Help: AirSense 11 "Thumps" on exhale?

[DrNefario]

I had this issue too. I described it as a 'click' noise upon exhale. It was loud enough that my wife said she couldn't fall to sleep if it was happening. I also found that it was the water chamber. Firmly reseating it made it stop. I was thinking of rubbing a thin film of food grade silicon grease at the seams of the chamber but it seems to have ceased making the noise now. I hope this helps.

[eternia]

I just got an AirSense 11 about a week ago. I have the same issue as the original poster. I've been using ResMed products since 2007 and never had a similar issue. I've been able to identify that the loud thumping noise itself is from the two AirFit 30i mask valves closing rapidly again on inhalation. When I feel the "vent" area where the hose connects to the tubing leading to the mask, it's clear the airflow is stopping *completely* on exhalation (then resuming rapidly, pushing the valves on the mask and making the thump; I took video to confirm this). EPR is **off**. SmartStart is off. Ramp is off. I tried another mask and same thing. I'm mystified. One person here said his issue was his water chamber wasn't seated properly. I don't see how this could effect this issue, but I checked, and mine is definitely in there and doesn't move during breathing. I tried speaking with ResMed and they refuse to say if this is a known problem or not (or otherwise provide guidance). DME says I can send it in for a check since it's under warranty. This is a very lengthy process, however (4-8 weeks), and I'm only inclined to do so if there's a reasonable chance my next device won't do the same thing. I'm trying to figure out if this is a common defect in AirSense 11. I can't think of any other setting to change that could change this. There shouldn't be any EPR since it's off... Even when I had EPR on at max on prior devices, it never did anything close to this.

[pholynyk]

How is this: >>>the loud thumping noise itself is from the two AirFit 30i mask valves closing rapidly again on inhalation. <<<

a problem with the AS11 machine?

This strikes me as a problem with the anti-asphyxiation valves or the mask venting area.

[cathyf]

How is this: >>>the loud thumping noise itself is from the two AirFit 30i mask valves closing rapidly again on inhalation. <<<

a problem with the AS11 machine?

This strikes me as a problem with the anti-asphyxiation valves or the mask venting area.

Maybe I'm not following, but he said this happens with 2 different masks, and that it is a result of the rapid cut-off of pressure coming out of the machine. Since he doesn't have EPR turned on, the pressure shouldn't drop on exhale at all. If it is really that the pressure goes from positive to zero, that's a whole lot bigger than 3!

(It also makes me wonder enough to go home and do some experimentation. My vauto will go to pressure support of 12, right? If it was programmed to be 12, and I was running it with IPAP=22,EPAP=10, would that be enough of a pressure difference to make the anti-asphyxiation valves make noise?)

[Gideon]

 it's clear the airflow is stopping *completely* on exhalation (then resuming rapidly, pushing the valves on the mask and making the thump; I took video to confirm this). EPR is **off**. SmartStart is off. Ramp is off. 

Let's look at your OSCAR charts of this occurring, Be sure to include the left sidebar and the Flow Rate, Pressure, and Mask Pressure charts with a 2-minute view.

[eternia]

OSCAR not needed... Pressure stops. When you first turn the machine on, I get the thump as the valves close from the pressure starting. This is the noise that is happening *every* time after exhalation... (Again, I video-ed showing this.) My real question is, is this happening to others besides the original poster? Is this a rare issue or common? Worth it for me to send my machine back to get looked at?

[Gideon]

The only situation I can envision this is if your pressure is low and your inhale is so strong that the device cannot keep up and you are actually pulling a negative pressure this opening the anti-asphyxiation valve. Try increasing the minimum pressure by 2 and see if this behavior continues