Hypothermia - very good article

[Rebel]

Good article and good advice to keep in mind.

At the beginning of this year I found an old chap who died of hypothermia overnight in a ditch. He was just five or ten minutes walk on reasonably easy terrain from the nearest houses. When I say found I mean I found the trail that led to him. Finding him was difficult, there were police with dogs and a helicopter and even though we were just a few feet from his body we spent hours looking.

 

[Paul K]

Appart from the rather confusing use of the 0 in the centigrade temps, the "This represents a 2oC (3.6oF) drop from normal body core temperature." should be 2 degree C not 20 but I think the degree symbol is at fault, this was a very nice article. During the last snowfalls (last week) had a 27C and 24C hypothermia patients in the same morning. The recovery process is very, very tricky and resource intensive.

Andy80F

Hey Andy

The degree symbol issue has been driving me mad! The degree symbol format is fine in the back end of the blog but as soon as I publish the article, it all goes to pot.

If you choose the 'print it' option at the bottom of the articles, a window appears with the article nicely formatted for printing. As if by magic, the degree symbol is fine here... A lot of people have been printing the article as they prefer to read long articles this way but I guess you could also read it on screen in this window if you wanted to.

Thanks for your feedback. I'll endeavour to get it sorted before the next temperature-related article.

All the best

Paul

 

[Pierr]

You might want to try add something like this in your stylesheet:


sub, sup {
font-size: .83em ;
}

sub {
vertical-align: sub ;
}

sup {
vertical-align: super ;
}

 

[mrcharly]

Good article.

For the people who report overheating, sweating then chilling, wool is your saviour. You need some wool layers next to the skin. These won't get stinky from the sweat and will still help you stay warm when they are wet. An old woolly pullover + a fleece and a windproof will deal with most uk weather. Or you can go for one of the fleece+windproof jackets - Montane do some fantastic ones that have multiple vent zips. By opening these fully you let the sweat out, then it's quick and easy to zip them back up when you stop. I absolutely loved mine, but it's a bit unusable now after soaking in diesel - repairing boat engines at sea isn't good for your gear. Shoot, I just googled it and seems they don't make them anymore.

 

[Nonsuch]

What's the protocol when you fall in cold water (out of your canoe, not wearing dry suit) then ? Get to shore, star-jumps to get your body heat up, then change clothing for spare dry clothing once you are feeling warm ?

NS

 

[sandbender]

What's the protocol when you fall in cold water (out of your canoe, not wearing dry suit) then ? Get to shore, star-jumps to get your body heat up, then change clothing for spare dry clothing once you are feeling warm ?

NS

First get undressed!

If you have access to your gear, change into the warm dry clothes. If your canoe and gear are away down the river somewhere then get undressed and get a fire on. That advice may be void if you are wearing something like a Buffalo top or have beached by a public park.

Edited to add:

Just realised you were responding to the previous post, I suppose the same holds true, I have never canoed or sailed while wearing wool but lots of folks used to and some somehow survived the odd dunking.

 

[SimonD]

First get undressed!

If you have access to your gear, change into the warm dry clothes. If your canoe and gear are away down the river somewhere then get undressed and get a fire on. That advice may be void if you are wearing something like a Buffalo top or have beached by a public park.

Edited to add:

Just realised you were responding to the previous post, I suppose the same holds true, I have never canoed or sailed while wearing wool but lots of folks used to and some somehow survived the odd dunking.

it actually specifically says in the article NOT to remove wet clothing but to insulate over the wet clothing. sorry to be a stickler but i figure it best we've all got the facts

 

[sandbender]

it actually specifically says in the article NOT to remove wet clothing but to insulate over the wet clothing. sorry to be a stickler but i figure it best we've all got the facts

Surely that is because the article is talking about a casualty who is already in a very poor state, whereas if you have just made it to the shore you are not yet that far gone and might benefit from not having your wet t-shirt leaching away your body heat?

 

[Paul K]

Hi Guys

I thought I'd add a few comments to the recent discussion about what to do if you've fallen in water, are wet and have no access to dry clothes. I think SimonD and Sandbender both make valid points. They seem to contradict each other but it's because the points relate to different situations. SimonD quotes my article regarding not removing wet clothes. This is in the section of my article covering the 'spontaneous' or 'passive' re-warming. This applies to a hypothermic casualty who you are treating (i.e there is more than one of you) and is probably past the early stages of hypothermia, being not fully alert, whereas I think the situation being discussed above was one where you had self-rescued after immersion, were on your own and had no spare clothing, sleeping bag or anything else to insulate yourself with.

With the exposure hypothermia victim, spontaneous or passive rewarming is the way to go. You wrap them in a 'hypothermia wrap' of sleeping bag, bivi bag etc and allow them to rewarm gradually from their own metabolic heat production. Taking their clothes off outdoors first is counterproductive. By contrast, in an immersion hypothermia case, you can re-warm more quickly as cooling has been quicker. Also, if all you have are your wet clothes, you are going to get cold very quickly just standing there. I've fallen out of my canoe into cold water often enough to know what this feels like! Thankfully, I've always had dry clothes and a Thermos of warm drink to help sort myself out.

If you don't have anything to change into or any shelter, then you need to light a fire and get out of your clothes. There is of course an assumption here that you are still 'with it' enough to be able to help yourself. The fire must be big enough to keep you warm while your clothes dry. Rather than using your body warmth to dry your clothes, which will just make you cold, it is much better to use the warmth of the fire to dry your clothes and keep you warm at the same time. The following link shows a real-life example from one of my old boss' TV programmes:

[video=youtube;TZbNDnuH-jA]http://www.youtube.com/watch?v=TZbNDnuH-jA[/video]

Thanks for the continued interest in my hypothermia article. Hypothermia and its treatment can be confusing. That's the whole reason I wrote my article! It's great that we can have healthy discussion about it here on BushcraftUK too.

All the best

Paul

 

[Paul K]

Thanks to Pierre - the degree symbol issue has been solved!

 

[Laurentius]

If your name is "Bare" Grylls however you will get your kit off at every opportunity.

 

[Martyn]

Very interesting read.
As I'm always feeling the cold, I have recently been taking my body temperature which happens to be 36C with my 100% Marino wool thermals on,
plus winter lined socks, plus heavyweight moleskin trousers, plus a very heavyweight winter shirt and Thermal Beeny, and sheepskin moccasins.
Taking a morning temperature within 10 minutes of getting up is anywhere 34.4C to 35.8C.
Those are all taken without leaving the house.
I have been to the quack but as yet have had no treatment.
Going back to ask what the heck is going on.

Nothing, you are pertfectly normal. Most peoples body temperature falls in the range of 35-37 degrees, with the majority being around 36 degrees.

...which is why this...

For our purposes as outdoors people, a better definition of hypothermia is the physiological one, i.e. a body core temperature below normal temperature. So hypothermia is defined as a body core temperature below 37oC (98.6oF).

...is nonesense. The rest of the article is very good though, but defining hypothermis as anything below 37 degrees is wrong, it's too high.

 

[Bothwell_Craig]

Normal core temp for a human is recognised as being, on average a pretty well maintained 37 degrees. It does however vary throughout the day by an average of 1.5 degrees (in males, females vary slightly lower) although the variation can be as much as just fractionally over 2 degrees. In normal waking adults ie. non shift workers, the body reaches its coldest inner core temp between 0300 - 0500hrs and it's highest at around late afternoon.

Therefore using a core of below 37 degrees to define or diagnose Hypothermia is unrealistic. It is also extremly difficult to get an accurate temp in an outdoor setting therefore using temp alone (or at all) is not a good (or normally viable) option in an outdoors setting

 

[Martyn]

Normal core temp for a human is recognised as being, on average a pretty well maintained 37 degrees. It does however vary throughout the day by an average of 1.5 degrees (in males, females vary slightly lower) although the variation can be as much as just fractionally over 2 degrees. In normal waking adults ie. non shift workers, the body reaches its coldest inner core temp between 0300 - 0500hrs and it's highest at around late afternoon.

Therefore using a core of below 37 degrees to define or diagnose Hypothermia is unrealistic. It is also extremly difficult to get an accurate temp in an outdoor setting therefore using temp alone (or at all) is not a good (or normally viable) option in an outdoors setting

Importantly, the 2 degree range you mention is 2 degrees below 37. Anything over 38 degrees is a pyrexia and anything over 37 degrees is a low grade pyrexia. It's very unusual to see a body temp over 37 degrees unless the body is fighting a disease process ...or possibly if there is a brain injury and thermoregulation has become messed up. It is however, extremely common for it to be in the 35.5 to 37 degree range, though more typically 36 to 37 degrees. Below 35 degrees is abnormally cold and there is usually a very apparent reason for it. This is based on taking many 10's of thousands of tympanic membrane temperatures on thousands of hospital patients over the last 15 years.

 

[Hugo]

Well I'm feeling much better cold wise.
some nice doctors have sorted me out.

Funny thing life.

 

[Bothwell_Craig]

Importantly, the 2 degree range you mention is 2 degrees below 37. Anything over 38 degrees is a pyrexia and anything over 37 degrees is a low grade pyrexia. It's very unusual to see a body temp over 37 degrees unless the body is fighting a disease process ...or possibly if there is a brain injury and thermoregulation has become messed up. It is however, extremely common for it to be in the 35.5 to 37 degree range, though more typically 36 to 37 degrees. Below 35 degrees is abnormally cold and there is usually a very apparent reason for it. This is based on taking many 10's of thousands of tympanic membrane temperatures on thousands of hospital patients over the last 15 years.

A woman during her menstrual cycle will typically show a core temp elevated by 0.5 degrees. A person engaged in continuous, vigorous exercise in hot, humid conditions can commonly reach a core temp of 40 degrees. They are neither fighting illness nor suffering brain injury.

An elevated increase in core temp does not mean that someone is suffering from Pyrexia (fever) indeed most recent research [British Medical Journal - September 2010] shows that pyrexia of unknown origin is not diagnosed as such until the increase temp of 38.3 degrees or greater has been observed as evident for a period of three weeks (patients own obs), three days of hospital obs or three outpatient visits.

Heatstroke is not clinically diagnosed until the temp is greater than 40 degrees AND there are signs of altered mental status [Patient Assessment - American Academy of Orthopaedic Surgeons / Nancy Caroline Emergency Care on the Streets UK Sixth Edition]

A body core temperature alone does not a clinical diagnoses make.

 

[Pierr]

What is the point of all this arguing?

First the mentioned article goes in those theoretical details (bolding added by me):

"Your body needs to maintain a core temperature of approximately 37oC (98.6oF)."

"Medically, hypothermia is defined as a body core temperature below 35oC (95oF). This represents a 2oC (3.6oF) drop from normal body core temperature."

You need to do something about a falling body core temperature before it gets to this stage. Hence, in the field, you need a more pragmatic definition of hypothermia.

"In reality, if someone has a body core temperature of 35oC (95oF) in a remote outdoors setting, they are already in trouble. " Presumably, except when in deep sleep when you are unlikely to wake up just to measure your temperature with some sophisticated appartus that would magically be immune to outdoor conditions, you will be doing some exercise are unlikely to flirt with the lower range.

And then there is a full secton about "What are the Signs and Symptoms of Hypothermia? ". Symptoms mentioned are shivering, loss of manual dexterity, mood changes, irritability and/or social withdrawal, the "umbles" ...

So again, what is the point of arguing about what exactly is a normal body temperature?

 

[Bothwell_Craig]

What is the point of all this arguing?

First the mentioned article goes in those theoretical details (bolding added by me):

"Your body needs to maintain a core temperature of approximately 37oC (98.6oF)."

"Medically, hypothermia is defined as a body core temperature below 35oC (95oF). This represents a 2oC (3.6oF) drop from normal body core temperature."

You need to do something about a falling body core temperature before it gets to this stage. Hence, in the field, you need a more pragmatic definition of hypothermia.

"In reality, if someone has a body core temperature of 35oC (95oF) in a remote outdoors setting, they are already in trouble. " Presumably, except when in deep sleep when you are unlikely to wake up just to measure your temperature with some sophisticated appartus that would magically be immune to outdoor conditions, you will be doing some exercise are unlikely to flirt with the lower range.

And then there is a full secton about "What are the Signs and Symptoms of Hypothermia? ". Symptoms mentioned are shivering, loss of manual dexterity, mood changes, irritability and/or social withdrawal, the "umbles" ...

So again, what is the point of arguing about what exactly is a normal body temperature?

Pierr

We're discussing. We've done it before, we'll do it again.

Unfortunately, when specifics are put up as being, well, specific, in relation to diagnosis then they'll be challenged if there's a challenge to be had.

Most medical science of today contradicts that which was taught "yesterday".

Martyn and I have crossed comments before in a medical vein but am sure I'd still have a pint with him and I'd trust he'd be the same!!

I think between us we have shown that one symptom does not make a diagnosis.

As to what is the point of arguing what exactly is normal body temperature? Well if we didnt have a starting point it would be of little value.

Does that answer your question?

 

[Martyn]

A woman during her menstrual cycle will typically show a core temp elevated by 0.5 degrees.

I'll remember that next time I'm menstruating.

A person engaged in continuous, vigorous exercise in hot, humid conditions can commonly reach a core temp of 40 degrees. They are neither fighting illness nor suffering brain injury.

But there is a clear causative factor driving the temperature and stressing thermoregulation. Semantics. Both examples are altered states of health and neither are normal resting conditions. I have worked in an intensive care unit for the last 11 years. We monitor all our patients temperatures either continually, via indwelling arterial catheter with an attached thermistor, via a rectal probe or hourly via the tympanic membrane. Believe me, I know the normal, resting human body temperature and it is in the range of 35.5 degrees to 37 degrees. If you go outside of that range, there is almost always a reason for it. Be it an altered state of health, a brain injury, a disease process or some other explanation. This is based on a longitudinal study with a sample size running into many thousands.

An elevated increase in core temp does not mean that someone is suffering from Pyrexia (fever) indeed most recent research [British Medical Journal - September 2010] shows that pyrexia of unknown origin is not diagnosed as such until the increase temp of 38.3 degrees or greater has been observed as evident for a period of three weeks (patients own obs), three days of hospital obs or three outpatient visits.

Well I dont know where you work, but we send blood cultures on any patient immediately their temperature is observed to be greater than 38 degrees. Though their is obviously a greater risk factor of an active infection being the causative factor in hospital in-patients. We would consider failing to act on a hospital in-patient with a temp of >38 for three days, to be medical negligence.

 

[Bothwell_Craig]

I'll remember that next time I'm menstruating.But there is a clear causative factor driving the temperature and stressing thermoregulation. Semantics. Both examples are altered states of health and neither are normal resting conditions. I have worked in an intensive care unit for the last 11 years. We monitor all our patients temperatures either continually, via indwelling arterial catheter with an attached thermistor, via a rectal probe or hourly via the tympanic membrane. Believe me, I know the normal, resting human body temperature and it is in the range of 35.5 degrees to 37 degrees. If you go outside of that range, there is almost always a reason for it. Be it an altered state of health, a brain injury, a disease process or some other explanation. This is based on a longitudinal study with a sample size running into many thousands.

Well I dont know where you work, but we send blood cultures on any patient immediately their temperature is observed to be greater than 38 degrees. Though their is obviously a greater risk factor of an active infection being the causative factor in hospital in-patients. We would consider failing to act on a hospital in-patient with a temp of >38 for three days, to be medical negligence.

You know where I practice my medical intervention and it's all pre hospital, mainly in hostile conditions of varying degrees.

No one has said you would fail to act on a hospital patient, we [and the BMJ] are talking about clinical diagnosis and thats what we have been talking about all along. You and I can debate the ins and outs of core temps to the nth degree but the reality and indeed the original point remains the same......

you cannot diagnose a medical condition be that hypothermia, hyperthermia or any other condition for that matter on ONE observation.