How do I (or the doctors) know I have OSA or CSA?

[johnrrr]

I had an overnight home test via the hospital which showed an AHI of 30.

I presumed - and as far as I know so does my doctor - that it is OSA.

Why? Just based on the statistically likelihood?

How would they test to find out if it is CSA vs OSA?

And is there any benefit in knowing?

Thanks

[ericore]

I had an overnight home test via the hospital which showed an AHI of 30.

I presumed - and as far as I know so does my doctor - that it is OSA.

Why? Just based on the statistically likelihood?

How would they test to find out if it is CSA vs OSA?

And is there any benefit in knowing?

Thanks

When they hook you up with a bunch of electrodes, if you think about it, how many of those do you think you need to detect obstructed airflow? Maybe one or two, but wait there was so many electrodes; who can forget?
Which means, the majority is for profiling your brain for CSA and other sleep disorders.
The equipment they recommend you, will also tell you if its CSA. OSA just gets the basic continuous air with ramp feature. Auto CPAP is for CSA.
Another big hint of OSA is snoring. If you don't snore, than its CSA.

[palerider]

When they hook you up with a bunch of electrodes, if you think about it, how many of those do you think you need to detect obstructed airflow? Maybe one or two, but wait there was so many electrodes; who can forget?
Which means, the majority is for profiling your brain for CSA and other sleep disorders.

noo, the electrodes are so they can get a good guess whether you're awake or not,

CSA vs OSA is determined by breathing flow and chest effort, not the EEG.

[palerider]

I had an overnight home test via the hospital which showed an AHI of 30.

I presumed - and as far as I know so does my doctor - that it is OSA.

Why? Just based on the statistically likelihood?

How would they test to find out if it is CSA vs OSA?

And is there any benefit in knowing?

what did the home test involve? and can you get a copy of the report?

some home tests are better able to determine between obstructive and central apneas, some are less able.

[Julie]

"Is there any benefit in knowing?"

Of course there is - a CSA patient won't be helped by a 'regular' Cpap, but would need an ASV (or related) machine to be effective.

[johnrrr]

The home test was quite basic. It had sensors on my heart, my neck, my finger, and a tube in my nostrils. There was nothing on my head.

I have always snored heavily so suspect it is OSA, but I just thought of it today - how do I, or the doctor, know for sure.

[metsfan302]

An in lab sleep stusy would better show centrals or an auto cpap could help show them also.

Insurances are starting to move toward the home studies to save money but when they really in the end tend to spend more money as most of the time an in lab sleep study usually gets ordered after ones gets the home study done

[johnrrr]

An in lab sleep stusy would better show centrals or an auto cpap could help show them also.

Insurances are starting to move toward the home studies to save money but when they really in the end tend to spend more money as most of the time an in lab sleep study usually gets ordered after ones gets the home study done

How does the auto-cpap help show them please? what are the signs?

[stienman]

How does the auto-cpap help show them please? what are the signs?

The auto cpap measures pressure and air flow very precisely, and can modulate both very accurately with the blower.

The mask has vents which have a known flow-through rate versus pressure.

The mask and tubing volume are known to the machine (this is why you have to select the mask type on the machine).

Thus the machine has a very good model of the pneumatic circuit formed by the blower, tubing, and mask. It then makes some assumptions about the airway and lungs, but these are less important.

So if the machine is applying a certain pressure, and it knows how much the vents will "leak" at that pressure, and it can measure the volume of air flowing through, it can tell if you're inhaling or exhaling, or neither. If you're inhaling, it has to increase the volume to maintain the pressure (or monitor the pressure drop). It can tell how much air you inhale. If you're exhaling, it has to decrease the volume to maintain the pressure (or monitor the pressure increase). If you are neither inhaling or exhaling, then the volume and pressure don't change.

Thus the machine can tell if you're breathing, whether you're breathing in or out, and how much air you inhaled or exhaled.

If the machine detects that you are not breathing for 10 seconds, it detects an apnea, but it doesn't know (yet) if it's central or obstructive. So it does something which I find very clever: it increases and decreases the volume by a small amount 4 times a second for several seconds.

Now if you increase the volume, the pressure goes up, and if you decrease the volume, the pressure goes down. But here's where that pneumatic circuit comes into play. If the airway is obstructed, then the pneumatic circuit has a low total volume - the tubing, the mask, and your mouth. If the airway is open, then the pneumatic circuit also contains your lungs.

So if you send a rapid (but small) volume change into the circuit, then the pressure changes - and the pressure changes a small amount if your lungs are in the circuit (because the total volume is larger, thus the pressure change is smaller). If the volume is smaller, then the pressure changes are larger, and thus the machine knows that your airway is obstructed.

So the machine can tell if you're breathing, whether you're breathing in or out, and if you aren't it can detect whether your airway is open or not.

But the machine actually goes even further. Because it has such precise volume and pressure measurements, it can detect if your airway is partially obstructed. If your tongue or throat relaxes just a little, the air has a harder time going in and out, and looking at the pressure and volume it can detect this, and increase the pressure.

It's this level of precise detection that seeks to prevent the problem in the first place, without simply placing you on a high constant pressure.

In my case, I have mostly obstructive apneas, and they generally only happen during REM sleep, so with my machine it starts out low, and then you can pretty clearly see when I'm in REM sleep as it detects the relaxation of my airway muscles and ramps the pressure up to keep them open. I've had a few central apneas, and looking at the data in sleepyhead is neat because you can see this detection routine in process.

I'm tempted to simulate both events to see if I can notice the 4Hz airflow, but it looks so low on the chart that I'm guessing it's not detectable even while paying attention to it. It's certainly not enough to wake someone up.

[LSAT]

I had an overnight home test via the hospital which showed an AHI of 30.

I presumed - and as far as I know so does my doctor - that it is OSA.

Why? Just based on the statistically likelihood?

How would they test to find out if it is CSA vs OSA?

And is there any benefit in knowing?

Thanks

When they hook you up with a bunch of electrodes, if you think about it, how many of those do you think you need to detect obstructed airflow? Maybe one or two, but wait there was so many electrodes; who can forget?
Which means, the majority is for profiling your brain for CSA and other sleep disorders.
The equipment they recommend you, will also tell you if its CSA. OSA just gets the basic continuous air with ramp feature. Auto CPAP is for CSA.
Another big hint of OSA is snoring. If you don't snore, than its CSA.

WRONG!!! WRONG!!! WRONG!!!

[Okie bipap]

I have not snored since the mid 90's when I had surgery to correct my sleep apnea. When I had my sleep study last year, my AH I was 49, with the majority being obstructive. I did not snore during the sleep study and do not snore now. Obviously not snoring does not mean I don't have obstructive sleep apnea.

[johnrrr]

thanks all, especially stienman for such a detailed reply!

[metsfan302]

thanks all, especially stienman for such a detailed reply!

Yea what he said

[palerider]

The home test was quite basic. It had sensors on my heart, my neck, my finger, and a tube in my nostrils. There was nothing on my head.

I have always snored heavily so suspect it is OSA, but I just thought of it today - how do I, or the doctor, know for sure.

you'd have to see the report. if you knew what the brand/model name of the machine you used, it might answer your question, some of them area able to determine whether you're making an effort to breath when not breathing. the sensor in your nose would of course record actual breathing, the one on your heart (possibly a chest movement sensor) could determine breathing effort, if you're not breathing, but your chest is moving, that's an OA, if you're not breathing and your chest isn't moving, it's a CA.

[palerider]

An in lab sleep stusy would better show centrals or an auto cpap could help show them also.

this is wrong, you don't need an autocpap to determine whether you're having centrals or obstructives, a resmed S9 elite cpap does that.