Hose Temperature/Humidity Logic Question

[bluemom51]

Hi - In my never-ending (and not yet solved) problem with excessive rainout with the Autosense 10 - I have a logic question. You read endless articles on keeping your bedroom very cool at night - I've seen many recommendations of about 68 degrees in the winter. I'm always hot, so that seems fine.

But then I see machines coming from the DMEs set at 80 degrees and some on the forum saying they have theirs at 84? If "comfortable" sleep for non-CPAP users is below 70, why should we be blowing 80 degree air (with force) into our lungs? Is is just to control or minimize the flood that can occur with using a humidifier (at least in the case of an Autosense 10-I'm on my 4th and they are all the same).

I have mine set at 79, but it never seems to make a difference - setting it to auto climate just results in a flash flood, so I have to use manual setting of only 2 to control the rainout. Anyway, I was just wondering about the logic of it all - bedroom very cool, but air blasting into our lungs very hot?

I have never tried dramatic changes - like going to 75 or 84 or anything other than 79 or 80. I don't know the scientific mechanics of which temperature settings result in which results...Particularly why it seems they want the CPAP air to be so hot? I could not sleep well in an 80 degree room, so how might 80 degree CPAP air be impacting my sleep?

Thanks for any suggestions/explanations you might have.

[mcsheltie]

The temperature of the room has nothing to do with the temperature of the air we breath. No matter how cold the room is by the time air reaches our lungs it is body temperature. So air coming from the CPAP at 80 degrees still has some warming up to do.

I can't sleep in a hot room (hot to me is above 65 degrees) but if I use my CPAP at room temperature it feels like there is an added wind chill! My nose is freezing.

And of course the temp used with a heated hose is purely an individual comfort thing, nothing else. We are all different.

As far as rainout goes. What worked for me was the hose set on 4 (mine ranges from 1-5) the humidity turned down as low as my sinuses and throat can tolerate and putting on a hose cover to minimize the difference in temp between the hose and the bedroom air.

[bluemom51]

Oh - that makes so much sense. Of course - our body temperature is 98 +/- so hotter than room temperature air coming in is fine. Good grief - why didn't I think of that. I may try increasing the air to 82 (have never gone above 80) and see if that reduces the rainout.

Yes, I have everything wrapped - the hose, the tube on the mask - everything. Believe it or not, ResMed, having admitted they built more base humidity into the Autosense 10 than the Autoset 9, told me to wrap the little the piece that holds the nose pillows in Duct Tape......I told the Tech guy that was not funny, and he said he wasn't trying to be - that people had actually done that to reduce the excess rainout from those machines. I suggested that maybe they should go back to the base humidity of the Autoset 9 on their next machine as it Never had rainout problems even when set to "auto" and many people have problems with the Autosense 10. Why do they always have to change a good thing. With machines number 1 and 2 that I tried, it was so bad, I could lift the mask and spray water around the room......

Anyway, thanks for the clear and perfectly logical answer regarding CPAP air temps - I love logic!

[Sleeprider]

It's not the air temperature you're changing, but the hose wall temperature.

[bluemom51]

Ok, but I'm a little lost. You're saying the air coming through the CPAP would be the room temperature. So what good is changing the hose wall temp - the air is coming through so fast, I would guess the air is not heated, so are you saying by increasing the hose temp more it should keep the condensation down, but it will not affect the temp of the air?

But then why do people say they notice a difference between setting the "hose temp" at 86 versus 80 in terms of them saying the air itself seems "hotter" with higher temps. Is it just their imagination?

[sonicboom]

Sorry to hear you are still struggling with rainout. I would turn the tube temp to 84 and see what happens. Should reduce condensation.

[Ghost1958]

Because warming the tube keeps the already heated air from the humidifier from cooling as much so one does in fact breathe warmer air. Warm air carries more moisture than cool. Which is why no condensation in a heated tube.
I have a personal belief that at least with PR machines with heated tubes, anyone getting rainout either has the tube turned off or it isn't working.
I routinely sleep in a 60 or less , sometimes 50 degree room humidty maxed out and tube Setting of 1 and NEVER have had even a damp hose.

[PoolQ]

A couple of things:
1. Cold air can indeed get into your lungs, anyone that lives in very cold climate knows to be careful not to freeze your lungs
2.The ONLY way the machine changes humidity is by the heater on the other side of the metal plate in the water chamber, the warmer the water, the higher the humidity
3. The only thing that gets warmer than room temperature is the water in the air stream. The air itself is basically always room temperature. It goes through the CPAP pretty dang quick. The air just carries the warm water into your lungs.
4. the heater in the hose helps to prevent the warm moisture in the air stream from dropping out in the tube. This is the same as air conditioning condensation-warm moist air hitting a cold surface.

[chill]

Cold air can indeed get into your lungs, anyone that lives in very cold climate knows to be careful not to freeze your lungs

Darn right! It was pretty common to get down to -40 where I grew up. The first couple of breaths outside were like having a knife shoved down your throat! You learn quick!