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Central Apnea Events
#1
Just started using Sleepyhead software to monitor my Resmed S9 autoset measurements. I am seeing some Central Apnea events and from what little I know about the cause of CA events, I am concerned. Does anyone know or have an opinion about how accurately the S9 can detect CA events? Not expecting Doctor level information but would just like to know if anybody's experience in this area for when I discuss this with the Doctor. I have seen some threads that suggest that high pressures might result in CA events???
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#2
It depends on how many you are having. If your total AHI is below 5, there is nothing to worry about. If your AHI is over 5, AND if the majority of the events are central events, then you *may* need to speak to your sleep doc.

For some people, when they start CPAP, the air flow confuses the brain into thinking all is well and there is no need to breathe. For nearly everyone who experience this, the CA events drop significantly with time. The trick is to start at a lower pressure then increase over time.

ResMed claims to accurately detect what they call "clear airway" events. Clear airway means the pules the machine sends out "echoes" back and says the airway is not blocked and logs it as a central event. It is fairly accurate. But it is not fool proof. The only way to tell for sure would be to have a chest belt sensor thingy. With CA events, there is no struggle. The brain says "There is no need to breathe" so the body doesn't fight it. But with OA events, the brain and body want air so there is chest (and other body) movement.
PaulaO2
Apnea Board Moderator
www.ApneaBoard.com


Breathe deeply and count to zen.

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.




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#3
The machine can detect central apnea but have flaws, cannot tell you whether you were asleep or awake. Spending a night in sleep lab hooked up with wires is the only way to diagnose central sleep apnea

A diagnosis of central sleep apnea (CSA) requires all of the following:
An apnea index > 5
Central apneas/hypopneas > 50% of total apneas/hypopneas
Central apneas or hypopneas occurring at least 5 times per hour
Symptoms of either excessive sleepiness or disrupted sleep
http://www.resmed.com/us/clinicians/abou...clinicians
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#4
Do you know anything about what classifies a hypopnea as obstructive vs. central? My sleep study did not differentiate and I don't think the ResMed S9 Autoset does either.


(12-02-2013, 03:21 AM)zonk Wrote: The machine can detect central apnea but have flaws, cannot tell you whether you were asleep or awake. Spending a night in sleep lab hooked up with wires is the only way to diagnose central sleep apnea

A diagnosis of central sleep apnea (CSA) requires all of the following:
An apnea index > 5
Central apneas/hypopneas > 50% of total apneas/hypopneas
Central apneas or hypopneas occurring at least 5 times per hour
Symptoms of either excessive sleepiness or disrupted sleep
http://www.resmed.com/us/clinicians/abou...clinicians

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#5
Curious about this too. My 30 AHI consisted of 119 hypopneas and only 5 apneas. They did not differentiate. This may explain why I am having so much trouble adjusting to CPAP. I feel worse on CPAP than without it, even though my S8 autoset tells me I am only experiencing 1.6 AHI. For the hours I sleep, that is... only 2-3 a night with the mask.



(12-02-2013, 09:36 PM)sir_sleeps_alot Wrote: Do you know anything about what classifies a hypopnea as obstructive vs. central? My sleep study did not differentiate and I don't think the ResMed S9 Autoset does either.

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#6
A hypopnea is when the airway is narrowed by X% but air is still flowing. The airway has to be narrowed a certain percentage or less for 10 seconds or longer. I think the percentage is 30%.

As far as I know, you would not have a narrowing of the airway with a Central event. I don't know if there is any thing that leads up to a central event happening, such as shallow breathing but that is not a narrowing, just less air.

The machines can tell the difference because of the pulses it sends out. It does know the difference between the three types.

Put on the mask and turn on the machine. Let it run so it is beyond the ramp and all that. Now, close your throat with your tongue. You'll start to feel the air from the machine pulsate. It will do the same thing if you simply stop breathing. Don't close the airway, just stop breathing after you breathe out.

The sleep study lumps them all together in the AHI because that's what the AHI is. The Apneas (both kinds) and the hypopneas. It is the overall reading used for the diagnosis. Somewhere in the sleep study report should be a breakdown of how many of which was what.

During a hypopnea, you are experiencing the same thing as during an OA event, just not as extreme. Low oxygen, increasing CO2, increasing body movement trying to wake you, etc.
PaulaO2
Apnea Board Moderator
www.ApneaBoard.com


Breathe deeply and count to zen.

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.




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#7
(12-02-2013, 09:36 PM)sir_sleeps_alot Wrote: Do you know anything about what classifies a hypopnea as obstructive vs. central?
Edit: From interview with Dr Dr Michael Berthon-Jones ... ResMed chief designer of AutoSet ( prior to S9 AutoSet enhanced algorthim )

Why doesn’t ResMed's AutoSet respond to hypopnoea?

When you are lying quietly awake, or when you first go to sleep, or when you are dreaming, you can have hypopneas (reductions in the depth of
breathing) which are nothing to do with the state of the airway. 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 settled, or if you are dreaming. And the annoying thing is that when you are on CPAP, this tendency to have what are called central hypopneas - hypopneas that are nothing to do with the state of the airway - is increased. If you make an automatic CPAP device that responds to hypopneas, you will put the pressure up to the maximum while the patient is awake

Do you think there is a misconception clinically that all hypopneas should be treated ?

For simple obstructive sleep apnea, central hypopneas should not be treated. They are not a disease. Everyone has them. And they don’t go away with CPAP. There is a rare and important exception: central hypopneas due to heart disease. This is called Cheyne-Stokes breathing. CPAP does help with that

Why doesn’t ResMed's AutoSet respond to apnea above 10 cmH2O in pressure?

I mentioned before that the higher the pressure, the more central hypopneas you will have. At a pressure somewhere around 10 cmH 2O, the central hypopneas become central apneas. On the other hand, the vast majority of obstructive apneas are already well controlled by 10 cmH2O, and we are only fine tuning using snoring and flattening. So it is a pretty good bet that if the pressure is already above 10 cmH2O, any apneas are most likely central, and you should leave them alone (except in patients with central apneas due to heart failure). But if the pressure is below 10 cmH2O, most apneas will be obstructive and you should put the pressure up. There’s nothing magical about 10cmH2O, it’s just a good place to put the line in the sand
http://www.resmed.com/au/assets/document...0906r1.pdf
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#8
(12-04-2013, 02:05 AM)zonk Wrote: Edit: From interview with Dr Dr Michael Berthon-Jones ... ResMed chief designer of AutoSet ( prior to S9 AutoSet enhanced algorthim )

Why doesn’t ResMed's AutoSet respond to apnea above 10 cmH2O in pressure?

I mentioned before that the higher the pressure, the more central hypopneas you will have. At a pressure somewhere around 10 cmH 2O, the central hypopneas become central apneas. On the other hand, the vast majority of obstructive apneas are already well controlled by 10 cmH2O, and we are only fine tuning using snoring and flattening. So it is a pretty good bet that if the pressure is already above 10 cmH2O, any apneas are most likely central, and you should leave them alone (except in patients with central apneas due to heart failure). But if the pressure is below 10 cmH2O, most apneas will be obstructive and you should put the pressure up. There’s nothing magical about 10cmH2O, it’s just a good place to put the line in the sand
http://www.resmed.com/au/assets/document...0906r1.pdf

This limit of 10 cm H2O above which the Autoset algorithm would not go must apply only to early ResMed AutoSet machines.

My S8 AutoSet II (which does not have the Enhanced AutoSet Algorithm) automatically adjusted the pressure as high as needed to treat obstructive apneas, up to 20 cm H2O if needed (for example if I rolled onto my back while asleep).

Although the S8 AutoSet II often would not increase pressure in response to a cluster of apneas, at other times it would respond quickly. I could not figure out why sometimes the machine increased the pressure in response to a cluster of events and why it sometimes failed to.

I later learned from using an S9 AutoSet that I often had clusters of central apneas, which I think explains why the S8 AutoSet II did not increase the pressure to some apnea clusters. Some apnea clusters did not quite match characteristics of the obstructive types of events which the S8 Autoset II was looking for before raising the pressure.

So I think that although undoubtedly the S9 AutoSet distinguished more accurately Clear Airway apneas versus obstructive apneas, the S8 AutoSet II could also to some degree distinguish obstructive versus central apneas.

--- Vaughn
Membership in the Advisory Member group should not be understood as in any way implying medical expertise or qualification for advising Sleep Apnea patients concerning their treatment. The Advisory Member group provides advice and suggestions to Apnea Board administrators and staff on matters concerning Apnea Board operation and administrative policies - not on matters concerning treatment for Sleep Apnea. I think it is now too late to change the name of the group but I think Voting Member group would perhaps have been a more descriptive name for the group.
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