CSA as a cause of OSA

[desaturator]

Imo CSA is not the "cause" of the OSA. It just allows the underlying OSA issue to be more visible.

I think authors of the paper acknowledge that. It seems that you have to be prone to airways collapse already, for the central apnea can trigger an obstruction.

Still, with the kind of equipment we are likely to have at home (xPAP machine, pulse oximeter) we probably don't have any way to distinguish between "true" obstructive events that would be relieved by increased PAP pressure, and partially-central events that might not be relieved; or, at least, not relieved as much.

I note that a lot of the discussion on this forum assumes that there is a relatively clear distinction between central and mechanical apneas, when perhaps that is too simplistic.

BW, DS

[Ratchick]

The term "mixed apnea" specifically defines an apnea that contains both central and obstructive factors within the same apnea - which I agree, sounds exactly like what they're describing, even if, more commonly, it's seen the other way around. When it starts obstructive and ends central, the treatment is as per obstructive apnea. So presumably if these mixed apneas were starting central and then ending obstructive as a single apnea, the control would be aimed at managing the centrals (because ASV is also going to control obstructive events too).

The problem is that a lot of people (rightly or wrongly) use that term to describe someone with reasonable numbers of both central and obstructive events. And that could be down to the fact that they really are "mixed" events that show aspects of both in one apnea rather than being both central and obstructive events that never cross over. I would imagine that part of that is down to the skill of whoever is analysing the data

I'm not sure if that's the correct usage, though - that A mixed apnea with both central and obstructive features (and which it sounds like is what is in that paper) is obviously correct, but a person WITH mixed apnea might have apneas that are mixed or a mixture of obstructives and centrals, that gets a bit murky. My understanding was always that the latter (a mix of individual OAs and CAs) came under Complex Sleep Apnea.

"I note that a lot of the discussion on this forum assumes that there is a relatively clear distinction between central and mechanical apneas, when perhaps that is too simplistic."

I would disagree here. I think it's fair to say that most of us giving the advice here are aware that the two apnea types can coexist, but it's like if you hear hoofbeats, you don't automatically think of zebras. The first option is to always control the most obvious issue first, and it just so happens that in most cases, that's obstructive, or obstructive-first mixed apneas. This is why we always ask for sleep study data, where possible, so we can, in fact, know what was seen before any therapy started. That said, none of us is a medical specialist (even if it sometimes seems like even the doctors are clueless). We just try and help people feel better with their xPAP therapy.

[desaturator]

[...] if you hear hoofbeats, you don't automatically think of zebras.

I once said that to a chap who, as it turns out, grew up in Zambia. I guess you know where this is leading, right ?

Anyway, my concern is that perhaps there really aren't horses and zebras, just equines. Some are more horsey and some are more zebra-y, but all have hooves. Just a thought.

BW, DS

[Geer1]

Still, with the kind of equipment we are likely to have at home (xPAP machine, pulse oximeter) we probably don't have any way to distinguish between "true" obstructive events that would be relieved by increased PAP pressure, and partially-central events that might not be relieved; or, at least, not relieved as much.

I can often get an idea by interpreting the flow and mask pressure graphs. The forced oscillation technique Resmed used shows low flow, low pressure amplitude if central and less flow, higher amplitude if obstructive. In mixed apnea you can sometimes see the moment obstruction sets in by how it changes part way through the apnea.

[Ratchick]

Anyway, my concern is that perhaps there really aren't horses and zebras, just equines. Some are more horsey and some are more zebra-y, but all have hooves. Just a thought.

Yeah, it's possible. And it'll be interesting to see if future research backs that up. I'm certain that people are being diagnosed overly simplistically, just from the number of people who clearly have both central and obstructive events but are only ever treated for the obstructive, or have pure central (like myself) and get told it's not worth treating.

And also that's why I defer to Geer1 on reading the data because they're far better than I am at spotting the subtle stuff.