A setback in therapy - unknown cause

Hi, I've been on CPAP for almost a year now and it's been a life changer. My original diagnosis was a mild AHI of 12 and I've been using a Philips System One REMstar Auto with A-Flex set to a generic pressure of 4-20 originally which my doc then changed to 4-12 based on my 90% pressure. My current AHI hovers between 1.5-3 (2-2.5 being the average). Two months ago or so I started experiencing sleep apnea symptoms creeping back in - night time awakenings especially towards the early morning, difficulty getting back to sleep, waking up groggy, shot focus throughout the day. Being a newbie I'm struggling to see a difference in data between the 'good' and the 'bad' period. One thing I noticed recently - my machine has ramped up the rate of what I believe is called Pressure Pulse - short puffs of air. So much so sometimes I might be reading before bed breathing normally and the machine keeps sending those puffs periodically for no reason. It happens when I'm laying still trying to get back to sleep at 4am often. Even my girlfriend noticed these and started asking me if they're normal. Have you got any suggestions on how to tune up my prescription? I wondered if those pulses of air sent by the algorithm could be circumvented by switching to CPAP mode set close to my 90% pressure.

Below I'm pasting in few days from this week and a random sample from December which was a standard month before the trouble began.

May




December

Welcome to the forum.

Pressure pulses are very brief and very small (around 1 cm I think) puffs (fraction of a second) of air that the machine uses to help it decide if the reduction in air flow it is sensing is related to the airway being obstructed or you aren't breathing at all but the airway is open.
There is no "ramp up" to a pressure pulse...there's a "puff" and that's it (think blowing out one candle puff). Now people do sometimes notice it and it can be annoying for sure when they do...and especially when they start looking for or expecting it.

These machines don't know if we are asleep or awake...they only measure air flow so when you notice these pressure pulses while awake it's just because the air flow changed and the machine is trying to decide what to call the event should the flow reduction continue enough to earn either an OA or hyponea flag or a CA/ClearAirway/Central flag. Awake breathing can really confuse the machine sometimes.

Pressure pulses happen even in cpap mode....because it has nothing to do with the auto adjusting algorithm and everything to do with figuring out if the airway is open or closed.

Best thing to try to do...ignore them. The more you focus on them the more annoying they will become. Try to keep your breathing regular and rhythmic as possible...don't hold your breath (that will cause them for sure).
It's just the machine trying to do its job and unfortunately...it's annoying and some people just notice it more than others for any number of reasons.

Now as far as the reports you shared...I think you might do better with a little more minimum pressure...maybe 1 cm more.
Worth trying...maybe the apnea events that are happening are disturbing your sleep causing you to wake up more and then the pressure pulses get noticed more when awake...and a nasty little circle develops. Maybe reducing the events with a little more pressure will let you sleep a little better and not wake up and notice the pressure pulses.

Thank for a very in-depth explanation Pugsy. I did suspect I might be focusing on pressure pulses more just because of the fact that I spent more time awake during the night recently and the whole thing is just coincidental rather than a cause and effect. I'll try bumping my minimum pressure a bit especially that now I'm so used to CPAP (I got on well from the jump) that 4.5cm feels like nothing at all let alone bothersome. I could easily go higher and save the machine ramping up from scratch when an event occurs.

sebski wrote: ↑

Tue May 28, 2019 3:47 pm

the machine keeps sending those puffs periodically for no reason.

PPs happen when you haven't taken a breath in several seconds and the machine starts trying to see if your airway is open. That's the only reason it does those.

Now, the pressure *probes*, those spikes on the pressure line, those happen when the machine thinks you're sleeping really well.... And it weirdly gets restless and starts jacking with the pressure every few minutes...

I realize this is far from your main problem, but I’ll just mention that good “sleep hygiene” includes restricting your activities in bed to sleep and sex. In other words, no reading. I resisted this advice for a long time, because I’ve loved reading in bed ever since I was a kid. But I’m now convinced it is in fact good advice. Maybe think about it?