Hypothermia

[Guest guest]

That makes a great deal of sense.

JOHN CARPENTER wrote:

Conversely

as the bag reflects heat away any external source of heat(ie sunlight)

is lost to the casualty. So our conclusion was always to have a black outer

bag (a bin liner without the holes) to absorb external heat,(as I am sure

you all know even in winter the sun in the mountains can be very fierce)

with a space bag or blanket inside, and an inner insulating source ie a

thin fibre pile, meraklon, or fleece blanket to help build up and retain

the heat. Add the second human body and things get even better. Those

are only personal views from personal experimentation, it would be interesting

to see what other people think and what ambulance crews do here. All

the best Carpenter

-----Original

Message-----

From: JAMES DAWDY <kc7rcy@...>

< >

Date: 28 March 2001 04:08

Subject: Re:

hypothermia

You can have high day temperatures and low night temperatures, but

that usually occurs only at certain times of the year- usually in the spring

and fall, and not for more than a few weeks a year. In the summer,

there are two temperatures...excruciatingly hot during the day, and swelteringly

hot at night. I having worked in southern Arizona, with temperatures

of 125F (51.6C) during the day and 100F (37.7C) at night. I

think in the dune deserts of Arabia or Central Asia you might have a situation

of hot days/cold night more often because of the thermal retention properties

of the terrain (I have also read the accounts you mentioned). I always

supposed that the sand will more easily radiate it's heat than the

hardpack gravel deserts of the American southwest, but thats just my guess.

Also, the altitude can affect the nightime temperature. Where

I live now is high desert (4500 ft above sea level). The summers

are hot, but rarely get over 100F, and the nights are fairly cool at about

78-85F.

The one hypothermia case I had in the desert was during winter.

Daytime temp was 65F-70F and nightime temp was maybe 50F. The individual

had gotten drunk, staggered out of the bar and passed out in the desert.

Of course, the ground gets quite cold, and by morning the patient was acutely

hypothermic. We carried very nice, hospital quality electronic thermometers

on the ambulance and they would not read rectally, so core temp was at

least in the low 80's.

Jim

germainsjy@... wrote:

> ** Original Sender: JAMES DAWDY <kc7rcy@...>

/snip/

> Maybe someone can explain the thinking behind this to me...I

live in the

> desert so I admit to not being on the cutting edge hypothermia

> treatment.

/snip/

,

more out of curiosity than anything (not living in a or having any

experience of deserts), is hypothermia not a problem a night? Annecdotal

stories often speak of sub-zero (?) night-time temps. I'm wondering about

an instance of (and mixing in hyper-t) someone e.g. "walking behind the

wrong dune/butte" and not being found until the early hours...

Germain

(living in damp, soggy, even positively wet Jersey, British Isles)

(but generally temperate - the climate, that is)

[Guest guest]

Stuart wrote:

>

> Space blankets are useful for preventing any further heat loss from a

> patient to a cold environment or for retaining heat that would otherwise be

> lost to the environment.

>

This is the critical point.

It is generally not possible to carry into the field, in a short term

rescue situation,

a heat source sufficient to rewarm a patient. Even warm air breather

devices will not accomplish this.

The important thing is to try to prevent further heat loss.

Fast rewarming, without extensive immediately available advanced life

support, is also generally contra-indicated. Cardiac and metabolic

complications may arise.

If the patient is still capable of generating any heat, the use of a

fibre blanket under the reflective blanket will help trap a layer of

gradually warming air (much like a fleece jacket) and will help with

slow rewarming. The most useful function of a space blanket in the open

is as a wind shield, not a thermal reflector.

If self-rewarming is not likely then keep the patient cold! carry then

out gently to avoid any mechanical shocks triggering arrythmias and, if

a pulse is not detectable do NOT start CPR unless it can be continued to

ACLS with a warm patient in hospital, this means until the patient is in

an ambulance or helicopter. It is not possible to continue CPR on a

carried stretcher.

The best way of rewarming a patient with severe hypothermia is on a

heart bypass machine.

Gerry .

--

Dr. Gerard CEng MIEE, (EI0CH, WEMT)

TELTEC Radio Systems and Propagation Group,

Trinity College, Dublin Ireland (Ph +353-1-6081743)

Dublin+Wicklow Mountain Rescue Team

[Guest guest]

I am assuming the ability to generate any heat is seen as still having the

shivering reflex?

Also what is the current accepted level for the amount of heat actually lost

by the head as I remember some of the earlier findings were questioned by a

study a few years ago?

How do you mean keep the patient cold, do you mean at a steady level, is

there a recommended temp (I realise that monitoring that would be very

difficult under the circumstances) for instance, or kept in a space bag and

not allowed to get any cooler, or warmer by using additional insulation?

is there any evidence that supports the point someone asked me once that it

was better to allow the casualty to breathe into the bag rather than have

his head exposed (with woolly hat), and thus retain any heat from the body

via breath inside the bag?

Re: hypothermia

>Stuart wrote:

>

>>

>> Space blankets are useful for preventing any further heat loss from a

>> patient to a cold environment or for retaining heat that would otherwise

be

>> lost to the environment.

>>

>

>This is the critical point.

>

>It is generally not possible to carry into the field, in a short term

>rescue situation,

>a heat source sufficient to rewarm a patient. Even warm air breather

>devices will not accomplish this.

>The important thing is to try to prevent further heat loss.

>

>Fast rewarming, without extensive immediately available advanced life

>support, is also generally contra-indicated. Cardiac and metabolic

>complications may arise.

>

>If the patient is still capable of generating any heat, the use of a

>fibre blanket under the reflective blanket will help trap a layer of

>gradually warming air (much like a fleece jacket) and will help with

>slow rewarming. The most useful function of a space blanket in the open

>is as a wind shield, not a thermal reflector.

>

>If self-rewarming is not likely then keep the patient cold! carry then

>out gently to avoid any mechanical shocks triggering arrythmias and, if

>a pulse is not detectable do NOT start CPR unless it can be continued to

>ACLS with a warm patient in hospital, this means until the patient is in

>an ambulance or helicopter. It is not possible to continue CPR on a

>carried stretcher.

>

>The best way of rewarming a patient with severe hypothermia is on a

>heart bypass machine.

>

>Gerry .

>

>--

>Dr. Gerard CEng MIEE, (EI0CH, WEMT)

>TELTEC Radio Systems and Propagation Group,

>Trinity College, Dublin Ireland (Ph +353-1-6081743)

>Dublin+Wicklow Mountain Rescue Team

>

>

>

[Guest guest]

JOHN CARPENTER wrote:

>

> I am assuming the ability to generate any heat is seen as still having the

> shivering reflex?

Shivering does not always occur in mountain hypothermia, as the casualty

is too exhausted. Exhaustion is often one of the underlying causes of

mountain hypothermia. It may be more common in immersion hypothermia

which usually has a fast onset.

> Also what is the current accepted level for the amount of heat actually lost

> by the head as I remember some of the earlier findings were questioned by a

> study a few years ago?

AFAIK 35 - 40%

>

> How do you mean keep the patient cold, do you mean at a steady level, is

> there a recommended temp (I realise that monitoring that would be very

> difficult under the circumstances) for instance, or kept in a space bag and

> not allowed to get any cooler, or warmer by using additional insulation?

More or less.

Note that I usually deal with mountain hypothermia (slow onset).

Immersion hypothermia which has a fast onset is more amenable to rapid

rewarming.

>

> is there any evidence that supports the point someone asked me once that it

> was better to allow the casualty to breathe into the bag rather than have

> his head exposed (with woolly hat), and thus retain any heat from the body

> via breath inside the bag?

Anecdotally, breathing into the bag will help conserve heat. It may be

effective while waiting for evacuation. However, during evacuation this

would place the patients face (and airway) out of direct observation and

monitoring and I would be careful about this. Transport by mountain

rescue stretcher is a rough and bumpy process and may promote motion

sickness (sea sickness), with an increased tendency to vomit. Also, in

my experience most conscious patients do not like their faces covered.

> Re: hypothermia

>

> >Stuart wrote:

> >

> >>

> >> Space blankets are useful for preventing any further heat loss from a

> >> patient to a cold environment or for retaining heat that would otherwise

> be

> >> lost to the environment.

> >>

> >

> >This is the critical point.

> >

> >It is generally not possible to carry into the field, in a short term

> >rescue situation,

> >a heat source sufficient to rewarm a patient. Even warm air breather

> >devices will not accomplish this.

> >The important thing is to try to prevent further heat loss.

> >

> >Fast rewarming, without extensive immediately available advanced life

> >support, is also generally contra-indicated. Cardiac and metabolic

> >complications may arise.

> >

> >If the patient is still capable of generating any heat, the use of a

> >fibre blanket under the reflective blanket will help trap a layer of

> >gradually warming air (much like a fleece jacket) and will help with

> >slow rewarming. The most useful function of a space blanket in the open

> >is as a wind shield, not a thermal reflector.

> >

> >If self-rewarming is not likely then keep the patient cold! carry then

> >out gently to avoid any mechanical shocks triggering arrythmias and, if

> >a pulse is not detectable do NOT start CPR unless it can be continued to

> >ACLS with a warm patient in hospital, this means until the patient is in

> >an ambulance or helicopter. It is not possible to continue CPR on a

> >carried stretcher.

> >

> >The best way of rewarming a patient with severe hypothermia is on a

> >heart bypass machine.

> >

> >Gerry .

> >

> >--

> >Dr. Gerard CEng MIEE, (EI0CH, WEMT)

> >TELTEC Radio Systems and Propagation Group,

> >Trinity College, Dublin Ireland (Ph +353-1-6081743)

> >Dublin+Wicklow Mountain Rescue Team

> >

> >

> >

[Guest guest]

> I am assuming the ability to generate any heat is seen as still

> having the shivering reflex?

Shivering is a compensatory mechanism intended to increase heat

production. Lack of shivering does not necessarily equate to lack of

ability to produce heat - you will produce heat as long as you have

cellular metabolism.

That being said, there are a lot of things happening to the body during

the stage when you lose your ability to shiver, and they are a

decreasing ability to maintain metabolism along with ensuing hypoxia and

lactic acidosis which interferes with this process even more.

> is there any evidence that supports the point someone asked me once

> that it was better to allow the casualty to breathe into the bag rather than

> have his head exposed (with woolly hat), and thus retain any heat from

> the body via breath inside the bag?

You need to consider that moderately to severely hypothermic patients

will be hypoxic and acidotic, and doing anything that might contribute

to this is certainly a bad thing.

Larry Torrey

[Guest guest]

Excellent info, Daryl. Thanks.

Hypothermia

<snip>

..Warm Air rebreathers, Hot-Packs, etc? For most people, the option of

lugging a Warm Air Rebreather around with them doesn’t .come into the

equation. The kit is likely to be used by MRT’s but, the casualty must be

able to suck quite hard to get any .benefit.

..Warm packs have a very limited life and they are a bit like carrying IV

fluids within remote environments i.e. “What do we .do once it’s run out?”

<snip>

..Daryl J Wight

The original posting was based on a rescue vessel, therefore these items

would be possible. I would suggest that given the likelihood of hypothermia

in casualties in an offshore rescue, just about every treatment option

should be available (whether under direction of an onshore doctor, or not),

including space blankets.

Stuart

www.magicphoto.co.uk

[Guest guest]

Excellent information Daryl, are you interested in the NBC Medical Battle Book it is about 3.36 Mb I have it in PDF and sent Rod Eglin a copy, also one intended for Tom Greaber (ex Ranger medic)?

JC

Hypothermia

Having just returned from a very un-hypothermic trip overseas, I apologise for my lateness in providing some input on my pet topic.

As we know, hypothermia is a pretty complex condition and, as Gerry noted, in mountain related hypothermia severe shivering may not be obvious due to exhaustion. The exhaustion is due to a burn up of glucose reserves resulting in the additional condition of hypoglycaemia, which can also be accompanied by dehydration.

In the late 90’s, the medical sub-committee of the Lake District Search & Mountain Rescue Association published new guidelines for use by Mountain Rescue Committee affiliated SAR teams. These guidelines have been widely accepted both in the UK and overseas. I will endeavour to obtain permission to publish a copy for the benefit of the list.

In the meantime I offer the following as a guide;

A mildly shivering casualty (i.e. one who can voluntarily cease shivering and is able to answer questions clearly) whom does not cease shivering on re-commencing exercise is in the early stages of hypothermia and needs immediate attention to prevent the condition progressing.

First and foremost – SHELTER, second – replace wet for dry. Psychologically, we feel a lot better (warmer) if we can offer a warm covering to BOTH the Head & Neck (up to 75% heat loss), followed by the application of dry socks, then replace other wet clothing.

Bag up wrapped in Space Blanket (very doubtful if a cellular blanket will be available on the hill), and forget the b******s about putting someone normothermic in the bag with the cold casualty. Simple physics dictates the cold person will chill out the warm person, and not vice versa! Get warm fluids into them, a Mars bar chopped and melted in water with added sugar or a tube of Hypostop, with a pinch of table salt and a pinch of lo-salt will effectively act to warm the core, alter the hypoglycaemic state, and combat dehydration. Any desire to urinate should be discouraged as this is effectively emptying the internal hot water bottle.

If the casualty is unconscious or appears to be dead, make no attempt to remove clothing or otherwise disturb. Offer shelter, cover, and arrange for evacuation by helicopter if possible. If the rescue authority is made aware this is probably a hypothermic casualty, they will arrange despatch of the SAR Budgie at the same time as assembling the MRT.

There is a high likelihood this particular casualty may appear life extinct, but is in fact in a state of hibernation. The heart will be in AF which with GENTLE handling will not change however, rough handling or performing CPR is likely to result in a change to a VF rhythm and death.

With gentle handling and smooth transport, it is quite possible for the hypothermic in AF to reach hospital, be actively rewarmed and hopefully, “brought back from the dead”, or at least the hospital has rewarmed and made an effort! Remember – You Cannot Be Cold & Dead – You Can Only Be Warm & Dead.

In immersion hypothermia, as has already been stated – fast chill down (especially where children are concerned) immediate resuscitation and rewarming, which is maintained from the scene to arrival at the medical facility. Both conscious and unconscious immersion injury patients should NEVER be lifted vertically from a water environment. Horizontal or double stropping in a sitting position is the order of the day. Water pressure on the body acts like a PASG, release that pressure by a vertical lift results in a massive blood pressure drop and death!

Other points to consider; Cold can also be beneficial – Cold casualties don’t bleed, once covered and rewarming takes place, you may find wet bits where they’ve started to bleed from other injuries! A casualty with a severe head injury may in fact have the injury protected by the cold. There are a couple of recorded cases in the US where this has been the case. Had they been normothermic, there is little chance they would have survived.

Warm Air rebreathers, Hot-Packs, etc? For most people, the option of lugging a Warm Air Rebreather around with them doesn’t come into the equation. The kit is likely to be used by MRT’s but, the casualty must be able to suck quite hard to get any benefit.

Warm packs have a very limited life and they are a bit like carrying IV fluids within remote environments i.e. “What do we do once it’s run out?”

Back at base – dunking our conscious casualty into a hot bath to restore full core temperature? Unfortunately, I cannot find the reference at present but, there is a move against this practice both from the water pressure syndrome mentioned above, and from the view peripheral circulation is rewarmed too quickly resulting in “After-Shock”. The advice is to rewarm the torso, keeping arms and legs outside of the bath – just don’t let anyone near with a camera as you perform the manoeuvre!

Hope this is of some interest and answers some of the questions raised.

Daryl J Wight

[Guest guest]

I would also be much interested in a copy of the NBC Battle Book PDF if possible. I have to teach this subject in May and would like to have the resource.

Thanks,

Moseley LEMT-P

Cleburne PD SWAT

Re: Hypothermia

Excellent information Daryl, are you interested in the NBC Medical Battle Book it is about 3.36 Mb I have it in PDF and sent Rod Eglin a copy, also one intended for Tom Greaber (ex Ranger medic)?

JC

[Guest guest]

Carpenter!

I would be interested in your PDF NBC medical Battle book if it wasn't too much of an imposition. My email address is :

mailto:macg@...

Regards!

Jude McGarvey offshore medic Canada

Re: Hypothermia

Excellent information Daryl, are you interested in the NBC Medical Battle Book it is about 3.36 Mb I have it in PDF and sent Rod Eglin a copy, also one intended for Tom Greaber (ex Ranger medic)?

JC

[Guest guest]

I have a paper which I wrote years ago at www.gunn27.fsnet.co.uk in

Lectures - Trauma - at the bottom is a hover button " Hypothermia "

See if this is still relevant. Opinions welcome as it was written 10

years ago. Missed a lot of this thread as away.

More unwelcome yellow forms from CPSM today - pain in the arse.

Davy Gunn