Airsense 10 "Puffing"?

[cby1]

As I understand it, the Airsense 10 uses some "gentle" puffing to detect whether the airway is open or not, so it knows how to score an event.

I notice this toward the end of my sleep period. It always happens just as I finish an exhale (not every exhale) - it's kind of disturbing. Does it make sense that it would be checking then, since I'm actually breathing at that point?

It also seems to happen if EPR is set to 2 or 3, but not 1. Then again, we're relying on my perception here, and not a lot of samples at EPR 1, at that - but I'm pretty certain. The only other possibility is that I actually exhale like that - which I don't think is the case.

Any ideas what this might be telling us? Does it suggest that I should be trying to use EPR=1 (or less) if I can stand it at the effective pressure (which can be a challenge)?

Thanks.

[archangle]

There are several possible reasons for this.

1) The machine tries to control the pressure at the mask, but its sensors are at the output of the blower and have to go through the humidifier, hose, and mask. I think sometimes, as you're switching between inhale and exhale, it's trying to be "smart" and may make some unintended variation at the other end.

2) If you have EPR turned on, it reduces the pressure as you exhale and ramps it back up when you inhale. You may feel this, and it may occasionally happen at the wrong time. You can turn off or reduce EPR if you want to.

You shouldn't feel the FOT (Forced Oscillation Technique) pulses unless you've stopped breathing for several seconds. FOT is what ResMed uses to detect a clear airway.

[palerider]

As I understand it, the Airsense 10 uses some "gentle" puffing to detect whether the airway is open or not, so it knows how to score an event.

resmeds us a technique called Forced Oscillation Technique (FOT) to determine if your airway is open or not, it does that by varying the pressure up and down by 1cm 4 times a second, after 6 seconds of not sensing any breathing (variation in airflow).

I notice this toward the end of my sleep period. It always happens just as I finish an exhale (not every exhale) - it's kind of disturbing. Does it make sense that it would be checking then, since I'm actually breathing at that point?

if you're still exhaling, and not pausing, then either you're not feeling FOT, or your machine is defective.

you can see FOT in the mask pressure trace on sleepyhead/resscan if you zoom in on it, it's pretty obvious.

[cby1]

Sure sounds like the FOT you guys describe. I'll have to look at SH. It seems to me I have a "long" exhale - maybe it's not long, maybe it's stopped in these cases.

[SleepyBobR]

I was concerned about this which was why I borrowed the AirSense for a week before buying it. I didn't want to find out I was bothered by the FOT after committing to the machine. I did not notice anything unusual on my first night but that's not much to go on. I'm not looking for a problem with the AirSense, just want to be sure there isn't one. So far so good.

[palerider]

Sure sounds like the FOT you guys describe. I'll have to look at SH. It seems to me I have a "long" exhale - maybe it's not long, maybe it's stopped in these cases.

go in SH, zoom in on the flow and mask pressure to where you can see the individual breaths. if it's doing FOT, then you'll see it in the traces.

fot kicks in six seconds after no flow variations from inhalation (flow trace above zero line) or exhalation (flow trace below zero line).