For those running APAP with a narrow range.....

[Lucky7]

Curious: how did you figure out where to set your max pressure?

Also, while I'm thinking about it: do you check for leaks at that max pressure? I guess my thinking is: if it's good at the Max pressure it's definitely going to be good below that.

Cheers.

[palerider]

Curious: how did you figure out where to set your max pressure?

Also, while I'm thinking about it: do you check for leaks at that max pressure? I guess my thinking is: if it's good at the Max pressure it's definitely going to be good below that.

Cheers.

"narrow range" is something that people that don't understand how to set pressures, or read pressure charts promote.

Max should *normally* be left at whatever the machine's max possible is and *ignored*. If you don't *need* the pressure, then the machine won't raise the pressure.

On the other hand, if you buy the 'narrow range' BS, and you lower the max, and you have a bad night, then you've prevented the machine from being able to do it's job by responding to your needs.

Technically speaking if you change your settings from 4-20 to 9-20, then you've "narrowed the range" but that's not what they're normally trying to con people into with a "narrow range".

[LSAT]

Curious: how did you figure out where to set your max pressure?

Also, while I'm thinking about it: do you check for leaks at that max pressure? I guess my thinking is: if it's good at the Max pressure it's definitely going to be good below that.

Cheers.

Your post indicates that you are using the ELITE model CPAP.. If that is the case you have a fixed pressure....there is no "range".

[Miss Emerita]

Some people need to cap their pressure to avoid aerophagia. Others find that their sleep is disturbed when their machine raises pressure in response to flow limitations, yet find that their FLs and AHI are unchanged with a capped max. So there can be reasons to cap the max.

Leaks occur for all kinds of reasons unrelated to the level of pressure generated by the machine. So the leak rate may be fine at the max pressure but high at lower pressures if, e.g., the mask shifts.

[Lucky7]

Curious: how did you figure out where to set your max pressure?

Also, while I'm thinking about it: do you check for leaks at that max pressure? I guess my thinking is: if it's good at the Max pressure it's definitely going to be good below that.

Cheers.

Your post indicates that you are using the ELITE model CPAP.. If that is the case you have a fixed pressure....there is no "range".

It's actually the Autoset. My bad.

[chunkyfrog]

Some people need to cap their pressure to avoid aerophagia. Others find that their sleep is disturbed when their machine raises pressure in response to flow limitations, yet find that their FLs and AHI are unchanged with a capped max. So there can be reasons to cap the max.

Leaks occur for all kinds of reasons unrelated to the level of pressure generated by the machine. So the leak rate may be fine at the max pressure but high at lower pressures if, e.g., the mask shifts.

This is why I have capped my maximum; but I might try boosting it up, just to make Palerider smile.

[Lane101]

Curious: how did you figure out where to set your max pressure?

Also, while I'm thinking about it: do you check for leaks at that max pressure? I guess my thinking is: if it's good at the Max pressure it's definitely going to be good below that.

Cheers.

"narrow range" is something that people that don't understand how to set pressures, or read pressure charts promote.

Max should *normally* be left at whatever the machine's max possible is and *ignored*. If you don't *need* the pressure, then the machine won't raise the pressure.

On the other hand, if you buy the 'narrow range' BS, and you lower the max, and you have a bad night, then you've prevented the machine from being able to do it's job by responding to your needs.

Technically speaking if you change your settings from 4-20 to 9-20, then you've "narrowed the range" but that's not what they're normally trying to con people into with a "narrow range".

That is not always true per the reasons noted by others above. In my case the Dreamstation APAP algorithms chase what appears to be percentage AHI improvements that result in unnecessarily high pressures. For example to take an AHI of 0.9 down to 0.6 my machine would jack up the pressure max from 10-12 CM to 16CM plus. At this level a one third decrease in AHI isn't worth such an increase in pressure.

As a result I've narrowed my pressure range to just 8 to 12 CM of pressure realizing consistently good results of AHIs of less than one. Did some testing to figure out this range. For example a fixed CPAP pressure setting of 10CM works well for me with AHIs consistently around 1.0+/-. Below 8 CM AHI starts to go up significantly.

Note that this is what works for me. Everyone should analyze what works best for them in conjunction with their doctor's advice.

[Julie]

But do you understand by having the max setting at 12 it could keep the min. pressure from rising any higher if needed?

[Pugsy]

That is not always true per the reasons noted by others above. In my case the Dreamstation APAP algorithms chase what appears to be percentage AHI improvements that result in unnecessarily high pressures. For example to take an AHI of 0.9 down to 0.6 my machine would jack up the pressure max from 10-12 CM to 16CM plus. At this level a one third decrease in AHI isn't worth such an increase in pressure.

Actually all auto adjusting machines (in auto adjusting mode) have certain criteria that has to be met before any machine will be increasing any pressures.

AHI all by itself isn't part of that criteria.

Auto adjusting mode also tries to prevent future apneas from materializing with the use of pressure increase from
not just the obstructive apneas and/or obstructive hyponeas (which are part of the AHI but don't forget that central apneas are also a part of the AHI and none of the regular auto adjusting cpap machines will ever increase the pressure when it comes to central apneas).
So the other stuff that can cause the machine to want to use more pressure are...snores and flow limitations which are NOT part of the AHI.

Your machine was probably sensing snores and/or flow limitations when it tried to increase your pressure.
You won't see snores or FLs included in the AHI at all....but they can and will cause the machine to increase the pressure regardless of whatever the AHI might be.

Snores and flow limitations are considered early warning signs that the airway is trying to collapse and that's why the auto adjusting machines will increase the pressure in an effort to prevent further collapse of the airway to the point of the apnea event fully materializing into and obstructive apnea or obstructive hyponea and becoming part of the AHI.

By limiting your max pressure it can't deal with those early warning signs from FLs or snoring (which can both impact sleep quality if you have very many of them) even if they don't grow up to be full fledged OAs or hyponeas.

Now sometimes people have more of a problem with higher pressures (aerophagia being one of those problems) than letting the snores and FLs slide creates a problem and those people it makes sense for them to limit the max.
The higher pressure can cause more of a problem than whatever the machine was trying to prevent causes a problem.
When that "more pressure" causes a bigger problem than the snores and FLs are causing then we suggest limiting the max.

Otherwise if you never, ever see the machine hitting whatever max pressure you are using then it really doesn't matter what you set the max at but if you are seeing the pressure line maxed out (at 12) for prolonged periods of time then it is entirely possible that some of those snores and FLs are growing up into full grown OAs or hyponeas and being included in the AHI.
Might explain the slight reduction in AHI when you let the machine go higher....it's preventing those OAs or hyponeas from ever happening because when it increases the pressure it stops the further collapse of the airway.

It's okay if that is what you want to do (limiting the max) but you need to understand the why behind the machine does whatever it does....and AHI alone isn't why the auto adjusting machines will try increasing the pressure.

[palerider]

That is not always true per the reasons noted by others above. In my case the Dreamstation APAP algorithms chase what appears to be percentage AHI improvements that result in unnecessarily high pressures.

You don't understand how the machines work. they don't "care" about AHI, the AHI is just what results from what they can't prevent.

For example to take an AHI of 0.9 down to 0.6 my machine would jack up the pressure max from 10-12 CM to 16CM plus. At this level a one third decrease in AHI isn't worth such an increase in pressure.

*WHY* is the machine increasing pressure? there's *always* a reason, and that reason is either apneas, hypopneas, snoring or flow limitations. if the pressure was high enough to prevent those things, then the machine would not be increasing pressure.

The AHI only measures apneas and hypopneas, not all sleep breathing disturbances. I'll reiterate what I said (and I stand by it).

Max should *normally* be left at whatever the machine's max possible is a

As a result I've narrowed my pressure range to just 8 to 12 CM of pressure realizing consistently good results of AHIs of less than one. Did some testing to figure out this range. For example a fixed CPAP pressure setting of 10CM works well for me with AHIs consistently around 1.0+/-. Below 8 CM AHI starts to go up significantly.

Good for you, you're happy to have something that's "good enough" for you, just like doctors are happy enough that an AHI of 5 is 'good enough' for them.

[Lane101]

That is not always true per the reasons noted by others above. In my case the Dreamstation APAP algorithms chase what appears to be percentage AHI improvements that result in unnecessarily high pressures. For example to take an AHI of 0.9 down to 0.6 my machine would jack up the pressure max from 10-12 CM to 16CM plus. At this level a one third decrease in AHI isn't worth such an increase in pressure.

Thank you for adding your insight.

Actually all auto adjusting machines (in auto adjusting mode) have certain criteria that has to be met before any machine will be increasing any pressures.

AHI all by itself isn't part of that criteria.

Auto adjusting mode also tries to prevent future apneas from materializing with the use of pressure increase from
not just the obstructive apneas and/or obstructive hyponeas (which are part of the AHI but don't forget that central apneas are also a part of the AHI and none of the regular auto adjusting cpap machines will ever increase the pressure when it comes to central apneas).
So the other stuff that can cause the machine to want to use more pressure are...snores and flow limitations which are NOT part of the AHI.

Your machine was probably sensing snores and/or flow limitations when it tried to increase your pressure.
You won't see snores or FLs included in the AHI at all....but they can and will cause the machine to increase the pressure regardless of whatever the AHI might be.

Snores and flow limitations are considered early warning signs that the airway is trying to collapse and that's why the auto adjusting machines will increase the pressure in an effort to prevent further collapse of the airway to the point of the apnea event fully materializing into and obstructive apnea or obstructive hyponea and becoming part of the AHI.

By limiting your max pressure it can't deal with those early warning signs from FLs or snoring (which can both impact sleep quality if you have very many of them) even if they don't grow up to be full fledged OAs or hyponeas.

Now sometimes people have more of a problem with higher pressures (aerophagia being one of those problems) than letting the snores and FLs slide creates a problem and those people it makes sense for them to limit the max.
The higher pressure can cause more of a problem than whatever the machine was trying to prevent causes a problem.
When that "more pressure" causes a bigger problem than the snores and FLs are causing then we suggest limiting the max.

Otherwise if you never, ever see the machine hitting whatever max pressure you are using then it really doesn't matter what you set the max at but if you are seeing the pressure line maxed out (at 12) for prolonged periods of time then it is entirely possible that some of those snores and FLs are growing up into full grown OAs or hyponeas and being included in the AHI.
Might explain the slight reduction in AHI when you let the machine go higher....it's preventing those OAs or hyponeas from ever happening because when it increases the pressure it stops the further collapse of the airway.

It's okay if that is what you want to do (limiting the max) but you need to understand the why behind the machine does whatever it does....and AHI alone isn't why the auto adjusting machines will try increasing the pressure.

Actually the Apneas and Hypopneas, that are the basis of AHI (Number of these events per hour), are used by almost all APAP algorithms in determining therapy pressure. They are the most common "Responding Events" to which the algorithms will adjust pressure. AHI is the summary statistic regarding these events. By noting that the algorithm was chasing small AHI improvements I'm just stating that it's chasing an immaterial reduction in Apnea and Hypopnea responding events. You are correct that the algorithms also typically respond to snoring events and some also respond to flow limitations. Even if it was snoring events or other early warning sighs that were triggering some of the unnecessary pressure increases the effect is still the same as what I noted in my original post. For me these were likely false early warning signs contributing to unnecessary increases in therapy pressure.

Algorithms do vary by machine/manufacturer in what events they respond to and how they respond. I've a clinical overview from Devilbiss that provides an overview of the way these algorithms work. It has a nice summary as follows:

"Responding Events (Respiratory events that trigger a therapy response)

Responding events are breathing events that, when present, trigger a response to increase pressure
and, when absent, trigger a response to decrease pressure. All Autotitrating device manufacturers
use a unique formula of responding events, but two events are common to all current Autotitrating
PAPs:
• Obstructive apneas – occur when patient airways close and breathing cannot occur
• Hypopneas – occur when patient airways are partially closed and breathing is limited

Obstructive Apneas

All manufacturers’ Autotitrating devices respond to obstructive apneas by increasing pressure;
however every manufacturer has a unique definition of an obstructive apnea which is dependent on
their algorithm’s detection and response capabilities. A few manufacturers allow professionals to
adjust obstructive apnea definition and create customized patient therapy.

Hypopneas

All Autotitrating device manufacturers increase pressure in response to their unique definition of
a hypopnea event. A few manufacturers allow adjustments to hypopnea definition for therapy
customization.

Snoring versus Flow Limitation

Snoring and flow limitation are similar in that both may occur prior to obstructive apneas and/or
hypopneas. All Autotitrating PAPs are proactively programmed to increase pressure in response to
snores or flow limitations to prevent the occurrence of obstructive apneas and hypopneas. There is
conflicting evidence as to which parameter allows the earliest response"


This clinical overview provides a brief APAP history noting that one early product only responded to Apneas and was too aggressive waking patients while another only responded to snoring and missed many Apneas and Hypopneas also waking patients due to its ineffectiveness.

The Apnea Board does have an overview of ResMed and Philips algorithms and it appears they respond to a similar array of events as follows:

ResMed (Per Apnea Board)

"When AutoSet detects an event, it doesn’t just apply a fixed pressure response. Instead, AutoSet assesses the severity of each event – whether it is flow limitation, snoring or an apnea – before determining and delivering the ideal, lowest pressure solution to treat the event. "

Philips For DreamStation (Per Apnea Board)

"Auto CPAP algorithms

This was copied from Philips training slides

General behavior

The Auto algorithms are designed to keep upper airways open and provide optimal therapy pressure. Not only do they respond to obstructive events, they also proactively search for the lowest possible pressure needed by the patient.

When a patient experiences obstructive events such as apneas, hypopneas, flow limitations or vibratory snores, the DreamStation Auto algorithms increase pressure in response.

Analysis of the Flow will lead to the event being classified as obstructive or central and will generate the appropriate response.

When a pattern of obstructive events occur pressure increases to achieve airway patency.

If the device classifies the event as central pressure remains unchanged.

Flow Limitation

Flow Limitation is determined by evaluating 4 parameters of the patient's breathing - roundness, flatness, peak, and shape. If two of the four parameters fall out of trend it is considered a flow limitation. If a flow limitation is detected a high pressure search is initiated in which pressure is gradually increased. Note: BiPap devices respond with IPAP.

Vibratory Snore (VS)

During a vibratory snore pressure vibrations are detected.

If 3 vibratory snores are detected within 1 minute with less than 30 seconds between snores the algorithm increases pressure by 1cn over 15 seconds.

Note that for BiPAP devices these events will create a response for EPAP.

Apnea (obstructive or central)

An apnea is the absence or reduction of patient airflow by at least 80% for 10 seconds or more.

If 2 obstructive airway apneas/hypopneas are detected within 3 minutes the algorithm increases pressure by 1 cm.

Note BiPAP devices will create a response to obstructive events with EPAP. CPAP or BiPAP devices do not respond to central apneas.

Hypopnea (H)

A Hypopnea is the reduction of patient air flow by at least 40% for 10 seconds or more.

If 2 obstructive airway apneas/hypopneas are detected within 3 minutes the algorithm increases pressure by 1 cm. Note: BiPAP devices will create a response with IPAP.

Respiratory Effort Related Arousal (RERA)

A RERA is a sequence of breaths that exhibit both a subtle reduction in airflow during a 10 second period and a progressive increase in flow limitation. If a breath sequence is terminated by a sudden increase in air flow (along with the elimination of flow limitation a RERA is indicated.

If 2 RERA events are detected within 3 minutes pressure is increased by 0.5cm.

Periodic breathing

Periodic breathing such as Cheyne-Stokes Respiration (CSR) is defined as alternating periods of hyperventilation with waxing and wanning tidal volume and periods of central hypopneas and apneas.

No therapy adjustments are made in response to periodic breathing. "

[Lane101]

That is not always true per the reasons noted by others above. In my case the Dreamstation APAP algorithms chase what appears to be percentage AHI improvements that result in unnecessarily high pressures.

You don't understand how the machines work. they don't "care" about AHI, the AHI is just what results from what they can't prevent.

For example to take an AHI of 0.9 down to 0.6 my machine would jack up the pressure max from 10-12 CM to 16CM plus. At this level a one third decrease in AHI isn't worth such an increase in pressure.

*WHY* is the machine increasing pressure? there's *always* a reason, and that reason is either apneas, hypopneas, snoring or flow limitations. if the pressure was high enough to prevent those things, then the machine would not be increasing pressure.

The AHI only measures apneas and hypopneas, not all sleep breathing disturbances. I'll reiterate what I said (and I stand by it).

Max should *normally* be left at whatever the machine's max possible is a

As a result I've narrowed my pressure range to just 8 to 12 CM of pressure realizing consistently good results of AHIs of less than one. Did some testing to figure out this range. For example a fixed CPAP pressure setting of 10CM works well for me with AHIs consistently around 1.0+/-. Below 8 CM AHI starts to go up significantly.

Good for you, you're happy to have something that's "good enough" for you, just like doctors are happy enough that an AHI of 5 is 'good enough' for them.

Actually I do have a good understanding of how these machines work. See my reply to Pugsy immediately above this one on this topic for the details. Almost all machine algorithms do respond to the apnea and hypopnea events that are tracked by the AHI statistic. As we've both noted AHI is just the number of these two events per hour. Per the details in my post above on algorithms, these machines care more about AHI underlying events more than anything else. Your statement above that they "don't care" is just plain wrong. As noted in my post above the algorithms may also look at other factors such as snoring and flow limitations.

Unclear why you are referring to having figured out therapy settings that take my AHI below 1.0 as just "good enough". Your statement is nonsensical. Given range of post therapy results CPAPTalk members have shared achieving an AHI that is below 1.0 is really excellent - and my Dr. agrees. In fact it takes an AHI above 5.0 for a diagnosis of sleep apnea.

It does not matter what the reasons for the unnecessary pressure spikes are. They are unnecessary as a lower pressure range (in fact even a fixed pressure of 10cm) addresses my sleep apnea just as well. The algorithms may look at snoring and flow limitations as early warning signs of upcoming apnea events. In my case, if my Dreamstations are reacting to these, they are false warnings causing unnecessary pressure spikes.

Finally in my case it would be wrong to leave the max pressure at the machines maximum. This is something I confirmed with my sleep Dr. In fact initially she wanted me to cap the machine at 16cm (machine can go to 20cm) when I started APAP and agreed, based on the results I shared in my first post that the narrower range I now use makes the most sense. One of her original reasons for moving me to an APAP was to enable collection of useful data on my sleeping patterns so we could optimize my therapy. Note that when the Philips recall was announced she also agreed, based on good AHI results from a few nights at my old 10cm fixed pressure prescription (from an original sleep study) that the safest thing for me was to go back to my old fixed pressure CPAP at 10cm. Again this is what works for me, each of us needs to determine, ideally with advice of a Dr. what is ideal for their situation.

Finally when we post here, unless we are MDs, we should generally be sharing what has worked for us and let our fellow users decide how to use that information to optimize their own therapy. Generic statements that a machine should always be set to its maximum pressure are not right and could even be wrong or cause injury if not right for an individual. In many cases overly aggressive pressure spikes can wake people up.

Bottom line is one should not always set an APAP to maximum range. The fact that manufacturers include the ability to set a custom range is the best evidence of that.

[Lane101]

But do you understand by having the max setting at 12 it could keep the min. pressure from rising any higher if needed?

Yes I do. Exactly what I'm trying to achieve by capping it as I don't need a higher pressure for an effective therapy. Should my AHI results go up then I would adjust accordingly.

[palerider]

Your statement above that they "don't care" is just plain wrong.

You don't know as much as you think you do.

Unclear why you are referring to having figured out therapy settings that take my AHI below 1.0 as just "good enough". Your statement is nonsensical. Given range of post therapy results CPAPTalk members have shared achieving an AHI that is below 1.0 is really excellent - and my Dr. agrees. In fact it takes an AHI above 5.0 for a diagnosis of sleep apnea.

5 is crap, 5 is an average of 12 minutes of sleep between interruptions. less even because there are things that disturb sleep that aren't counted in AHI.

If you're happy with what is 'good enough' for doctors, good for you, move along and let other people get *better*.

It does not matter what the reasons for the unnecessary pressure spikes are. They are unnecessary as a lower pressure range (in fact even a fixed pressure of 10cm) addresses my sleep apnea just as well.

Nobody asked you, you know? you decided to throw your 1 cent in here.

Finally when we post here, unless we are MDs, we should generally be sharing what has worked for us and let our fellow users decide how to use that information to optimize their own therapy. Generic statements that a machine should always be set to its maximum pressure are not right and could even be wrong or cause injury if not right for an individual. In many cases overly aggressive pressure spikes can wake people up.

Bottom line is one should not always set an APAP to maximum range. The fact that manufacturers include the ability to set a custom range is the best evidence of that.

blah blah blah.

You have little *practical* knowledge, and apparently nothing beyond your little world.

Stay there.

[Lane101]

Your statement above that they "don't care" is just plain wrong.

You don't know as much as you think you do.
Lane101: Thoroughly researched APAP algorithms per above post.

Unclear why you are referring to having figured out therapy settings that take my AHI below 1.0 as just "good enough". Your statement is nonsensical. Given range of post therapy results CPAPTalk members have shared achieving an AHI that is below 1.0 is really excellent - and my Dr. agrees. In fact it takes an AHI above 5.0 for a diagnosis of sleep apnea.

5 is crap, 5 is an average of 12 minutes of sleep between interruptions. less even because there are things that disturb sleep that aren't counted in AHI.
Lane101: Statement is nonsensical, my AHI is below 1.0, why are you talking about an AHI of 5 that is the threshold for a sleep apnea diagnosis?
If you're happy with what is 'good enough' for doctors, good for you, move along and let other people get *better*.

It does not matter what the reasons for the unnecessary pressure spikes are. They are unnecessary as a lower pressure range (in fact even a fixed pressure of 10cm) addresses my sleep apnea just as well.

Nobody asked you, you know? you decided to throw your 1 cent in here.
Lane101: Again you are nonsensical, per my post above my Dr. agrees with me and the spikes do not deliver any material therapy result improvement.

Finally when we post here, unless we are MDs, we should generally be sharing what has worked for us and let our fellow users decide how to use that information to optimize their own therapy. Generic statements that a machine should always be set to its maximum pressure are not right and could even be wrong or cause injury if not right for an individual. In many cases overly aggressive pressure spikes can wake people up.

Bottom line is one should not always set an APAP to maximum range. The fact that manufacturers include the ability to set a custom range is the best evidence of that.

blah blah blah.
Lane101: Again nonsensical response to valid perspective

You have little *practical* knowledge, and apparently nothing beyond your little world.

Stay there.
Lane101: Why are you so insulting?

Palerider, Given your nonsensical, incorrect and insulting remarks there is no need to continue a dialogue here. You do not know what you are talking about and may actually put people at risk of injury if they blindly follow your advice instead of determining what is ideal for their situation, ideally with medical advice as in my case. I've no intention of responding to any future posts from you on this topic.

For everyone else: My posts immediately above provide a good example of my sleep Dr. approved APAP therapy that works well for me consistently delivering AHIs below 1.0 as well as an excellent overview of how some of the major APAP manufacturer adjustment algorithms work. Also to everyone have a happy Thanksgiving!