Question of the Day:
Over the weekend I was in a discussion about hypothermia. We were discussing the "burrito wrap" and while wrapping the patient/victim in a Sleeping bag "burrito"; if a "thick" emergency blanket were available, should you place the em-blanket immediately next to the person or could/should it be placed on the outside of the sleeping bags as a sort of bivy?

The agreed upon theory that came up was the emergency blanket would act as a Vapor Blanket: but the "issue" was, being a VP, would the blanket accelerate or impede recovery if the VP was placed next to the skin?
Part of the discussion was, the blanket as a VP, could/would make the body, as it was heating up, misread the retained vapor and inadvertently "turns down" the heat production (similar to what the body does in a normal situation when the skins feels warm moisture). Or would it speed up recovery if paced next to the skin?

Which solution is better?

A. Next to skin

B. Bivy style

C. Don't use the emergency Blanket

D. None of the above

Maybe outside to reduce breeze.

Perspiration is not an issue when suffering from hypothermia, so the VB concept does not contribute.

I could be wrong though.

If by "thick emergency blanket" you mean the scrimmed mylar emergency blanket, I would say that the best use in this situation would be to use it as a reflector to a fire built next to the victim. The lightweight mylar sheet works just as well for this as the "thick" one (which has just about 0 insulative value).

YMMV.

Steven, I think all parties would agree the perspiration might not be an issue in the moderate to severe cases; until the body starts warming up and then it could be an issue- that is what the question is all about. Can the VP at some point lessen the recovery?

Stephen, no not one of those cheesy thin Mylar sheets, it is a thick blanket like the thicknesses of 2 or more layers of a blue tarps with a Mylar coating on one side.
Far more insulating value than the cheap Mylar sheets but nothing like a sleeping bag or regular blanket or even a thin fleece blanket.

Edited by bestbuilder on 12/03/2012 14:07:06 MST.

if your patient is now sweating ... i dont think they are hypothermic anymore ;)

I don't know whether putting the mylar radiant/vapor barrier outside or inside a sleeping bag would be best. I suspect the conditions would influence that decision. If the hypothermic person is wet, it might be better to put the mylar blanket inside the sleeping bag to protect the insulation from becoming damp. On the other hand, if the sleeping bag has a very light and breathable shell fabric and it's very windy, it might be better to put the mylar on the outside.

In any case, I think there is one important detail that is often overlooked when people use radiant barriers (like space blankets, etc.). The aluminized surface has not only a high reflectivity to IR wavelengths emitted by a person (in the neighborhood of 10 microns), but also a low emissivity. If the mylar goes inside the sleeping bag, near the skin, the aluminized side of the blanket should face OUT. In this case the blanket itself is relatively warm and it's job is to reduce IR emission. If it were turned around, aluminized surface facing in, the blanket itself would be just as warm and IR emission from the non-aluminized surface would be much greater. IR emissivity of most plastics (including mylar) is nearly 1. Putting a radiant barrier against your skin with the aluminum surface facing you reduces evaporative heat loss but not emission of radiant heat. It would be about the same as one layer of clear cellophane (the aluminum surface does nothing for you in this case).

If the mylar blanket goes outside the sleeping bag, the aluminized surface should face IN. In this case, in contrast to the first example, the mylar blanket is cold. Its job in this case is to reflect radiant heat emitted by the person. If it were turned around, aluminum side out, the blanket would still be cold, so very little would be achieved by the low emissivity of the outward-facing aluminum surface, and the inner surface, facing the person, would have a much higher IR absorbance.

These guidelines hold for use of radiant barriers in any situation, emergency or no. Radiant barriers that are aluminized on both sides are ideal because they work in almost any configuration.

Edited by ckrusor on 12/03/2012 14:58:08 MST.

Same discussion at portlandhiker.org with no definitive conclusions

I think that if you had the alumized layer on the outside, then you would have no radiant heat loss which is maybe 25% of your heat loss. http://en.wikipedia.org/wiki/Thermal_radiation

If you have aluminum layers inside, then you get some benefit but not as much - there is radiative heat transfer happening inside insulation

All the emergency blanket manufacturers have pictures with the shiny side facing in and the colored side facing out. Color at visible wavelengths is different than reflection at IR wavelength (emissitivity). If the colored side has less emisitivty, then it would be better facing in and shiny side facing out.

A lot of people talking about the shiny saide reflecting heat back to you, but I think it's more like you want the shiny side out so you don't emit so much IR.

Well really YOU spooning with the victim, wrapped in the E-blanket, with the insulation over you both.

But take yourself out of the equation if it is another big ugly dude I suppose... ;-)

The only reason to use the insulation first would be in a very stiff breeze in my opinion. You don't want the heat blowing away.

As mentioned, the best way is to use another person's body heat for the rewarming phase. BUT given your question, I might say that using the e-blanket next to skin first with the sleeping bag over top might be faster initially. It can take a bit of time to warm-up a sleeping bag. Then, once the sleeping bag has warmed-up, I'd remove the e-blanket and put it on the outside to reduce the clammy VBL feeling.

The fastest way to warm someone up is to spoon inside a bag (or two), on a good pad, inside a tent. If you've got a third person, fire up the stove and start making hot water bottles. Hell, get a three-man spoon going...

Provided I had access to sleeping bags, jackets, shelters, etc., I wouldn't bother with space blankets at all.

If spooning a naked or half-naked partner in a real emergency is something someone wouldn't consider, then I don't think they should be a partner.

Spooning wasn't discussed in the original question, but is addressed below.

Colin and Jerry,
What I hear you saying is that the aluminized surface should be facing out if next to the skin; almost like it is reflecting the colder air/wind outside away from the body. If not please explain.

Raymond,
I even have trouble getting my wife to spoon when I'm warm and healthy; I guess I'm doomed if I every get in a bad situation (nobody will want to).

Spooning- I am of the opinion that "spooning" being the right thing to do for a Hypothermic person is a myth- developed by a male co-ed to entice an uninformed victim into a compromising situation.
Spooning puts the rescuer into a situation where his/her health could suffer. It could cause the rescuer to become a liability, never something you want in a rescue situation.

Edited by bestbuilder on 12/03/2012 18:02:01 MST.

The aluminized surface should be on the outer layer, facing out, so you emit less radiation

Or, less effective, anywhere inside

Or, maybe it's even better to suspend above you - http://en.wikipedia.org/wiki/Multi-layer_insulation

or, if you have a fire, it's probably better behind you refecting radiation from fire

I think it would warm you up more to be in a bag with hypothermic person, because they would be warmer than ambient. In bag with hyperthermic person is no danger to you. You can wear a base layer and you don't have to cuddle to get benefit.

> opinion that "spooning" being the right thing to do for a Hypothermic person is a myth
> Spooning puts the rescuer into a situation where his/her health could suffer.
No worries, to each his own.

But you can be very sure that if it is a cold night, my wife and I sleep 'very close together'. And we can put one quilt over the other when we are that close. Benefits:
* Heat loss from 2 sides rather than 3 sides
* Body temperature 'hot water bottle' on the 3rd side
* Double the amount of down insulation.

> entice an uninformed victim into a compromising situation.
When it is -10 C outside???? You jest!

Cheers

Back in 08 I recall hearing in Wilderness First Aid that spooning was no longer recommended. I believe there were two reasons give but my notes aren't handy so I could be wrong
1. You don't want to create a second victim by getting another person in a sleeping bag with a cold and wet victim.
2. At some stages of hypothermia an extra body may not be that helpful.

If no one else comes up with more complete answers I'll try to get more info tomorrow but I gotta run soon.

I take a short (16 hour) "wilderness first aid" refresher course at least once every three years (BSA rules for backcountry outings) and also occasionally attend winter camping lectures by NOLS and Outward Bound staff. Not only has "spooning as hypothermia first aid" not been taught during the 21st century, it has been discouraged.

Don't go and ruin it for everyone.



Just sayin'

If someone is hypothermic but alive, their skin temperature must be above 80 degrees F? Maybe 70 F?

If you put them in a sleeping bag, you would want to take all their wet clothes off.

If you got in with them, the fact that they're 70 F or 80 F would be no danger to you. Especially if you were both wearing some clothes.

I can see how organizations might not want to recommend because they're afraid of lawsuits.

My 1960 "Freedom of the Hills" suggests warming someone up by lieng next to them wrapped in a tarp or whatever.

a hawt nalgene wrapped in a fleece works better ....

like i said if they start to sweat, they arent hypothermic anymore ... so either way will work

of course if shes (or he depending on yr tastes) is young, hawt and willing ... spooning is ALWAYS an acceptable method in that case ;)

Maybe hypothermia treatment should be practiced ahead of time to make sure it's done correctly

Maybe hypothermia treatment should be practiced ahead of time to make sure it's done correctly

if shes hawt i volunteer to demonstrate the spooning technique ;)