Whether it is a mass shooting event or a violent attack, helicopter emergency medical services (HEMS) physicians can be faced with patients suffering from very traumatic injuries. And in the past several years, major advancements have been made that allow teams to treat these patients more effectively in the pre-hospital setting, meaning better outcomes – ultimately, the goal of all physicians.

The different nature of the traumatic injuries patients typically sustain

We asked several medical professionals to identify the key differences between stab wounds and gunshot wounds (GSWs), and why these necessitate different approaches to the care given. Jamie Eastman, Preceptor of Boston MedFlight and US Army Reserve Detachment Commander, pointed out that while penetrating trauma such as gunshots and stabbings can both incur life-threatening wounds, typically, they inflict different injury patterns. Stab wounds will be single-entry, sustained at point blank range, and often affecting the torso or abdomen. “Stab wounds can show medical providers the possible route and depth the weapon took, [which] may still be impaled in the patient. This can guide the team on which organs are possibly affected,” he said.

Trying to get actual hemorrhage control can be difficult in the groin

GSWs, by contrast, depend on the caliber of the weapon, and distance from the target. Injuries can affect any part of the body, plus you have the added jeopardy of entry and exit wounds. “Guns also are used more so than knives for self-inflicted injuries,” Eastman pointed out. “With self-inflicted shots, we tend to see penetrating head injuries, which can pose devastating outcomes depending on caliber and proximity.”

While geographic location may not immediately seem relevant to the conversation, it becomes so when referring to the nature of the injuries medics are treating. Gun laws play a significant role in determining the injury of the patient. Dr Tom Hurst, Medical Director of London’s Air Ambulance, told AirMed&Rescue: “We see mainly stab wounds, GSWs remaining relatively rare in the UK. Almost all GSWs we see are low-velocity rounds, which, while more damaging than knife wounds, do not cause cavitation damage in the way high-velocity rounds do. It is, however, much harder to make an assessment of the track a bullet takes after it enters the body – this makes predicting which structures might be damaged a major challenge.” He concluded that while a GSW carries a higher risk of major organ or blood vessel injury, the management principles remain very similar.

Dr Halvard Stave, anesthesiologist and a doctor working for Norwegian HEMS, shared his experience with AirMed&Rescue, saying that in Norway, they see more knife wounds than GSWs. However, the teams are prepared to deal with every eventuality: “We regularly train advanced bleeding control, and we are addressing external wounds with packing, compressing and bandaging,” he said. “We use a tourniquet if needed. Some of our HEMS [teams] are using QuikClot. Everyone has got an iTClamp. All HEMS are able to perform resuscitative thoracostomy, but more training is done by the urban services.”

Treatment protocols

With the differences established, Eastman continued to describe the ways in which immediate care is affected: “With stab wounds being more likely in the torso and abdomen, these patients are more likely to get direct pressure and tranexamic acid (TXA) intravenously when possible. GSWs can also affect the torso and abdomen.

But they are also likely to affect the extremities, where tourniquets will be the first line for hemorrhage control. The neck, armpit, and groin are also likely and for these, we will wound-pack with hemostatic gauze such as QuikClot. Trying to get actual hemorrhage control can be difficult in the groin. Wound packing and direct pressure can be difficult. Having a circular object like a tennis ball may be required to apply over the combat gauze to get enough downward pressure into the groin.”

For London’s Air Ambulance, the choice of products for control of hemorrhage depends on the injury sustained, as Dr Hurst explained: “For junctional hemorrhage we advocate wound packing and direct pressure. For non-compressible torso hemorrhage, our clinical approach is permissive hypotension and rapid transfer to the emergency department (ED) if the patient’s physiology and clinical trajectory suggests they will survive to hospital.” The medical team uses “fairly standard” products for control of compressible hemorrhage: Blast bandage, Olaes dressing and ChitoGauze XR Pro hemostatic gauze. They also carry CAT and SOFTT-W 4 tourniquets, surgical skin staplers and sutures.

Dr Hurst added: “Where the patient is in severe shock and rapidly deteriorating, the approach changes to one of volume resuscitation, temporary hemorrhage control, and preservation of coronary and cerebral perfusion in the pre-hospital phase. Volume resuscitation is with whole blood or blood products. Temporary hemorrhage control and protection of central perfusion is with resuscitative endovascular balloon occlusion of the aorta (REBOA) or resuscitative thoracotomy, depending on the patient condition and location of the wounds.”

Tension pneumothorax may need to be considered and addressed, depending on the location of the wound. Analgesia should be provided if required – London’s Air Ambulance uses fentanyl ‘lozenges’ (oral transmucosal), intravenous (IV) fentanyl, or IV ketamine, depending on patient-specific factors.

Volume resuscitation with whole blood or blood products presents its own challenges that require solutions, said Ernst-Ulrik Haxthausen, Senior Product Manager at MEQU: “The storage of whole blood and blood products at cold temperatures is crucial for preserving their viability and preventing bacterial growth.”

He added: “Warming blood and blood components before administration to patients with major bleeding trauma is necessary to prevent adverse reactions and ensure patient safety. Rapid infusion of cold blood can lead to a drop in the patient’s core body temperature, resulting in hypothermia. Also, the function of clotting factors can be impaired at lower temperatures. By warming the blood, clotting factor activity is preserved, which is particularly important in patients with bleeding disorders.”

Interestingly, in Norway, different HEMS teams will rely on different solutions – some will use whole blood, some use LyoPlas and pRBC

POCUS – tech allows for greater accuracy in diagnosis

When dealing with stab wounds and GSWs, the potential for internal injuries to be fatal is substantial, therefore enabling pre-hospital medical teams to identify such injuries is key to improving the treatment being given. One tool that can be used to do just that is point-of-care ultrasound (POCUS) machines, which are getting smaller, lighter and better by the day. Obviously, they have their imperfections – great by the roadside, less useful in a helicopter en route to hospital.

Eastman said: “Most teams – military and civilian – are two providers (nurse and paramedic). If the patient is in extremis, your priorities are focused on tourniquets, direct pressure, IV/intraosseous (IO) access, blood products, TXA, and airway management. Reaching for the ultrasound typically gets held for secondary/tertiary assessment. That said, if all these things are completed and you still have time on a longer transport, it can help the team determine where/what is bleeding. Our civilian team has the Butterfly [ultrasound] product, which works well in transport due to its size and ability to attach to a cell phone or small tablet.”

The medical team are always going to be the primary diagnostic experts – as Dr Hurst said: “The key to assessing the severity of these injuries is clinical examination.” The location of the wound(s) and the patient’s physiology need to be integrated with the response to any treatment and the trajectory of any change in condition.

Nonetheless, the team augment their assessment with ultrasound, often en route to hospital, where required. Dr Hurst added: “We currently use the Philips Lumify handheld ultrasound, with all images uploaded for clinical governance review. We are also trialing the GE HealthCare Vscan Air.”

In Norway, Dr Stave explained that conscious patients with thoracic and abdominal injuries are “load and go” to the trauma center. And in these situations, the medical team often makes use of ultrasound devices in flight/ambulance. “We have different ultrasound devices in cars and helicopters,” he added. “In HEMS, we use iViz, and we scan on ground and in flight. We are skilled in FAST (focused assessment with sonography in trauma) and FATE (focus-assessed transthoracic echocardiography), and use this on many different type of patients.”

Replacing lost fluids faster

Eastman explained to AirMed&Rescue that protocols can differ between military and civilian organizations when it comes to the blood products carried, and their administration: “On my US Army deployment in 2018–19 we carried one whole blood (WB) unit and two packed red blood cells (pRBC) units per aircraft. Our protocol was to administer the WB first and then use the pRBC as necessary. At my current civilian flight program, we carry one liquid plasma (LP) unit and two pRBCs. Our protocol is to administer the LP first and follow with the pRBC. The LP and one pRBC can be given simultaneously on acutely ill patients.”

Haxthausen explained that there has been a growth in the use of whole blood in HEMS around the world due to several advantages: “The main advantage of using whole blood over component therapy is its ability to provide all essential blood components in a single transfusion, which can be crucial in life- threatening situations. Whole blood provides a balanced ratio of red blood cells, plasma, and platelets, which is more physiologically appropriate for treating trauma patients. This balance aids in better hemostasis compared to component therapy, which can sometimes result in imbalances and suboptimal clotting.

“Studies have shown that the use of whole blood can improve survival rates for patients suffering from severe trauma, particularly those experiencing massive hemorrhage. This is due to the immediate availability of all blood components necessary for effective clotting and oxygen transport.”

Just a few years ago, carrying pRBC on a civilian air medical helicopter was considered to be groundbreaking, and now, thankfully, it has become widely adopted. However, it’s not just pRBC that can make the difference to a patient’s outcome. Dr Hurst told AirMed&Rescue that in addition to the packed red cells, the teams can carry either whole blood or thawed fresh frozen plasma. “These,” he added, “are warmed using the MEQU °M Warmer System. Vascular access is obtained either through peripheral venous cannulation or central venous cannulation, usually of the subclavian vein. All patients with shock get 2g of tranexamic acid, and the hospital’s major hemorrhage protocol will be activated by our team while en route to the ED.”

Haxthausen described how the °M Warmer System is chosen for HEMS as it is small, robust and intuitive to use, and works to rapidly bring the cold blood products up to temperature: “The system is easy to set up and takes less than 30 seconds to implement. And the warm-up time (the time from connecting power to the warmer until the output temperature is 37°C) is less than 10 seconds. The °M Warmer System warms blood and other infusion fluids from 5°C to 37°C at flow rates of up to 150mL/min. And on a single charge of the Power Pack+ (the rechargeable battery pack), at least 2L of fluid can be warmed from 5°C to 37°C.”

Interestingly, in Norway, different HEMS teams will rely on different solutions, as Dr Stave explained – some will use whole blood, some use LyoPlas and pRBC. All teams carry tranexamic acid, tourniquets and different packing devices.

With the increase in the use of whole blood across the globe for treatment in major traumatic bleeding injuries, and recent US Food and Drug Administration approval, Haxthausen expects to see the °M Warmer System entering a greater number of HEMS in the near future.