Question about Rain Out

[CollegeGirl]

In addition to all these factors already discussed in this thread, this one's a biggie:

How much humidity is naturally present in the climate in which you live. This makes a big difference, and helps explain why people with the same mask, setup, house temp, etc. can still get different amounts of rainout.

[ozij]

Just another vote for a heated hose.

O.

[packer]

I would like to hear about this from other members

humidity in the air seems to me to be a big part of the rainout equation

how much difference running central air conditioning in the house?

can we watch the weather on TV and look for dewpoint?

thanks Packer

[Missy]

RG~Why do you use a Radio Shack adapter. Just curious, I have had my heated hose for a couple of months now. It helps, but does not eliminate rainout, but I'll take it. It's worth being able to use the Aura. Thanks!

Dawn

[GeneS]

Maby there is more to rain out than dropping temperatures to the dew point causing rain out. Increasing pressure will do the same as dropping temperatures but I do not think the pressure increases after the vapor is added. Could water vapor be blown down the tubing without actually forming a saturated mixture with the air? Wind can blow rain and I dont think that the humidity on the ground is necessarily 100%. It may not have time to mix. I never calculated the air velocity in a cpap hose to compare it with wind velocity so I will do that. It seems that small hot humidifiers with a lot of vapor and low mixing time might contribute to lack of mixing. I think we need to think more about different ideas. I do not use a heated humidifier and have never had rain out so it is hard to experiment but I can think about different possible causes.

GeneS

[Patrick A]

[quote="topher"]I have never had rainout, only ben on cpap 4 months 17cm, maybe higher cm less chance, who knows?

[Linda3032]

All interesting ideas, but I still believe that the pressure has alot to do with rainout. I get it because I have a low pressure. If I run my humidifier on 1, even in a warm room or in a cold room or in the desert or in Arkansas, I get it.

Climate? I doubt it. Not if you live in a central air/heated house. One of the Florida Aura users posted that he never gets it -- but he has a high pressure too.

[ozij]

Here's a very simple condesation experiment for those of you who have glasse.

Take your glasses off, blow on the glass very slowly (with your mouth open) like some of us do in when we want to clean them. You get a layer of condesation.

Do it fast - a quick forcefull breathing out - I certainly saw a difference.

The amount of humidity in the surrounding air will effect how much water is taken along as your cpap blows. With the pressure constant, Your humidifier will empty faster in a dry environment.

Rainout is the bugbear of those of us who have been told "at that pressure you don't really need a humidifier". Of course, the tellers have never slept with a cpap at any pressure....

O.

[billbolton]

My room temperature is between 65 and 68 winter and 70 and 75 summer.

I'd be very surprised if you got much, if any, any rain-out at those ambient room temperatures!

Cheers,

Bill

[Guest]

The volume of flow increases as cpap pressure and leaks increase and it seems that the heated humidifier vapor output would not increase that much with increased flow. If you have about the same amount of vapor mixing with more air the humidity would be less. This would mean that at low pressures the humidity of air entering the hose would be higher than the humidity in the hose at high pressures settings. Also at low pressures there is more detention time in the humidifier chamber and in the hose so more vapor could mix with the air and become saturated and there would be more time to cool down in the hose and condense. It seems to follow that at low pressure settings rainout problems could be greater than at high pressures.

GeneS

[GeneS]

Experiment

Someone who has low pressure and a rainout problem could try the following to see if low flow caused by low pressure is contributing to rainout.

I have a new Ultra Mirage 11 Nasal Mask. The pressure flow curve is as follows. I assume other masks are similar.

Pressure (CM H2O) Flow (Liters / Min)
4 18
8 29
12 38
16 46
20 53

Most people with a pressure of 18 or so and a flow of 50 or so do not seem to have rainout. (At least on this forum) My guess is that the problem is more likely caused by low flow than by low pressure. You could try to modify the mask by enlarging the exhilation port so that the flow was about 50 Liters / Min at your low pressure of 7 or whatever. The flow can be increased by enlarging the exhilation port preferably on an older spare mask. The amount it would need to be enlarged can be estimated by calculations but trial and error would work as well. You could check the actual and modified flow rate with encore pro prior to using the mask during sleep. I would try a short sleep first and check sleep results with encore pro. I do not know if this will solve the problem but I think it would be worth trying. I do not know if this would effect the way the machine works but I do not think it would effect it. If we never try anything we probably will not solve the problem.

I am not recommending modifying medical equipment but if the experiment showed that increased flow reduced rainout the manufacturer could be notified and maby they would manufacture a modified mask for people with low pressure and rainout problems.

GeneS

[Lubman]

Here's a new complication with a special case -- I use CO2 rebreathing (under a doctor's direction) where the non vented mask feeds a 12" tube to collect CO2 and then into an in hose valve which is where the venting occurs (e.g. where I breathe out)

So I have a hose cover on the rest of the machine hose, but in the non vented mask and in the uncovered deadspace tube, I get rainout.

Any ideas how to shield the tubing without taking the risk of blocking the exhale venting???

Lubman

[cpsleeper]

Hi,

I just had my first night with a machine - the Resp. Bipap M Series Auto with Biflex and humidifier...

I had terrible rainout (thought I would drown) and also experienced a strange noise which started about half way through the night. It was a popping type noise right as the air came through the end of the hose into my mask while inhaling each and every time. I use the respironics comfort gel nasal mask.


My questions...

What was this noise and why all the rainout? My pressures are 10/7 I think.


Another question... how do I use the cool air passover with this machine?? I heard that works good if you're very hot natured.



I see where I might need to cover my hose, but does the position and height of the machine really matter? Why does it matter? My doctor told me nothing about how to operate the machine. I ordered it online so I need all the help I can get.

Thanks,
cpsleeper

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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, bipap, humidifier, hose, rainout, auto

[debst99]

I have only been on cpap 7 days and no rainout, but it does sound like it could be a problem for me. My humidifier is set on 3 because when it was set at 2 I had nosebleeds the next morning.. I have sinus problems and had thin membranes in my nose as a kid so many nosebleeds back then. It is warm here now with the air conditioning set at 77, but actually would be warmer where I sleep (which is upstairs). Sounds like I could have a problem in the winter from the posts. My pressure is set at 8 and have a mirage swift II mask (pillows). Where would be the best place for me to get a hose cover? I have alot of medical debt this year so would like to get the best for less (is that possible)? Thanks everyone.

[billbolton]

It was a popping type noise right as the air came through the end of the hose into my mask while inhaling each and every time.

That sort of sound usually indicates that you have a fair amount of water (from rain out) in the hose and it is partially obstructing the air flow.

Cheers,

Bill