Health risks without a humidifier: true or false?

Do CPAP breathers who do not use a humidifier incur a significantly higher risk of respiratory-tract infection than those who do? I heard a claim that recent studies support, if not prove, that conclusion. But I'm skeptical. Has anyone here heard the same thing; and if so, provide more compelling evidence than "I heard someone say so"? I'm hoping someone can point me to an article or research report on this notion.

I have done just fine without a humidifier, but the person who relayed the claim to me strongly cautioned my that I was putting my health in jeopardy. But I'd rather avoid the minor hassles of humidifer management -- fill, empty, clean, rinse, repeat -- unless I'm convinced the cost is worth the claimed benefit.

The thing is, I can't imagine how slightly drier air from a CPAP without a humidifier can hurt that much. According to my calculations, a CPAP doesn't change the humidity of room air all that much. At room temperature (25 C / 77 F) and relative humidity of 70%, a CPAP set for 10 cmH2O reduces the relative humidity at most 2.7%, down to 67.3% in the mask (by raising air temperature 0.8 C / 1.4 F; spreadsheet available on request).

But relative humidity varies much more wildly with elevation, season, and daily weather. On a rainy day the relative humidity is 100%; on a normal "dry & sunny" summer day the wetherman might report humidity around 65%. In winter, the air in a heated home might have a relative humidity 5% or lower.

If the "higher infection" claim above is true, and given these large natural variations, why aren't normal, non-CPAP people -- who sleep perfectly well without benefit of a respiratory humidifier -- perpetually afflicted with bronchitis?

Obviously, their respiratory tracts are (mostly) healthy.

Ergo, my skepticism. Of course, that doesn't mean the claim is wrong. It does mean I'm not convinced that I should change my habits and begin the fill/rinse/repeat regimen.

Can anyone here shed more (and better) light on the question?

I can't show you any sort of report but I can tell you that I was a lot more uncomfortable after 20 minutes of no humidifier than a whole night with a low humidity setting.

That said, it makes sense. The CPAP without a humidifier dries out your sinuses. Due to that, the natural mucus that develops to help move germs from your nose and throat (where they will end up, CPAP or not) dries out and therefore the germs just sit there - or move to your lungs and cause infections. The mucus is a natural barrier to infection, and drying it out can't be good for you.

My understanding is that it is mostly a comfort and compliance thing, but since pressurizing the airway, along with the constant venting needed to do that, changes things so much, I guess humidification can be thought of as a way to take some stress off the body. So, in that sense, anyway, it could be considered a medical/health thing too, right?

RT magazine said this in June 2006:

"The nasal airway is essential for proper conditioning of air with heat and humidity before entering the lungs. The nose also has an efficient mechanism for recapturing water vapor during expiration. However, breathing cold dry air with nasal CPAP can alter the structure and function of the nasal mucosa, thereby overwhelming these mechanisms. Patients can experience many upper airway symptoms . . ."
--http://www.rtmagazine.com/issues/articl ... -06_08.asp

Maybe the sources for that article in the reference list will point in a direction for a more definitive answer for you.

But even the humidifier salesmen admit that not everyone needs a humidifier:

Humidification is not necessary for all patients; however, adding a humidifier to your system may resolve symptoms experienced by some people: Nasal congestion, dryness, or tenderness / Mouth breathing (commonly referred to as "mouth leak") / Dry throat
--http://www.resmed.com/us/patients_and_f ... c=patients

August 31st will be my 2 year anniversary on my APAP. Last summer and again this summer I have chosen NOT to use any type of humidifier. I have not noticed any increase in sinus infections or change in my allergies. I stop using the humidifier in the spring and won't start until the temperatures are low enough that the heat has to be on constantly.

In my opinion it is a matter of personal preference, nothing more unless I see it in writing where it is more beneficial to use a humdifier with data to back it up.

Ive used a CPAP since 1995 and never used or felt the need for a humidifier and Im in a low humidity area

a few years ago humidifiers were promoted as being essential for every CPAP user

Have never used one, never felt the need of it.

why aren't normal, non-CPAP people -- who sleep perfectly well without benefit of a respiratory humidifier -- perpetually afflicted with bronchitis?

Well if you live in my climate where winters are long and the in door climate is drier then most deserts - yes there are more respiratory problems in the winter. Anyone who has issues with sinuses will tell you winter is a beast - you go and visit the green houses just to get a sniff of humid air. People here buy humidifiers for the whole house for the winter (and de-humidifiers for the summer) Humidifier discussions are popular around the water cooler - which kind , what size, water mishap stories, the gross things that grow in then if you don't clean them....

My sinuses love the humidifier attached to my cpap.