How do I fix AHI ???

[Portageegal]

My leak rate was 0.0 last night, with a pressure of 12.8. My AHI was 15.8 with the AI 6.6 and HI 9.2. What do I do? My pressure is set for 10-14 on auto. I have the S8 auto and a quattro FFM. I am so damned frustrated. I feel a lot better than before, but really crave that perfect AHI. My sleep study AHI was 58.7.
Carol

[MoneyGal]

Hmmm. There will be others here who have more experience than I do, but the first thing I wonder about is why your pressure was set with the range it has. I have the same setup as you, but my pressure is set at 4 - 20 (although my sleep doc said I was unlikely to need more than 16). Would expanding the range - especially upwards - reduce your AHI? We already know it isn't a mask fit issue...

[mdbarthe]

I'm not an expert, nor do I consider myself knowledgeable beyond my two years experience of XPAP therapy. But....I have read many times from those forum members who do read extensively and are very knowledgeable that with the Resmed Autos they tend to over-report the HIs. In fact, I have read where some of the knowledgeable posters say to divide the HI number in half to get a more accurate report.

In your case, I personally, in my humble opinion would not be too concerned with AHI, but rather what the AI numbers are. You most likely already know that anything under 5 for AI is acceptable. How long have you been an APAP user? Might you still be getting used to the machine? It takes a good two weeks or so to see how your therapy is going.

I really count a lot on how I feel. I can tell even before I read my data how good a night I had just by the way I feel.

[mdbarthe]

MoneyGal has a good point. Why is your pressure setting so "tight"? I was titrated at 13cm/H20, but my auto pressure range is set between 10-20cm/H20. I don't know that makes a lot of difference in your case, but I just find it curious that the range is so "tight".

[SharkBait]

My leak rate was 0.0 last night, with a pressure of 12.8. My AHI was 15.8 with the AI 6.6 and HI 9.2. What do I do? My pressure is set for 10-14 on auto. I have the S8 auto and a quattro FFM. I am so damned frustrated. I feel a lot better than before, but really crave that perfect AHI. My sleep study AHI was 58.7.
Carol

What were you titrated at?

Remember your machine utilizes the A10 algorithm so it won't increase pressure over 10 after Apneas unless it detects snoring or flow limitations.

[Paul56]

My leak rate was 0.0 last night, with a pressure of 12.8. My AHI was 15.8 with the AI 6.6 and HI 9.2. What do I do? My pressure is set for 10-14 on auto. I have the S8 auto and a quattro FFM. I am so damned frustrated. I feel a lot better than before, but really crave that perfect AHI. My sleep study AHI was 58.7.
Carol

How long have you been running the machine at those settings?

Do you have SETTLING engaged?

If not, then I would suggest engaging it and setting the time for about how long it takes you to quiet down and start to fall asleep. Events that happen while you are awake are not meaningful and so will not be recorded by the machine during SETTLING.

Basically you need to have the lower range number (10 in your case as it is now set) set high enough to take care of the majority of the events. If you have been running your machine for a while at those settings then you might consider bumping up the lower number, but don't make too many changes at one time. If you have not been using SETTLING then engage it first and gather more data for a while to see where the numbers go.

[Portageegal]

I've been using since Oct. I narrowed the range by uping the minimum to 10 because of something I read here. It hasn't made much of a difference. I am usually at a pressure somewhere between 11-13. I do look at the AI's more than the total, but still want better numbers.

[SharkBait]

I've been using since Oct. I narrowed the range by uping the minimum to 10 because of something I read here. It hasn't made much of a difference. I am usually at a pressure somewhere between 11-13. I do look at the AI's more than the total, but still want better numbers.

Did you have a titration study done? What is the pressure indicated on your rx?

[Portageegal]

Settling is used and I fall asleep within a few minutes of my head hitting the pillow.

[spitintheocean]

MoneyGal has a good point. Why is your pressure setting so "tight"? I was titrated at 13cm/H20, but my auto pressure range is set between 10-20cm/H20. I don't know that makes a lot of difference in your case, but I just find it curious that the range is so "tight".

My understanding was that experienced members here have commented APAP machines often have trouble responding to certain events requiring the higher pressure in time to provide the necessary pressure if the range is set too far apart, that's why it isn't recommended to leave the machine at default settings of 4 - 20. I guess the question arises as to when are the settings so tight that the benefits of auto titrating are defeated and one may as well rely on a CPAP device?

Paul

[ozij]

Protageegal,
On Resmed machines, the machine will never respond to hypopneas (at any pressure), and when the pressure is above 10, the machine will respond to apneas only if they are acompanied by snores or flow limitations. If you happen to have eliminated snores and flow limitations with your minumum pressure, then you're up against the stream without a paddle when an apnea happens.

Which leaves you with two options on the Resmed:
Set the minimum pressure to eliminate most of your apneas - that would either be your Rx-ed pressure, or the machine's 95% reccomendation.
Alternatively:
Drop the minimum pressure so that you have flow limitations and snores to drive the pressure up where apneas never happen. It's a slightly paradoxical option - I can imagine it won't work often - and I've never had a Resmed machine and so have never tried it - but it is a logical option.

Other autos behave differently.

O.

[riverdreamer]

Protageegal,
On Resmed machines, the machine will never respond to hypopneas (at any pressure), and when the pressure is above 10, the machine will respond to apneas only if they are acompanied by snores or flow limitations. If you happen to have eliminated snores and flow limitations with your minumum pressure, then you're up against the stream without a paddle when an apnea happens.

O.

I'm not entirely sure this is accurate, Ozij. I keep reading all these things about how Resmed doesn't this, and Resmed doesn't that. It isn't what I see happening in my charts, so I think maybe there are some misconceptions.

Breath-by-Breath Monitoring and Flow-Time Curve Analysis

AutoSet devices monitor breathing on a breath-by-breath basis and deliver only the pressure that patients need--when they need it.

AutoSet devices actually act preemptively by monitoring the patient's inspiratory flow-time curve. A flattening of the inspiratory flow-time curve typically precedes an upper airway obstruction, which will cause an apnea, hypopnea, or snoring.

By monitoring and responding to the flow-time curve, AutoSet devices reduce the number of respiratory events and arousals, enabling better sleep quality.

Studies suggest that using the flow-time curve is preferable to responding to apneas and hypopneas directly and that clinicians should use the flow-time curve to achieve optimal pressure during titration.3,4

It seems unlikely to me that a hypopnea or apnea will appear completely out of the blue, with no change at all in the airflow. Maybe sometimes, but how?

Apneas may occur suddenly, without being preceded by flow limitation or snore. These sudden apneas are generally associated with sleep onset, change in body position, or rapid eye movement (REM) onset.

I do agree that if the lower pressure is set too far below what is needed to prevent an apnea, that it might take too long to get there before the apnea is over. If the apnea only lasts 10 seconds or so, there may not be time to prevent it. With the software, it is very easy to see how long an event lasted, and how it relates to any changes in pressure, or even if there was no change in pressure. So it isn't really necessary to use conjecture about whether the unit is responding at all. You can see.

The only reason I am contradicting you, is that I see people get all concerned about not having the right machine, when it may not be an issue at all. I know that people respond differently to different machines, and I am all for having the one that works best. I just hate to see people throw away something that may not be the problem.

Protageegal may need to increase her lower pressure, and/or her upper pressure. Without data, it is hard to tell. Maybe the unit tries to stop these apneas, but can't get high enough because of the top limit. Maybe it can't raise the pressure fast enough, because the lower limit is too low. Or, maybe it isn't responding because of the Resmed's programming. If we had a chart of her data, we could tell for sure. Without it, I would try changing one thing at a time, and letting it ride for a while, to see how things go. I know I am new here, but I work with medical research, and have learned a thing or two about how to see if something is working, or not.

[ozij]

Protageegal,
On Resmed machines, the machine will never respond to hypopneas (at any pressure), and when the pressure is above 10, the machine will respond to apneas only if they are acompanied by snores or flow limitations. If you happen to have eliminated snores and flow limitations with your minumum pressure, then you're up against the stream without a paddle when an apnea happens.

O.

I'm not entirely sure this is accurate, Ozij.

I am. Please read the interview with Dr. Michael Berthon-Jones in the following official publication by Resmed:

http://www.resmed.com/en-en/assets/docu ... 1891r1.pdf

In 1990, Dr. Berthon-Jones joined ResMed, where he is currently Chief Scientific Officer. He has been a key force in the evolution of "intelligent CPAP devices" popularized by ResMed as AutoSet® technology. In fact, Dr. Michael Berthon-Jones helped to invent the AutoSet® algorithm that drives these devices.

What are hypopneas and why doesn't ResMed's AutoSet respond to hypopnea?
Hypopnea is a reduction in the depth of breathing, where as an apnea is a cessation of breathing. Hypopneas are "central" (controlled from the brain) - they have nothing to do with the state of the airway being obstructed. They are a normal occurrence for everyone. For example if you sigh, which you do every few minutes, you usually have a hypopnea immediately afterwards. This can also happen if you have just rolled over and are getting ettled, or if you are dreaming. And the annoying thing is that when you are on CPAP, this tendency to have central hypopneas is increased. If you make an automatic CPAP device that responds to hypopneas, you will put the pressure up to the maximum pressure while the patient is awake.

Why doesn't the device respond to apnea above 10 cmH2O in pressure?
The vast majority of obstructive apneas are already well controlled by 10 cmH2O. At higher pressures, events are more likely to be "central" in origin - that is they are controlled by the brain, rather than caused by an airway obstruction. Such central events are best left alone, (except in patients with central apneas due to heart failure).

Breath-by-Breath Monitoring and Flow-Time Curve Analysis

AutoSet devices monitor breathing on a breath-by-breath basis and deliver only the pressure that patients need--when they need it.

AutoSet devices actually act preemptively by monitoring the patient's inspiratory flow-time curve. A flattening of the inspiratory flow-time curve typically precedes an upper airway obstruction, which will cause an apnea, hypopnea, or snoring.

That describes flow limitations

It seems unlikely to me that a hypopnea or apnea will appear completely out of the blue, with no change at all in the airflow. Maybe sometimes, but how?

The fact is they do. It seemed unlikely to the poeple who created the Autoset. But "unlikely" is not "impossible".

I do agree that if the lower pressure is set too far below what is needed to prevent an apnea, that it might take too long to get there before the apnea is over.

That is a frequent misconception of how automatic machines function. Automatic machines do not raise pressure in an attempt to stop an apnea while it is occurring. They need time to analyze the breathing pattern, conclude an apnea has occurred, and then respond by raising the pressure. If the minimum is too low, some machines will let many apneas occur before they reach the right pressure.

With the software, it is very easy to see how long an event lasted, and how it relates to any changes in pressure, or even if there was no change in pressure. So it isn't really necessary to use conjecture about whether the unit is responding at all. You can see.

Very true. People have seen how apneas occur above a pressure of 10, and the Resmed does not raise the pressure.

The only reason I am contradicting you, is that I see people get all concerned about not having the right machine, when it may not be an issue at all.

As you can see, it is very much an issue.

I just hate to see people throw away something that may not be the problem.

So do I.

I would try changing one thing at a time, and letting it ride for a while, to see how things go. I know I am new here, but I work with medical research, and have learned a thing or two about how to see if something is working, or not.

Changing one variable at a time is one of the basic principles of research methodology, one of the subjects I happen to have taught.

O.

[ozij]

Protageegal,
On Resmed machines, the machine will never respond to hypopneas (at any pressure), and when the pressure is above 10, the machine will respond to apneas only if they are acompanied by snores or flow limitations. If you happen to have eliminated snores and flow limitations with your minumum pressure, then you're up against the stream without a paddle when an apnea happens.

O.

I'm not entirely sure this is accurate, Ozij.

I am. Please read the interview with Dr. Michael Berthon-Jones in the following official publication by Resmed:

http://www.resmed.com/en-en/assets/docu ... 1891r1.pdf

In 1990, Dr. Berthon-Jones joined ResMed, where he is currently Chief Scientific Officer. He has been a key force in the evolution of "intelligent CPAP devices" popularized by ResMed as AutoSet® technology. In fact, Dr. Michael Berthon-Jones helped to invent the AutoSet® algorithm that drives these devices.

What are hypopneas and why doesn't ResMed's AutoSet respond to hypopnea?
Hypopnea is a reduction in the depth of breathing, where as an apnea is a cessation of breathing. Hypopneas are "central" (controlled from the brain) - they have nothing to do with the state of the airway being obstructed. They are a normal occurrence for everyone. For example if you sigh, which you do every few minutes, you usually have a hypopnea immediately afterwards. This can also happen if you have just rolled over and are getting ettled, or if you are dreaming. And the annoying thing is that when you are on CPAP, this tendency to have central hypopneas is increased. If you make an automatic CPAP device that responds to hypopneas, you will put the pressure up to the maximum pressure while the patient is awake.

Why doesn't the device respond to apnea above 10 cmH2O in pressure?
The vast majority of obstructive apneas are already well controlled by 10 cmH2O. At higher pressures, events are more likely to be "central" in origin - that is they are controlled by the brain, rather than caused by an airway obstruction. Such central events are best left alone, (except in patients with central apneas due to heart failure).

Breath-by-Breath Monitoring and Flow-Time Curve Analysis

AutoSet devices monitor breathing on a breath-by-breath basis and deliver only the pressure that patients need--when they need it.

AutoSet devices actually act preemptively by monitoring the patient's inspiratory flow-time curve. A flattening of the inspiratory flow-time curve typically precedes an upper airway obstruction, which will cause an apnea, hypopnea, or snoring.

That describes flow limitations

It seems unlikely to me that a hypopnea or apnea will appear completely out of the blue, with no change at all in the airflow. Maybe sometimes, but how?

The fact is they do.

http://www.resmed.com/au/clinicians/com ... clinicians
(The Vantage is called Spirit in Australia)

How AutoSet Spirit Responds to Apnea
Typically prevents apneas, by treating flow limitation and snore. These usually act as early signals for more severe apneic events. In the event of a sudden apnea that occurs without any preceding flow limitation or snore, AutoSet Spirit increases the pressure after the apnea has ceased to prevent further apneic events Pressure response is based on the duration of the apnea If no further events occur, AutoSet Spirit gently decreases the pressure, towards the minimum set pressure

(All added emphasisi mine)

I do agree that if the lower pressure is set too far below what is needed to prevent an apnea, that it might take too long to get there before the apnea is over.

That is a frequent misconception of how automatic machines function. Automatic machines do not raise pressure in an attempt to stop an apnea while it is occurring. They need time to analyze the breathing pattern, conclude an apnea has occurred, and then respond by raising the pressure. If the minimum is too low, some machines will let many apneas occur before they reach the right pressure.

With the software, it is very easy to see how long an event lasted, and how it relates to any changes in pressure, or even if there was no change in pressure. So it isn't really necessary to use conjecture about whether the unit is responding at all. You can see.

Very true. People have seen how apneas occur above a pressure of 10, and the Resmed does not raise the pressure.

The only reason I am contradicting you, is that I see people get all concerned about not having the right machine, when it may not be an issue at all.

As you can see, it is very much an issue.

I just hate to see people throw away something that may not be the problem.

So do I.

I would try changing one thing at a time, and letting it ride for a while, to see how things go. I know I am new here, but I work with medical research, and have learned a thing or two about how to see if something is working, or not.

Changing one variable at a time is one of the basic principles of research methodology, one of the subjects I happen to have taught.

O.[/quote]

[riverdreamer]

OK, the UBB code is too complicated with multiple layers of quotes to keep up with individual points.

However, everything I posted is what Resmed has up on their site currently, regarding the Autoset II. In addition, I have a Resmed Autoset machine, and it does respond to hypopneas. Unless we want to say the software is not correct, in which case all bets are off. My sleep study claimed all of my hypopneas were obstuctive, which is the opposite of what the expert you quote above claims. Regardless, if there are flow limitation or snores, then it responds, whether it is an apnea or a hypopnea. And yes, I mentioned some reasons why there might be no flow limitation. If, however, it is anything obstructive, it is extremely unlikely to happen without the flow limitation. Think about it. How can the airway close down , either partially or completely, without progressively putting a limit on the flow? It CAN happen if you are holding your breath, either because of movement, or due to a centrally caused issue. In those cases you don't want the pressure to increase.

As to whether I have a misconception about how long it takes to respond, the Resmed raises the pressure in response to flow limitation, which occurs before the apnea, so it CAN respond to prevent the apnea. But it only raises the pressure in a set pattern, .2 every so many seconds, so if the apnea only lasts 10 seconds, then it may not respond quickly enough to prevent that particular apnea, or at least to prevent it completely. It may shorten the span. I'm sorry, I don't have the quote, and I think at this point it is better to read entire pages of information, rather than quotes out of context. I do see patterns on my data that completely support this. I don't know as much about how the Respironics work, but that is how the Resmed does. There is plenty to read on the Resmed site, some of it older, some more current.

I see and understand what you are saying, but don't agree with the interpretation of everything, especially based on what I see in my therapy. Even with the best, and most clear data, not everyone will agree on interpretation. Whether or not this is the best machine for Protageegal, I can't say, but I think without more data, nobody can.