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Hissing sound on inhale Resmed air sense 10

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martyf +0 points · 23 days ago Original Poster

I have found in the last number of months, there is a hissing sound when i inhale using the Resmed air sense 10 machine. I have changed the gasket to no avail. Someone noted that if you change the tube setting from slimline tube to regular it helps. I changed the setting to regular, but still use the slimline tubing and I think it has helped with the noise. Since I have not actually changed the tubing itself, what impact does the change in machine setting have on the actual pressures that I am getting?

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Sierra +0 points · 23 days ago Sleep Patron

The AirSense 10 does not measure pressure at the mask itself, but only estimates it. To correctly estimate the pressure at the mask the machine needs to know how much restriction there is in the tubing so it can subtract that amount from the pressure it measures right in the machine. The other issue is that there is constant bleed air flow out the mask vent. It also needs to compensate for that lost air flow. The tube setting you choose just changes the pressure drop calculation. Same when you select the mask type. However that said, if you have the machine in automatic mode it will set the pressure to whatever works. Your mask pressure indication on the machine or if you use SleepyHead or OSCAR may be somewhat in error from what it really is, but since the machine is in auto it just adjusts based on the occurrence of apnea events. It self corrects. If you are in fixed pressure CPAP mode then the error becomes more significant. The pressure you think you are getting at the mask will not be correct. And, in CPAP mode the machine cannot self correct.

That all said, you should not be getting any hissing sound on inhale. I don't see how the tube size setting would help. If you actually go to a larger tube size it would reduce the velocity in the tubing. But I use a slimline and do not hear any hissing on inhale compared to exhale. You say you have replaced the gasket. Do you mean the gasket on the water reservoir? If so, then I would also check the silicone gaskets that seal the reservoir to the machine. Also make sure you are fully inserting the reservoir into the machine. Last, have you replaced the air inlet filter recently? The machine has to supply the most air during inhale and the velocity through the filter will be highest on inhale. If it is getting plugged it might hiss???

Hope that helps some,

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martyf +0 points · 23 days ago Original Poster

Since I have central apnea, the set pressure is at 9.0. Does that mess up the pressure by me changing the setting of the tube to regular?

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Sierra +0 points · 23 days ago Sleep Patron

I also have central apnea issues and my AirSense AutoSet machine is set to CPAP fixed pressure mode, 11 cm in my case. If that is what you are doing then yes if you set the tube type or mask type improperly compared to what you are actually using then the indicated mask pressure will not be what you are actually getting at the mask. I cannot however give you any idea how much it will be off though. The error must be significant or they wouldn't give a different setting for a different type type.

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martyf +0 points · 23 days ago Original Poster

Thank you very much for the information. I guess I will put it back to slimline. If I cannot eliminate the hissing, I guess I will get a new machine. Wish I knew when Resmed will be coming out with a newer model.

Thanks again,

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martyf +0 points · 23 days ago Original Poster

I did not see any silicone gasket that seal the reservoir to the machine.

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Sierra +0 points · 23 days ago Sleep Patron

See the technical manual at the link below. Air filter on page 21, and the reservoir to machine seals on page 24+.

AirSense 10 Technical Manual

A new model seems to be somewhat overdue now. But, who knows??? My wife has an S9 that is getting up there in age, and I would like to get the new model too. However, at least in Canada there is now a huge difference in price between the ResMed and DreamStation. I like the ResMed better, but it is hard to justify the extra $400 per machine cost.

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martyf +0 points · 23 days ago Original Poster

Thanks for your help. If I do not resolve the problem, I will order a new one. Of course after I get it a new model will come out.

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Sleepea +0 points · 22 days ago

I had a hissing problem a few times, it was always because the water chamber wasn't in the unit correctly.

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martyf +0 points · 1 day ago Original Poster

I just received my new Resmed airsense10. First night, absolutely quiet! The wife was able to get a good nights sleep. My ahi was slightly higher 1.7 compared to 0.7 The new machine is set to autoset mode with pressure L 5 to H 10 as compared to old machine cpap mode and pressure of 9

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Sierra +0 points · 1 day ago Sleep Patron

One reason you may be getting a higher AHI with the AutoSet is that with the minimum pressure set at 5 cm, it is going to take some events to trigger the increase up to say 9 cm if that is what you basically need. So you incur some events early in the sleep just to get the pressure up to where it needs to be.

With your settings this is how I would set up the AutoSet model.

Min Pressure - 7 cm, or you might even want to try 9 cm considering that is what you used before. Max Pressure - 10 cm Ramp Time - Auto Start Pressure - 7 cm or 9 cm (set it to match your minimum pressure) EPR - On EPR Type - Ramp Only EPR Level - 3 cm

Set this way with a minimum pressure of 7 cm it will start you off with 7 cm on inhale and reduce it for comfort to 4 cm on exhale until you go to sleep. When you go to sleep then it will stop the reduction on exhale. Pressure will then be controlled by the machine depending on what events occur. If you are comfortable with 9 cm for going to sleep then it will start at 9 cm and reduce to 6 cm on exhale. That is what I use and find it very comfortable.

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martyf +0 points · 1 day ago Original Poster

By the way, this morning after using it showed pressure at 7.1 I assume this was what it reached at peak?

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Sierra +0 points · about 8 hours ago Sleep Patron

If the Essentials has been set to Plus under the Clinical Menu Options there is a pressure displayed in the sleep report that is the 95% pressure (95% of the time pressure is less than that). It is averaged over the period selected for the sleep report. See page 19 in the Clinical Manual.

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martyf +0 points · about 7 hours ago Original Poster

Sierra, I am so happy to find someone as knowledgeable as you to get info from.

Thanks, Marty

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