I'm having problems with rainout, it's been very disruptive for me and I'm trying to understand a couple of things better. I'll start with my two questions and then provide the long backstory!
Firstly, if I am getting rainout with no water in the humidifier of my Dreamstation and the humidification turned off, does it make sense to use the heated tube, or should that be off too? I understand the purpose of the heated tube when the air entering the machine is being warmed and humidified, the heated tube prevents that water from condensing out as it would when it comes in contact with the cooler tube. But since I am still getting rainout with no humidification, the moisture must be present in the room air. What concerns me is the heated tube might be heating that air up, then when it reaches the last 18inches of unheated tube to my mask, it could cool and condense out there.
Secondly, I notice most people find rainout inconvenient because they have to empty the water out the tube and then continue therapy. I find that once the tube has become wet, even after emptying out the water I feel starved when I try to start therapy again, like the air can't travel as effectively in the moist tubing. Is that just psychological or something? I don't notice anyone else with that issue, but it's very consistent with me and means once I have rainout at night I have to try and sleep without the CPAP machine, which is a bad night for me and everyone around me!
Backstory is I've been using CPAP with great success for around 8 years now. I live in a cool climate in Australia and during winter when it has been raining and the nights are cold (minimum is around 1 degree C or 34 F ) I get rainout. I have tried all of the following without success:
- Stopping humidification altogether (I am definitely not having problems with dry air)
- Machine on the floor, tubing hung over the bedhead
- Covering around the tube
- Tube under the bed covers
- Short tube direct to machine without humidifier
Even with the machine lowered I still get rainout, which suggests to me it is occurring at the mask end of the tube.
We keep the bedroom very cold in winter (probably colder than people in similar climates in the US or Europe would keep it, Australian building standards don't have strong requirements for insulation) and we have had massive rainfall recently. I've come to accept that the humidity and ambient temperature of the room must be the root cause. I'm trying a dehumidifier tonight which will also raise the temperature a little, and I have high hopes.
But even if that works the question of whether tube heating is useful without humidification is still relevant to getting the best results I think.
Sorry for the long essay, I've seen rainout discussed endlessly but always in the context of balancing humidification with tube heating, so I'm hoping this might start a useful discussion.