Resscan Interpretation

[kenmac1005]

I have been using my Resmed VPAP Auto 25 for almost two year and a few weeks ago finally spent enough time to get the ResScan software and card reader working. Long story I'm sure you have all heard it many times before.

Starting to get used to the data. Reviewing detailed data every day. i have a million question and am most way through the Resmed Guide. Before I get to real interpretation can someone help me level set with some of the data I'm seeing.

!. My AHI shows between 10 and 12 per hour while the AI is very much under control at below 1. ie between 2 and 8 to 10 Apneas per night. (Sleep study over 50) So the AHI is mostly HI. So much so that at times the hypopnea seems continuous. ResScan shows continous hypopnea for 15 to 20 mins. However when I look at the detail data more closely it shows multiple events spaced exactly 1 minute apart which I hope means the machine is sampling or at least only recording every minute. Is that true? My VPAP pressure is 4 to 14 and rarely gets over 8 or 9.

Any interpretation of high and continuous hypopnea if that is in fact is what it is:

PS

a. I have read here that the S8 hypopnea data can be somewhat overstated, often caused by leaks etc. i manage the leak situation pretty well with very few leaks these days.
b. My other theory is that because I am a side sleeper one on the pillows gets cut off and causes the S8 to think its hypopnea. I know this happens just from lying on my side before sleep and sometimes have to reposition the Swift FX pillows to ensure a regular flow.

Am I on the right track. Any help on interpretation would be gratefully received. I'd love to eliminate the hypopnea if its real but dont want to be chasing ghosts.

Ken

[Xney]

Hiya,

While apneas are "worse" in a big sense, hypopneas will still interrupt your sleep just like an apnea will. You have to consider your AHI rather than your AI as your measure of treatment.

If the hypopneas are obstructive in nature (likely), the answer is higher pressure. You may need to increase the minimum of your APAP range if they machine isn't doing a good job of raising the pressure to eliminate them.

AHI of >= 10 is definitely too high. You want to get that # to <= 5 most nights.


As for the mask type, I would say whatever is comfortable and doesn't leak is great. I use nasal pillows myself!

I don't know if S8s over-estimate hypopneas - that's beyond my knowledge. Maybe somebody can comment on that? If they do, I'm not sure how you would measure it accurately to get a good estimate of your AHI on APAP.

[avi123]

Ken, can you show these graphs here: Pressure, Events, and Leak?

Usually, hypopneas shown by Resmed Autoset machines should be disregarded.
On top of it, without EEG and RIP you can't tell if it's an obstructive or central hypopnea.

Check this:

From an interview with Dr Michael Berthon-Jones (Resmed chief designer of their Autosets, in 2002).

Q. Why is it important for an automatic CPAPdevice
to respond to flow limitation, snore and apnea?

A.The characteristic flattening of the flow-time
curve caused by flow limitation is the very best
signal for fine-tuning the pressure, once you have
eliminated apneas and snoring. But if you are just
falling asleep, you can go very quickly from having
a totally open airway to snoring very loudly, in a way
that produces somewhat chaotic or messy flowtime
curves, without seeing the characteristic
flattening. So the best approach is to respond very
quickly to loud snoring, and then fine tune using
flattening. Rarely, you can go straight from awake
and unobstructed to asleep and apneic, and so it
can be useful to increase pressure in response to
apnea as well. However, actual apnea is pretty rare
on AutoSet, because in most cases the responses
to snoring and flattening get the pressure up
quickly enough to prevent apneas.


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

A.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.

Q. 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 cmH2O, 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 10
cmH2O, it’s just a good place to put the line in the
sand.

Can you over-treat apnea?

You can’t over-treat obstructive apnea. You
really don’t want the patient having unresolved
obstructive apneas. And we want not just to prevent
apnea - we also want to keep the airway sufficiently
open for the subject to breathe easily and regularly
and stay asleep.

But you can use too much pressure. The higher
the pressure, the greater the side effects. Although
this has never been proven, it is rather obvious - no
pressure, no side effects! So you want to use the
lowest pressure possible while keeping the airway
nicely open.

Likewise can a device that responds to
hypopnea over-treat it ?

The funny thing is that it can both over-treat and
under-treat. It will put the pressure up through the
roof in some subjects, who have lots of central
hypopneas. And it can completely miss repetitive
severe silent inspiratory flow limitation that is totally
disturbing the patient’s sleep without there being
any hypopneas. If this occurs without CPAP, it is
called upper airway resistance syndrome. It is just
as bad for you as obstructive sleep apnea. But a
CPAP machine that responds only to hypopneas
will treat your obstructive sleep apnea, and give
you upper airway resistance syndrome instead.

How can Automatic CPAP devices help
optimise treatment ?

CPAP devices, whether automatic or not, can
tell us - the clinician, the technician - about what is
going on when we are not there. Is the patient using
the device? Is there a leak, and if so, when and how
much? If it is an automatic device, what is the
pressure doing? How well is the patient breathing?
How steadily, how much? This might be particularly
important if the patient also has heart disease or
lung disease, or has had a stroke, and has other
reasons, apart from sleep apnea, for having
abnormal breathing during sleep.

[kenmac1005]

avi123,

I really appreciate your help. Today I signed on with my mac and noticed the rest of your post for some reason my pc browser would not scroll on the site. This gives me a lot more data.

I'm a gadget freak so just ordered an oximeter to see if the high level of hypopnea is affecting my oxygen levels. As always the more you learn the more you realize how little you know!!

I did send you a complete report if you had any trouble with the screen view I originally sent.

Anyway I'm looking forward to getting a better handle on my health and hopefully contributing to the forum as my knowledge and experience increase.

Thanks again

Ken

[billbolton]

Today I signed on with my mac and noticed the rest of your post for some reason my pc browser would not scroll on the site. This gives me a lot more data.

That article is from 10 years ago and is not at all reflective of the capabilities of more recent xPAP machines, which have much better methods than those available in 10+ years ago for understanding and scoring what is happening with your airway.

You SHOULD DEINITELY be paying attention to the hyponeas your S8 is scoring, and your current hyponea score is high enough that you need to put some work into understanding what is causing them

Cheers,

Bill

[avi123]

Today I signed on with my mac and noticed the rest of your post for some reason my pc browser would not scroll on the site. This gives me a lot more data.

That article is from 10 years ago and is not at all reflective of the capabilities of more recent xPAP machines, which have much better methods than those available in 10+ years ago for understanding and scoring what is happening with your airway.

You SHOULD DEINITELY be paying attention to the hyponeas your S8 is scoring, and your current hyponea score is high enough that you need to put some work into understanding what is causing them

Cheers,

Bill

Bill Bolton in Australia, in what year do you assume that Resmed got the patents for the features in the present S9 machines?

[avi123]

Bill Bolton, to save time, I assume that before the year 2000 Resmed recieved approval for the patents that are the features in the present S9 machines.
So when Dr Berthon-Jones gave the interview in 2002, he already knew which of his patents were approved.

Bill, do you know yourself what could be the causes of many Hypopneas shown in VPAP Auto 25? Let's say about 25 Hypopneas per hour plus about OAI of 6 , but no CAs.

Any possibility that the VPAP Auto 25 is defective?

[kenmac1005]

The past few nights I have upped the min EPAP to 6- Max IPAP stayed at 14. No affect on the number of Hypopneas. Also noticed the PS was at zero where it is recommended to be 4. When I made it 4 I got a massive pulsing injection of air on each inhalation so ramped it down to 1 which i assume is no better than zero.

I'm taking my machine to my doctor to get his view on if it is malfunctioning. Dont want to involve the DME unless i need to replce it because they are a pain to deal with.

[Xney]

At PS=0 you're basically in CPAP mode.

In my opinion, if you're having hypopneas, you need more pressure - an EPAP of 6 is probably too low, even if it can "auto up" over time.