasing the cpap pressure by one or two cms be more likely to push the tissues of throat, tongue, and soft palate into a position that opens the airway a bit more?

If the airway was still open a 1 or 2 cm pressure increase would not push the tongue back in my opinion. The tongue base was designed to remain enduringly stable during coughing, sneezing, talking, laughing, suddenly and deeply inhaling, with pressure fluctuations that far exceed that little 2 cm delta. It's after occlusion occurs when those severe survival-based diaphragmatic pressures start to kick in. That's the point at which the base of the tongue can conceivably get pulled back rather tightly IMO.

On the flip side of that same coin of consideration, the 1 or 2 cm pressure increase would have to be very quick to even stand a snowball's chance of staving off a rapidly escalating airway collapse. It would have to occur toward the beginning of that sequence, and we know that apnea detection and response, unfortunately, simply cannot occur that quickly in any APAP machine. Arguably incipient apneas are sometimes detected as less-severe FL and H because of partially-mitigating static pressure already in place. So treating FL and H is sometimes a case of treating what would have otherwise been A (had it not been for some inadequate static pressure already in place).


My opinion only, as always. .

ozij wrote:

Maximum pressure for command on apnea:
Maximum pressure beyond which no pressure increase will be applied following the detection of an apnea in breathing

From PB's manual.

Till this thread, I thought "Maximum pressure for command on apnea" meant how hard you push against an apnea. On reading the thread, and re-reading the manual, this definitely has another meaning... probably did all along .


O.

um it means "command" on apnea, or what command should I perform? when I see an apnea at this "pressure"?

In the case of the 420, it checks delivery pressure, based upon decision tree checks for cardiac oscillations then decides if it should maintain, drop or increase pressure.

The command on Apnea setting defaults to 10 cm pressure. This is the same as the Resmed A10 algorythm. Where Resmed says i won't respond to apnea at or above this pressure for fear it may be central... Respironics says I'm going to apply pressure 3 times over 6 events and if its still there I'll put up one of those NR flags so no one knows I just screwed up.

The 420e being the smarter machine says I'll use my built-in pneumotach sensor and listen for cardiac oscillations (sign of an open airway, meaning if there is no air flow it is most likely a central apnea which doesn't respond well to increased pressure). So if I hear one I know for sure you are having a central apnea, if so I'll flag it as such on line 2 and maintain or drop pressure, if I see another event like a Flow Limitation, snore I know those are obstructive and respond with pressure.

Now your Rapport study indicates that only 60% of central apnea are associated with that open airway (in order for the 420e to "hear" the cardiac oscillations). So that means 6 out of 10 central apnea seen will have an open airway, the others could be closed airway same as a blockage with the tongue, in that case it is still okay for the machine to apply pressure since the airway is collapsed anyway.

Now this is the really cool part, the "command on apnea" setting on the 420e is changeable. That means if you don't follow the "mold" for when central apnea is more likely to occur (10 cm or higher pressure), you can tweak the 420e to have a lower/higher command on apnea pressure, actually changing how the machine responds.

I start having CA's above 9.0 cm pressure. Most other auto's go nutso when I use them, they start confusing my central apnea for obstructive, if I'm under 10 cm pressure they increase which only makes them worse.

With the 420e, I lowered that "command on apnea" setting from default=10 to 9.0. Now my 420e will start looking more carefully for CA at a lower pressure threshold for me.

snoredog wrote:But the 420e is technically identical to the 418P it's predecessor in function.

I vaguely recall the 418p supposedly had one or two more command-on parameters. Problem with my vague memories is they're almost always wrong.

But I thought command-on-snore or command-on-hypopnea might have been on the 418p.

Maybe it was command-on-command, which would have made for one heck of a runaway algorithm! .

-SWS wrote:

snoredog wrote:But the 420e is technically identical to the 418P it's predecessor in function.

I vaguely recall the 418p supposedly had one or two more command-on parameters. Problem with my vague memories is they're almost always wrong.

But I thought command-on-snore or command-on-hypopnea might have been on the 418p.

Maybe it was command-on-command, which would have made for one heck of a runaway algorithm! .

Cogratulations, snoredog! Grrrr or not, you must be very proud.

-SWS your vague memeories are quite correct (and I've just rediscovered a way of tricking the PDF copy protection: Print with Microsoft Office Document Image writer, and use tools to send the text to Word.):

PB in the SL3 help for the GK418,P and Rem + Range wrote:The Algorithm box tells you that
• The device is being controlled automatically for the GK418A on the events “Apnea” and “Acoustical Vibrations” and for the GK418P on the events “Apnea,” “Acoustical Vibrations,” and “Flow Limitation.”
• the events “Hypopnea” and “Apnea with CArdiac oscillations” can be controlled for the K418P as required. In order to activate or deactivate automatic control for these two events, click the appropriate boxes or leave them blank. The function “Command on apnea with CArdiac oscillations” is only available on the P model.
The second box sets
• the maximum automatic pressure to be applied after an “apnea”. The automatic pressure used after an event that has been detected cannot exceed the Max pressure for command on Apnea that has been set. This value is set using the slider to select a value between Pmin and Pmax.
• the pressure increase to be applied after a “Flow Limitation” event. The pressure step can be set using the slider between 0,1 and 0,3 cmH2O.

(my emphasis)

rested gal wrote:

NightHawkeye wrote:According to these researchers the answer to your first question is that without additional pressure, the partially occluded airway collapses in on itself when the opening is narrowed

So, if I understand you, the answer you're giving, NHE, is that more pressure applied by a hypothetical tech-with-a-triggerhappy-finger-on-the-button would likely open the obstructive apnea to at least some extent?

Correct.

rested gal wrote:If so, it looks like we're viewing the results of the researchers you quoted the same way.

.

Which raises the question of just how fast an APAP can (or should) raise pressure in light of an imminent airway collapse. (Probably not gonna get the answer to that today ... although it does add emphasis to the ongoing 420E discussion).

rested gal wrote:I guess I think soft tissue would get moved aside before something as big as a tongue would be pushed farther down. IF pressure were raised.

Never underestimate the power of suction ...

... (NHE, for self-preservation purposes, is deliberately avoiding illustrative descriptions at this juncture.)

'-SWS wrote: ... the 1 or 2 cm pressure increase would have to be very quick to even stand a snowball's chance of staving off a rapidly escalating airway collapse. It would have to occur toward the beginning of that sequence, and we know that apnea detection and response, unfortunately, simply cannot occur that quickly in any APAP machine.

NHE, in the interest of furthering the discussion, wishes to suggest that the last statement might be better worded as something more like ...

... we know that apnea detection and response, unfortunately, simply does not occur that quickly in any existing APAP machine.

NHE believes this to be an important distinction at the heart of the current discussion. Ultimately, response time is an important differentiator between machines, possibly even the most important consideration. .

Regards
Bill

-SWS wrote:One thing that I liked about the single-patient model Bill just cited, is that it shows that high nasal impedance can contribute to an ordinary apnea occurring down at the pharynx.

More on the same topic from yet an additional source (bold emphasis mine):

J Am Board Fam Pract 15(2):128-141, 2002. © 2002 American Board of Family Practice wrote:Another cause of OSA is nasal obstruction. The nose, best viewed as a variable resistor, contributes to nearly 40% of total airway resistance.[23] This resistance is greatly influenced by the vasomotor reaction of the nose to several factors, such as hormonal effects, metabolic changes, and numerous pharmacologic agents.[23] Olsen et al[24] measured the respiratory effort in a patient during sleep and suggested that the oral airway resistance was greater than the nasal airway resistance. With the nasal pathway being the preferred route for nocturnal breathing, an increase in nasal resistance will invariably increase the possibility of collapse of the nonrigid portion of the upper airway, namely, the pharynx.

In anecdotal agreement with this, snork1 as I recall found that his CPAP pressure requirement dropped considerably after nasal surgery. I believe also, sometime later, snork1 then went on to use a dental device and had no further need for CPAP therapy.

Regards,
Bill

-SWS wrote:

ozij wrote:20050016536 is a patent application from Jan. 2005.

Meaning the design contained in any 2005 application is submitted too late to represent what's inside any machine having received a May 2003 FDA approval.

Hmmm, good point.

How about 6299581?

SAG

rested gal wrote:Got a hypothetical question...

IF -- in a sleep lab setting with a full PSG titration going -- a person had an obstructive apnea involving tongue, soft palate, and back of throat all collapsing on each other, but there was still a thread of air being breathed in and out, and IF the sleep tech did immediately raise the pressure a cm or two, would that additional pressure be more likely to:

1. open the airway a bit more?

2. close the airway more firmly?

3. do something else?

4. do nothing?

Depending on the amount of pressure and speed of response, I would say somewhere between "open the airway a bit more" to "completely resolve the event", since that's basically the philosophy of BiPAP titration.

SAG

BTW, talking about obsolete stuff, I would think that with the introduction of the Sandman line from Covidien, GK420E is on borrowed time.

SAG

Snoredog wrote:Oh NO!!! my youngest daughter (16yrs) just informed me she passed the get out of High School early test One graduating June 1 with her DDS and another wanting early tuition grrr

If I didn't have 4 dogs....

Oh the oldest is doing her residency at the VA in Long Beach, supposed to be a pretty good program

Smart girls! Congrats to them both! I know what you mean about the dogs...

StillAnotherGuest wrote:BTW, talking about obsolete stuff, I would think that with the introduction of the Sandman line from Covidien, GK420E is on borrowed time.

Obsolete? Perhaps not the most accurate descriptor available ...

According to PB's website:
The family of GoodKnight® 420 CPAP systems, offering the smallest, lightest sleep therapy devices on the market and patented technology that reacts to breathing changes more quickly for improved comfort.

If, as some here have claimed, the 420E has the fastest responding algorithm available, then perhaps when the Sandman line includes APAP, the website will read:
Covidian/Puritan Bennett's sleep therapy family line continues to lead the industry with its Sandman CPAP systems, offering the smallest, lightest sleep therapy devices on the market and patented technology that reacts to breathing changes more quickly for improved comfort.

A couple of points regarding patents also deserve to be made.
1. A patented technique can be used in any number of APAP machines.
2. A single APAP machine can employ techniques from any number of patents.

When a company "owns" a patent, the company is free to use the techniques in that patent as it sees fit. That includes mixing and matching features from any number of patents. Algorithms, per se, are not patentable, but rather the techniques are. The distinction has blurred considerably in recent years, of course, largely from software companies which have overloaded the patent system by attempting (and succeeding in many cases) to patent algorithms ...

Regards,
Bill (striving toward impartiality ... )

StillAnotherGuest wrote:BTW, talking about obsolete stuff, I would think that with the introduction of the Sandman line from Covidien, GK420E is on borrowed time.

SAG

The Sandman would have to be pretty good to displace the 420e in my opinion, but sales will ultimately dictate that, I'm trying to find the faults with the 420e that would make that happen much sooner but I'm not finding many.


http://www.puritanbennett.com/prod/prod ... VNT&id=321




All we can hope is that it has as many if not more features as the 420e.

But seeing it has a "memory card" doesn't look very promising from a patient point of view.

maybe they will come out with Sandman iPhone and I can check how I did the night before from my iPhone

StillAnotherGuest wrote:

rested gal wrote:Got a hypothetical question...

IF -- in a sleep lab setting with a full PSG titration going -- a person had an obstructive apnea involving tongue, soft palate, and back of throat all collapsing on each other, but there was still a thread of air being breathed in and out, and IF the sleep tech did immediately raise the pressure a cm or two, would that additional pressure be more likely to:

1. open the airway a bit more?

2. close the airway more firmly?

3. do something else?

4. do nothing?

Depending on the amount of pressure and speed of response, I would say somewhere between "open the airway a bit more" to "completely resolve the event", since that's basically the philosophy of BiPAP titration.

SAG

That makes sense (and provides further insight). BiPAP pressure is adjusted to keep the airway open using different pressures on inhale and exhale. I assume that lowering either pressure below the titration values would likely lead to airway collapse. On exhale the pressure from the lungs is positive across the orifice allowing the airway to remain open while the machine provides a relatively low pressure. On inhale the airflow reverses creating a negative pressure differential across the orifice and the airway is prone to collapse, except that pressure provided by the machine has been raised sufficiently to "splint" it open.

Kinda suggests the tantalizing possibility that a quick responding APAP could very well keep impending apneas at bay. Of course, that would require a real-time highly accurate assessment of the need for a pressure increase. I suppose it's this second point, the real-time analysis, which becomes the stumbling block to better APAP performance.

Regards,
Bill ( ... who is not at all convinced that this second point is nearly the obstacle it appears to be at first glance)

Snoredog wrote:

StillAnotherGuest wrote:BTW, talking about obsolete stuff, I would think that with the introduction of the Sandman line from Covidien, GK420E is on borrowed time.

SAG

The Sandman would have to be pretty good to displace the 420e in my opinion, but sales will ultimately dictate that, I'm trying to find the faults with the 420e that would make that happen much sooner but I'm not finding many.

http://www.puritanbennett.com/prod/prod ... VNT&id=321




All we can hope is that it has as many if not more features as the 420e.

But seeing it has a "memory card" doesn't look very promising from a patient point of view.

maybe they will come out with Sandman iPhone and I can check how I did the night before from my iPhone