[Equipment] Constant, high volume airflow from CPAP with mask on

[Alden]

ResMed AutoSet II CPAP user for 5+ years. Have been successfully using SwiftFit FX nasal pillows and a chin strap of my own design for several years. All was ok. Over the last 6 months or so the machine wakes me up with a high volume, constant flow of air. The nasal pillows are in place, the mask is not leaking. I adjust the mask anyway but the flow continues. The only way to stop it is to shut the machine off, wait a minute or so then turn it back on. Doesn't always work. Sometimes when I turn it back on the flow is again constant and high volume. Obviously I am not having an apnea event, I am wide awake. Under normal breathing (non-apnea event) isn't the air flow supposed to activate only when you breathe in, with a cessation of air flow on exhalation? Then in an apnea event isn't the air-flow supposed to become constant until the increased air pressure bypasses the obstructed airway and then return to normal status? Praxair, the company that sold me the machine is no longer in business in my area. I can find no local resource for info on the machine or answers to my questions. Hope someone here can help. Thanks.

[justMongo]

It doesn't work the way you describe. With PAP, there is always flow from the generator. It has to flow to flush CO2 from the mask. The pressure remains constant while the generator controls flow to maintain pressure.

Now, with an Autoset, the pressure should run at the minimum set pressure until the machine detects a need to increase pressure. Obstructive apnea, hypoapnea, flow limitation are triggers for increased pressure. The machine retreats slowly from the pressure increase.

Are you actually using ResScan? The S8 requires a special data card and reader.
It's difficult to see what's going on without a fully data capable machine and the ability to read the data.
The high sample rate data for flow and pressure would be useful. I do not think an S8 records high sample rate data.

The ResMed AutoSet II is an S8 generation machine. Your machine may be running Open-loop due to a failure -- most often a sensor.
You should consider an updated machine. Or, you may have changed... If we had the data, we might be able to see that the machine had good reason to increase pressure (which will increase mask vent flow) because your minimum pressure is now set too low. But, one should not make blind adjustments without data. I would wager it's been over 5 years since you've had a sleep study.

There are several repair services listed on the supplier list -- top of page. But, it may not be economical to repair.

Some people, and I am not saying you, interchange the words flow and pressure -- or they misunderstand the meaning of flow and pressure.

[zonk]

Over the last 6 months or so the machine wakes me up with a high volume, constant flow of air. The nasal pillows are in place, the mask is not leaking.

Profile shows "CPAP Pressure: 6.0", 6 is not on the high side, what is AHI and leak rate showing on the screen?

Have the pressure checked with manometer and as the machine is older one, I would upgrade to a newer machine
Supplier #2 on this list http://www.apneaboard.com/forums/Thread-...plier-List have a good reputation for used and new machines
Machines choices http://www.apneaboard.com/wiki/index.php...ne_Choices

[trish6hundred]

Hi Alden,
WELCOME! to the forum.!
Hang in there for more responses to your post and much success to you as you continue your CPAP therapy.

[GP49]

Have you tried a complete shutdown of the machine so thst its volatile settings get a chance to reset? Not the ones you see on the screen, those should remain. There is a lot of stuff going on in the microprocessors of our machines and yours may have glitched from a msins supply spike or noise...or whatever (just one of thise things...).

Unplug it from the mains in the morning...not just turning it off...and do not plug it back in until bedtime. I'd prefer several days off the mains, but that would leave you without the machine as you sleep. This is unlikely to work, but doesn't cost anything to try.

[Alden]

Have you tried a complete shutdown of the machine so thst its volatile settings get a chance to reset? Not the ones you see on the screen, those should remain. There is a lot of stuff going on in the microprocessors of our machines and yours may have glitched from a msins supply spike or noise...or whatever (just one of thise things...).

Unplug it from the mains in the morning...not just turning it off...and do not plug it back in until bedtime. I'd prefer several days off the mains, but that would leave you without the machine as you sleep. This is unlikely to work, but doesn't cost anything to try.

thanks for this tip. I did try that several times previously to no avail. However I did discover the problem last night....which I am embarrassed to admit. I had completely forgotten about the filter in the back of the machine. I have not changed it for a long time and it became severely clogged. This caused the machine to work very hard to draw air in which in turn increased the flow rate and, as I noticed for the first time the pressure readout spiked as well. My wife noted during this episode that the machine was making a lot of noise. With my hearing aids out I didn't notice. When I held the machine closer to my ear I could hear it laboring. And that's when I remembered the filter. I took it out and it was filthy. I ran the machine that evening without a filter and it performed extremely well and extremely quietly. I installed a new filter this morning and all is well. Thanks to everyone for offering advice and also in helping me understand my machine better.

[Alden]

It doesn't work the way you describe. With PAP, there is always flow from the generator. It has to flow to flush CO2 from the mask. The pressure remains constant while the generator controls flow to maintain pressure.

Thanks for this clarification. I fully understand now.[/font][/font]

Now, with an Autoset, the pressure should run at the minimum set pressure until the machine detects a need to increase pressure. Obstructive apnea, hypoapnea, flow limitation are triggers for increased pressure. The machine retreats slowly from the pressure increase.

Are you actually using ResScan? The S8 requires a special data card and reader.

Yes I use ResScan and periodically send the card in to a company who creates a report they mail to me. I am required to file this report with the Feds as part of my transportation licensing requirements. I never read the report myself.

It's difficult to see what's going on without a fully data capable machine and the ability to read the data.
The high sample rate data for flow and pressure would be useful. I do not think an S8 records high sample rate data.

The ResMed AutoSet II is an S8 generation machine. Your machine may be running Open-loop due to a failure -- most often a sensor.
You should consider an updated machine. Or, you may have changed... If we had the data, we might be able to see that the machine had good reason to increase pressure (which will increase mask vent flow) because your minimum pressure is now set too low.

There was a good reasons it was increasing the pressure which I discovered last night and note in detail in my reply to a post further down. The jist of it is I screwed up and failed to change the filter, which became clogged causing the machine to struggle to provide air flow. See below.

But, one should not make blind adjustments without data. I would wager it's been over 5 years since you've had a sleep study.

You are rifht, I haven't had a sleep study since the original one several years ago. Is it recommended to have one periodically?

There are several repair services listed on the supplier list -- top of page. But, it may not be economical to repair.

Some people, and I am not saying you, interchange the words flow and pressure -- or they misunderstand the meaning of flow and pressure.

I do understand the difference but was clumping the two together in my explanation. In actually both flow rate and pressure increased.
Thanks for all your insightful comments. I now have a much better understanding of the whole process.

[trish6hundred]

Hi Alden,
It’s great to hear that you found the problem with your machine and that you had such an easy fix.
Good job.