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Warming of IV fluid

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What methods do you use to warm your IV fluid. Also does anyone know how long to put a bag in the microwave to heat it?


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Either have an approved fluid warmer for IV fluids (tubing warming device) or the fluids in an warm device before administration.

There has been successful lawsuits against hospitals that have used microwave, it can change osmolarity, and as well have "hot spots"...

R/r 911

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we just put a few bags on the dashboard so the defroster keeps them nice and toasty. if it's sunny just put a dark piece of paper over them to keep them from getting funky in direct sunlight.

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Just so happens that this one is right up my alley er igloo..... sorry, it is so long but was compiling a Hypothermia Guidelines for backcountry treatment and this may help out, for whatever its worth, and there is that word "NEVER" again :oops:

Classic IV warming is not an efficient strategy of rewarming per say It is merely a good strategy in preventing/stabilizing hypothermia

Emerg Med (Fremantle). 2001 Jun;13(2):181-5.

Reliability of modern microwave ovens to safely heat intravenous fluids for resuscitation.

Delaney A. Emergency Department, Gosford Hospital, New South Wales, Australia.

OBJECTIVE: To determine if intravenous fluid heated in modern microwave ovens is warmed to a consistently safe temperature, as has been advocated in a number of texts and journals.

METHODS: Five, 1L bags of normal saline in Viaflex (Baxter Healthcare, Old Toongabie, NSW, Australia) containers were heated for 2 min on high setting in 16 different microwave ovens. The output power ranged from 650 to 1,000 W. All microwave ovens were equipped with electronic timers and turntables. Initial and final temperatures were recorded with a TestoTerm 1100 electronic thermometer (Dade Behring, Lane Cove, NSW, Australia), accessing the centre of the fluid via the injection port. The average and standard deviation for each measurement was determined for each microwave oven.

RESULTS: In nine out of the 16 microwaves (56%) tested, the fluid had reached an average final temperature greater than 42 degrees C and thus was greater than the recommended maximum temperature for the heating of intravenous fluids. All microwave ovens with an output power of greater than 900 W overheated the fluids. However 13/16 microwaves (81%) had a temperature range less than 3 degrees C, thus if correctly calibrated could be appropriate for heating intravenous fluid for resuscitation.

CONCLUSIONS: The increased output power of modern microwave ovens can lead to overheating of resuscitation fluids, if the simple algorithm currently recommended is followed, leading to potentially serious complications. Microwave heating of intravenous fluid could be a safe, simple, cheap and effective means of heating intravenous fluids for resuscitation, but care needs to be taken to calibrate individual machines to ensure a safe temperature is reached.


Acad Emerg Med. 2000 Oct;7(10):1169.

Shaken. Not stirred-temperature change and heat loss during delivery of IV fluids

Fields E, Hsu C.

Beth Israel Medical Center, New York, NY.

Microwave-heated intravenous fluids are used in the rewarming of hypothermic patients.

OBJECTIVES: To study the effect of both shaking of the microwaved bag and heat loss during delivery.

METHODS: Twenty 1-liter normal saline bags were heated individually in a commercial microwave, immediately randomized into a "shaken" or a "non-shaken" group. The temperature of the fluid was recorded initially out of the bag and then at one minute intervals by a blinded observer as the fluid ran "wideopen" through ambient temperature tubing.

RESULTS: No statistically significant temperature difference occurred in any of the measured time intervals between the shaken and the non-shaken bags. Seventy percent of the overall temperature losses occurred in the first three minutes out of the microwave for both groups.

CONCLUSIONS: Absence of shaking of the microwaved fluids does not produce "hot spots." Higher initial temperatures out of the bag should be considered as well as warming of the IV tubing.


Ann Emerg Med. 1985 Sep;14(9):876-9.

Microwave warming of resuscitation fluids.

Leaman PL, Martyak GG.

Hypothermia is a common complication in fluid resuscitation of the hypovolemic patient. Warm intravenous (IV) fluids have been shown to be a valuable adjunct in volume replacement to prevent this complication. A rapid method of warming IV fluids is the microwave oven. Heating time for liter bags of crystalloid to 39 C was determined to be two minutes at high power, 600 W. Fresh frozen plasma was thawed with five 30-second exposures to microwave radiation. Microwave warming of packed red blood cells (PRBC), 4 C to 37 C, resulted in a 17-fold increase in plasma hemoglobin over that of water bath controls, (P greater than .01). Heating on a warm cycle to room temperature, 21 C, caused an average 26% increase in plasma hemoglobin. Therefore, we do not advocate microwave warming of PRBC because of the possible danger of local overheating, which causes hemolysis. We warm PRBC secondarily by diluting with microwave-warmed, calcium-free crystalloid.


Am J Emerg Med. 1985 Jul;3(4):316-9.

Microwave heating of intravenous fluids.

Anshus JS, Endahl GL, Mottley JL.

Microwave heating of intravenous (IV) fluids is a viable alternative to heating by conventional means, such as by blood warmer(s) or an on-site warming oven, for administration to hypothermic patients and trauma victims. Three 1-l bags each of lactated Ringer's solution, normal saline solution, 1/2 normal saline solution, and 5% dextrose in water were packaged in parenteral containers and heated in a microwave oven from room temperature (21 degrees C) to 40-42 degrees C in 3 minutes. Little difference between temperatures of the four solutions was detected at each of five intervals up to two hours after heating for 3 minutes. Samples were taken before and after heating to assess any potential alterations in sodium, potassium, chloride, calcium, glucose, and lactate levels; differences were within the range of variation of the methods used. Though the plasticizer in the polyvinyl chloride containers is stable to microwave heating, data on other components is incomplete.


J Emerg Med. 1985;3(6):435-42.

Preventing hypothermia in trauma patients by microwave warming of i.v. fluids.

Aldrete JA.

Warming plastic bags containing intravenous solutions in a microwave oven (MWO) raised the temperature from 18 degrees C to an average of 34.1 degrees, 40.2 degrees, and 42.8 degrees C when treated for 120, 150, and 160 seconds, respectively. Fluids at 18 degrees C, when passed through a blood warmer, resulted in temperatures at the distal end (DE) of about 27 degrees C; but if the bags were priorly warmed to 42 degrees C, fluids arrived at the DE at a temperature of about 30 degrees C. Fluids heated by MWO to 42 degrees C through a single short tubing 180 cm long arrived at the DE at a temperature of 33.7 degrees C. Fluids administered at operating room ambient temperature of 18 degrees C arrived to the DE with a temperature of about 19 degrees C, thus most likely contributing to lowering the body temperature of traumatized patients treated with large volumes given at rapid flows. One group of 19 patients undergoing repair of injuries to extremities received infusions warmed by MWO to 42 degrees, while other groups received them at about 20 degrees. After an initial fall, average temperature in the former tended toward normal levels while in the latter, body temperature declined. The simple expedience of MWO warming of the bags to 42 degrees C, and flowing through shorter administration tubing, appears to ameliorate this complication and in some cases prevents it.


Am Surg. 1984 Dec;50(12):656-9.

Microwave ovens. A safe new method of warming crystalloids.

Werwath DL, Schwab CW, Scholten JR, Robinett W.

The multiple trauma patient often presents hypothermic. The infusion of warmed parenteral fluids is one of the least invasive methods of core rewarming the hypothermic patient. This study discusses and describes a safe, efficient method of warming normal saline and lactated Ringer's solution by microwave radiation. A 650-watt microwave oven was used to warm single liters of nondextrose containing crystalloid from room temperature (70 F) to 101 F. Total heating time required was 120 seconds. The technique involved midcycle (60 seconds) interruption with agitation and end-cycle agitation. Intra- and extrabag temperatures were confirmed with three separate thermometers. It was concluded that by following the recommended protocol, hospital personnel could be taught this safe method of rapidly warming nondextrose containing crystalloid.


Anaesthesia. 2000 Mar;55(3):251-4.

An assessment of the thermal safety of microwave warming of crystalloid fluids.

Lindhoff GA, MacG Palmer JH.

Department of Anaesthesia, Dumfries and Galloway Royal Infirmary, UK.

We performed an in vitro study to determine the thermal safety of a domestic microwave to warm intravenous crystalloid solutions. Five-hundred-millilitre bags of crystalloid, randomly allocated to groups which differed in power setting, timer setting and whether or not agitation was performed after warming, were heated in a microwave oven to a calculated temperature of 39 degrees C. Timer accuracy was checked by stopwatch. Bag temperature was measured using an infrared tympanic temperature probe and fluid temperature was measured with an in-line thermocouple. Mean times measured by stopwatch were higher than set. No in-line temperatures reached 40 degrees C. Wider overall ranges and a higher mean were found with the tympanic probe compared with in-line temperature measurement. There were significant differences between the in-line temperatures of shaken and unshaken bags at each power setting, but not when groups were added together. There was no change in colour or odour of bags or fluid. One bag developed a pinhole leak when the packaging was removed.


Perit Dial Int. 1994;14(2):163-7.

Control of microwave heating of peritoneal dialysis solutions.

Deutschendorf AF, Wenk RE, Lustgarten J, Mason P.

OBJECTIVE: To determine if microwave heating of dialysis solutions to 37 degrees C produced focal overheating (hot spots) and caramelization of dextrose.

DESIGN: In vitro determination of conditions for controlling time, temperature, and procedures. Bags had been stored at ambient room temperature.

MAIN OUTCOME MEASURES: Solution and external bag surface temperature determinations. Dextrose degradation products

determined spectrophotometrically. Microscopy for potential caramel precipitates.

RESULTS: A microwave oven with no rotation tray produced uneven heating of bags of two commercially available concentrations of dialysis solutions. The greatest hot spots were evident in spike ports. External bag surface temperatures were within 0.20 degrees C of reservoir temperatures. Initial solution temperatures correlated with temperatures of the solutions after microwave heating (r = 0.895). No statistically significant differences were found between dextrose degradation product concentrations of unheated and heated solutions, including hot spots. No precipitates were observed microscopically.

CONCLUSIONS: Despite the presence of solution hot spots in bag infusion ports, 37 degrees C temperatures were achievable in the bag reservoirs with no evidence of increased glucose degradation. This outcome is assured if the initial temperature and the microwave conditions (procedure, time, mixing of solution) are held constant, and the external bag temperatures are measured after heating.


J Trauma. 2000 Jun;48(6):1052-6; discussion 1056-7.

Hyperthermic resuscitation is safe and effective after hemorrhagic shock in dogs.

Wiley D, Sheaff C, Nagy K, Reiman H Jr, Leslie C, Barrett


Department of Surgery, Mt. Sinai Hospital, Chicago,

Illinois, USA.

OBJECTIVE: To show that resuscitation from hypothermic, hemorrhagic shock using 65 degrees C intravenous fluid results in a more rapid return to euthermia compared with 40 degrees C intravenous fluid, without significant endothelial or hemolytic injury.

DESIGN: Fourteen anesthetized beagles (10-12 kg) were cooled to a core temperature of 30 degrees C and hemorrhaged to a mean arterial pressure of 40 to 45 mm Hg for 30 minutes. The animals were randomized to receive either 65 degrees C or 40 degrees C intravenous fluid through a specially designed catheter at a rate of 80% of their blood volume per hour until euthermic (37 degrees C) or for 2 hours.

MATERIALS AND METHODS: Blood pressure, pulmonary artery pressure, heart rate, and core temperature were continuously monitored. Blood samples were collected at baseline, after hemorrhage, 2 hours of resuscitation, and at postmortem examination after 7 days of survival. Laboratory measurements included complete blood count, plasma-free hemoglobin, and osmotic fragility. Values were compared using the Student's paired or unpaired t test with p approximately 0.05 indicating significance. Postmortem examination included light microscopy of the proximal superior vena cava or right atrium.

RESULTS: Animals receiving 65 degrees C intravenous fluid warmed 3.6 degrees C/hour, significantly faster than the 40 degrees C animals (1.9 degrees C/hour). There were no significant differences in plasma-free hemoglobin or osmotic fragility. Endothelial injuries were found in two animals in each group. These defects occurred along the path of catheter insertion and not at the infusion site.

CONCLUSIONS: Central intravenous fluid at 65 degrees C is a more rapid means of treating hypothermia than standard 40 degrees C intravenous fluid. It is safe even in hypovolemic animals.


J Emerg Nurs. 1991 Apr;17(2):68-9.

Comment on: . J Emerg Nurs. 1989 Sep-Oct;15(5):416-20.

Questions about hypothermia: speed of rewarming and use of microwave ovens to rewarm i.v. fluids.

Berman WL.

Ann Emerg Med. 1986 Feb;15(2):228-30.

Warming nondextrose crystalloid in a microwave oven.

Werwath DL, Schwab CW, Scholten JR, Robinett W.


Aust Nurs J. 2001 Oct;9(4):35.

I.V. fluids and microwaves oven safety.

[No authors listed]


Surg Gynecol Obstet. 1985 May;160(5):400-2.

Rapid warming of infusion solution.

Yamada Y, Yasoshima A.

A useful method was developed to warm solutions rapidly used for infusion and peritoneal irrigation, frozen plasma and blood for transfusion. It takes only two minutes to warm 1 liter of saline solution from a room temperature (24.5 degrees C.) to a body temperature (37.0 degrees C.) with the 600 w electronic range. The time necessary to warm a solution to any temperature can be simply determined. With an infrared sensor, the time setting is not necessary.

A large volume of a solution can be rapidly warmed. The time necessary to warm any solution can be shortened with higher wattage. Whole blood did not suffer any change from the rapid warming. A living fish was also not damaged by the electronic range, which directly vibrates and heats water molecules with high frequency electromagnetic waves. With the present method, troublesome warming procedures which have been done in many hospitals, even at midnight, are not necessary anymore.


Migration testing of plastics and microwave-active materials for high-temperature food-use applications.

Castle L, Jickells SM, Gilbert J, Harrison N.

Ministry of Agriculture, Fisheries and Food, Norwich, UK.

Temperatures have been measured using a fluoro-optic probe at the food/container or food/packaging interfaces as appropriate, for a range of foods heated in either a microwave or a conventional oven. Reheating ready-prepared foods packaged in plastics pouches, trays or dishes in the microwave oven, according to the manufacturers' instructions, resulted in temperatures in the range 61-121 degrees C. Microwave-active materials (susceptors) in contact with ready-prepared foods frequently reached local spot temperatures above 200 degrees C. For foods cooked in a microwave oven according to published recipes, temperatures from 91 degrees C to 200 degrees C were recorded, whilst similar temperatures (92-194 degrees C) were attained in a conventional oven, but over longer periods of time. These measurements form the basis for examining compliance with specific and overall migration limits for plastics materials. The testing conditions proposed depend on the intended use of the plastic for microwave oven use for aqueous foods, for all lidding materials, and for reheating of foods, testing would only be required with aqueous simulants for 1 h at 100 degrees C; for unspecified microwave oven use, testing with olive oil would be required for 30 min at 150 degrees C; and for unspecified use in a conventional oven testing with olive oil would be required for 2 h at 175 degrees C. For microwave-active materials, it is proposed that testing is carried out in the microwave oven using a novel semi-solid simulant comprising olive oil and water absorbed onto an inert support of diatomaceous earth. The testing in this instance is carried out with the simulant instead of food in a package and heating in the microwave oven at 600 W for 4 min for every 100 g of simulant employed. There is an option in every case to test for migration using real foods rather than simulants if it can be demonstrated that results using simulants are unrepresentative of those for foods. The proposed testing conditions were validated as being realistic by measurement of the specific migration of

various components from different plastics into foods under actual conditions of use and comparing with migration into

simulants. Migration of plasticizers from PVC and VC/VDC copolymer films was monitored for both microwave reheating and cooking of foods. Total oligomer concentrations were measured from poly(ethylene terephthalate) (PET) trays, and volatile aromatics from thermoset polyester trays, using both types of container in microwave and conventional



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So the question still remains what is the "BEST" way to deliver warmed fluids to your patient, instead of shocking them? or getting ice cubes forming in the lines and infusing abnoxiously cold fluids... remembering "DO NO HARM"!

Well.... this is what I came up with....why in fact heat the IV bags at all?

The heat loss "from the bag to the patient is my biggest headache" .....in -25 C and a lovely breeze out of the north west! I just can't do this in my present deployment, as not many helos have a microwave as an option, let alone a proper IV hook.

I digress.

So I use an approved "disposable heat pack" (lots of different types on the market that have been approved as to not burn when applied directly to skin) test them so you get a consistent heat range, just drip the fluid onto a thermometer to see what temp. your delivering at the patient site. I coil the "extra long med set line" in an "S" shape, then tape it securely in the heat pack using 2 like a sanwich and closer to the patient the better, about 6 inches was found to be acceptable for temps in the 36 to 41 C range (I use the real cheap carbon/oxygen activated ones the hand/foot warmers as they last up to 8 hours) about a buck and a half too, thats the scottish heritage speaking there! :wink:

Any other thoughts on this or other suggestions I am all ears.


Late entry: we have played around with the "heaters" for MREs as well, the water activated type for the IV bags themselves....be very, very careful with is method as they get damn hot really fast, we melted a 1000 cc bag cause we got talking, it is quick and dirty trick when you miles/kms from a warm enviroment....but don't look away for more than 1 minute, this method of heating IV bags is great if you are using then "JUST" as heat packs to groin or axuilla areas, but wrap them and pad them in towels PLEASE! before applying. Your Mileage may vary, and I am not suggesting any use this untill you get it approved by your medical director, mine volunteered to be the gueani pig, and was nice and toasty in the SKED.

oops another cheers.


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Well, you could use something like this,

TA-200%20Horizontal%20200x150.jpg ,

that connects with the IV tubing between the patient and the bag and heats the fluid there.

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I have worked with Thermal Angels and like them, they are somewhat expensive. I would not microwave an fluid.. I attended a hearing against a nurse anesthetist whom microwaved fluids and they removed her license, citing references of endangerment.

R/r 911

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Are you aware of the "enFlow" IV fluid and blood warmer? It advertises itself as palm size and "delivers fluids/blood at a continuous 40-degrees C from KVO to 200 ml/min". It is dry heat and "can be placed close to [the] infusion site to minimize heat loss". It is "low cost". (Quotes from the magazine advertisement for it.)

http://www.enginivity.com is the Web site for it (it is made by Enginivity LLC).

Didn't know if you all knew of it yet or not. You can get a free trial of it, but I don't know if that is only for people who got the magazine mail-back card or not - you can probably call or e-mail and ask.

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