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Cpap induced hypothermia?

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truckerdad57 +1 point · almost 8 years ago Original Poster

When using cpap (or bipap) in cold ambient air conditions (below 40 deg f) have others experienced waking up with Uncontrollable shivering (stage 2 hypothermia)?

The larger than normal quantity of cold air into the airway overwhelming the body's efforts to stay warm. As specially designed pap are used in cold water immersion hypothermia cases for re warming it makes sense to me.

I've had it and it scared the poop out of me. I work with truck drivers who use cpap often in unheated semi truck sleeper berths and regularly get reports of this.

I can't find any research on the topic. The cpap machine manufacturers just refer to the technical specifications for the machine.

Could this be a potential research question?

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MakeSleepAPriority +0 points · almost 8 years ago

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.

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TheCentralScrutiniser +0 points · over 4 years ago

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.

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sleeptech +0 points · over 4 years ago Sleep Enthusiast

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.

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