Developing central sleep apnoea?

I've been trying a Bi-Level machine (resmed S9 VPAP S) to see how it feels. The short of it is, its great. Much easier to breath and its really cut down on flow limitation events which may have been linked to UARS. Its early but I also feel better.

However, I've noticed a sharp increase in central events. My guess is I'm now actually treating obstructive events and UARS which is opening the door for centrals to occur.

At what stage do you start to consider that you may have complex sleep apnea?

gary1001 wrote:I've been trying a Bi-Level machine (resmed S9 VPAP S) to see how it feels. The short of it is, its great. Much easier to breath and its really cut down on flow limitation events which may have been linked to UARS. Its early but I also feel better.
However, I've noticed a sharp increase in central events. My guess is I'm now actually treating obstructive events and UARS which is opening the door for centrals to occur.

you may just be hyperventilating yourself with that 11ps.

palerider wrote:you may just be hyperventilating yourself with that 11ps.

Yea, thats something to consider.

It looks odd having an EPAP of 5, but is just felt so much easier to breath. After reading this wiki entry on UARS, wiki/index.php/Upper_Airway_Resistance_Syndrome it made some sense. Comparing the flowrate curve between CPAP and Bi-PAP, the tops are round oppose to flat. This didn't really happen until I lowered the EPAP to around 5. This is touched on in the article.

"That is, nearly all patients who switch from CPAP to bilevel state that it is easier (subjectively) to breathe out with bilevel. And, during their titrations, the ratty airflow signal disappears on expiration (objectively) and is replaced by a smooth and rounded curve indicating normal expiration."

I guess the only thing is to monitor. If it keeps happening I'll try a closer gap by lowering the IPAP.

Out of curiosity, anyone know what is an acceptable range for centrals events?

gary1001 wrote:

palerider wrote:you may just be hyperventilating yourself with that 11ps.

I guess the only thing is to monitor. If it keeps happening I'll try a closer gap by lowering the IPAP.

if you are inducing centrals by hyperventilating yourself and screwing up the breathing reflex by blowing off too much co2, then you're in uncharted territory for me as to whether there's any danger, or it's just going to look funny on the charts.

I believe you need the higher ipap to overcome the flow limitations that result in the flattopped inhalation waveforms, but (someone correct me please) I don't think that a crazy low epap is needed for that, since that's your exhalation. it might lead to more obstructives though.

having a lower ps by raising the epap would cut down on your hyperventilation, and still keep you open on inhalation.

note, this is just theory as I understand it and I'd (as always) welcome more knowledgeable corrections. maybe we can get sludge's attention

Last night (before I read your post), I lowered the IPAP - 12 and kept the EPAP of 5.



As you can see, the centrals are completely gone however the crappy flow curve returned . I also felt crappy this morning - hit by a bus.



My guess is you are right. The high PS is causing me to over-breath. I'll raise the EPAP by to 2 and restore the IPAP of 14 to have a PS of 7 (14-7).

One thing I noticed is having a low EPAP is sooo much easier.

Palerider suggested tightening the ps, which sounds like good advice to me. Comparing your first report to your second report, you didn't do that. The first report shows a min. IPAP of 11.4 (with a range up to 16), and the second report shows a min. IPAP of 12 (straight pressure). Eliminating the ranges of EPAP and/or IPAP is not what he meant. Even though you set a range of 5 to 8 on EPAP, you were still starting with an aggressive ps of 7. How about setting ranges on both so that the high ps can fluctuate downwards when it is not needed?

M'ohms wrote:Palerider suggested tightening the ps, which sounds like good advice to me. Comparing your first report to your second report, you didn't do that. The first report shows a min. IPAP of 11.4 (with a range up to 16), and the second report shows a min. IPAP of 12 (straight pressure). Eliminating the ranges of EPAP and/or IPAP is not what he meant. Even though you set a range of 5 to 8 on EPAP, you were still starting with an aggressive ps of 7. How about setting ranges on both so that the high ps can fluctuate downwards when it is not needed?

the vpap S is a fixed dual pressure machine, it doesn't have auto capabilities. the first report included a brief session at a lower ipap, that's why it looked like it was variable pressure. just fyi.

Thanks for the correction! I always learn a lot from you!

M'ohms wrote:Thanks for the correction! I always learn a lot from you!

I'm more familiar with the product line on the resmed side, and looking for what is in the reports they make, so I might notice an easy to miss little detail... the first report (except for a few minutes in the first segment) was done at 16/5 straight pressures...

thus my hyperventilation statement

I can't imagine breathing like that all night. I would surely pass out!

M'ohms wrote:I can't imagine breathing like that all night. I would surely pass out!

my thinking is that's where the centrals are coming from... his respiratory reflex "passing out" as it were

palerider wrote:my thinking is that's where the centrals are coming from... his respiratory reflex "passing out" as it were

I was thinking about it. The tidal volume should be a key metric, i.e. if one is hyperventilating, breath would be too quick and/or deep thus the greater volume. The two nights do have different med volume - 700 compared to 500. While 700 isn't high, maybe it is just too much. It is interesting tho that reducing the IPAP by 2 meant a drop of 200.

Then again, a couple of nights doesn't really make a trend..

gary1001 wrote:Then again, a couple of nights doesn't really make a trend..

well put

I'm still wondering if central apnoea is emerging when I actually treat obstructive or resistance issues. The trend seems to be, when I up the pressure or use a FFM, flow limitations stop and centrals seem to cluster (note I use a FFM for only the first couple of hours).