Pressure loss with heater/humidifier

Iamemjay · Post by **Iamemjay** » Wed Sep 16, 2015 1:56 am

I have recently noticed that when the humidifier is attached to my Apex Sense CPAP machine, the exit air pressure is significantly less. My machine is set to my prescription pressure of 7. I have no idea if it is normal for a humidifier to reduce the pressure or if indeed the machine has been preset by the distributor to compensate for such a pressure loss.

Any comments?

AlabamaAl · Post by **AlabamaAl** » Wed Sep 16, 2015 6:24 am

I don't know much about your machine, but I would first check for leaks around the seals. Also Sleepyhead data can provided some clues to if this is a leak or an obstruction. There should not be a reduction in pressure because a humidifier is installed.

ChicagoGranny · Post by **ChicagoGranny** » Wed Sep 16, 2015 7:39 am

Iamemjay wrote:I have recently noticed that when the humidifier is attached to my Apex Sense CPAP machine, the exit air pressure is significantly less.

And how do you know that the pressure is lower? Did you measure it with a manometer?

If you are judging by the sound, you may be fooled. A humidifier acts as a sound muffler.

Iamemjay · Post by **Iamemjay** » Wed Sep 16, 2015 7:53 am

It's not the sound but rather the very obvious extra volume of air exiting the hose into the mask - feel it onto my hand, most noticeable when I put the mask on. It's a VERY different experience. If it is true that there should not be any reduction in volume/pressure then I'll go looking for an obstruction in the humidifier. Thanks.

ChicagoGranny · Post by **ChicagoGranny** » Wed Sep 16, 2015 10:26 am

Iamemjay wrote:If it is true that there should not be any reduction in volume/pressure

If the system is set up properly, any drop in pressure would be detected only by a sensitive manometer. And it would not be enough of a drop to affect therapy.

Matt00926 · Post by **Matt00926** » Wed Sep 16, 2015 11:08 am

Is it a heated humidifier or a moisture exchange one

BleepingBeauty · Post by **BleepingBeauty** » Wed Sep 16, 2015 11:27 am

Iamemjay wrote:I have recently noticed that when the humidifier is attached to my Apex Sense CPAP machine, the exit air pressure is significantly less. My machine is set to my prescription pressure of 7. I have no idea if it is normal for a humidifier to reduce the pressure or if indeed the machine has been preset by the distributor to compensate for such a pressure loss.

Any comments?

I'm assuming you mean the AirSense machine. I've never heard of Apex Sense.

Are you sure your machine isn't set with some kind of exhalation pressure relief? EPR can be set to 1, 2 or 3cm so that the exhalation pressure is lowered by that amount. (If your inhalation pressure is 10 and the EPR is set at 3, your exhalation pressure would be 7.) The humidifier has nothing to do with EPR, so you would feel the same exhalation relief with or without the humidifier running (or even just attached).

Iamemjay · Post by **Iamemjay** » Wed Sep 16, 2015 11:38 am

A heated humidifier. I have now dismantled and thoroughly cleaned the humidifier and checked for leaks and obstructions. Found none. To make sure it is not all in my imagination I asked my wife to check (hand-felt pressure at the mask end of the hose. She said "strong/not strong" to the comparative outputs. It doesn't make any logical sense to me, but that's what I have.

Iamemjay · Post by **Iamemjay** » Wed Sep 16, 2015 11:48 am

The machine is an Apex XT Sense CPAP. In my reading of the specs I've never discovered anything about any bypass as suggested. I had occasion to use it without the humidifier for a couple of nights last week and was shocked by the difference, hence these questions. Given the replies I have received here I have already contacted the manufacturer's support line to see if they can throw some light on the matter.

Wulfman... · Post by **Wulfman...** » Wed Sep 16, 2015 3:14 pm

The only way to know FOR SURE is to check it with a manometer.

You can have it checked by a local DME or you can make your own manometer. Do a forum search on "homemade manometer".

If it's a straight CPAP machine, set it for a specific pressure when checking.
If it's an APAP (capable of pressure ranges) set it for a specific pressure when checking.

Den

.

palerider · Post by **palerider** » Wed Sep 16, 2015 4:10 pm

https://www.google.com/search?client=ub ... 8&oe=utf-8

in normal operation, the extra resistance of a humidifier is compensated for in the blower so that you get the proper pressure delivery.

if you feel that the pressure is too low, I suggest taking the machine to your local cpap supplier and asking them to test the output, and check it over.

it's possible that there's something that is wrong, assembled incorrectly, a leak, etc... or you may just be misjudging the amount of air (which is very easy to do)

you can make a home-made manometer, use the search box above to find articles that are on this site from people that have done that.

Iamemjay · Post by **Iamemjay** » Thu Sep 17, 2015 12:25 am

Thanks everyone for your comments.

Firstly there is no doubt about the pressure drop. It is really severe.

Without this discovery I was already having doubts that I was receiving the correct pressure and had determined to build a manometer. This has cemented that determination.

I will also follow through with my enquiry of the manufacturer in case there is something I am missing (EPR) or whatever. Perhaps there is a fault.

In the meantime I have already ceased using the humidifier.

Thankyou

ChicagoGranny · Post by **ChicagoGranny** » Thu Sep 17, 2015 7:34 am

Iamemjay wrote:In the meantime I have already ceased using the humidifier.

If your nostrils don't dry out, you might find the humidifier is unnecessary. I don't use mine except for some days in the winter when the gas heat seems to run all day.

Iamemjay · Post by **Iamemjay** » Thu Sep 17, 2015 7:58 am

I'm already surprised. When I first started using the machine in April the humidifier was absolutely essential. I would experience extreme dryness until I got the settings right - one below the maximum. Now, I'm getting some dryness, but still at a tolerable level. The biggest issue now is adjusting to a much higher pressure level than I have become accustomed to as well as increased noise. I'm missing that muffler you referred to!

I guess time and patience will fix that, for me and my wife!

ChicagoGranny · Post by **ChicagoGranny** » Thu Sep 17, 2015 8:27 am

Iamemjay wrote:The biggest issue now is adjusting to a much higher pressure level than I have become accustomed to as well as increased noise.

This is both puzzling and concerning. You do realize a pressure of 7 cm is a very low pressure? 10 cm is considered average and many of us have much higher pressures as high as 16 to 24.

I have always considered 7 as the minimum pressure I could tolerate. Anything below 7 causes a feeling of not enough air (suffocation).

The machine should also not be very loud at 7. It helps with the noise to place the machine just below the level of the mattress. I have a small child's chair on which I set my machine.

Also, a hose cover helps damped the noise traveling down the hose - https://www.cpap.com/productpage/snuggl ... cover.html

Do you have data with that machine so you can do a quick daily check on AHI and unintentional mask leak level?

Pressure loss with heater/humidifier

Pressure loss with heater/humidifier

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