10 Things to Review When Selecting a Blood / Fluid Warmer

Your EMS medical director has added blood administration to patients suffering from hemorrhagic shock to your protocols. Cool right? Now the EMS Chief and purchasing officer have a new set of problems, one of which is choosing the right blood warmer for your company. There’s a lot to consider, and in this article I’m going to give you my top 10 things to look for when shopping for a new blood/fluid warmer.

1. Cost– Yes, none of us like to admit it, but cost of equipment is a major factor when deciding on new equipment. There is a lot more that goes into cost than just buying the capital equipment. You need to consider costs of disposables (and these prices vary greatly), accessories like mounting brackets and spare batteries (by the way, have you considered in your budgeting that batteries typically have a limited lifetime and that they need to be replaced every 3 years or so?), and support. At the end of the day, if the company doesn’t think they can afford it, they’re not going to buy it. This can result in buying a cheaper alternative product that lacks performance. There are blood/fluid warmers however that have figured out how to optimize the cost vs performance equation.
2. Needs to Fit Your Role– In EMS we operate in all kinds of conditions. But rarely are those conditions neat, orderly, spacious, and controlled. We work out in the field and our equipment needs to be able to handle that. Buy a warmer that can be attached to an IV pole on your cot, but also can be fastened multiple different ways such as with a carabiner or a strap. We, as prehospital providers, find ourselves in weird situations sometimes and we need equipment that can hang with us. The fluid warmer should be very portable and lightweight. I’ve been on a few calls where I had to leave equipment in the truck just because it wasn’t portable enough. Your fluid warmer should also be durable. Check your warmer’s IP rating to see if it can handle dust, dirt, and wet environments. An IP rating of 56 is more than adequate to handle any austere location. If you are a HEMS agency then you need a warmer that complies with Safe-to-Fly and Air-Worthiness requirements.
3. Immediate Warming and Real Time Sensing / Temperature Adjustment– having a heating element that is in contact with the IV tubing or cassette and set at a certain temperature isn’t the best technology out there. The most advanced warming solutions will safely warm blood in just a few seconds, thus ensuring that the patient gets blood/fluids at the right temperature nearly from the first drop. These advanced solutions sense the fluid temperature hundreds of times per second and adjust the warming in real time in accordance with the flow rates so that the patient would get blood/fluids at body temperature at all times. This becomes really important when using intermittent (bolus) flow methods compared to continuous flow, since intermittent flows demand the warmer to react in fraction of seconds to rapid flow changes.
4. High Flow Rate Capable– not all warmers are created equal. You want to ensure that you are giving your patient warm blood/fluids, especially when there are high flow rates (say, around 200 mL/min). Basically, can your fluid warmer heat fluids at a rate fast enough to body temperature and maintain that temperature throughout the transfusion? This becomes vitally important when giving blood. Blood is stored at 4℃, but needs to be warmed to 38℃ before entering the body. Why? Because giving cold blood to your patients is going to decrease their core temperature. And for every decrease in core temp by 1℃, you decrease your coagulation function by 10-15%. So we need warm fluids from a cold bag, we need it fast, and not too hot. That all may sound simple enough but there are only a few warmers on the market that are up to the challenge.
5. Ability to Warm Intermittent Bolus– This factor is huge, and if cost didn’t play such a huge factor, I would probably list this as my number one. Your warmer needs to be able to handle intermittent flows. If you’re curious about what that means, let me explain. Instead of continuous flow provided via gravity or pressure bag, intermittent flow utilizes push-pull methods, hand operated pumps, or Lifeflow-like infusers to rapidly infuse fluids over a short amount of time. Since the flow rate isn’t constant, the warmer you buy must be smart enough to detect these changes in flow and react immediately to ensure properly warmed fluids are being infused. Further, the warmer you buy must not break due to the elevated pressure (and we are talking about a lot of pressure!). Remember: bolus flows are typically applied towards your sickest patients. Therefore, make sure that they get the best level of care possible!
6. Patient Safety– The next thing you need to consider when buying a warming unit is the safety of the patient. All warmers in the market obviously have the right safety certifications to operate as per their intended use; however, some warming elements may be more prone to cause problems to the patients than others. Our job as providers is to first do no harm. We should diligently try to fulfill that by ensuring that the equipment we use on our patients isn’t going to do any unnecessary harm to them. For example, did you know that 3 warmers with aluminum heat exchangers have been recalled over the past 2 years or so due to toxicity concerns? A study found that IV fluids had elevated levels of aluminum after passing heating elements containing aluminum. Of course, there is more to safety than just aluminum heat exchanger: go ahead and check with the supplier about overheating safety mechanisms, system’s over- and under-heating alerts, thermal shutdown mechanism, potential for excessive sheer-force and cavitation, and so on.
7. Reliable Power Source– As with all the equipment we carry in EMS, a warmer should come with compact, but powerful batteries. You’re gonna want a battery with enough power to warm the fluids to the correct temperature regardless of their starting temperature, and be able to have an efficient delivery rate. Plan for battery capacity that is capable of warming at least double the volume of blood products that you carry since additional blood products may be pushed to the point of injury and the last thing you want is to deal with battery replacement in the field. You also need the battery to be rechargeable and have extra batteries on a charging station to switch out in case it has been fully exhausted. And as briefly mentioned in [1] above, don’t forget to check what the replacement cost for the battery is.
8. Easy To Use– Let’s face it, our equipment needs to be dang near dummy proof. It’s not that we as prehospital providers aren’t smart (nothing could be further from the truth). But when “you know what” hits the fan, our heart rates increase and our fine motor skills and cognitive abilities decrease. Therefore, it’s important to have equipment that is very simple to operate, including blood warmers. Speaking from experience, getting warm fluids into a patient wasn’t my only priority when I had a bad trauma patient. As medics we’ve got to secure an airway, assess breathing and possibly breathe for the patient. We have to get IV/IO access to start the fluids in the first place. We are also thinking of pain management and all the while praying to whatever deity we believe in that our patient doesn’t crash. During all of this we can’t be encumbered with a complex piece of machinery. One reason is that we might forget how to operate it. Secondly, we are less likely to use it if the equipment is too complex. So when looking for a fluid warmer, keep simplicity and ease of use in mind.
9. Continuum of Care– What we do in the ambulance isn’t just to keep the patient alive while they are in our care. We try to set the patient up for the best possible odds of survival throughout their stay in the hospital. We can do this in several ways including using warmers that use the same warming units as those used in the trauma bays and operating rooms. This way the same consumable can be used in the ambulance, then in the helicopter that transfers the patient to the ER, and then utilized in the OR. This makes the continuum of care more effective in that you aren’t switching out warming units every time the patient moves to the next echelon of care, reducing the time they have to wait for their next unit of blood to be administered. And yes, reutilizing the disposable also reduces the total cost for the health system, and the importance of being cost conscious has been already discussed.
10. Trusted Brand– Talk to other EMS agencies that use the warmer that you are interested in. Do they like it? What would they change about it if they could? Are they happy with the level of customer service that they get? There are several brands out there that warm fluids but you need to choose the right one for you. Look at studies comparing different types of blood warmers (see example Here). Another good source of guidelines to start off with is the one provided by the TCCC. Click to Here to read a summary of these guidelines.

That’s my list of things you should consider when purchasing a blood/fluid warmer. If you take each of these into consideration and do your research, I’m positive that you’ll come away with a choice in fluid warmer that you and the end users will be pleased with. Finally, if there is something that COVID taught us, it is that complex solutions lead to complex supply chains and therefore to many months of lead times when the unexpected strikes. Make sure that the consumable of your solution of choice is simple enough to manufacture in large quantities, fast! Make sure that there are no chips that need to be placed into this consumable, otherwise you will be at the mercy of the market availability of chips! If you think that this may not happen to you, take a look at the car and phone industries that are currently struggling with a shortage of a chip for their controller (as a rule of thumb, if the disposable’s price exceeds $100, it probably has a chip in it, or the manufacturing process is complex, or both). You need a solution that is simple and you need a partner that can commit to fast turnaround time from order to delivery. If you need a place to start, here’s my personal choice for fluid warmers. Do yourself a favor and visit QinFlow.com and check out the Warrior and Warrior lite models. These models meet all the requirements I mentioned above and more. These two models were built with EMS and Search and Rescue in mind. They were designed by Israeli Special Operations veterans for the Israeli Defense Forces. The Warrior has been in over 50 thousands of field tests with the IDF and other agencies in very austere environments, as well as hospitals, and they hold up exceptionally well. QinFlow’s solution to warming fluids is truly phenomenal, and the only one that can keep up with rapid bolus flows. The Warrior is also fielded with San Antonio Fire and many other HEMS units around the Nation. If you’re curious about how much money they could save your EMS company use their saving calculator. If you do your research, you will find out that the Warrior provides the best performance at the lowest cost of ownership; a true win-win.