Half a croissant, on a plate, with a sign in front of it saying '50c'
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Personal blood temperature conditioner

Inspired by "Personal Blood Cooler" idea (which didn't go far enough)
  [vote for,

Tap your artery and divert your blood flow through this external pack (solar or battery powered). A dial will regulate your blood temperature to either hot or cold. In 60 C in the desert simply turn the dial all the way to "cold" and feel instant relief from the scorching heat. In -60 C on the north pole, fell free to take off your jacket and crank up the blood temperature to hot - you won't notice a thing.

Even in moderate climates, you will save on heating bills and you'll never complain about someone making the room too hot or cold for your comfort - each person will have their personal unit and will set their own comfortable temperature.

ixnaum, Aug 04 2010

(?) Cutaneous thermoregulation http://www.mayoclin...ntent/78/5/603.long
[mouseposture, Aug 06 2010]

Warming or Cooling Core Temperature From The Inside Out http://medgadget.co...rt_cooling_g_1.html
I just watched a teevee show where this was hailed as an invention of the Defense Advanced Research Projects Agency (DARPA) [Grogster, Aug 07 2010]

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       Welll.....the problem with this idea is that it taps into an artery (and presumably a biggie, if it's to have much effect).   

       Your arterial blood is at a pretty constant temperature anyway, unless you're in real difficulty. So trying to adjust its temperature would be either pointless or dangerous.
MaxwellBuchanan, Aug 04 2010

       Dangerous? very (maybe not so much with more research into how to do this safely). Pointless? no. Since blood circulates through the entire body it has the potential to act as a coolant or heating fluid. I believe it would be quite effective.
ixnaum, Aug 05 2010

       Excellent! Now if I can only figure out how to float around the room, I'll feel like the Baron in the movie "Dune" (only with fewer complexion problems). Bun! [+]
Grogster, Aug 05 2010

       //Since blood circulates through the entire body it has the potential to act as a coolant or heating fluid.// Not "potential." It already works this way, with skin as the heat exchanger.   

       [MB] dropping the temperature of arterial blood is a pretty commonplace occurrence: happens when the arterial blood enters the capillaries. I'd rephrase your criticism as "Altering core [as opposed to peripheral] body temperature would be dangerous." Nonetheless, it's occasionally done, typically by means of gastric lavage, though ventilation with warmed air, or as an incidental effect of laparotomy.   

       All of those methods work better than this idea, but none of them *look* as good. Extracorporeal circulation is a well-developed technology, so this should be feasible. Probably could be made portable, but if not, portable intraaortic baloon pumps exist, and could presumably be used to heat or cool cool arterial blood in situ.   

       I don't think this method would actually make people comfortable. I think that: in hot weather, it would make you shiver violently and feel horribly cold, whereas, in cold weather, you might *feel* OK, but you'd still need warm clothing to avoid frostbite.
mouseposture, Aug 05 2010

       //I don't think this method would actually make people comfortable.   

       We won't know until we try (not me). Also why would you "shiver violently?" Maybe if you adjusted your temperature wrong .... but just crank it back up a little until you are comfortable.   

       I was thinking about the frostbite problem too, but I decided that it would not be a problem either ..   

       from wikipedia: "At or below 0 °C (32 °F), blood vessels close to the skin start to constrict. The same response may also be a result of exposure to high winds. This constriction helps to preserve core body temperature. In extreme cold, or when the body is exposed to cold for long periods, this protective strategy can reduce blood flow in some areas of the body to dangerously low levels. This lack of blood leads to the eventual freezing and death of skin tissue in the affected areas."   

       If core body temperature is normal with no signs of dropping, the body will have no reason to use this protective strategy of restricting blood flow. If blood flow is not restricted, there is no worry of frostbite. I admit I may be wrong about this, because the wind may be the main trigger for the constriction (not temperature). In that case, just go out dressed in nothing but thin wind proof jacket and you'll be fine against frostbite (even if it's -60C)
ixnaum, Aug 05 2010

       //If core body temperature is normal with no signs of dropping, the body will have no reason to use this protective strategy of restricting blood flow.//   

       I am pretty sure that the constriction of peridermal blood vessels does not happen in response to changes in core temperature, but in response to skin temperature.
MaxwellBuchanan, Aug 05 2010

       anno extensively edited as the original included factually incorrect material and faulty reasoning. The following is better, I hope.   

       re: shivering: I think I may have been talking through my hat.   

       Re: frostbite:" What's the rate of bloodflow through your fingertips? What's the rate of heat loss at an ambient temp of, say - 50C, if the fingertips are, say, 0C? What's the specific heat of blood? Now, how hot would the blood flowing through the fingertips have to be, to keep them above freezing? I don't know any of these numbers: I merely intuit that the necessary blood temperature would be dangerously high for every other part of the body.   

       Pace [MB] it appears (<link>) that constriction of peridermal blood vessels DOES happen in response to changes in core temperature. However, for frostbite, it's more important that "Local cooling of the skin [also] produces a powerful localized vasoconstriction that can decrease skin blood flow essentially to zero." So there's a positive feedback effect which makes it even harder to prevent frostbite by heating blood.   

       There's a way to test it, though. This is best done in somewhere with 1) cold winters and 2) high rates of alcoholism. First, find a volunteer with, say, pneumonia, or anything that'll cause a high fever. Next, administer enough vodka to cause A) peripheral vasodilation and B) unconsciousness. Finally, recover your research subject from the snowbank where he or she has passed out. IMPORTANT: do this prior to the onset of hypothermia. (A rectal thermometer will help with monitoring core body temperature. That's why unconsciousness is essential.) I hypothesize that frostbite will occur.
mouseposture, Aug 06 2010

Grogster, Aug 07 2010


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