Author Archives: Stephen Alexander

Why Does Blood Need to Be Warmed?

I’m a big believer in knowing why you are doing something and not just following blindly because your protocols tell you to. In this article I’m going to talk about why we warm blood before giving it to patients. The World Health Organization strongly recommends warming blood products when they are given at rates at and above 100mL/min. We can cause serious harm to our patients, even cardiac arrest, when we infuse cold blood. While cardiac arrest is a rare consequence of cold transfusions, hypothermia is not. In fact, up to 66% (2 out of 3) trauma patients are hypothermic upon admission to the hospital. That’s an alarming number that I think we as prehospital care providers can change for the better.

Let’s think about our trauma patient for a second. We arrive on scene to find a person who has been in a car accident, or shot, or fell off a ladder. Regardless of the mechanism of injury, what we know for sure is that they have been in this condition for some period of time (unless you witnessed the accident happen in front of you). What’s the average response time of your agency? If you work in a rural or remote area, it could be an hour or even longer before you arrive on scene. During this time your patient is being exposed to the elements. Even in warm temperatures, trauma patients can become hypothermic quickly. And if your trauma patient is hypovolemic due to blood loss, they are losing the ability to retain what heat they have.

Now let’s consider the path our trauma patient is going to take on their road to recovery. We as prehospital providers are going to provide care in the field by stabilizing the patient’s injuries and starting the resuscitation process by obtaining IV access and infusing blood products. Then we are going to transport them to the nearest appropriate facility where they will continue their journey to recovery. Keep in mind our transport time is probably going to be as long as our response time. Finally, once at the hospital, trauma teams will expose the patient again to do their own assessment. The patient may require surgery also. This means being exposed in a cold OR and being put under by anesthesia. (Note that anesthesia impacts the body’s ability to thermoregulate.) Then our patient will spend time in PACU and finally ICU. 

That’s a long time for your trauma patient to be without warmed blood. We as providers can stop this from occurring by limiting exposure and warming blood products before they are infused into the patient. Trauma patients that are admitted to the ICU with hypothermia have a significantly greater risk of mortality than those patients who are normothermic upon arrival (Balvers 2016). We as prehospital providers can set our patients up for the best possible odds of survival by keeping them warm. One way we can do this is simply by limiting the amount of time the patient is exposed. Keep the patient covered with heat reflective blankets when not actively assessing the patient. The other way we can prevent hypothermia in our trauma patients is to ensure that we warm blood products, which are stored in coolers at near-freezing temperature, prior to infusing them to patients. 

So that’s the first reason we warm blood before giving it to our patients, to help in preventing hypothermia. Another reason we need to warm blood before infusing is because blood doesn’t work when it’s cold. What do I mean by this? The function of blood is to carry oxygen to our tissues and remove waste products. Blood also clots to prevent excess bleeding when vessel damage occurs. However, the enzymes that carry out these functions can’t work when blood is cold. Blood is stored near freezing to prevent growth of bacteria and to increase shelf life, but the life-giving functions of blood only work when blood is warmed back to body temperature.  

The way oxygen is transported through our body is by attaching to hemoglobin within red blood cells. When red blood cells circulate through the pulmonary arteries, the oxygen diffuses into the blood and attaches to hemoglobin. When blood circulates to tissues that are in need of oxygen, the oxygen molecules leave the hemoglobin molecule and diffuse into the cells that need it. There are several factors that affect how well oxygen binds to hemoglobin. These same factors affect how well hemoglobin offloads oxygen to cells that need it.

This relationship can be visualized by the oxyhemoglobin dissociation curve. That’s a fancy sounding name but don’t let it intimidate you. The curve, shown below, has the amount of oxygen (measured in partial pressure) on the horizontal axis and the saturation (percentage) of hemoglobin on the vertical axis. As the amount of oxygen increases, so does the percentage of saturated hemoglobin. When red blood cells pass through the lungs, you want hemoglobin to have a high affinity for oxygen. When blood reaches the tissues that need oxygen, you want hemoglobin to have less affinity for oxygen.

Factors that affect this phenomenon include temperature and pH among others. At increased temperatures, hemoglobin holds on to oxygen less tightly. The heat produced by metabolism in cells causes the hemoglobin to bind less tightly and therefore offload the oxygen to tissues that need it. Now what happens if we cool things down by infusing cold blood? Well the oxygen is going to stay stuck to hemoglobin and not go to the cells that need it like your heart, liver, kidneys, and brain. This is one very important reason we warm blood, especially when bolusing it. 

This brings us to our third reason we warm blood products; clotting factors. The way our blood clots is described by the clotting cascade. I’m not going to get into details, but just know that it requires several different enzymes, all to function properly, in order to clot. Most enzymes have a physiologic range at which they perform best. Those conditions are usually at normothermic temperatures (38), and physiologic pH (7.35-7.45). Outside of these parameters, enzyme activity suffers, and clotting factors are no different. At hypothermic temperatures, clotting factor activity decreases. This results in more blood loss, and more heat loss, less oxygen carrying capacity and eventually death if not corrected. 

These three factors; hypothermia, coagulopathy, and acidosis make up what is known as the trauma triad or lethal triad. The lethal triad shows the relationship between these three conditions and how one propagates the other. However, when one side is corrected, the other two sides of the triangle are also corrected. Thus, when we combat hypothermia by first warming blood products before administering them, we are also helping to correct acidosis and coagulopathy. 

I hope that by now you have a good idea of why you need to warm blood before giving it to the patient, especially when giving in rapid, mass transfusions. The more we know as prehospital providers, the better we can treat our patients and improve their odds of survival. By warming blood, we increase the oxygen delivering capabilities of red blood cells. We also ensure that the clotting factors are able to function properly and help control bleeding. 

If your agency is thinking about starting to carry blood products (which is an excellent idea in my opinion), you also need a warmer that is up to the job. QinFlow’s line of Warrior and Warrior lite warmers are the ideal solution for the pre-hospital and inter facility setting. They also make products that work in the ER/OR settings, all while using the same consumable, to eliminate waste and transition from one warmer to another seamlessly. QinFlow’s consumables are 100 percent aluminum free and utilize a simple design free of microchips. The former eliminates aluminum toxicity concerns (read my article “Aluminum: The Hidden Danger in Blood Warmers”) while the latter ensures affordable per-use price as well as product availability to meet demand, a major issue that has surfaced during COVID (read my article “COVID: Weak Points Exposed and Lessons Learned”). 



Balvers K, Van der Horst M, Graumans M, et al. Hypothermia as a predictor for mortality in trauma patients at admittance to the Intensive Care Unit. J Emerg Trauma Shock. 2016;9(3):97-102. doi:10.4103/0974-2700.185276

Ghosh I, Haldar R (2019) Blood warming in trauma related transfusions-Precepts and practices. J Cardiovasc Med Cardiol 6(4): 094-097. DOI: 10.17352/2455-2976.000101

COVID: Weak Points Exposed and Lessons Learned

Saying that the past two years have been unpredictable is an understatement. In the winter of 2019 our world changed in a way we could not have foreseen. COVID-19 puts a huge strain on our economy and healthcare system. While very unfortunate, crises such as COVID expose us where we are weakest. During the pandemic we have seen shortages in manufacturing supplies such as computer chips and other products. This brings up a great point of another consideration to take into account when purchasing a new piece of medical equipment. This article will focus on blood/fluid warmers, however regardless of the product you are in the market for, these same considerations will apply. 

The cause for supply shortages is multifaceted. Some reasons being increased demand for the product, as is the case for plastics. COVID put a huge demand for plastics just within the medical industry alone. The increased need for ventilators and disposable tubing and PPE are just a few of the products that caused the increased demand. Other factors include decrease in supply due to material shortages or low workforce from manufacturers. We saw that many agencies mandated that all non-essential laborers stay home to slow the spread of the virus. Those companies that did stay open often operated below max capacity in the factories to promote social distancing between employees. In reality all these factors combined resulted in shortages in vital supplies.

Of all the materials to have a shortage, plastics would probably be  the last guess for a lot of people. Yet that is what we are seeing today. Due to raw materials shortage and high demands, it’s becoming increasingly difficult for companies to maintain production of plastic disposables. This is important to consider because companies such as 3M utilize an all plastic consumable in their blood warmers. Consumers, such as EMS agencies and hospitals are having increased difficulty in obtaining disposable sets for their warmers. This should raise immediate concern. Often in trauma situations, mass transfusion protocols are necessary. Blood given rapidly must be warmed to body temperature prior to being infused into the patient. If you have no tubing set for your blood warmer, how can you warm blood and save your patient’s life?

Another consumer good that is experiencing shortages is microchips. Reasons for microchip shortages are many including manufacturing plants closed due to COVID. However that’s not the only way COVID caused the microchip shortage. Consumer consumption of chips drastically increased as people were shut indoors. Purchases in laptops, gaming consoles, and other electronic devices. Car sales also were higher than what was expected. Electric vehicles are also gaining popularity of consumers and more and more automotive companies are branching into that market. As such, microchip consumption continues to increase. Another reason for the shortages is sanctions against the Chinese tech companies. With a centralized means of production, most chips are produced in Asia. Only 12 percent of chip manufacturing is conducted in the U.S. Therefore sanctions really cut into the supply of chips this year.

Yet another reason for a microchip shortage is the current shipping crisis. When the Suez was blocked, chip companies were among the many who suffered. Chip companies were unable to receive necessary materials nor able to send their goods to consumers. This compounded with decreased manufacturing capacity due to factories being shut down, increased demand from consumers wanting tech goods that use microchips, and sanctions against the world’s largest producer of microchips, we can see how all these conditions have led to a mass shortage of microchips. 

Products that utilize microchips are being delayed in manufacturing. This includes blood warmers that use microchips in their disposables. Again we face the same challenge as discussed before. When utilizing a complex disposable solution for blood warming, consumers are at the mercy of manufacturers. When supply chains are interrupted, as has been the case with this pandemic, our patients suffer the cost when utilizing overly complex solutions. 

So what is the answer to these shortages? One answer is to use a blood warmer that comes with a simple design, that is microchip free, and uses readily available materials to produce. QinFlow’s Warrior warming set fits that description. They do not utilize microchips and are made from materials that are easily sourced. QinFlow’s Warrior disposable uses stainless steel, PVC tubing, and EPP foam for a lightweight yet durable product. The great news is QinFlow’s line of products are also aluminum free, which is a big deal if you have been paying attention to recent recalls of infusion devices containing aluminum. QinFlow’s disposables are also competitively priced. 

Another great advantage of utilizing QinFlow is that their disposable is compatible with ALL the warmers they produce. That’s right, you can use the same consumable from the Warrior lite while in the field to the Warrior AC used in operating rooms and intensive care units. This streamlines the transition of care of the patient while also reducing cost to the patient and waste produced which is great for the environment. 

We see that COVID showed us that using complex solutions puts the consumer at risk of supply shortages. When opting for a simpler solution, this allows more reliability in supply chains. The engineers at QinFlow have known this for a long time. They have backgrounds in Israeli Special Operations and Search and Rescue. People from these professions know that simpler solutions are often more reliable than overly complex designs when the unknown strikes. This is why QinFlow has not experienced the shortages that other companies offering more complicated designs have suffered. This allows them to keep supplying their customers who are saving lives on the front lines the peace of mind of a reliable product in these uncertain times. 

Aluminum: The Hidden Danger in Blood Warmers

Recently, there have been growing concerns from regulatory agencies, such as the FDA, as to the safety of aluminum containing medical devices, especially those involved with the infusion of fluids into patients. Just this past year, the FDA has recalled six intravenous fluid warming products due to evidence showing increased levels of aluminum. According to the FDA, “Exposure to toxic levels of aluminum may not be easily recognized and exposure effects may cause serious adverse events including death”. Some manufacturers have provided a potential solution by using coated aluminum surfaces. While these solutions certainly show improvement, they still release detectable levels of aluminum into infused fluids. The question is, are these levels safe or not? In this article, I will unfold some information about the recent recalls, the risk in aluminum, and other safety considerations regarding blood/fluid warmer. But I would like to start by making it clear to the reader that —

I’m not an expert, just an informer. First let me say that I am no expert in the field of toxicology, therefore it is beyond me to say for certain the safety of aluminum based warmers. That job I leave to regulatory agencies such as the FDA. However, once I reviewed the evidence and recalls put out by the FDA, I felt that I needed to make sure other providers are aware of the risks and recent recalls of these products. We should trust the sophisticated and rigorous medical approval system that we have in place. Therefore, it is my viewpoint that aluminum-based heaters that are regulatory cleared must be 100% safe to use. Nonetheless, we as critical care paramedics, nurses, and physicians must, as a minimal requirement, understand the risks associated with this method of warming. We owe it to our patients to be as well informed and up to date with the risks of certain treatments we provide, especially given the growing number of recalls of aluminum based warming devices.

Peer reviewed research of the risks. Aluminum toxicity can lead to a plethora of diseases ranging from Alzheimer’s, autism, breast cancer, to pancreatitis and pneumonia just to name a few (Igbokwe, 2019). In infants, aluminum toxicity is associated with impaired neurological development (Bishop, 1997). What’s even more alarming is that aluminum can also cause decreased iron absorption and anemia. Imagine trying to infuse blood products to correct anemia, and exposing your patient to toxic aluminum that causes the problem you are trying to reverse! Recalls of blood/fluid warmers due to the potential of aluminum leaching are typically identified as Class I recalls. These are the most serious as they are for devices that may cause serious injury or death! Patients most at risk are pediatric patients, specifically neonates and infants, pregnant women, geriatric populations, and those with decreased renal function or on dialysis.

Why manufacturers like to use aluminum in fluid warmers. Aluminum is used in a wide spectrum of medical devices, and when compared to other materials, it’s easy to see why. Aluminum has a large strength-to-weight ratio. This means that aluminum compared to other materials is stronger and lighter. Aluminum is also a good thermal conductor. In addition, aluminum is very malleable, thus it can be formed to almost any specification. Aluminum is a plentiful material as well; in fact, it is the most abundant metal in earth’s crust, making it very cost effective. All these reasons are why we find aluminum, not just in medical equipment, but in our everyday lives. It’s a good, plentiful, strong material that has countless applications. However, this article seeks to explain why using aluminum may not be the best option with respect to blood/fluid warmers.

Advancements in analytical technology have changed the stance on aluminum. If aluminum is unsafe, then why did the FDA approve of its use in fluid warmers initially? The answer is basically “you don’t know what you don’t know”. Regulatory agencies such as the FDA are only as good as the technology they have available to them. In recent years, advancements in technology have enabled regulators to measure more accurately the levels of aluminum produced from blood warmers that use that material. Keep in mind that when the FDA approved aluminum containing medical devices, it was before sensitive testing instruments were used to detect the minimum allowable limits of aluminum that is set forth today. This means that there was no way of knowing if these devices were leaching aluminum or not into the infused fluids. Therefore, these devices were developed, approved, and put on the market. Only until recently are regulatory agencies capable of measuring the threshold limits produced by these products, and the results — for some of these devices — are concerning.

Increased concern over aluminum containing warmers evident by 3 FDA recalls of 6 warming devices in just 6 months. Since March of this year there have been three separate recalls on fluid warmers that contain aluminum. The FDA has warned that the aluminum used in the heating elements is leaching into the fluids and being infused into patients. In March of 2021 ThermaCor 1200 disposable sets were recalled. The customers were notified of a Toxicological Assessment that there was potential aluminum leaching into fluids. Later, Eight Medical International’s Recirculator disposables were recalled in July of this year. The most recent recall was of 4 Smith Medical’s Level 1 configurations for the same reason, leaching of aluminum. This is on top of yet another global recall of the enFlow device in 2019. With so many recalls in such a short period, it does raise concern that blood warmers containing aluminum in their heating elements pose a potential risk to patients. You can read the FDA’s Letter to Health Care Providers on the recent recalls here.

Researchers find that coated aluminum may not prevent leaching. Manufacturers of blood/fluid warmers with aluminum heaters often make a distinction between uncoated and coated aluminum heaters. The latter (i.e. coated aluminum) is expected to be safer for patients, compared with non-coated aluminum. This makes sense. However, even blood/fluid warmers that utilize coated aluminum may pose a risk to patients. In June of 2019, researchers found that aluminum was still detectable in fluids infused with devices that use coated aluminum. The study compared aluminum release of coated and uncoated fluid-warming devices. The results of the study found that while aluminum release was less in coated devices, it still was elevated above baseline. In fact, the researchers stated that “our methodology does not have the ability to differentiate between the concentrations we measured and the FDA threshold.”(Perl, 2019).

Manufacturers may be predisposed to maintain the status quo. Despite the recent recalls, the default claim of manufacturers that use aluminum heaters is that the aluminum remains below the acceptable limits set forth by regulatory agencies. However, the accuracy of this claim is debatable, and the data that is used to defend these claims is often open for contradicting interpretations. At least in one recent case, the Canadian FDA publicly refuted such a claim proposed by Smiths Medical. Without getting into the specifics of this particular case, it’s easy to understand why manufacturers may resist a change. It goes without saying that they must trust that their solution is 100% safe in order to commercialize it. However, is it possible that this high level of confidence may also be fueled by some sort of an ‘organizational predisposition’? Let me try to explain: these manufacturers assumed significant risks and invested millions of dollars to overcome the demanding regulatory barriers that stand between any medical device innovation and the marketplace. Even after commercializing the product, they had to invest significant budgets in continuous engineering and regulatory affairs. Therefore, they need to see positive returns following these huge investments, otherwise future innovation might suffer. Certainly, a very complex and delicate situation that manufacturers must contend with.

Other associated risks of blood/fluid warming. It should be noted that warming fluids does come with other risks besides aluminum leaching. Let’s review some of these other risks:

  • Hemolysis. One risk is hemolysis due to the age of blood products given. This isn’t necessarily a risk associated only with warming blood products, but just a general risk overall. As the products age, red blood cells have a higher chance of rupturing. That’s why it’s important to infuse blood products before the expiration date.
  • Excessive sheer force, turbulence, and cavitation. Hemolysis might be accelerated by suboptimal design of the fluid path of the warming element. You expect your blood/fluid line to be smooth and homogeneous, then why make exceptions for the warmer’s fluid path (or as it is often called, the cassette)? In other words, preferably the fluid path of the warmer should be designed in an ‘undisrupted’ fashion. That is, and to the extent possible, the fluid path design should avoid for example abrupt turns, connection points, and flow changes (e.g. from a wide to narrow carrier and vice versa) in order to minimize sheer force, turbulence, cavitation, and air bubble formation, to name just a few potential complications associated with high flows and elevated pressure. Why don’t you simply try to look under the hood of your chosen warmer?
  • Over/under heating. Another risk is over/under heating the fluids/blood being infused. I believe that under heating is a bigger and more common issue especially with high flows and with intermittent flow methods. If your agency requires high flows or uses an infusion device that utilizes intermittent flow, most warmers cannot keep up with the job. If the warmer can’t physically warm the fluids to body temperature at the rate being infused, you’re introducing hypothermic fluids into your patient. Even room temperature fluids are far below body temperature, especially for severely sick patients suffering from shock.
  • Aggressive heat transfer process. It seems logical that a relaxed heat transfer process from the heat exchanger to the blood/fluids is safer than an aggressive heat transfer process. Therefore, why not add this to your evaluation criteria? The most relaxed heat transfer mechanisms require a warming surface of 15-20 ml. We all love solutions with small priming volume, but we need to acknowledge that this may come at a ‘price’. And the price is a potentially aggressive heat transfer process from the heater to the blood, especially at elevated flows.
  • Unavailability. One of the most prominent risks associated with your blood/fluid warmer over the past years is that you will not be able to use it since there is a shortage of disposable sets or a recall of the device. Ask users of enFlow, Level 1, ThermaCor, Thermal Angel, and several others to understand how frustrating this can get. And if there is one thing 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. Therefore, 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, which is currently experiencing significant shortages.

A solution. Clearly the wrong answer to prevent aluminum leaching from blood/fluid warmers is to not utilize a warmer. Myself and other colleagues have written extensively about the importance of warming fluids, especially blood products in rapid transfusions. You can read some of those articles here .One practical solution to this problem is utilizing a warmer that is aluminum free in the first place, or, if you decide to use an aluminum warming solution, then do your due diligence about the solution. There are several prehospital and hospital solutions that are aluminum free, such as the Thermal Angel, Quantum, and Ranger, to name just a few. QinFlow’s Warrior is another excellent example of an aluminum-free warmer: it has battery and AC power sources and it therefore fits both prehospital and hospital settings. It has amazing performance levels, measured in maximum delivery rates. And as importantly, its per-use price is very competitive. You can read more about the Warrior here.

Summary & Conclusion. New, more sensitive, monitoring technology has made it possible for regulatory agencies to detect trace levels of aluminum, before unknown to us. Exposure to toxic levels of aluminum, according to the FDA, “may cause serious adverse events including death”. With that information, three recalls of 6 devices have been issued within the past few months over growing concern of elevated aluminum levels in fluids infused by products containing aluminum heating elements. We’ve seen that not even coated aluminum surfaces prevent leaching into fluids. The only way to ensure that zero aluminum is leaching into your patients is most probably to utilize solutions that are aluminum free. While there are several options out there, the QinFlow’s Warrior is a good place to start. Their fluid path is 100 percent aluminum free. They are also amongst the most cost efficient solutions on the market. A true win win. QinFlow’s disposable cassettes have a comfortable and gentle priming volume of 19mL. Finally, the Warrior is rugged enough to withstand high pressures of intermittent flow and can warm near freezing blood products to body temperature within seconds, safely!




Bishop NJ, Morley R, Day JP, Lucas A. Aluminumneurotoxicity in preterm infants receiving intravenous-feeding solutions. New England Journal of Medicine 1997;336: 1557–61

Igbokwe, I. O., Igwenagu, E., & Igbokwe, N. A. (2019). Aluminium toxicosis: a review of toxic actions and effects. Interdisciplinary toxicology, 12(2), 45–70.

Perl, T., Kunze-Szikszay, N., Bräuer, A., Quintel, M., Röhrig, A.L., Kerpen, K. and Telgheder, U. (2019), Aluminium release by coated and uncoated fluid-warming devices. Anaesthesia, 74: 708-713.

Does Your Warmer Handle Intermittent (Bolus) Flows?

In a previous article I discussed the top ten things you need to look for when choosing a blood/fluid warmer. In this article I want to talk about one function that, in my opinion, is absolutely necessary for your warmer to have and unfortunately completely overlooked. That is the ability to warm and handle intermittent flows.

Let’s start with a short background: most EMS service providers rely on gravity flow or pressure bags to try to infuse blood/fluids into a hypotensive patient. They might, if they were lucky, get a couple hundred CC’s into the patient before they arrived at the hospital. From there, if the physician determined that the patient needed a rapid bolus, the trauma team could utilize their rapid infusers in hospital. So why don’t we use the rapid infusers the trauma units have in EMS? Well they are simply too large (let alone that they are not battery powered). The model of rapid infusers that I have seen used are as tall as an IV pole and very, very bulky. This is fine when you’re in a trauma bay where space is a given. But in the back of an ambulance, space is a very limited resource. So an answer to this problem was introduced by handheld, push-pull, and syringe style infusers that allow for rapid infusion of blood products or fluids, in a matter of minutes, in an intermittent fashion.

So what exactly is intermittent flow? Intermittent flow is a term used to describe the flow of fluids generated by infusing devices such as the LifeFlow, hand pumps, and other push-pull style methods that infuse blood/fluids at very high rates and volumes and under increased velocity to patients in need. Some of the intermittent flow methods have been around for many years. However, newer intermittent flow infusers have been introduced recently, especially in the EMS world. This has to do, to some extent, with the continuous expansion of blood programs across the nation: EMS teams discover that transfusing blood fast to patients is often tricky due to the viscosity of the blood.

How do these devices operate? LifeFlow for example is using a 10cc syringe that can be reloaded fast to deliver a unit of whole blood (~500cc) in just 2 minutes. Some push-pull methods are using a 60cc syringe and a 3-way stopcock to achieve the same effect. Similarly, a recently introduced high-flow hand pump uses a 50cc squeeze chamber and wide trauma line to deliver the same results. The point here however is that irrespective of the method being used, all these handheld infusers are designed to deliver a large bolus of blood/fluids in a relatively short amount of time, and they are all capable of exceeding 200mL/min!

Further, unlike continuous flow, and as the name implies, intermittent flow starts and stops abruptly due to the nature of how fluids are being delivered. These rapid flows and intermittent patterns are extremely challenging for your blood/fluid warmer. Therefore, if your agency is utilizing intermittent flow devices, or if you are considering using such methods in the future, then I highly suggest that you are using a blood/fluid warmer that is up to the job. The QinFlow’s Warrior is one great example of a warmer that has been designed to meet this challenge, and I will address it in greater detail later in the article. For now, I would like to share with you some of the clinical aspects of intermittent flows.

So now that we know what intermittent flow is and how they are generated, let’s address the question of which patient population we as providers are going to utilize it on? Intermittent flow devices are used for the sickest patients. These patients are suffering from hypovolemic shock and need fluids/blood now! Think of the patient who has suffered from severe hemorrhage, or fluid displacement such as in septic shock, or a dehydrated hypovolemic pediatric patient. Patients that fall into these categories don’t have time for gravity flow, pressure bags, or even the highest flow rates that standard IV pumps can produce (most max out at 999mL/hr). These patients have already utilized all of their compensating mechanisms and by the time you arrive on scene to help them, they can be just minutes from irreversible, decompensated shock. These patients are the sickest of the sick patients we are going to see. So these patients are going to be treated with rapid IV fluid/blood bolus before it’s too late.

This presents a problem however. Do you think it’s a good idea to infuse a rapid bolus of cold blood products (stored at 4℃) into a hypovolemic trauma patient? Some of you may know the answer, but I’m going to explain why for those of us who might not know exactly why this isn’t a good idea. Let’s look at the trauma triad. It’s a triangle with three conditions on each side. They are; hypothermia, acidosis, and coagulopathy. When one side gets worse, it causes a chain reaction to make the other side worse, thus creating a vicious circle that results in death if not corrected.

Let’s say we make the hypothermia side worse by bolusing cold fluids into a patient. In this scenario, I highly doubt that a provider would do this on purpose, however if you are using an inadequate blood warmer that can’t efficiently warm intermittent flows, you might do this unintentionally. How does this affect acidosis and coagulopathy? For every 1℃ in core body temperature, coagulation function decreases by 10-15%. Which means less ability to form clots and more blood loss. More blood loss means less oxygen delivery to tissues. Tissues deprived of oxygen revert to anaerobic respiration for energy production, a byproduct of which is lactic acid. This worsens the acidosis, which by the way also hurts coagulation and oxygen carrying capacity of red blood cells. Metabolic acidosis also decreases cardiac performance meaning less blood circulating in the body, triggering further hypothermia. Thus the downward cycle of death continues. All because we didn’t prevent the hypothermia side of the lethal triad.

However, when we warm the patient (via warm, rapid blood bolus), clotting factor activity increases, thus decreasing blood loss. Less blood loss means more red blood cells to carry oxygen to tissues. More oxygen to tissues means more efficient, aerobic respiration, and decreased lactic acid production, reducing acidosis. Correct the metabolic acidosis and your patient’s cardiac function will improve. Plus we are giving the patient blood products so more life saving red blood cells and clotting factors will be circulating in your patient!

So we can see that giving warm blood is absolutely essential in preventing the trauma triad! Better still when we can infuse those blood products via rapid (most likely intermittent) flow. But if we’re going to be rapidly infusing blood using intermittent flow, we need a warmer that is “smart” enough to recognize the intermittent flow pattern quickly, capable enough to warm those rapid flows, and responsive enough to stop the warming immediately when the infusion stops (i.e. this typically happens when the intermittent flow device reloads) so as to avoid overheating. And this process should go on and on until the transfusion is done. This is an extremely complex task for any warmer out there and not all blood/fluid warmers can deal with intermittent flows. In order to successfully handle rapid intermittent flows, a blood/fluid warmer has to meet four criteria. They are: real time temperature sensing, robust mechanical structure, high delivery rates/high efficiency, and optimal priming volume.

An example of a warmer that was validated to effectively warm intermittent flows is the QinFlow’s Warrior. The Warrior senses fluid temperatures hundreds of times per second. When a bolus flow is identified by the sensors, the Warrior’s highly efficient heat exchange process allows it to respond as necessary to warm the fluids to the proper temperature before being delivered into the patient. The heating will cease as soon as the sensors identify that the flow has stopped, avoiding overheating.

As discussed earlier, when using intermittent flow, your warmer also has to be able to handle the high flow rates that are pushed out by these methods. Intermittent flow mechanisms are capable of delivering more than 200mL over one minute, at high velocity! Having a warmer that can physically handle this elevated pressure is essential. If your warmer can’t withstand the high flow rates, it’s time to get a warmer that can. The last thing your patient needs is to have a warmer break in the middle of a blood transfusion.

Apart from physically withstanding the high flow rates and pressures of intermittent flows, your blood/fluid warmer has to be able to warm those fluids to body temperature just as fast. Whole blood is stored at 4℃ and needs to be warmed to 38℃ before entering the patient. At a flow rate of 200mL/min (or more), your blood warmer has to be able to perform this function. A critical part of warming fluids efficiently and adequately is to have sufficient priming volume. Sufficient priming volume allows the transfer of heat from the warmer to the fluids in a relaxed and incremental manner to ensure safe, yet rapid heating to match the high flow rates produced. The Warrior has a comfortable 19 mL priming volume which best fits the challenge of safely and effectively warming rapid intermittent flows.

I hope this article has shed some light on not only the importance of warming blood/fluids, but also how necessary it is that your blood warmer be able to handle intermittent flows. Fortunately, technology in EMS is ever evolving as we strive to better treat patients. Remember, you’re only as strong as your weakest link. The same goes for patient treatment. If your warmer can’t manage high flow rates and is the “weak link” in your treatment then it’s time to get a blood/fluid warmer that can.

It should not come as a surprise that the QinFlow Warrior can cope with the intermittent flow challenge. The engineers at QinFlow have roots in Israeli Special Operations and Search and Rescue. For decades these individuals have been coming up with solutions to save patients. Whether on the battlefield, natural disasters, or in civilian EMS, QinFlow’s experts have developed solutions with real world experience and application. The Warrior is one of their finest answers to solving the problem of blood/fluid warming in general and intermittent flow handling in particular across the entire continuum of emergency care. Irrespective of the infusion method used, from pressure bag to rapid intermittent flow methods, you can trust the Warrior to warm near freezing blood/fluids (4°C) to body temp within seconds! You can check out the Warrior and other solutions from QinFlow Here.

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 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.

10 Reasons Why Your Agency Needs To Carry Whole Blood

Medicine has improved a lot, especially pre-hospital. However, hemorrhagic shock still accounts for about 40% of preventable deaths due to trauma each year [1]. Much of our current knowledge of how to treat hemorrhagic shock was gained by the past twenty years of the War on Terror. We have learned that addressing massive hemorrhage actually takes precedence over airway as evident by MARCH and HABC treatment algorithms. So apart from stopping the bleed, we need to replace what was lost. By now we should all know that crystalloids and colloids aren’t going to cut it. If blood is what is coming out, blood is what needs to go back in. It’s that simple.

As with all new protocols there are people in opposition. That includes putting whole blood in the field for hemorrhagic shock. Whole Blood is either fresh (from a walking blood bank), or stored by refrigeration. Since it’s impossible to say for certain a patient’s blood type in the field, Whole Blood is type O pos for emergency use. Type O neg is very hard to come by because so few people have that blood type. Opponents say that it’s too risky to give to patients when you don’t know their blood type and also there’s too many logistics issues. Well, I’m here to tell you today that putting Whole Blood out in the field is possible and is what we should be doing in our patients best interest. So here are my top ten reasons why you should start a Whole Blood program

1. Research supports it

Both military and civilian entities have proven that Whole Blood works. They didn’t always know this though and this lack of knowledge had devastating consequences, especially on the battlefield. The Army Rangers ran into this problem when they tried to perform fluid resuscitation for hemorrhagic shock using only crystalloids. The results turned what little blood soldiers had left into diluted Kool-Aid. Civilian trauma centers also saw this in the 1980s-90s when drug related violence caused large numbers of gunshot wounds. Volume resuscitation using crystalloids led to worse patient outcomes.

In the early 90’s military trauma surgeons started using fresh whole blood as a result of shortages of stored components. Using whole blood showed great improvement in patient outcomes. Since then, there have been several case studies and retrospective studies showing that Whole Blood works for patients with severe hemorrhage.

2. Better than components

Whole Blood contains much more than what components do. Whole Blood contains all the necessary clotting factors and plasma ratio that components lack. Components are usually given in a 1:1:1 ratio of red blood cells, plasma, and platelets. This all sounds good in theory but actually delivers less than Whole Blood . Components deliver a hematocrit of only 29% as compared to 38% with Whole Blood [2]. There is also a lower platelet concentration in components compared to Whole Blood as well as clotting factors. And if there’s one thing that a patient needs when they suffer severe hemorrhage, it’s their clotting factors and platelets.

3. Other programs have laid groundwork

Programs like STRAC and agencies like Memorial Hermann’s LifeFlight, Cypress Creek EMS, and Harris County ESD #48 have really shown us that implementing a program isn’t hard, but the logistics need to be in place beforehand. States like Texas have led the way and we can follow the template that they use for our own and modify as necessary to fit your agency’s needs.

4. Easy to train

Nurses are allowed to start blood products in most states and paramedics are allowed to continue those same blood products. Whole Blood would be just another blood product that RNs and paramedics could use to treat their patients.

In pre-hospital medicine, simplicity is key. It’s hard to calculate fluid resuscitation for pediatrics when using components. Whole Blood makes it much easier. Give the patient the volume based on their weight from one bag of Whole Blood instead of divided between three different components.

5. Minimal equipment

EMS agencies including HEMS all carry the necessary tubing to administer blood products. Whole Blood can be given through the same IV tubing so no new/ additional equipment is needed. Compared to components, Whole Blood only requires refrigeration. Whole Blood is more compact, delivering all the components in one bag instead of three. This reduces the amount of IV tubing needed.

Blood needs to be warmed before being delivered to the patient. A blood/fluid warmer is an essential piece of equipment that you must carry. Make sure that your blood/fluid warmer can handle high flow rates (150-200 mL/min even at 4 degrees Celsius input temperature) while warming the blood to body temperature. Equally important, make sure that your warmer has the capacity to handle intense bolus flows (aka intermittent flows). Both requirements are not trivial to accomplish; therefore, make sure you have the right equipment. A recent study by Lehavi A, Yitzhak A, Jarassy R, et al., tested several brands and found that the Warrior by QinFlow was the best performing blood/fluid warmer on the market [3]. The study was later referenced by the Committee on Tactical Combat Casualty Care (CoTCCC) Advanced Resuscitative Care Guidelines and Management of Hypothermia Guidelines [4] [5].

6. Minimal waste

Opponents of Whole Blood in the field say that EMS won’t use it in time before it expires, thus increasing waste. However, programs such as STRAC and others have shown that partnering with a local hospital reduces waste. When a unit of Whole Blood gets close to its expiration date, that unit is then rotated into the hospital’s inventory where it is more likely to be used before it expires.
7. Medics want better protocols

Get any group of medics together who work for different agencies and eventually they’ll start talking protocols. It usually ends up being a competition about who has the best protocols. We like having the free-range to treat patients to the best of our knowledge. Medics will go on and on about RSI, field amputation, chest tube insertion. Now medics have heard about Whole Blood and they want to be able to say it’s within their protocols. Apart from pay, EMS agencies really only have what protocols they allow their medics to do that separate them from other agencies. It can be a great recruiting/retention tool to say you have the most up-to-date protocols.

8. Saves lives

When it comes right down to it, saving lives is why we got into this field. There is so much evidence from case studies that it should really be a no-brainer at this point. Whole Blood is the answer for a patient suffering from hemorrhagic shock. Old habits die hard however and that’s no more evident than in EMS. While most people agree that “We’ve always done it this way” is the most deadly saying, not much changes. Whole Blood isn’t something to be scared of, nor is it too complicated to get the logistics in place. Whole Blood is a simple solution to a very real problem. Patients are dying before they can get to an OR. Whole Blood given in the field can give them a fighting chance.

9. Minimal risk to patients

One major concern people have with Whole Blood is the risk it poses to females who are Rh negative and have childbearing potential. Whole Blood is O pos due to the emergent setting it’s given in. The risk people are worried about is an Rh negative female receiving a blood transfusion containing Rh antigen and producing antibodies that could later harm a fetus that is Rh positive in the future. One thing to consider is that a woman can’t get pregnant if she died from massive hemorrhage. Also there’s only about a 20 percent chance she will make the antibodies once exposed. Overall there is only about a 6 percent chance she will develop a life threatening condition to her baby. These disorders can be treated via intrauterine transfusions so the overall risk of infant mortality due to a blood transfusion is extremely low. We have to treat the hemorrhage before we start worrying about the risk it might pose to an infant years down the line. The woman’s life is at risk now, give her blood.

10. It’s the right thing to do

We as healthcare professionals have vowed an oath to help others in need. In order to do that we must keep up with the latest tested and proven treatments for our patients. We are our patient’s advocates. We must speak up for them when they cannot. It is our job to stay up-to-date on research and know what is best practice for our patients. Doing something because “that’s the way we’ve always done it” is wrong. Our patients deserve better. There are a lot of advances in medicine and all may not be practical to push out to the field of EMS. But whole blood isn’t one of them. Whole blood is more compact, easier to use, and all around better for our patients. It’s time to push Whole Blood out to the field where it is needed.

If you would like to read further about this topic please read the sources down below. To learn more about QinFlow and the Warrior blood/fluid warmer click HERE.

  1. Curry N, Hopewell S, Dorée C, Hyde C, Brohi K, Stanworth S. The acute management of trauma hemorrhage: a systematic review of randomized controlled trials. Crit Care. 2011;15(2):R92. doi:10.1186/cc10096
  2. Ponschab M, Schochl H, Gabriel C, et al. Haemostatic profile of reconstituted blood in a proposed 1:1:1 ratio of packed red blood cells, platelet concentrate and four different plasma preparations. Anaesthesia 2015; 70: 528–36.
  3. Lehavi A, Yitzhak A, Jarassy R, et al. Comparison of the performance of battery-operated fluid warmers. Emerg Med J. 2018;35: 564–570.
  4. Frank Butler, John B. Holcomb, Stacy Shackelford, et al. Advanced Resuscitative Care in Tactical Combat Casualty Care: TCCC Guidelines Change 18-01 (14 October 2018). JSOM Volume 18, Edition 4 / Winter 2018.
  5. Bennett, B. L., Giesbrect, G, et al. Management of Hypothermia in Tactical Combat Casualty Care: TCCC Guideline Proposed Change 20-01 (June 2020). Journal of special operations medicine : a peer reviewed journal for SOF medical professionals, 20(3), 21–35.