On a recent post the practice of using Povidone iodine and/or Betadine on an open wound was discussed and eventually debunked by several knowledgable board members. This got me to thinking about many of the other "tried and true" survival techniques we have all heard of or used that are now know to be useless at best and often border on being downright dangerous.

So at the risk of offending some, but hopefully educating others, I offer a few of my own recently held (false), beliefs:

1. If lost in the desert, the mashed pulp of many cacti will provide life sustaining fluid. Fact: Cacti contain a highly acidic solution that will induce vomiting if drunk.

2. Moss only grows on the North side of trees. Fact: Moss will grow anywhere there are proper conditions.

3. Drinking hot tea or coffee will keep you warmer than drinking cold soda or juice. Fact: It's the calorie content, not the heat of the beverage that produces body heat.

Now to let go of the most dearly held misconception yet...bear with me folks, this is gonna hurt:

4. "If your feet are cold, put on a hat." Fact: We do not lose more heat from our heads than from any other portion of the body with the same surface area.

Okay, I had my Oprah moment and bared my soul, let me hear some of your true confessions.

I'm not sure i can agrea.



It depends on the cactus, some can provide a drink. You just have to find the right one (that is, if they grow there..).



Well i'm not sure i agrea. I don't have scientific numbers. but isn't it obvious that pouring warm stuff inside (warmer than you body temperature, but not to much to burn you), will raise the core temperature?



The bloodvessels will narrow on you limbs, when your cold. They DON'T norrow down, on you neck and head (brain don't work well if they did)

My favorite myths--

Carrying 5 custom knives is better than carrying a well thought out sak. And six knives? You don't need any training....


Thant a "worst case scenario" is anything close as to what the 'worst case" actually is...

If I edc enough gear, I can prepare for anything

I can outrun/ outclimb that bear

Even though I'm 40 and drive a desk all day, I can immediately go out and hike five hard miles with a 13 kg pack.

A little tiny fishing kit is more useful than a little tiny sewing kit.

In regards to your comment: "I can outrun/ outclimb that bear"

I'm reminded of the punchline to the old joke, "I don't have to outrun that bear, I only have to outrun you."

I think you are referring to:
http://wildernessmedicinenewsletter.wordpress.com/2006/10/27/frozen-mythbusters-myth-2/

Let's say there's nothing special about your head - fine. So if you're feet are cold, don't bother putting on a hat? According to the article, your head is 10% of your body's surface area and therefore responsible for 10% of the heat loss. It is also the only part of the body I've seen people routinely neglect to cover in the coldest of weather.

If your feet are cold and every other part of your body is covered, put on a hat. Trust me.

"...Fact: We do not lose more heat from our heads than from any other portion of the body with the same surface area..."

Could you cite your source of this "fact" for us please? Everything I have read says the opposite. Here is just one source, a google search, or most emergency care manuals, will turn up a lot more...

Oh, and here’s my myth: You can’t make a fire with wet wood.
Corollary: Split large chunks of wet wood to get to the dry wood inside.

With the right tinder, I can almost always make a fire no matter how wet everything else is. Batoning is a waste of energy, and a chance to get hurt or break your knife.

I have not done any research about "covering your head when your feet are cold cover your head", but there is thr hard fact that Heat Rises, no exception. So probably the heat in your body will tend to rise to the highest point which is the head, and from there it will keep on going up. The only thing I can confirm is that any time I put on a hat I feel warmer all over.

1. Had one occasion many years ago where I resorted to getting water from a barrel cactus. (We had plenty of water in the Jeep, but that didn't help when we lost the Jeep. Thus the orienteering courses.) It didn't make me throw up, but it did taste really, really bad.

If I had to do it over again, I would have made a solar still and thrown chunks of cactus into it.

2. Never had to rely on this one, but I will bet that in most cases the north side of the tree is the "proper" condition since it gets the least direct sun. But you are right. In dense forests, I have seen places where moss is everywhere.

3. Another one I have no experience with. I generally don't drink cold drinks in the cold. I read somewhere that the body is pretty good at adjusting the temperature of just about any liquid to body temp by the time it reaches the stomach.

4. I have a good experiment for this one. Get naked in a blizzard as see what falls off first. I suppose all surface areas of the body lose heat equally, but the body begins shutting off blood to the "less essential" parts. Also, some parts are just harder to supply blood to (farther from the heart, fewer and smaller blood vessels etc). That's probably why most frostbite injuries occur to toes, fingers first, then noses, ears.

OBG,
You might not have had a chance to check out thseng's link before posting, so here it is again: http://wildernessmedicinenewsletter.wordpress.com/2006/10/26/introduction-to-frozen-mythbusters/

This covers both the fact questioned by PC2K about hot liquids and the heat loss from our head in addition to lots of other good info. I'm not saying if cold you shouldn't wear a hat, I was always under the mistaken impression (as the article states most people believe), that we lose 70% of our body heat from our head.

The cacti info can be found here: http://www.sbs.utexas.edu/mauseth/ResearchOnCacti/introduction.htm

Look under, "poisons".

NightHiker,
The funny thing is, if someone else had posted this info not too long ago, I too would have disagreed. This information comes from a credible source (Wilderness Medicine Newsletter), and seems to be up to date (2/14/07).


"... The idea that we lose heat faster through our scalp, because of the constant blood supply to the brain, is simply a myth. (One that I personally have believed for many years.)"

Dr. Gordon Giesbrecht, PHD

"On a recent post the practice of using Povidone iodine and/or Betadine on an open wound was discussed and eventually debunked by several knowledgable board members."

At the risk of being somewhat blunt - BS!

Povidone Iodine is one of the most widely used antiseptics in the world. "IF" it slowed cell growth x% so what! It kills ring worm, fungus, sprep and every other commonly known topical organism that causes infection.

I read that article you linked to. And I'm pretty sure that their claims about ingesting cold vs hot fluid to combat hypothermia are going to be debate for a VERY long time, by the majority of people who live were there IS snow. I'm in the same area as the conference they referenced and having lived here most of my life and liking winter, I think they are lacking on that count.

Hot fluids are passive calories. If you doubt that, here is a simple experiment. Take a cold shower. Take your oral temperature. Quickly drink a liter of hot water(chug it if you can). Take your temperature, and again in ten minutes. If taken orally, you'll get a spike for obvious reasons immediately afterwards, but your temperature will climb a few degrees.

It isn't long term, it's a short term effect. And it's probably mostly morale, aka mindset, that is effected. You FEEL warmer, and unlike alcohol, it isn't a trick. I'll stick with warm fluids in winter and cool in summer, thank you.

the hot water thing I"m calling shenanigans on. Your body, from what I remember, needs to heat anything it digests to an accepateble temperature. To do so requires calories. Calories are fuel. Fuel keeps you warm. you"d burn more calories heating something in your stomach, than you would if the temp needs to drop.
Now, I"m not saying I"m right, merely passing on what I"ve learned.

From a fast skimming of this article, it seems that if you are shivering (pretty common in really cold weather if not properly clothed), you can lose over 55% of your body heat from the head. And if not exercising, but have an elevated heart rate due to something like impending panic ("Oh my God, I'm lost in the woods!"), you can lose about 50% of your body heat, again through the noggin. Makes a hat sound good to me...

Alcohol will kill all those things as well but that doesn't make it appropriate to put in a wound.
PI is mostly used to disinfect skin BEFORE surgery not in wounds.
Using diluted PI to irrigate a wound is mainly to sterilize the water not your wound.

Medicine is not static it evolves as the knowledge expands; many former practices are no longer considered appropriate.

The medical "practice" for cleaning and disinfecting wounds has evolved over the years while apparently your medical training has not.

The USCG teaches that one can lose up to 40% of your body heat through your exposed head. This does not mean that you can only lose 10% here and 25% there. It means that if the rest of you are properly clothed except for your head, you can still lose that 40% via your head.

That's why I said hot water. It's already at or above body temperature. I call it "free calories" because you don't need to use calories to heat the fluid.

Then again, I also call my black winter jacket "free calories" because if I go out in the sun it absorbs heat that way rather than having to only rely on body heat to warm the air spaces.

Or are you backing me and I'm just too groggy on cold meds to realise it? :P

Yep. You are transfering the calorie content of the fuel into your body in the form of heat. All other things being equal, a hot cup of cocoa is going to give you more energy than the same cup after it has cooled.

OBG,
Just to clarify, I believe the article says that your head and neck amount to 7% of your bodies surface area, if you are shivering, that 7% sheds 55% more heat raising the actual heat loss from the scalp to about 10% of total body surface area which is the figure the article cites. Then to really confuse the issue, if you start sweating from the shivering, it drops back down to 7%. And yes, a hat still sounds good to me also...

Ironraven & Mr. Badger,

If you look at my original post, the comparison is between hot coffee/tea & cold soda/juice, the inference being that soda/juice is full of sugar (calories), and coffee/tea is not.

The heat in this case is the energy provided by the calories, not the actual temperature of the liquid. I believe the example given in the article states that the human body is made up of 15 liters of water, if you dump one liter of water heated to the normal temp of coffee or tea, it will only raise the temp of the bodies fluid by 3/10 of one degree.

I fully agree that all things being equal if the choice is b/t a hot beverage or a cold one, in cold weather the hot one always wins out.

That makes more sence then. I just skimmed the site that was sourced without reading it in depth.

Sorry, not true.

As a general rule, warmer fluids and gasses rise amongst cooler fluids and gasses, because they expand and become less dense (and therefore lighter) when heated - convection. I doubt that convection is that big a factor in how heat flows around the human body, given all the pumping, churning and general mixing of fluids going on.

I'd imagine that conduction is the dominant factor and (like radiation), it doesn't care which way "up" is.

There are exceptions to warmer fluids rising via convection, too. Between about 4 deg C and freezing water starts to expand again as it cools (and expands a whole lot more on freezing). This means that you can have cool water rising through warmer water via convection.

But, hats are good :-)

eeph

Ironraven, I was backing you . I too wear dark colors in winter, for the same reasons.
eeph, maybe standing still, not much. But, and I'm sure you seen it, looking at someone who has recently exercised, through a thermal lens, you can clearly see the excess heat rising off the body. Moreso in the head area, if thats its only vent out (due to clothing).
So, I think that convection WILL play a part in this, given the above situation. The human body will do what it can to release excess energy in the form of heat. HEat is transferred to the blood vessels closest to the surface of the skin. As there are far more of these on the head, than any other body part, due to the fact that the brain is selfish & will attempt to regulate its temp the best it can, it only stands to reason that we lose more heat through the head than other parts. Also, the head has little fat on it (for most of us ), and thus requires thermoregulation through convection.
Wow, ok, my brain now hurts. Alot.

While teh 70% figure is a little (or a lot) high, I will continue to cover my head when in extreme (hot or cold) temps. It may only be 9% or my skin surface, but it's still 9%. A wool blend beanie is much better than none.

Sorry, my brain is full of snot, I'm not thinking so well.

I actually hadn't even thought about the need to cool warm/hot beverages. If the core temp goes up, the body will send more blood to the extremities, improving your dexterity. Makes sense to me.

Consider the surface area of your head is the same as your upper back or chest (remember the rule of 9's). You wouldn't go out in 20 degree weather with your upper back exposed, would you?

Let me get this straight. I'm standing on the shore, my J3 Cub nosedown in an Alaskan lake.I managed to pull our survival kit out. My flight partner produces a quart of Florida Sunshine OJ and proceeds to drink. Meanwhile, to test this theory I am going to ingest a quart of Tea. And being irish I am from the highest per capita teadrinkers in the world ( 6 cups daily on average.)Now, has anyone considered any other factors in this test? Anyone? To drink Tea or Coffee I am going to BOIL water. I am going to have a FIRE. Bounces a valencia off the monitors of anyone who needs further explanation. I think these guys came up with this while standing hatless.

Some cacti will make you vomit if you eat the pulp or moisture it contains. Others will give you diarrhea. But getting past the darn spines will drive you crazy, anyway.

Moss grows where there is moisture and shade. A cluster of trees provides a lot of shade, and low branches provide shade, so moss grows all around the trunk. A single tree with limbs high enough to expose the trunk to the sun will usually have moss on it's north side. But not all growth on a trunk is really moss. It's good to know your mosses.

Sure, it's the calories that heat the stove, but if you're verging on hypothermia, do you really want Hagen Das? And I thought the doctor's example of dumping a quart (or whatever) of hot water into a larger amount of cold water was kind of stupid. You're pouring a cup or two of hot water into a bag the size of your fist (or two). It's going to stay there for a bit, then gradually flow into your small intestine. And it's going to cool down more slowly than his example.


If your feet or hands or other body part is cold, cover up whatever part is exposed. It doesn't matter how much body heat is lost through the head... in a cold situation, ANY is too much.

Sue

If I can manage to drag my SS thermos out of that Cub, we can sip on my hot coffee while the fire is heating the water for your tea. But I may never fly with you again...

Let's keep some other important facts in mind. It's not just a matter of heat loss from the "head area." A key element in advancing hypothermia is the cardiac and pulmonary functions affected. It has been passed on to me that some key controlling organs (glands) for these functions are located in the head/neck area and must be attended to in treating hypothermia. Thus, I have always taught that in treating advancing hypothermia special attention must be paid to this area which means three things:

- cover head and neck (this is why a gaiter feels so good!)
- drink warm (not hot) liquids to warm the throat area.

I would also keep in mind that much of "conventional" wisdom, while not the "entirely sufficient" explanation has some value hidden in it, i.e. if it can't hurt, why not do it? So, check that it doesn't hurt - then do it, too. Like put on a hat!

*catches the valencia* Thanks for breakfast.

I was talking about a controlled condition experiment, say in your house. Fire is going to help, but if you have the thermos that OBG mentioned, it's going to help more than your buddy's cold, slushy OJ. Of course, tea hot OJ is nice to, once you have the fire going.

Chris, got any more? *waves the empty orange peel with a grin*

All I know is that when I shaved my head or keep it really close cropped, any type of hat regulates body temperature really well. Anything from a cotton cap to a wool watch cap. Think about it, when the body starts to cool down it restricts blood flow to your hands and feet and other extremities. It puts more blood flow to the head. If your feet are cold put on a hat works because the heat loose through your head is now slowed with insulation, more heat is retained, so more blood can now be reapplied to the extremities. And yes, you can loose alot of heat through your head, but it is amazing what a 1/4 inch of hair will do to slow that transfer down.

"...it is amazing what a 1/4 inch of hair will do..."

Go ahead, rub it in...

Thermoregulation is not simply a matter of body surface area (BSA); it also has to do with vascularization of the area. For example, in the reverse case of hypothermia, where hyperthermia is the problem, it is not uncommon to place cold packs in the groin area and under the armpits and sometimes round the neck region. Why? Because these areas contain major blood vessels, yet represents probably less then 2% of BSA. Likewise, the head, while comprising approximately 9-10% of BSA does have an increase in vascularization over other parts of the body. In addition, as noted by others, insulation by body fat has an effect on heat loss/retention in any particular area of the body and the head has little body fat for insulation.

If I remember correctly, in the impromptu study, thermal sensors were placed on various parts of the body (and presumably in the rectum to monitor core temperature) then used to examine the surface skin temperature of various parts of the body/core. This was then used to “debunk” the myth to “wear a hat if your feet are cold” paradigm. What they should have used is a thermal imager looking at heat loss/retention of the whole body under various conditions.

One thing to keep in mind is it that infants and young children have a larger BSA of the head then teens and adults. Therefore, even under their theory (with which I do not agree) children would be at greater risk for heat loss through their heads.

Pete

I agree. I've got a full head of hair, but when it gets cold, a lightweight Wigwam Thermolite Cap makes a big change. I'm already in wool socks and layered around my core, keeping my head warm is simply the next step.

This is another "straw man" argument. You should to drink something that is hot AND full of sugar.

Its like one of those multiple choice survival quizzes:
You're hypothermic - Do you:
A. Build a fire and make a hot cup of coffee.
B. Drink a cold bottle of OJ.
But they don't give you "C. Build a fire and warm up the OJ" or "D. Build a fire and make a hot cup of coffee with lots of sugar."

It is my personal opinion that people who drink tea or coffee without sugar are a little off anyway.

Sue

Don't forget the diuretic effect of tea and coffee. Dehydration is a factor in hypothermia as well

I carry decaf with me too...

I need a math check....

A calorie is defined by "Any of several approximately equal units of heat, each measured as the quantity of heat required to raise the temperature of 1 gram of water by 1°C from a standard initial temperature, especially from 3.98°C, 14.5°C, or 19.5°C, at 1 atmosphere pressure."

1 Liter of water = 1000 grams

From article
"As far as the temperature of the liquid is concerned, it is more comforting to drink a warm liquid in the cold. But, think of the physics. Take an average man, weighing about 170pounds (80kg). Since we are 70% water, that 170pound (80kg) man is 120pounds (56kg) of water or 15 gallons (56liters) of water (one gallon of water weighs 8 pounds). So, if you were to take 1 quart (1 liter) of hot tea water at 110ºF (43.3ºC) and pour it into 15 gallons (56liters) of cool water at 90ºF (32.2ºC), it will raise the temperature from 90ºF (32.2ºC) to 90.3ºF (32.4ºC), not enough to make a clinical difference. But, if instead, you throw into that 170pound (80kg) man, 1 quart (liter) of a fluid containing sugar, now he has fuel to put into the furnace to burn, to get warm, stay warm, shiver, function, survive, and thrive."

In order to raise your temp the same amount (56 liters (56000 grams), 0.2*C) would require you to consume 2,800 calories to do the same thing as drinking the hot tea. Correct?

If calories are life the guy drinking the tea is going to live longer than the guy drinking cold sugar watter.

Not exactly. The 'calories' we use to measure energy in food area actually kilocalories (1000 regular calories). So it only takes one food calorie to raise the temperature of 1 liter of water 1 degree Celsius. Raising 56 liters of water 0.2 degrees would require 11.2 calories of food (assuming the conversion from sugar to body heat were 100% efficient, which it isn't).

I used to teach a course in micro-climatology, and things like wind chill and hypothermia were a small part of it. At several points in the course I would paraphrase from the Monty Python sketch about Dennis Moore:

"Blimey, this redistribution of heat is trickier than I thought."

Another myth that I have heard:

Is that if you are dehyrdrated you would be worse off drinking soda because it has caffiene in it. I've read recently that that is not true. After doing a study they determined the end result after the body has processed the caffiene is you would still get a net 70% (if I remember right) increase in water. Not as good as drinking 100% water, but still better than not drinking it at all...

I read recently that this effect isn't as bad as it once was thought to be. You do lose some of the fluid due to the diurectic effect, but if that's all you've got to drink then drink it.

This isn't the study I read, but is another example:
caffiene research

And you are most worried about warming up the moving fluid, blood, that has nice big pipes that are near the digestive tract. Short of a nozzle and some piping, I can't think of a more effective way of doing that.

You are so right. The people who claim that drinking caffienated beverages is worse than drinking nothing at all are totally off base, and I was glad to see that old adage debunked in a fairly recent National Geographic article. Along the same line, I've often heard that drinking alcoholic beverages are worse than drinking nothing at all. But just put me in Death Valley for 3 days with 3 cases of beer along with the nonalcoholic bloke who drinks nothing at all and see who comes out healthier--and happier. I don't doubt that plain old water is better for hydration purposes, but many 19th century sailors and some of my friends have proved that you can survive for extended periods without drinking it.

The wilderness article states that drinking a liter of warm liquid will raise your core body temp 0.3 degrees. A cold liquid will lower it by the same amount. A very hot liquid may raise your temp even more. This 0.6 to 1.0 degree difference in core temp is very very significant. Why they think this is insignificant is beyond me. It is so important that the joint commision for hospitals is requiring the collection and reporting of data on mild hypothermia postoperatively for surgical patients and extra efforts are being used to prevent even mild hypothermia in the operating room. Even a couple of degrees makes a huge difference in bloods ability to clot in a trauma situation. Also the "fact" is that surface area is not the common denominator for heat loss. Due to differences in radiation, insulation, conduction, convection, blood supply and autoregulation your head loses a lot more heat under almost all circumstances than your fat ass.

If the average regular beer is 5 percent alcohol and has 43 calories per 100 ml, the rest is probably water. So you'd be better off drinking it than not drinking anything. Well, unless you drink so much that you walk off a cliff or something. And the calories would probably help your digestive system absorb the water faster than drinking just plain water.

Beer: The Desert Health Drink

Sue, who can't even get past the smell

I'm glad to see that many of these issues are being discussed and debated. Not that you need me to point it out but everyone's comments are welcome and valid, the problem arises when we confuse "opinion" with "fact". Anyone is welcome to disregard the experts and continue to believe anecdotes or a one time personal experience but If you chose to do so, Isn't it your responsibility to point that out and prevent confusion?

You start with a claim that hospitals are keeping track of hypothermia data for post operative patients and that the .6 degree difference is vitally important, great, if that's the case more power to them, but what does that have to do with the benefits of drinking a calorie laden cold drink over a cup of hot tea in a survival situation? I suppose if your BOB is equipped to handle open heart surgery this may be an issue but I would bet that for the majority of us this isn't the case.

Then you go on to make this statement:



If this is in fact true, I would love to see what you base it on so I can re-evaluate my position, until then I will stick with the experts in this field.

When they say that there is abundant scientific information then "debunk" it with a test that actually measures nothing similar to the realities of the human body, it makes me question their scientific integrity. Hypothermia research is based on thousands of rescues and just as many failed ones, scientific testing on lab animals, and *gags at the thought* Dr Mengele's "research".

These three guys are saying they crunched some numbers and tossed some water in a bath tub and they can change the world. Sorry, science doesn't work that way. They've got some interesting theories, but their experimental methodology seems shoddy and it flies in the face in other laboratory research and massive amounts of real world experiences. If their results can be substantiated by experimental data that results in a treatment regimen that actually produces quantitative and qualitative improvements in the prevention and treatment of cold injuries, great. But until it is, it stinks of bad science and isn't supported by generations of experience. If science worked that way, the team that claimed to have found cold fusion fifteen years ago would have multiple Nobel prizes and the Saudi royal family would be living in a tent.

Alcohol will cause vasodialation of the blood vessels of the skin, and will cause greater loss of body heat, and alcohol can seriously impair your judgment.

I have not been able to find the complete article in the Wilderness Medicine Newsletter, so it is hard to know what the study’s parameters, measurement methodologies and controls were based upon. However, based upon the limited description of the study in the “Myth Buster” Newsletter, I must disagree that the myth has been debunked.

Simply measuring core temperature (what the Myth Buster article states) is not a true indicator of the variations in heat loss/retention from various parts of the body.

It is not uncommon to find the “experts” in the scientific field to disagree in examining the results of the same study, no less so in studies that have the appearance of being scientific or controlled, but in fact are flawed in either design, data collect and/or interpretation.

What this limited “study” would show, if anything would be a theory, not a fact. As the study would have to be repeated by others, the observations reproduced, peer reviewed and then stand the test of time before it would become fact.

Also, even if the commonly stated heat loss from the head (I have read everything from 40% to 70%) is only 10%, that 10% loss can be substantial. Keep in mind it is not only the overall loss of 10%, but the rate as well. The rate of heat loss, likely plays as big, if not a bigger factor in the rapid development of hypothermia.

Pete

Being somewhat of a skeptic myself I'm encouraged to see many of you holding my feet to the fire on this as these issues are potentially matters of life and death, but I ask you to meet the same standard you are holding me to. If my source was an article from the Assistant Sports Editor of The Podunk Times then I would expect to be questioned and doubted, but this is a well established, highly professional group of wilderness medicine experts, if we don't believe these guys, who can we believe? Please don't tell me, "The USCG has always taught...", or "Generations of experience and science have shown..." How about some links to sites and/or comparable experts that show up-to-date research and results? Of course "experts" often disagree, should we then throw out all "expert advice" and go by instinct alone?

You may not like the results, but I've shown you "my" experts and research, I apologize to all the non-poker players, but I'm calling the table, show me what you've got.

If you take caffeine, nicotine and alcohol out of the equation who the wants to survive anyhow?

M

THE CLAIM: You lose most of your body heat through your head.

THE FACTS: "Put on a hat," parents tell their children before sending them outside on bitter winter days. While that might be sound advice, the popular belief behind it -- that most of the body's heat escapes through the head -- is misguided. The amount of heat released by any part of the body depends largely on its surface area, and on a cold day you would lose more heat through an exposed leg or arm than a bare head.

Dr. Daniel I. Sessler, an anesthesiologist and expert on hypothermia at the University of Louisville medical school, said the popular myth stems from military experiments conducted five decades ago.

Here's an interesting link: http://jap.physiology.org/cgi/content/abstract/101/2/669

and another: http://cat.inist.fr/?aModele=afficheN&cpsidt=1690440

And this quote: "both groups showed dips in temperature during surgery and recovery, but there was no significant effect of the hats alone. Conclusions: Our results indicate that the combined use of preoperative reflective hats and jackets, but not hats alone, significantly reduced temperature drop during outpatient surgery. Intraoperative reflective blankets had a small, but not significant, effect on temperature. We conclude that the prevention of intraoperative heat loss is provided by preoperative reflective hats and jackets, is not improved with intraoperative reflective blankets, and is more closely related to the total body surface area covered than which area is covered. "

Can be found here: http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ija/vol6n2/temp.xml

I think thats the idea

I really don't want to get into the argument about the science and methodology of the experiments, but it seems to me that if I dress for cold weather except for my head thats where I'm going to lose the most heat, and putting a hat on will help retain heat keeping my feet and every thing else warmer (relatively) speaking. But then again nothing keeps my feet warm except a nice friendly snow bunny.

I have a question: Does body temperature have an effect on the rate of heat transfer? I think "Yes", and if so, as the body cools does the percentage of heat lost through the head increase? I think "Yes" to that question also.

That last statement assumes the various surface areas have the same temperature. If they do have the same temp, then heat lost per square inch should be the same. But what if the two skin surfaces are not at the same temperature?

My theory is that once your feet are cold, heat lost through your head is already starting to increase as a percentage of skin surface area -- maybe just a little; but as your body starts to shut down it's (non-essential) extremities the primary skin surface with heat to give up is the head.

Just a theory, I'm no scientist and I don't play one on TV (or on the internet).

Now you're talking...

RAS,

One of the articles I linked to above seemed to show that test subjects immersed suddenly in cold water who did not have their heads covered, did in fact show a higher percentage of core temperature drop than those whose heads were covered.

The total heat loss over the bodies surface area didn't change, but the bodies reaction to the sudden cold probably caused the vasoconstriction that changed the core heat loss percentage (I could be misunderstanding the article, I'm not a scientist).

I'm not sure how this could be utilized in a survival situation unless you're willing to lug a Mustang suit around with you!

page 2019 (8 of 18) of

http://www.ms-se.com/pt/pt-core/template-journal/msse/media/1106.pdf

quotes an interesting statement from a study in 1957.

"This means that at –4°C the heat loss from the head may amount to half the total resting heat production of the man."

http://jap.physiology.org/cgi/content/abstract/10/2/235

50% of RESTING heat production.

i think i'll keep my beanie on, thank you very much.

Please, by all means keep your beanies on and I will do the same, but let's not do so out of ignorance. I believe the 1957 study you link to is the same one referred to here:

"Dr. Daniel I. Sessler, an anesthesiologist and expert on hypothermia at the University of Louisville medical school, said the popular myth stems from military experiments conducted five decades ago."

The popular myth being the 50% figure. I'm certain at the time, they were using the best techniques and instruments available such as they were. If you want to base your survival decisions on outdated data from 1957 while ignoring the current 10% figure from todays experts, go right ahead...just don't invite me on your next 2 week backcountry campout (yeah, likes that's gonna happen

"...The rate of heat loss is relatively the same for any exposed part of the body, not simply the head..."

I just guessing here, but I suspect that most of us who buy into the hat thing do so on the assumption that, while outdoors in the cold, the ONLY part of the body that is exposed is the head, and possibly the hands. Most of us are wearing some form of clothing from the ground up, so if you are getting cold anywhere else, cover that exposed part with a hat, and you will feel warmer...

Hey, I buy into the hat thing too, all I'm saying is that it's good to know that when I cover my head, I'm helping to keep in 10% of my bodies heat, not the 70% (or 50%, or 35%, etc.), I had always heard and believed. None of these experts are telling us it's no longer advisable to wear a hat, but isn't it better to know the truth?

If Garmin announced tomorrow that they were terribly sorry but they and all the other GPS manufacturers had been lying for several years, their units are only accurate to 1/4 mile at best, would we stop carrying them? I hope not, if I'm lost I'd rather know where I am to the nearest 1/4 mile than nothing at all, but It sure would be good to know. If ACR's PLB's typical operating life was reduced from 40 hours to 4 hours, would that prevent you from activating it when needed? Of course not, but again it sure would be good to know. 'Nuff said (I hope!).

Some of the information from the Wilderness Medicine site seems rather poorly expressed, IMHO.

Did anyone notice the authors of these articles?

"These myths are explained and debunked by Dr. Murray Hamlet, DMV, Dr. Gordon Giesbrecht, PHD, and Frank Hubbell, DO."

Dr. Murray Hamlet, DMV (apparently, more properly, DVM), is a veterinarian who received his degree from Washington State University.

Dr. Gordon Giesbrecht, Ph.D is a professor at the University of Manitoba in Winnipeg, Manitoba, Canada, where he operates the Laboratory for Exercise and Environmental Medicine.

Frank Hubbell, DO is a Doctor of Osteopathic Medicine, and is the founder of SOLO (Stonehearth Open Learning Opportunities in Conway, NH).

A vet, a teacher and a doctor... why is the vet listed first?

Sue

As for the “myth” about putting on a hat when your feet are cold, I sincerely doubt that it’s so cut-and-dry.

For one, if you’re cold, a large majority of your warm blood will be constricted into your core and head. So, where exactly are you losing most of your heat then? It may be true that you lose heat evenly when your body temperature is normal, but once your body temperature starts dropping, you’ll lose more heat from where the blood concentrates. If your feet are cold, it’s probably because the blood went somewhere else.

Secondly, I’ve seen only a little bit of discussion about hair. If you’re considering surface area to be the most significant factor, your hair increases your head’s surface area dramatically. In calm weather, your hair may be able to create a nice insulating layer. In more harsh weather, where this “myth” actually comes to practical use, the wind will be blowing your hair around so much that it may actually start acting as a heatsink.

Somehow I find more credibility in the various thermal images I’ve seen showing people in cold weather. These images normally show people in winter clothes as a dark colored body with a big, bright spot depicting their head. So, where are they losing the most body heat from then? This “myth” needs to be looked at in the big picture, as applied to people who are in a survival situation and are cold. If the norm for this scenario were to be naked, then maybe the difference in heat loss between your head and the rest of your body wouldn’t be significant. However, being naked is not the norm, and if you’re naked in the cold, you have bigger problems that to grab a hat. The myth simply means, in all its glory, “Don’t forget your hat.”

I am - painfully - trying to understand this thread ...
and starting to wonder ...

"Did I miss something or what ?... Am I supposed to hike buck (sp?) naked (like that guy, doing exactly that in Great Britain... when he is not serving time in jail for exhibition !!! ), with only a hat on my head ?????"
(see my avatar ?!!)

I guess, then I would loose much more heat from other body parts ..

My own take (not a scientific one, I fear ..) on that "heat loss from head" stuff was (up to now...) that if you are normally dressed and wear NO HAT, then a great deal of heat is lost from the head area.
Covering your head might help keeping warm, more than adding a layer elsewhere.
OTOH, in the dead of winter, adding a parka over a simple T-shirt might beat the hat thing as far as rate of heat loss is concerned....

___________________________

Edited :

Oooopsss... I had not read all the recent posts.
Looks like Raydarkhorse, or JCWohlschlag also said about the same thing, if differently ...

Yup, I think that as far as this topic goes, we have again reached the beating a dead horse stage...

Thanks, Susan. I should have jumped on that myself. Always consider the source.

M

As it has been pointed out, it may be true that if one examines the total heat loss/retention of a naked person, the head may (or may not, as I still do not see their published data, just their statement) only account for approximately 10% or the BSA of the head. However, if one is clothed and of course heat loss/retention will vary with the amount and type of clothes one is wearing, an uncovered head may account for 50%+ of the total heat loss/retention of the body.

Pete

There you go again, using common sense, logic, and your fantastic ability to research to make "us" chest thumpers look silly again. Makes me, think, once again, "why didn't I think of that?"...

Great job...

I always figured the alcohol thing was more about the hard stuff. I can see where 190 proof Jack could screw you up a lot of different ways if you were in a survival situation. The weak stuff like beers, wines, grog, etc... doesn't have much alcohol in it. Years ago it was the larger percentage of what people drank. Sailors mostly drank the low alcohol stuff (and some rum....arrr!) on long voyages. It keeps better than water, what's it going to do, ferment and go bad? The alcohol kills all the nasty germs so it was the safest thing to drink. Our ancestors weren't a bunch of drunks, they were survivors. (I'm not much on beer myself, but I like Stella. Let's see, a gallon a day for each person. Ouch! that could get expensive.)

Always thought the caffeine thing was kind of stupid too. I went for a period in my life where the only thing I drank was Dr. Pepper. Maybe I should be dead already.

About wearing a hat. Probably just a smart thing to keep your core areas covered in the cold. And your head IS a core area. A big puffy vest, while looking kind of dorky, works amazingly well at keeping you warm.

Another myth I've always thought was stoopid is the swimming after you eat. Don't even mention the word swim while you're eating around my grandmother. She'll start telling you about disfigurement, maiming, and death while sizing you up for a coffin. And nothing will change her mind. O.K. not really survival related, but I guess if you have to swim across a river after eating your fill of snare caught wood rats and black berries you won't die from cramps.

Argumentum ad Hominem
Translation: "Argument against the man", Latin
Alias: The Fallacy of Personal Attack

Type: Genetic Fallacy

Exposition:
A debater commits the Ad Hominem Fallacy when he introduces irrelevant personal premisses about his opponent. Such red herrings may successfully distract the opponent or the audience from the topic of the debate.

Earlier, you said:



I think you're being rather inconsistent here. Earlier, you used the expert status of your source to buttress your argument. Now, when someone questions the credentials of that expert, you claim it's an ad hominem attack. You can't have it both ways.

That's another good one. Something that everyone knows is true, but when put to the test it fails.

Lasd02, thanks for the post & interesting discussion you have generated.




Based on what I've read so far during this thread the jury is still out on this one, but I do know one thing for sure...the few times in my life that I've needed to take a cold shower the part where I had to wash my torso & head was by far the most brutal. The hands, feet, arms & legs sure do not seem to affect our response to the cold water the same way that the torso, neck & head do. My gut feel on this would be this is a built in survival instinct that makes us greatly desire to get those more vulnerable parts out of the contact with life draning cold more quickly BECAUSE THEY ARE LOSING HEAT FASTER. But I have no scientific proof.

I think the study you have quoted screams for more research.

For arguments sake, lets say the air temperature is 50degrees F with zero air movement (no wind chill factor). A naked person stands still in that environment. Arbitrarily let’s say the person looses 1000 BTUs in an hour. By the “debunk” SBA rule, the head (9%) would account for 90 BTUs while the remaining body would give off 910 BTUs.

Now, if we clothe the body (not he head) with clothing that achieves 70% efficiency. That would mean that 30% or 273 BTUs are still lost from the areas of the body other then the head. 273 + 90 BTUs = 363 BTUs so the loss from the head is now 24.79 % of the total heal loss.

If the body were clothed in clothing that provides 80% efficiency, then 20% would represent 180 BTUs of loss from non-head regions of the body. 180 + 90 BTUs = 270 BTUs. So now the heat loss from the head is 33.33…%.

So you can see, the greater efficiency of heat retention of the clothing worn on the body, there is a greater percent of heat loss from the uncovered head.

Comparing core temperature to BSA heat loss is like comparing apples to oranges. The body will divert blood flow to various parts of the body to maintain a survivable core temperature for as long as possible. If the “study” was not conducted with thermal imaging, then it is flawed.

Pete

Absolutely, but the 9% from the head could just as easily be the 9% from any other part of the BSA. As the study claims, you will lose the same amount of heat from an exposed head as from an exposed leg (given the same BSA %).

Thanks for the nod, I'm starting to get a little discouraged here.

Blackeagle,

Had I based my argument solely on the credentials of the researchers, you would be correct. I have listed links to research, other non-associated experts (Dr. Daniel I. Sessler, Univ. of Louisville Medical School), and the original source.

In return, those who disagree have offered this:
















Opinion, conjecture, anecdotel evidence, outdated research from 1957...Well, now that I've alienated a good portion of this boards most active members, I think I'll let this one go. It's been fun playing but I have a feeling the Moderators may be getting tired of this thread.

The fact that your point isn't solely based on the researchers credentials doesn't mean that their credentials aren't relevant, and it doesn't make questioning those credentials an ad hominem attack.

THIS is the link to the Newsletter that discusses this. One particular quote is significant:

Susan, the fact that one of the founders of SOLO was part of this mess is why I didn't write it off as three cranks.

Now that would be Argumentum ad verecundiam or an appeal to authority. Which is a false arguement unless the person is an expert in the field. When you make an appeal to an authority the opposite side has the right to question that authority. Ad hominem attacks are only irrelevant attacks on a person, questioning an experts credentials isn't irrelevant, its central to the debate.

As someone else said, it may not make your feet feel warmer, but a hat will help prevent heat loss from your head. Doc Gordon is no different than other scientists who claim, DESPITE the overwhelming majority f the scientific institution and historical facts developed by that institution, that global warming is man-made and we can do something about it.

In other words, a person with credentials who makes a claim that goes against the remaining scientific community's findings is probably the person you DON'T want to listen to.... let alone quote as your source for facts.

Also....note that Doc Gordon didn;t say how he dubunked this "myth" (if he did and you're aware of it, please post....I'm sure it would be interesting).

Why is there hair on our heads??

Why is it that, when we go out in cold weather, our heads are usually the LAST thing to get cold? Because there's so much heat rising from it!

Why, in today's society, do we go against historical and empirical evidence, and sometimes even common sense and logical thought, and jump to believe the first accredited person who makes a statement or claim contrary to what the rest are saying? Because sometimes (we) are seeking to discredit and undermine all (we) believe in and the first hint of evidence that wafts by (we) grab and hold on to.

There is considerable heat loss through the head and covering it in cold weather will help to warm other parts of the body. If the head is losing generous amounts of heat, the body works harder to replace that heat, diverting attention from other body parts. Source: Doctor Stretch.

It will take more than Doc Gordon and two others to convince me and others otherwise.

Why would a moderator "tire" of this thread? What are they, parents to stop the bickering? It's an arguement...clear and simple. As you can see, the moderator's wisely stayed out...or watched from a distance.

With all due respect Lasd02, you dismissed the opinions of the members simply because they didn;t include a "source" for posting what to them is known as "empirical evidence". You did include a source, or three, and are pontificating that, since you did, you must be right. Well, I don;t think so. I don;t think it's necessary for anyone who is in agreement with the majority of the scientific community to have to try and discredit Doc Gordon's "theory". Conversely, I think it is you who has to provide MORE THAN Doc Gordon and his fellows if you choose to discredit or go against the overwhelming majority. Does that make sense?

this horse is dead. long live the horse.

you wrote: "Please, by all means keep your beanies on and I will do the same, but let's not do so out of ignorance."

i do not keep my beanie on out of ignorance, i keep it on out of experience. when i'm cold i put on my beanie, and guess what? i get warm.

and i think that's what your original myth was about - and what you are trying to determine. as has been said here, in better words than mine, when your feel that your feet are cold, it's your body telling you to get warmer. and most people overlook a hat as a means to becoming or staying warm. just watch the crowd shots at a winter football game sometime - i think you'd be surprised at how many people wear hats - and the ones that look miserable are hatless.

"I believe the 1957 study you link to is the same one referred to here: "

no, my first link was to a 2006 paper from the american college of sports medicine entitled 'prevention of cold injuries during exercise' in which they quoted and referred to my second link. that researcher was from the laboratory of biophysics, university of western ontario, london, canada. it doesn't state whether or not the military had anything to do with it or not.

please do not misunderstand, i think you raised valuable ideas and issues. and i hope you continue to do so. you certainly inspired a lot of people to respond to your initial missive. congratulations on stimulating the group!

and on the trail, i'll be the one in the beanie.

So, is it OK to wear my hat in the winter again?

no.

Ok, I was trying to let this one go but you called me out Stretch. I'm reading these last few posts and trying to keep it in but now I look like this:



I can't do it, I've got to let it out!


Blackeagle & AROTC: Susan did not present any information to discredit the education, training or expertise of the authors of the original source, she simply implied that the entire argument should be dismissed because it was written by a Doctor of Veterinary Medicine (yeah, what do they know!), a PHD. who operates the Laboratory for Exercise and Environmental Medicine and Dr. Hubbell, the founder of SOLO (look it up), or as she puts it, She is trying to remove the focus from the argument and onto the authors and then not even providing any facts to discredit them! You want to question their credentials? Ok, let me see your proof that they sent away for their diplomas from the back of a matchbook.

RAS: Fine, I concede. In this very limited circumstance (hypothermia victim that is in that small window where they are shivering but not yet sweating), the research shows 55% heat loss from the head. But that is the ONLY exception to the 10% rule. Again, if you want to believe and teach that we lose 55% of our body heat from our head based on that limited circumstance, go right ahead.

Stretch: Wow, where to begin? First, you need to go back and re-read my citations.

The, "abundant scientific information" SUPPORTS the 10% figure.



Someone from the original article already beat you to that question.

#3 What difference does hair on your head or facial hair make?

None.
In order for hair or fur to provide a protective thermal barrier, it has to be much denser than what we humans grow and it has to be in layers of different types of fur to provide a thermal barrier. Beards are great, but they do not keep you any warmer. And bald is beautiful.

And finally, I'll answer your question and ask one of my own. I try not to ignore common sense and logical thought, but as you can see, common sense isn't all that common. With the same sincerity that you and others feel that I'm trying to defy logic, I feel that you are refusing to let go of BAD information simply because of, "but we've ALWAYS done it this way" reasoning.

Now my question, what is it going to take to convince you that the old figure (70%,50%,25%, you pick), is wrong and the 10% figure is correct? I don't have any personal stake in the outcome either way, no agenda here, just passing on new information that I hope will make a difference to somebody, someday. I have a feeling that you and many others just don't want to admit that maybe you're wrong (I'll admit it, I LOVE to be right), but I have a suspicion that no matter how many links I provide, or how established my "experts" are, many here will keep on spreading the bad information.

And I want you all to take note, in this picture:



I"M WEARING A HAT!!!!

You've got to admit, it's a fairly significant exception in that the victim is well on the way to dying. It would be much better to wear a hat and keep the number in the realm of 10%.

But your head is so big I can almost feel the heat from here.

Stretch, you said,
"Why, in today's society, do we go against historical and empirical evidence, and sometimes even common sense and logical thought, and jump to believe the first accredited person who makes a statement or claim contrary to what the rest are saying?"

It sounds to me like LASD has done his research and qouted more than "the first accredited person"

Questioning an expert's credentials doesn't necessarily require proving, "they sent away for their diplomas from the back of a matchbook." It is perfectly legitimate to ask whether their degrees or previous research qualify them as experts on a given subject. Just having a PhD or an MD doesn't make someone an expert in every subject that could possibly be covered by that degree. For example, I've got an MA in Geography and I'm well on my way to getting a PhD (another year and a half, I hope! ). However, that doesn't mean that I'm an expert in geomorphology, or paleoclimatology, or demography. I know a little bit about these subjects, but no more than any amateur who's done a little reading and attended a couple of talks (in other words, just enough to get into trouble). On the other hand, if you want to talk about transportation or location science, I really am an expert.

Since we're discussing heat loss from the human body, I'd say that the fact that the first author is a veterinarian is possibly relevant. Of course, the best way to make this sort of judgement would be to look at a full CV, but since the blog didn't provide CVs, their degrees are all we have to go on.

First off, "Woo Hoo! Two Pages!!"

Sorry, back to business.

Blackeagle,

That's why I continue to direct everyone back to the original link from Wilderness Medicine Newsletter and SOLO, if you research for a bit it becomes pretty clear that this is arguably THE site when it comes to well, wilderness medicine (of which hypothermia is a key concern).

If you were asked to submit an article for (just a guess, sorry if it's unknown): http://www.vub.ac.be/EWGLA/homepage.htm
and then were asked by one of your peers to show your credentials before they would trust your article, wouldn't you be a little offended? Don't established, respected groups deserve the benefit of the doubt sometimes? I don't ask to see my Doctors diplomas before I allow him to take care of me, the fact that he's been hired by Huntington Memorial Hospital speaks for itself.

I think you might want to reexamine what you’re construing as opinion, conjecture, or outdated research. By removing the actual context from my quote, you’ve made it sound as if I pulled this idea out of my butt.

The point I was trying to make from the full part of my earlier post is that the research presented only state various figures and not the scenario in which these figures apply. What use is it to know how much heat escapes your head versus your body when you’re naked? And how do those figures vary between a person who is vasodilated (normal core tempterature) versus vasoconstricted (hypothermic)? I have no plans to be naked in the cold, and the entire purpose of this site is learning how to be equipped so you don’t end up naked in the cold. Personally, I am much more interested in how much heat escapes your head versus a body that is clothed in various ways, and the research you presented offers no insight into this curiosity.

If you have a specific argument about the point I was trying to make… about a normally-clothed body… then by all means make it. Until then, don’t quote my typing out of context in order to deem my (and others’) arguments as “opinion, conjecture, or outdated research”.

Never get discouraged...

"...and some rum....arrr..."

Hey, whatcha got against the demon rum??? With the right mix it is great stuff...

And what appears to be a kilt!!!

Actually, in academia, they don't even trust your credentials! No matter how many degrees you have, no matter what work you've done in the field before, a good journal is going to send your paper out for other experts to go over it with a fine toothed comb.



In the words of Ronald Regan, "Doveriai, no proveriai." ("Trust, but verify").

In the words of Dolly Parton, "Hire good people, then watch them like a hawk"...

JCWohlschlag: If I offended you by taking your quote out of context, I apologize. The point I was making by doing so was that many (including you), were asserting startling conclusions without supporting them. Now that your quote is copied here in its entirety, allow me to question yours in the same way you question mine (without supporting research).

"For one, if you're cold, (how cold? does it matter? I would certainly think the temperature we're talking about makes a big difference. Why not state it so we can check your research?)
a large majority of you're warm blood will be constricted to your core and head. (Really? What exactly is a 'large majority'? Certainly well over 50%, so you're saying that our bodies have the ability to re-distribute, what? 75% of our blood into our core and head? Does this cause extreme swelling of the head? Where does this warm blood then go? It must just re-circulate between the core and head, otherwise it will reach those cold extremities and cool down.)"

"...your hair increases your head’s surface area dramatically. (Are you seriously asserting that hair adds surface area to the head? I suppose it does, in the same way that fingernails add surface area to our hands or teeth add surface area to our mouth, come on...)

"...the wind will be blowing your hair around so much that it may actually start acting as a heatsink. (I'm not taking this out of context, anyone is free to read your quote above. Again, are you seriously saying hair acts as a heat sink? I suppose that's because of the dense concentration of blood flow that courses through our hair.)"

"These images normally show people in winter clothes as a dark colored body with a big, bright spot depicting their head. (Let's see...hmmm, these people are dressed up in their toasty winter parka's and insulated snow pants, now where in the world is the heat signature going to show up??? What? The head you say? I'm still not sure what your point is here, I hope you didn't seriously think that I'm trying to argue that only if we are naked does this 10% loss apply. That isn't what the original article or my later follow up points are saying at all. It seems like you focused on one small experiment and are trying to make it sound like the basis of my whole argument.)"

"The myth simply means, in all its glory, “Don’t forget your hat. (No, that's not the myth at all, the myth is that we lose 70% of our bodies heat through the scalp.)"

Sorry for the tone of this reply, It came out on paper (so to speak), harsher than I intended.

OBG,

I'm really dating myself with this one but, "The Five Chinese Brothers" was one of my favorite books in elementary school.



I guess you could say he's wearing a Kimono (or the male version of one).

Blackeagle,

"...a good journal is going to send your paper out for other experts to go over it with a fine toothed comb. "

Exactly! Am I wrong to assume that The Wilderness Medicine Newsletter didn't have their own experts go over the article before publishing it?

Verify, by all means verify. I hope you and others continue to follow this research and stay up-to-date, I know I intend to. If the 10% figure gets scientifically proven wrong, I'll be right back here with my tail between my legs eating humble pie and wearing 2 hats!

I've looked at their website, and I don't find any evidence that it's peer reviewed.

Listen...ask Dan Rather whether even large organizations such as the one he used to work for "go over" articles or not. Sometimes they do, sometimes they don;t. Other times they print or air it regardless of its authenticity.



No Lasd02, you won;t be back here eating humble pie. Look, you started a great thread, I think. You made some good points. The point here though, is that Doc Gordon says the heat loss through the head thing is a myth. It ain't. You will wear a hat in the winter as I'm confident you do now, so there is no need to say you'll "start" wearing one (or two) "if" you're proven wrong. Lasd02, the thing is, your sources don;t need to be discredited. You don;t need t be proven wrong! Your sources NEED to discredit empirical evidence. I ask again....how did Doc Gordon, et al< debunk the "myth"?

Say a man writes in the Scientific American that the earth is actually shaped like a triangle. Nobody needs to prove him wrong.... he's already known to be wrong! "He" is the one who has to prove his theory and, thusly, prove wrong what is already known. Is this still not making sense? I'm asking sincerely here, because I think maybe I'm not being clear.

I believe the important part is using it on an OPEN wound. You find every ER or OR in the US uses it ONLY before the cut someone open. It's great at killing microbes, yes, but stuff can survive it. And it damages the he!! out of your tissue. But, hey, if you want to take longer to heal cuz you decided to kill all the different cells that were starting to clean your wounds and fix them, go ahead.

I could not find in the many posts if this link had already been posted, but gives some addtional information for thought and (IMHO)makes the issue more complex.

Pete
Heat Loss Thorugh the Head - Update

The actual statement of the "myth" is: "Up to 75%" means it can also be significantly below 75%, including its normal 7-10% -- the "myth" isn't much of a myth. Later in the article the author states, I just don't see what the argument is about. These statements are not contradictory.

That was my feeling for the site. It a blog that claims to present the latest in wilderness medicine (which may or may not be true), but a comparison between it and the journal Nature reveals huge differences between a true peer reviewed journal and "TMC Books, LLC is just three guys working out of an old barn in the White Mountains of New Hampshire." (follow the 'about us' sections to TMC books, the company that publishes the Wilderness Medicine Newsletter. When relying on research, especially where it concerns my health, a publication with a lack of peer review isn't going to be my first choice. For that matter neither is Discovery Channel, Mythbusters, or even this site so far as it concerns medicine or similar subjects. Scientists generally try to present serious new research in a peer review article, if they don't you have to ask why.

And for the record this is the very place a person would question the authority cited and determine whether a fallacious appeal to authority is being made.

Hey, I like Mythbusters, at least they show you their methodology and at least seem to let the chips fall.

I propose that the sapient quote from the update you link to is found here:



In this case, the excercising test subjects, the increase in heat loss through the scalp was temporary (I would say a matter of minutes, but that's just my opinion), and returned to the 7% figure. The ONLY exception listed here (and I did refer to this in an earlier post), is the shivering hypothermia victim, which again, I feel is too limited a population to base our general heat loss figures on.

Instead of making the claim, "Wear a hat because you can lose 55% of your bodies heat through your scalp.", It would be much more accurate to say, "Wear a hat because you can lose 10% of your bodies heat through your scalp, unless you happen to be a near death hypothermia victim in which case it jumps to 55%."

Great show. If more TV was like that, I'd consider owning a TV. But not the place I'm going to go to find out the best way to treat a possible heart attack while I wait for the paramedics (not that I think they'd do a segment on that).

One other possible issue with the “study” is the methodology or measuring device may not have been able to detect all forms of heat energy being loss. Was the device capable of measuring radiant, convection and conduction forms of heat loss? Or just measuring skin or core temperatures. Remember the adage is based upon the percent of heat loss through the head, not just relative temperature of the head compared to other parts of the body.

Pete

Temperature change is a measure of energy lost from the body. Measuring radiation, sensible and evaporative convective heat loss to the atmosphere would just tell you the mechanisms, and would not change the total heat loss.

These studies are based on the energy conservation principle, so that

Net radiation + Sensible convection + evaporative convection + metabolic heat production + change in heat storage = 0.

Change in body temperature, multiplied by body mass and specific heat, give you a change in body heat storage.

No Stretch, I think you're being clear. Here is my theory on how this came to be. The military needed to research how their soldiers' bodies adapted to cold weather (among other things of course). With the best instruments and methodology available in 1957, military scientists carried out said research and papers were published announcing the results. Somewhere in that research a figure was stated claiming a percentage of heat lost from our heads (I'm still not sure what the figure was, I've always heard 70%). Through the years, this information was passed on from study to study, article to article, and mouth to mouth until it became the undisputed fact.

Now, several decades later, more up-to-date research is being conducted and more accurate figures are being presented. I understand your point that it's not "my" facts that need to be proved and I agree, but I don't agree that it comes down to "Doc Gordon" against the world. I'm confident that as we hear more and more about this, the 10% figure will eventually become the new accepted figure (or I will eat that humble pie!).

Why do I think this? If we lost 70% of our body heat from our head, your dearly loved empirical evidence should allow me to walk outside in 30 degree weather with nothing on but a warm hat and maybe a pair of light cotton shorts (or anything else that covered 30% of my BSA) and be warm, I don't know about you, but that doesn't work for me. I do wear a hat when cold, but when I take it off, I don't suddenly start shivering and hypoventilating as I would expect from such a drastic heat loss.

You are more then likely correct, but what I am saying or trying to say: Is measuring either skin temperature or core temperature really measuring total heat loss from the body? Since compensatory mechanisms exist within the body (shunting, shivering, etc.), core and skin temperatures will be maintained until heat loss exceeds the body’s ability to maintain thermic-homeostasis. Therefore measuring core or skin temperatures are only a measurement of the body’s ability to maintain thermic-homeostasis, not heat loss. To the best of my understanding measuring core and/or skin temperature is not measuring heat loss through radiation, convection and conduction.

It would seem to me, if one wants to measure total heat loss, then thermal imaging is necessary.

Pete

Wow, a Zulu-tanned horsehide.
Cool.

-Blast

Lasd02, I wasn't even poking fun at the authors of the information you offered, I was just wondering. The vet may be the most informed person on human heat loss on the face of the planet, which is fine with me. Everything that he says may well be true. It doesn't FEEL quite right, but that's just my opinion. He may have left out some important stuff that would have made me feel a bit better about it, and I think he could have explained it a bit differently/better. But that's also just my opinion.

Also my opinion: I know some vets that I would prefer to have do major surgery on me than many doctors. I worked for vets for thirteen years, so seeing the 'D.M.V.' threw me off, as I'm used to seeing DVM (Doctor of Veterinary Medicine) rather than 'Department of Motor Vehicles'. I went to my acronym finder site and typed in DMV, and there wasn't anything about a doctor's title (remember, this came from their own article). Anyway, I asked because in a human-related article, one might tend to think that they would list the human doctor first. It just seemed a bit strange to me, along with the typo on the DVM.

Now, keeping in mind that I just read ParamedicPete's last post and only understood part of it (small part, not large part), please recognize that I'm just tossing this out there, and don't even know if what I'm saying makes any sense to anyone else. Humor me on this, okay?

If a person's head is covered by 7-10% of their total skin surface, and the whole body is covered up except the head, and there's a cold wind blowing, does the 7-10% of the heat loss end when that 7-10% is gone, or is this one of those diminishing returns situations (I don't think that's the right phrase), where you lose the 7%, then you lose another 7%, and another and another, until your shivering can't compensate for the continued heat loss?

I'm sorry, but these are the kind of questions I ask EVERYONE. You're not my only victim... The vet I worked for in CA years ago got used to them, but he would warn relief vets before he left on vacation . One guy looked at me funny after assimilating one of my questions, and said, "Have you ever noticed that you have... odd thought processes?"

I just recently discovered that I have ADD, after all these years! Maybe that has something to do with it... or not.

Anyway, this has been a GREAT topic that you started. I wish you wouldn't take everything so personally, though. This is a DISCUSSION board. We discuss things. Sometimes we have a severe case of 'topic creep' (a term new to me). But just because we air our views doesn't mean we're attacking you, or even attacking the info you offer. Just imagine all of us in a large room chattering away and voicing our opinions --- the decibel level would be incredible! That's all it is. Don't take it personally, because it just isn't personal.

You've got 95 posts showing here. I've got... OMG! 1198! (Hey, Mods! Where is the rolly-eyed guy?) Do you think this means I'm opinionated? Think?

Sue

No apology necessary, my friend. It takes more than forum posting to offend me… I’d simply prefer to have my points debated on their merit if not simply for educational purposes.


Good point. I will admit that some of my notions are not supported by correlating research, however I do not believe that my points need correlating research. I’m not arguing against the results of your presented evidence. I’m arguing against the validity of the experiment as a whole in relevance to practical use of the myth.


You’re right. The environmental temperature may make a difference. However, I am not in a position to give this data, but we both agree that it might be an important factor to look at.


I do apologize for not explaining vasoconstriction correctly. As I understand, the body constricts the blood vessels on the surface of the skin and of the extremities simply to make the blood recirculate through them drastically slower than the blood in the core and head. The way I previously stated it was far too simplistic.

My point, however, still stands. Your evidence mentioned nothing about the rate at which different parts of the body lose heat in a vasodilated person versus a vasoconstricted one. Does it not make sense that a person who has symptoms of hypothermia such as vasoconstriction would lose a higher percentage of heat from their head and core than a person who’s in a normal physiological state? From your above comment, it appears that you do agree with this point.


Yes, I am asserting that your hair adds surface area to your head. Your analogies, on the other hand, kind of suck. (No offense.) Think of how a radiator’s fins add surface area when compared to just a stack of tubes. Even look at a heatsink in a computer for the effect… the fins or studs (large hairs, effectively) are simply there to add surface area.


I did say that it may act as a heatsink. After all, heat does conduct through different materials at different rates. When you touch an object and it feels cold, it is because that object is absorbing heat from your body through conduction. To put that in application to hair, ask yourself if your hair has ever felt cold when you touched it. If the answer is yes, then it proves that hair can conduct heat away from what it is touching. Put a convective air current through hair, and it may very well lose whatever heat it has absorbed to the air through convection.

Of course, the rates at which these occur are unknown to me, and your evidence only really eludes to the hair not doing a very good job of insulation. If it doesn’t do a good job of insulation, then maybe it does pretty well at facilitating the loss of heat. Maybe, as we are supposedly an evolutionary “tropical” animal, that’s what it was designed for. I don’t know. I’d love to see some research somewhere that answers these curiosities, though.


Actually, that is exactly what I am saying. Your research appears to simply say that people lose heat evenly through all exposed skin. And I quote:

So he took several test subjects, all volunteers, of course, (you have to wonder what problem they caused at the university), wired them to monitor their core temperatures, and discovered that we do indeed lose heat through any exposed part of the body and the amount of heat we lose depends on the amount of exposed surface area. The rate of heat loss is relatively the same for any exposed part of the body, not simply the head.

Therefore, it does appear to me that you are saying that the 10% heat loss from the head only applies to naked people, because that is exactly what your article (as quoted) is saying as well. So, I’m simply asking how on Earth this myth can only apply to exposed skin. As far as I know, none of us who read ETS, or have half a brain whatsoever, will be venturing into the cold naked. I sincerely doubt that many would be dumb enough to do so in just a T-shirt. So to me, this myth would apply to people who have at least made an effort to dress properly for their cold environment, except for a hat… especially for us here on ETS. Since in these circumstances, pretty much only our heads would be what might be exposed, then it seems logical that even your research states that most of our heat would be lost through the head.

So, I apologize if I misconstrued what your argument is. Your article says that people lose heat evenly through all exposed skin. I was simply saying that those results are irrelevant to a person in the cold who is reasonably dressed except for a lack of a hat. I invite you to clarify exactly what your argument is if I have misinterpreted it, as it appeared that you were trying to argue exactly what your article said.


True, that is what the myth specifically states, and if you think that somehow you only lose 7–10% of your body’s heat through your head even when properly winter dressed, except for a hat, I have a bad feeling you’re going to get a nasty surprise. So, when naked, the myth is not true. When properly dressed except for a hat, the myth may very well be true, hence “Don’t forget your hat.”


Don’t worry. I’m quite mature enough to not take words on a forum personally. The point that I’m trying to make is that the Wilderness Medicine research, while probably being scientifically correct, has absolutely no relevance to the myth since none of us will be going into the cold with completely exposed bodies thinking, “I have a hat. I’m saved!”

Besides, dead horses deserve to be punished for dying on us in the first place. Damn unreliable horse.

Partly, this discussion has strayed into hostile territory because we all have a tendency to confuse good advice with hard scientific evidence. Good advice may not always be "good" to the extent it claims - and science can inform us about its quantitative value. For instance, chicken soup may not cure the common cold, but science does confirm that it may be useful - for a number of somewhat complex and unrelated reasons. Those who used chicken soup as the sole treatment regimen for the cold were ill-informed - but anyone who might contend that it is of no value is almost equally wrong. And here's my point - the rate of mortality and morbidity from eating chicken soup is quite low, yet its salutary effect on the sick is well-documented in experience, thus, it is recommended! To the case in point I offer the following:

In support of keeping head and neck warm -- Three medical sources after a cursory review of the hypothermia treatment literature on the Internet:

?Individuals employing heated, humidified aerosols have been impressed with their benefits, which appear greater than can be explained by the small heat exchange. Most of the heat transfer takes place in the upper airway, not in the lungs where it would warm the heart. Investigators have speculated that warming the base of the brain and the brain stem may be responsible for the salutary effects.?

?The hypothalamus, a portion of the brain stem, is the body?s main thermometer
where most of the information from the temperature receptors in the core and skin are
integrated. The hypothalamus monitors these temperatures and when they start to vary, it
signals the body to bring the temperature back by voluntary and involuntary means.?

?Airway Warming
Airway warming accelerated rewarming to a statistically significant degree, compared with passive rewarming, whether it occurred before and/or after the period of airway warming. There is a thermal countercurrent heat exchanger in the cerebrovascular bed of humans known as the rete mirabile. This heat exchanger may preferentially rewarm the brainstem.?

So, until something better comes along, I will continue to insist on head and neck coverings (along with a whole host of recommended actions in cold weather) as beneficial to the person operating in cold conditions or suffering from early signs of hypothermia.

Cheers,