How do you prevent hypothermia?

[blindsideflank]

Winter is upon us and with the cold comes hypothermic patients. I'm not just talking the patient that fell in the icy lake, but almost every patient we bring in (especially trauma patients. In regards to the huge (and unrespected) increase in morbidity and mortality from even mild hypothermia (see deadly triad in trauma) and how poorly we keep our patients warm, I pose the question. What is your service and you doing for these patients?

Blanket warmer? what company/model?
IV warmers? company/model?

Specific practices that you perform?

It is -30C here today, we have 2 cars without heat working properly and no spares available. My car has heat and we have it cranked in the back at all times that the vehicle is running. We keep our normal saline under the bench seat to keep warm but often forget about it there (and throw gear on the bench making it unaccessible).

The GE enflow is used on our planes but not on car. No blankets warmers are used.
Our local SAR uses a one time use chemical heating blanket

I'll and some articles and stats later, that may shock you.

GO!....

 

[MonkeyArrow]

Nothing. I'm here in Atlanta, GA and we'll just add an unheated blanket or two. Of course, our transport times here are very short to a trauma center and the lows here don't dip much further than the low 30s/high 20s.

 

[Tigger]

The back has an actual thermostat that works pretty well. It stays set at around 68 I think. As an aside, I cannot stand when people leave the back doors open on scene, especially in cold weather. My general rule is that providers should not ever be wearing jackets in the back, if you are comfortable with a coat on, I bet you patient is not.

Extra blankets kept on the cot, along with a towel to be used as a hat. Maybe a plastic blanket if it's snowing. If the patient has been outside for a good long time I might wrap them in a disposable space blanket if I can find one.

Our IV fluids are kept on a fluid warming tray (Smithworks). It also heats the entire IV cabinet so tubing stay warm too. If I can avoid it I won't use the liter we keep in the bag since it is not heated. Anecdotally warmed fluid is much more comfortable than "room temp," so I try to be mindful.

 

[DesertMedic66]

The lows don't ever really get below 50 in my area so we don't get too many calls at all or just patients who are hypothermic. Our heaters in the back work very well. We have blankets.

For my internship area we respond up into the mountains so the only additional thing we do is toss a couple of bags up by the windshield with the defroster on and may tape on some hot packs.

 

[EpiEMS]

As an aside, I cannot stand when people leave the back doors open on scene, especially in cold weather. My general rule is that providers should not ever be wearing jackets in the back, if you are comfortable with a coat on, I bet you patient is not.

Extra blankets kept on the cot, along with a towel to be used as a hat. Maybe a plastic blanket if it's snowing. If the patient has been outside for a good long time I might wrap them in a disposable space blanket if I can find one.

^This.

If I think I'd be cold without a jacket, I throw an extra heavy blanket on the cot, and a plastic blanket if weather is expected to be inclement.

 

[blindsideflank]

Refer to the case conclusion if you don't want to read all of this. Basically the conclusion shows how all these efforts still leave people hypothermic. It doesn't have to be cold outside to cause compromised people to become hypothermic, and I think we forget that.

published this case report in Air Rescue Magazine. 2013 Feb. 3:32-34

Vu E, Tallon J, Peet H, Schlamp R, et al. A cool case: Prehospital intravenous fluid and blood warmer in aeromedical evacuation.

Conclusion

Major trauma and haemorrhagic shock are often complicated by administration of cold blood products and intravenous fluids. Strategies to mitigate coagulopathy, acidosis, and hypothermia have been identified as priori- ties in these clinical settings. There are few technologies available for the out-of-hospital warming of IVF and blood products. We have recently tested a device that meets our requirements for being compact, portable, durable, lightweight and operationally sound. This device is a valuable tool in prehospital emergency care and critical care transport to mitigate effects of cold IVF and blood products in the setting of haemorrhagic shock and acute coagulopathy of trauma shock.

 

[blindsideflank]

http://chguv.san.gva.es/Inicio/Serv..._PROTOCOLO_HipotermiaTransfusionSanguinea.pdf

16% more blood loss with even 1 degree Celsius loss.

Jems had some stuff on the deadly triad and it talks about different definitions for hypothermia when referring to trauma. I'll dig it up...(end of article)
http://www.jems.com/article/patient-care/trauma-s-lethal-triad-hypothermia-acidos



I've also read 240% increase in mortality and 0ver 70% of ambulance patients come in hypothermic (I know this is area specific but once again I guarantee you are bringing lots of patients in that are mildly hypothermic without realizing it) but I can't recall the source

 

[Medic Tim]

I love the space blankets. Every partner I have ever had has looked at me like I have 3 heads when I pull them out. They are underutilizes by many. Crack a couple of hot packs under them and they work even better .... To the point you need to take them out. Fluid warmers are also nice. I also have access to nice wool and thermal knit blankets. We are working on getting a blanket warmer ( hot/cold cooler)

 

[johnrsemt]

Here we have thermostats in the back of the truck.

Thing to remember is the PATIENTS COMFORT not the tech; so if the patient is cold turn up the heat, even if you are melting; same in the reverse (and I am always cold, so even in the summer I have a sweat shirt handy).

The other side, how do you stay warm? nitrile gloves are NOT warm;

 

[blindsideflank]

The other side, how do you stay warm? nitrile gloves are NOT warm;

WE NEVER stay warm at this time of the year.... Baffin boots, snowpants, 2 jackets a balaclava and a toque, but your hands freeze.

Back to every saying that they keep ambient temperature high, I don't believe that is enough. the studies show even a 1 degree celsius drop in a trauma patient causes serious harm. Your patient can also become hypothermic in the summer, dont forget this.
I am looking into blanket warmers and through my research have noticed a lot of disregard to IV bag warmers (claiming it just cools in the line anyways). IV line warmers are highly touted but expensive.

 

[Carlos Danger]

Common sense stuff:

- Keep your vehicle as warm as possible and move your patient into it ASAP
- Wrap them with blankets (wool if available)
- Wrap a space blanket on the outside of the wool blankets, especially if you are going to be outside for more than a minute
- Cover their head/neck/shoulders
- HME on vent tubing

Warming IV fluids actually has minimal effect.

The only thing that REALLY works to raise a patient's temp is forced-air warmers (Bair Hugger)

 

[MonkeyArrow]

Common sense stuff:
Warming IV fluids actually has minimal effect.

The only thing that REALLY works to raise a patient's temp is forced-air warmers (Bair Hugger)

I'm just curious, do you have a source that found warmed IV fluids don't matter?

 

[Carlos Danger]

If you are talking COLD fluids vs. warm fluids, then yes it might make a difference, especially if you are giving more than a couple liters.

But room air fluids vs. "warmed" fluids, it just doesn't matter. So assuming you can keep your IVF at roughly room-temp, there are other interventions that give you much more bang-for-your-buck.

JWK laid it out well a while ago:

If you have to "dump in fluids", your patient doesn't really care from a comfort standpoint.

I teach this to my anesthesia students all the time, because a lot of people want to warm IV fluids in the OR, but it really doesn't do much. It is physically impossible to warm a patient with IV fluids, and they really have a negligible cooling effect as well unless you're running in massive amounts of fluid, which is not the current trend in resuscitation.

It's really simple physics - for all practical purposes, the body is a big bag of water.

70kg x 37degC = 2,590 kcal

Add one liter of IV fluid at room temp

1kg x 20degC = 20 kcal

Add the calories and divide by total weight

2,610 kcal / 71kg = 36.76degC

So - adding a liter of room temp IV fluid drops your temp, at most, 1/4 degree celsius. Not very clinically significant.

And if you do a calculation with warmed fluids - give a liter of IV fluids warmed to 40 degC - and their temp, in theory, would increase 0.04 degC. Even less clinically significant.

And lets remember - unless you're warming your fluids right up to the hub of your IV catheter, the fluids you're infusing are closer to room temperature than they are to the fluid warmer you're using.

Now - does warming fluids hurt anything? Of course not. Does it help anything? More than likely, in most cases, no, because you're just not giving the volume of fluids that would make any significant difference. When you start talking about infusing refrigerated blood products, then it becomes a little more worthwhile.

For those of you who spend a lot of time in hospitals, you will rarely see fluid warmers used. And lots of refrigerated blood products are given without warming because they're allowed to run in over a couple hours. Unless you're pouring in liter after liter of fluid during those 30-45 minute transports, which I suspect you're not, it just doesn't make a difference. If hypothermia is a true concern, you should be using forced-air warming blankets (BairHugger or similar).

One caveat I would point out - the idea of using a heating pad to warm fluids is a bad one. You have no idea how warm those fluids are. If you're going to warm fluids, it needs to be done with a device intended for that purpose. The same concept follows for heating IV fluids in a microwave, which was tried in the past. Warmed IV fluids are one thing - but infusing hot IV fluids can be extremely dangerous.

 

[triemal04]

If you are talking COLD fluids vs. warm fluids, then yes it might make a difference, especially if you are giving more than a couple liters.

But room air fluids vs. "warmed" fluids, it just doesn't matter. So assuming you can keep your IVF at roughly room-temp, there are other interventions that give you much more bang-for-your-buck.

JWK laid it out well a while ago:

Problem is for a lot of the country, during a lot of the year room temperature does equal cold fluids. Pretty much all the bays I've seen, even if they were "heated" still meant the inside of the trucks stayed at a very cool/cold temperature.

It's also worth keeping in mind that, if you are dealing with a truly hypothermic person, whatever extra heat is contained in the IV fluid will be lost once it is infused through a peripheral vein.

 

[WildlandEMT89]

Blankets and the thermostat in the back of the ride. Working in phoenix we only have a cooler for fluids so fluids above ambient are out of the question. we will wrap fluids in some warm blankets to keep them from getting too cold though.
One thing to note is that as far as I know, it is a DHS violation to operate an ambulance without climate control in the pt compartment.

 

[OnceAnEMT]

One thing to note is that as far as I know, it is a DHS violation to operate an ambulance without climate control in the pt compartment.

Now that is interesting. I've never noticed this before. Anyone able to confirm?

 

[WildlandEMT89]

Now that is interesting. I've never noticed this before. Anyone able to confirm?

Im not so good at finding DHS documents as they differ a bit from state to state, but as far as being a star of life certified ambulance (which pertains to everywhere):

3.13.1 ENVIRONMENTAL SYSTEMS.
All ambulances will be equipped with a complete HVAC system(s) to supply and maintain clean air conditions and specified level of inside temperature in both driver and patient compartments. The various systems for heating, ventilating, and air conditioning may be separate or a combination system, which will permit independent control of the environment within the driver’s cab and patient compartment. All ambulances will be equipped with heating, ventilating, and air conditioning systems that can be made to collectively operate using re-circulated air and outside ambient air and will be capable of maintaining interior temperature of 68° F to 78° F. The ambulance must conform to the testing requirements as specified by AMD Std. 012. The air systems will be high volume capacity with low velocity delivery for minimum draft circulation. Environmental system components will be readily accessible for servicing at the installed location(s). Connecting hoses for heating and the air conditioning system will be supported by rubber-insulated metal clamping devices at least every 18 in.

3.13.3 HEATING CRITERIA.
The heating system(s) will have sufficient capacity to simultaneously raise the temperature in each compartment, to a minimum dry bulb temperature of 68° F, within 30 minutes. The testing must conform to the type testing requirements as specified by AMD Std. 012. Heater(s) will, to the maximum extent possible, be connected to the chassis manufacturer’s furnished interconnection points.

3.13.4 AIR CONDITIONING CRITERIA.
The air conditioning system(s) will have sufficient capacity to simultaneously lower the temperature in each compartment to a maximum dry bulb temperature of 78° F, within 30 minutes. The testing must conform to the type testing requirements as specified by AMD Std. 012. When available, chassis manufacturers’ interconnection points will be utilized.

this can be found here http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB4QFjAA&url=http://www.usfa.fema.gov/downloads/doc/DraftKKK-A-1822FCC.doc&ei=20h9VNmKLYnmoASD64DQCA&usg=AFQjCNEUgFru6phkFaZxc8U-_7z1fenwiA&sig2=tCA2Z-XMI3qKK0tjAysW7A&bvm=bv.80642063,d.cGU

 

[blindsideflank]

In regards to the iv fluid calculation, I wonder if it's that simple. When you consider blood flow in a hypothermic patient and conductivity through tissues I don't know if his calculations are accurate.

To play the devils advocate I did this.
A quick google search says the head and torso weigh 40kg (if someone really shut Down peripherally 100%)...
So 40kgx37C
Then add 2 litres of fluid at room temp 2x20
And divide by 42
This causes a drop of almost. 1 degree Celsius. Which is proven to be significant in trauma.
Not saying this is correct but his calculation can have more factors involved.

As for thoughts about afterdrop? Insignificant (dr brown). And dispute about giving 2 L of fluid to someone? Well cold septic patients? Specific traumas and the straight hypothermic patient (can require 2-5L throughout rewarming (dr brown)) although I'm unsure how much of that occurs I'm the prehospital setting.

Source? Drdougbrown.com his lectures on accidental hypothermia (last few minutes of lecture 2 discusses dliid resus)

 

[jwk]

In regards to the iv fluid calculation, I wonder if it's that simple. When you consider blood flow in a hypothermic patient and conductivity through tissues I don't know if his calculations are accurate.

To play the devils advocate I did this.
A quick google search says the head and torso weigh 40kg (if someone really shut Down peripherally 100%)...
So 40kgx37C
Then add 2 litres of fluid at room temp 2x20
And divide by 42
This causes a drop of almost. 1 degree Celsius. Which is proven to be significant in trauma.
Not saying this is correct but his calculation can have more factors involved.

As for thoughts about afterdrop? Insignificant (dr brown). And dispute about giving 2 L of fluid to someone? Well cold septic patients? Specific traumas and the straight hypothermic patient (can require 2-5L throughout rewarming (dr brown)) although I'm unsure how much of that occurs I'm the prehospital setting.

Source? Drdougbrown.com his lectures on accidental hypothermia (last few minutes of lecture 2 discusses dliid resus)

I think you're overthinking this, making it more complicated than it is. It really is a simply physics (specific heat) concept. Nobody shuts down peripherally to the point that blood isn't circulating. If that was the case, then hypothermia should be really great for increasing the volume of the central circulation, which it does not. You may have trouble getting an IV in a cold patient because their superficial peripheral circulation is all constricted, but I'll still be able to pop in an arterial line on that same patient because there's still plenty of blood circulating.

Like I said - does warming fluids hurt anything? No. Does it help? Not much. It might slow down the rate of overall heat loss, but it's a negligible effect. I don't usually warm fluids in the OR unless I'm giving blood products that are cold (maybe 5deg C for red cells. Now, for massive fluid resuscitation, I would certainly be more inclined to warm the fluids, but more than likely I'd be giving blood products as well, so to save time, I'd probably warm everything.

If you want to warm patients, I mean really warm them, the best way to do that is with a forced air warmer (Bair Hugger or similar). In order to warm a patient, you have to constantly keep adding heat. Unless you are constantly physically adding heat to anything, you'll have heat loss. That's why forced air warming is the gold standard in the OR. Those of you who have any concept of SCIP know that fluid warming, warm blankets, space blankets, etc., while potentially helpful, do not meet ANY standard for "actively warming" a patient. The only things that do that are forced air or recirculating hot-water pads. I have no idea if there are easily portable forced air warming systems that would be good for pre-hospital use. They're a little bulky, have a long fat hose to connect to the blanket, and probably wouldn't help much except on extended transports.

 

[Alpiner]

I'm only an EMT student but do a lot of kayaking and the biggest cause of hypothermia is when people underestimate the alarming rate that moisture will suck heat away from your body.