Great idea TruckerDad. I'm thinking the outcomes research question would be something like "How does the health of truckers using CPAP without heated humidity in cold sleeping environments differ from those who don't ?" There may be both negative and positive effects. What we need is a lot of truckers in the network to have a large number of people respond to outcomes research surveys. So the immediate question is how can we get lots of truckers signed up? Any ideas? The great thing about MyApnea.org is that it's not just a place to talk. The talk can be turned into real research with real impact for everyone. The larger the number of members completing surveys, the more impact the outcomes have which can result in more diagnostic and treatment changes for sleep apnea and sleep.
I'm a 55 year old male who works in anaesthesia and especially in cardiothorasics, and have much experience in both inducing and reversing hypothermia.
I started using CPAP machine therapy for my own sleep apnoea in the early winter months of 2017 (January/February) and frequently awoke shivering, even though the ambient temperature was not so low as previously to have caused shivering. At that time I was using the CPAP without warmed and moistened air and kept the machine on the floor, where I did observe it was drawing in much colder air than would be the case higher up.
I moved the CPAP machine such that it was at the same level as my heart. However, the shivering persisted, though not to as great an extent as previously so. My specialist had never heard of this issue.
I then started using the water tank and warming the air and all was fine throughout the summer months. However, despite using the warming unit and keeping the machine at heart level, I have recently started shivering again since the cold winter is drawing in.
On each occasion I ascertained that it was not attributable to hypoglycaemia. My only conclusion, without extended formal research, is that it is down to the CPAP machine forcing in larger volumes of relatively cold air than my body has been accustomed to.
I know from my readings of anecdotes on this forum and elsewhere, that I'm not alone in this experience.
I can tell you that from a mechanical point of view, and backed up by mountains of research, CPAP does not increase the amount of air you breathe. It opens you airway, but the amount of air moving in and out of your lungs (your tidal volume) is unchanged and is purely determined by the work of your muscles. I know this sounds counter intuitive, but CPAP is a CONSTANT pressure system. There is an in flow and an out flow, keeping the pressure in your airway constant. The amount of air that moves in and out of your lungs is determined by a CHANGE in pressure caused when your muscles work to either expand or contract your lungs. This is not changed by CPAP. Think of it like this: when you jump you change your elevation (if only a little bit). Now whether you stand on the ground floor of a building and jump, or on the top floor of a building (starting at a higher elevation) and jump, the height you can jump is the same. You may start and finish at a higher or lower level, but the change in your elevation due to the jump is the same.
That does not mean that cold air from CPAP can't make you feel cold, it just doesn't do it because you are breathing more air. There may well be some aspect of CPAP use that causes hypothermia in some patients, but I seriously doubt that it simply because of the amount of cold air they are breathing. Largely because without CPAP they would be breathing the same amount of air at the same temperature as they do with it. Also, a good humidifier can make the air warmer than it is in the room around you. It is more likely that some internal biological imbalance is causing the hypothermia. I'm afraid I haven't heard anything about this before. But I do know that CPAP only removes an obstruction from your airway. It does not change the amount of air you lungs push in and out.
I'm hot natured and sleep under a sheet only, No blankets. I also use CPAP with a nasal mask while breathing air at room temp only with no heat or water. I keep the temperature at around 66 degrees F while sleeping and have experienced what I believe is hypothermia 3 times now with the last incident being worst by far. I woke up shaking extremely cold and foggy minded. I drove to work in what seemed like a dream. I kept running off the road shoulder but made it there. I opened the door stepped out and melted to the ground. Next thing I'm in the hospital for 8 days while they tried to figure out what happened to me. I told them that it was hypothemia but they didn't believe it. MRI, Brain scan, blood work all was normal except that now I have Atrial Fibrillation. I believe what sleeptech said above is correct but I also know what happened to me.
I think I know why it happened. I seem to always move my mask around until i get a small amount of leakage. I can breath easier when there is a little moving air it seems. I believe that this leakage, i.e. the moving air, causing evaporation in my nasal passages further reduces the air temperature I take in. After enough time my body core temp drops to the point of hypothermia. It's a combo of things, low metabolism, cold house, evaporation cooling due to leaking mask, a sheet as the only cover. etc.
Needless to say I have taken steps to prevent this from happening again. It was so scary.
There is no need to make your mask leak to get more circulation. Every mask has a controlled vent to maintain a ventilation flow. It lets out air all the time no matter whether you are breathing in or out. It is to keep CO2 from building up in the mask. The larger the mask the larger the designed vent flow.
If you have issues with cooling off while using a CPAP it would make a lot of sense to use both a humidifier and a heated hose. The humidifier heats up the water used, and the heated hose controls the final temperature to what you want. The normal setpoint is 27 deg. C or 81 deg F. But, it is adjustable.