HYPOPNIAS - ARE THEY CENTRAL OR OBSTRUCTIVE EVENTS?

[spottymaldoon]

According to my machine I seem to get a lot more hypopnias than apneas and I'd like to know whether these are obstructive events or whether I am just having 'lazy' or shallow breathing? If so, that would make them 'central' rather than obstructive by nature, wouldn't it?
Thanks Spotty

[PaytonA]

They can be either. What is your 90 or 95% pressure and ditto for leaks.

Best Regards,

PaytonA

[justMongo]

Generally obstructive.

[Possum]

According to my machine I seem to get a lot more hypopnias than apneas and I'd like to know whether these are obstructive events or whether I am just having 'lazy' or shallow breathing? If so, that would make them 'central' rather than obstructive by nature, wouldn't it?
Thanks Spotty

They can be either. You can check to see if the hypopnia is associated with any other events in your data, such as flow limitation, leak, P95 pressure (95th percentile of your pressure, or max). If so, then they are most likely obstructive. Mine come out of nowhere, so they are more likely central - i.e. your autonomic nervous system and/or diaphragm being "lazy."

[archangle]

The machine can't tell the difference. You might get some sort of clue from looking at the breathing patterns and the shape of the waveforms, but it's iffy.

The medical community used to sort of assume hypopneas are all obstructive. They've begun to entertain the idea of central hypopneas in the past few years. I think it's still sort of up in the air whether there are central hypopneas and how to distinguish one from the other.

Yet another reason you need a fully data capable machine with airflow waveforms and need to review the data.

[spottymaldoon]

What is your 90 or 95% pressure and ditto for leaks.

Thanks, Payton:

90% pressure is 10.0
90% leak is 60.0

Archangle: Interesting - from what people are saying, modern machines can record breathing patterns - does this pick up "shallow" breathing or "lazy diaphragm" events? I was contemplating trying a strain gauge/belt to do this but if the machines can do that now I'll trade in my old one.

Possum: Thanks for your input

[justMongo]

Archangle: Interesting - from what people are saying, modern machines can record breathing patterns - does this pick up "shallow" breathing or "lazy diaphragm" events? I was contemplating trying a strain gauge/belt to do this but if the machines can do that now I'll trade in my old one.

Today's machines sample flow at about 25 samples per second. The normal shape of the inhalation waveform rises to a rounded peak, then falls with roughly the same shape. When the airway is partially restricted the top of the inhalation waveform becomes flattened. ResMed scores Flow Limitation by that shape. Flow Limitation is often a precursor to OA or HA.

Machines can certainly measure shallow breathing because they integrate the area under the flow curve to calculate Tidal Volume (VT) which is in the neighborhood of 500 ml. It does not flag a 300 ml VT as shallow as it may be normal for a person.

A decrease in flow by X% for Y seconds does flag as a hypopnea.
(I have forgotten X and Y.)

There is no scoring for lazy diaphragm. Except perhaps in the brass section of a band.

And, your leak rate is too high.

[PaytonA]

Mongo,

X= 30-50 and Y=10. Do not worry Mongo it is just the creeping onset of senility.

Spottymaldoon,

Mongo is right. Your leak rate is too high. It appears high enough that it might make your other indicators suspect. You will see any shallow breathing as a reduction in the tidal volume but the machine does not give you the cause.

Best Regards,

PaytonA

[zonk]

I don't know about M series auto but the S8 AutoSet didn't increase pressure to treat apnea above 10 to avoid runaway pressure and causing central events. But increase pressure in response to snoring and flow limitation up 20 which are considered signs of obstructive events (not central events). ResMed S9 AutoSet and AirSense 10 AutoSet, PRS1 Auto 50/60 series and DreamStation Auto ... can distinguish between obstructive and central events and doesn't increase pressure in response to central events whenever detected

When I first used S8 AutoSet, Hypopnea numbers, always seem on the high side but the S9 AutoSet amd later AirSense 10 AutoSet took care of it, AHI numbers come down to below 1 and stayed like that to this very day ... YMMV

[zonk]

What is your 90 or 95% pressure and ditto for leaks.

Thanks, Payton:

90% pressure is 10.0
90% leak is 60.0

90% leak mean leak was at or below 60 L/m 90% of the time, but the number 60 does not tell us much, how long stayed at 60

M series report total leak (mask vent leak rates at any given pressure + mask and mouth leaks)
If we subtract mask vents leak rate from total leak, will give us net unintentional leak