Low apneas - high hypopneas

[andyjh64]

Hi, can anyone give me their thoughts on consistently low apnea results but high hypopneas?

I am using a Resmed S8 which has limited data reporting capabilities on the display,but looking at these for the first time recently I've discovered that over a month long period, my AHI is about 9.6. This figure has been almost entirely due to hypopnea events, as the apnea rate is a very pleasant 0.5. Weekly and Daily reports yield similar results. Mask leak rate is about 0.5

My current maximum pressure is 15 but it never seems to go above about 11.

Should I be concerned about this high Apnea-Hypopnea discrepency? And is there something I can do about it such as increasing the minimum pressure? My understanding of hypopneas is that they are episodes of shallow breathing, so are they in themselves harmful?

Thanks for any insight you can offer guys

[zonk]

From interview with Dr Dr Michael Berthon-Jones ... ResMed chief designer of AutoSet (prior to the 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

Read more http://www.resmed.com/au/assets/document...0906r1.pdf

[Paptillian]

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).

I don't understand this part. A lot of folks here with obstructive apnea have pressures above 10 cmH2O.

[andyjh64]

That's very helpful Zonk. Thanks

[Sleepster]

My current maximum pressure is 15 but it never seems to go above about 11.

I would guess that maybe you need to put the machine in CPAP mode at a fixed pressure of 12 and see what happens.

But that is just a guess.

You should talk to your doctor about this. It may be that your insurance will cover a new machine. The S9 is much better than the S8, and the AHI it reports is more reliable.

Keep in mind that the difference between a hypopnea and an apnea is rather subtle. To score an apnea the breathing rate has to fall below a certain percentage for 10 seconds. The same is true of a hypopnea. The percentage is different, of course.

The other thing you can do is get an oximeter so you can see if you are getting significant desats during these hypopneas.

Also, how you feel is important. Do you feel that you are getting restful sleep?