Running Fast and Warm
RAPID INFUSERS AND BLOOD WARMERS GIVE PATIENTS THE VITAL FLUIDS THEY NEED IN THE WAY THEY NEED THEM—AT THE RIGHT SPEED AND THE RIGHT TEMPERATURE.
When it comes to military medicine, one key to successful treatment of the wounded boils down to one word: fast. Medical personnel need to think fast and act fast—and in order to do that, they needs tools that can function fast. Two of these tools that can help hasten needed critical care to patients are rapid infusers and blood warmers, which are instrumental in treating those suffering from trauma.
Rapid infusers are designed to administer fluids—such as blood products and IV fluids—much faster than a regular gravity drip. Rapid infusers come in different varieties and range from the bag that is manually squeezed to get fluid into a patient to a sophisticated machine that users can program to administer the desired amount of liquid. To complement rapid infusers, and ensure that fluids are entering patients at their normal body temperature, medical professionals use blood warmers, because they don’t have the luxury of time to wait for blood products and IV liquids to warm naturally. And when lives are on the line, the speed of these products is critical.
“I’ve got a limited team of folks. I can’t afford to wait for the blood to warm up on its own, I can’t put the blood in a microwave, and I can’t waste the precious resource of an experienced medic or nurse to just stand there and physically squeeze a bag. For those folks, it is ease of accomplishing the task with excellence. We get warm fluid at a rate we tell the rapid infuser to do it, it’s easy to use, and it works every time,” said Air Force trauma surgeon Colonel Donald Jenkins.
This is especially important when dealing with trauma for several reasons. For one, if the injury is significant, there is a possibility that the patient will go into shock and getting resuscitative fluids to the patient quickly will reverse that condition. Also, medical professionals want to avoid three other major problems that may arise—all of which are difficult for a patient to recover from.
“In resuscitative physiology, we talk about the triangle of doom or the triangle of death, and that’s hypothermia [when the body temperature drops below its normal metabolism], acidosis [an increase of acidity in the body], and coagulopathy [a defect in the blood’s ability to clot]. What happens when you have this triad is you get into a situation that you cannot stop bleeding—even nonsurgical bleeding, so things just ooze from everywhere,” said Colonel Kenneth Azarow, chief of the department of surgery at Madigan Army Medical Center. “The second thing is, you get a drop in blood pressure and the last thing is you find it very difficult to return back to normal from this state. Once you have those three things happening, you’re kind of on the downward part of the curve as far as survival. If you can avoid them, you have much better outcomes.”
There are several products on the market that give military medical teams the tools they need to keep patients far away from this triangle of doom.
The Power Infuser, manufactured by Zoll Medical Corporation is one component of Zoll’s suite of integrated resuscitation products. Developed in cooperation with Walter Reed Army Institute of Research, Department of Resuscitative Medicine, the Power Infuser is the first portable electronic pump specifically intended for controlled delivery of IV fluids and blood in the battlefield environment. Medical personnel in the military know the importance of control. Too much fluid might dislodge clots and dilute the blood’s oxygen carrying capacity in patients with uncontrolled hemorrhage or cause other complications. On the other hand, critically hypovolemic patients can die without adequate field intervention, particularly if they cannot be delivered to a hospital quickly.
The Power Infuser flow rates are adjustable between 0.2 and 6 liters per hour without the need to elevate the IV bag. A bolus setting accurately delivers 250cc in 2.5 minutes. Active in-line air elimination and occlusion detection provide additional safety during infusion. Long battery life, rugged construction and a weight of only nine ounces make it ideal for use in the field or in transport. The Power Infuser has been tested and approved by the U.S. Army and Air Force for use in both rotary wing and fixed wing aircraft.
Ease of use is critical for any deployed piece of equipment. Special operations combat medics have commented that the Power Infuser is small, easy to carry: “It is plug and forget with few checks and balances. You don’t have to worry about the patient’s bag not infusing while in transport due to falling down to the floor. It also decreases the chance of introducing air into the patient’s circulatory system.” Transport teams within the U.S. Air Force have found it equally helpful in their missions. Deployed teams found the size of the pump and the rate of infusion beneficial. “It isn’t much bigger than the palm of your hand and can infuse fluid at 100ml/minute.” Teams also found the Power Infuser easy to set up and use. “The air elimination feature of the cartridge was one of the biggest selling points for us. We wanted to make sure that members know that they can rapidly infuse fluids and ensure patient safety.”
Preventing hypothermia in hemorrhagic shock victims is becoming increasingly more difficult. Recent reports from OIF/OEF indicate that the occurrence of hypothermia in casualties during resuscitation and surgery is problematic regardless of the ambient temperature. The Power Infuser, when coupled to the enFlow IV Fluid and Blood Warmer (Enginivity LLC, Vital Signs Inc.), can deliver warm IV fluids and blood at a temperature of 40º C. The enFlow warmer is a small, lightweight warmer weighing only nine ounces. It can be operated from either a battery source or an AC power supply. Two liters of warm fluid can be delivered from a fully charged 28 volt lithium battery. This combination of technologies allow personnel to now deliver controlled volumes of warm IV fluids or blood in the battlefield environment to address the concerns of shock induced hypothermia.
Another device is the Belmont FMS (Fluid Management System) 2000, simply known by its users as “the Belmont,” which acts as both a rapid infuser and blood warmer in one product. Manufactured by the Massachusetts-based Belmont Instrument Corporation, the device has received much attention since it hit the market in 1999, and has been mentioned in the Los Angeles Times and the Journal of the American Academy of Orthopedic Surgeons as one of the essential tools that has aided military medics in saving lives. In addition to ink, the Belmont can also be seen on the small screen—there is a brief shot of the product in the HBO documentary “Baghdad ER,” by Jon Alpert and Matthew O’Neill, which documents the work of the 86th Combat Support Hospital in Iraq.
It’s not surprising that the Belmont has received so much attention, as it has been used by the military since it was initially made available for sale, as well as being used by many major United States hospitals including Massachusetts General Hospital, the Mayo Clinic, and Johns Hopkins Hospital. Belmont Instrument’s president, George Herzlinger, Ph.D., credits the success of the product to its unique features, which were suggested by a panel of military surgeons and incorporated into the infuser.
Among the features of this rapid infuser is its built-in pump that allows users to choose what rate they want fluid to flow into patients—anywhere from 2.5 milliliters to 750 milliliters of fluid per minute—depending on the condition and needs of the person being treated. (And when needed, the user can even give the patient an immediate high flow of fluids simply by pressing the button marked “bolus.”) While fluid is being infused into the patient, the Belmont alerts the user of how much fluid that has been infused and monitors for air bubbles—automatically removing any that may develop—thus eliminating the possibility that a patient will suffer from an air embolism.
On the warming side of the equation, the Belmont is able to warm fluid with dry heat almost instantaneously, with blood being able to reach 37.5 degrees Celsius, the normal human body temperature, within 90 seconds to two minutes flat. And in order to keep up with the intense demands on the battlefield, the user can run the Belmont on batteries and can warm at least five liters of fluid with a single battery discharge.
Besides being fast and user friendly, the Belmont also includes an IV pole that adds a level of convenience that is much needed on the battlefield.
“It’s one of those products that you can hang a bag of blood, and have that blood warmed and in the patient in 45 seconds,” said Army Captain Tom Chenowith, CRNA, who used the Belmont during his tour of duty in Iraq. “Soldiers are alive today because of the Belmont. We were able to sustain their lives long enough so the surgeons could fix them. When we were in Baghdad, we pumped over 100 units of blood products through the Belmont on this single patient, and ten years ago, that would never happen and they would not have survived.”
Likewise, blood warmers have been an instrumental tool in saving lives. One product designed to warm both blood and IV fluids is the Thermal Angel, manufactured by Estill Medical Technologies, Inc. Keeping fluids warm is imperative in the prevention and treatment of hypothermia—the third most serious condition a trauma patient may develop next to hypoxia (a shortage of oxygen in the body) and hypovalemia (low blood volume).
“As a result of both battle and nonbattle injuries, the military was having a problem treating injured troops in adverse environments. That, coupled with delayed evacuation is making soldiers very prone to develop uncontrolled, or accidental, hypothermia on the battlefield,” said Brandon Lopez, co-owner and vice president of operations at Estill Medical Technologies. “The tactical field professionals out there really recognized that with hypothermia in trauma patients, you’re going to have fluid resuscitation requirements, you’re going to delay your surgical intervention, and ultimately increase the risk of acute mortality.”
In addition, having warm fluids can help treat patients suffering from shock, another risk that injured soldiers face.
“The ability to have warm fluid running into a patient, rather than cold fluid makes the job of tackling shock a lot easier,” said Sergeant Daniel Crowe, platoon medic with Alpha Company, 2nd Ranger Battalion, 75th Ranger Regiment. “Patients stand a much better chance at a quicker recovery from large volume loss.” Crowe noted that the Thermal Angel has become a staple in his unit’s deployment packing list and the warmer has been included in all of their medical Strykers, so it can be used to treat soldiers at the point of injury.
The Thermal Angel is able to treat soldiers so efficiently due to its ability to warm fluid to the patient’s core body temperature within 45 seconds. Because of its internal safety mechanism, this 9-inch and 9-ounce device is able to regulate the temperature of fluid 5,000 times per second, ensuring the patient’s safety during treatment. Other safeguards include a timer that will only allow fluid to be warmed 72 hours continuously, reducing the risk of patient infection, though it still allows the fluid to move. Estill Medical Technologies guarantees that these safety features will work with every Thermal Angel, every time, because a great deal of care goes into each unit. Before any Thermal Angel goes out the door, it is individually calibrated and flow tested to ensure the safety of each and every one.
Another important feature that makes the Thermal Angel unique and easy to use is the fact that the product is disposable— thus eliminating the need for extensive training, cleaning, calibration or maintenance. This allows the unit to follow one patient from the point of wounding to evacuation and treatment. “What this does for the military is it streamlines the training requirements, because now they have a single device that every single unit and every single echelon is trained on, and it also decreases the logistical footprint associated with managing that trauma patient,” Lopez said. “So the equipment actually travels with the patient—you get an injured soldier on the battlefield, and that same Thermal Angel travels with that patient onto a casualty evacuation helicopter, where that helicopter takes that same Thermal Angel to a battalion aid station or to a field hospital of some sort.”
Because of the reliability and ease of use of the Thermal Angel, it has literally become a godsend for wounded soldiers—as well as those being treated in civilian settings. Although the military was not involved in the design of this product, medical staff quickly saw how useful the Thermal Angel is in treating patients and incorporated it into its treatment options.
“The military really has led the way in preventative medicine, and pertaining to fluid warming itself the military recognizes that the prevention of heat loss really should start as soon after wounding as a tactical situation permits,” Lopez added. “In the civilian market, that’s what is considered the golden hour during transport. You really can help increase the patient’s chance of survival, getting to that patient as soon as possible, and keeping and maintaining that patient’s normathermia.”
Another emerging fluid warming product is Merlyn Medical’s FlexWarmer, which recently received approval from the U.S. Food and Drug Administration. This product, designed to treat patients on the scene of an injury, works through the use of a hand warmer—simply a bag of clear sodium acetate gel—that is often used by skiers or those living in cold regions of the United States.
To work the FlexWarmer, first all users need to do is insert IV tubes into the small, 18 ounce warmer plate. Once the tubes are securely placed inside, the user simply snaps the heating pack into place and the friction of this motion triggers the product to being warming. Within two minutes, the IV tubes are warm enough to administer fluid to a patient. Though the FlexWarmer is not designed for warming blood, it is ideal for when patients need to be given liquid nutrition and other fluids.
“You keep nutrition, or whatever solution you’re going to be giving to the patient, chilled and so if you have time, you set the bag with the nutrition or fluid you’re going to infuse out for 45 minutes to an hour so that it would become room temperature,” said Merlyn Medical’s vice president of marketing Nancy Hoover. “If you don’t have time to do that, the fluid goes into the patient cold, directly from the refrigerator and you’d just put plenty of blankets on the patient because that icy fluid is going through the body rather rapidly. The warming has become more and more important when you’re in the field and in an emergency situation, since you don’t have the luxury of taking something out and letting it heat up to room temperature for 30 to 45 minutes.”
The FlexWarmer will be available for sale in early 2008, and Hoover said Merlyn Medical is already in talks with the military and has no doubt that it will be an asset for use on the battlefield.
Though blood warmers and rapid infusers are saving lives of soldiers now, like any other tool used in military medicine, there is always room for improvement. In order to treat patients in any environment, medical professionals believe that these devices will continue to get smaller, making them even more convenient to use.
“I definitely think the future of the technology, as far as the military is concerned, is to make this smaller and less obtrusive because we have some pretty austere environments that exist and it’s hard to take the tools we want to take that benefit these injured combatants if they’re gigantic machines,” said Jenkins.
And there are other possibilities for these products that may be far into the future before they are successfully integrated into the current technology. For example, Azarow said that he believes at some point rapid infusers will be combined with dialysis capabilities that will simultaneously deliver warm fluid while filtering toxins out of a patient’s body. ♦