Helicopter emergency medical services (HEMS) are expanding throughout the world, particularly in high-income countries, offering shorter transport times to hospital and allowing access to locations outside the roadmap. The prehospital medical care provided by specially trained HEMS doctors, paramedics and flight nurses can avoid preventable deaths after trauma.
Uncontrolled post-traumatic bleeding is a leading cause of preventable deaths among trauma patients. The most common incidents that cause significant blood loss are road traffic accidents, falling from a height, and penetrating injuries caused by an object piercing the skin. Such incidents can occur in both military and civilian locations and require rapid access to critical care.
Immediate treatment is vital as up to 80 per cent of deaths in the first hour, and more than 50 per cent of deaths in the prehospital setting, are due to hemorrhage. Improvements have been made in critical care practice around the world based on new technologies and pharmacological agents entering the market, which target hemorrhage and coagulopathy, or impaired ability to form clots.
Immediate treatment is vital as up to 80 per cent of deaths in the first hour, and more than 50 per cent of deaths in the prehospital setting, are due to hemorrhage
HEMS teams can provide a range of medical procedures with the kit they currently carry.
Dr Per Bredmose, Consultant in prehospital care at Norwegian Air Ambulance, outlined the equipment currently used by the services in his country. He explains that the selection of these resources was made based on ‘best practice, from my time with London HEMS, published literature, and visiting other services as inspiration’.
The kit includes tranexamic acid (TXA), freeze-dried plasma, and ‘packed red blood cells’, which are red blood cells (RBCs) that have been separated for blood transfusion. They also carry two types of tourniquets – both a one-handed combat application tourniquet and an inflatable pneumatic tourniquet.
Their equipment also includes nasal catheters for facial and carotid or jugular bleeding called Epistats, and iTClamps, which can temporarily control severe bleeding by sealing the edges of a wound. Kerlix sterile gauze, a plain form of gauze to pack wounds, is also part of the kit.
A similar set of equipment is used by the UK’s East Anglian Air Ambulance. Dr Rob Major, HEMS Consultant at the organisation, told AirMed&Rescue: “Our teams carry TXA, packed red blood cells and Lyoplas (a freeze-dried blood plasma compound). We carry these on our aircraft and vehicle whenever we go out on taskings. Our team also use Celox gauze, a special gauze that is impregnated with chemicals to stop bleeding.”
He added that the HEMS crews 'also use invasive arterial monitoring and ultrasound routinely in bleeding patients to monitor blood pressure and aid diagnostics'.
Kelly Miller, Vice President of Clinical Services with emergency air medical services provider Air Methods in the US, explained the kit carried by her team: “We currently carry either whole blood or a combination of packed RBCs and fresh plasma on over 130 of our aircraft. Additionally, we carry TXA, tourniquets, and hemostatic dressings on all aircraft.”
Our teams carry TXA, packed red blood cells and Lyoplas. We carry these on our aircraft and vehicle whenever we go out on taskings. Our team also use Celox gauze, a special gauze that is impregnated with chemicals to stop bleeding.
Taking a closer look into some of these widely-used products, TXA is the most common anti-fibrinolytic medication in the prehospital setting. It is taken either in tablet or liquid form, or by injection. In trials, TXA decreases the mortality from significant bleeding due to trauma, especially when taken within the first three hours, reducing overall mortality as well as death due to bleeding.
TXA is on the World Health Organization’s list of essential medicines and is available as a generic drug. It is produced by many companies and sold under many names, as both a standalone medication and in combination with other drugs. Major pharmaceutical manufacturers and supplies of TXA include Pfizer and Sanofi-Aventis.
Tourniquets work and save lives
In terms of modern tourniquets, widely used in military and civilian settings, these devices are used to stop traumatic bleeding so that medical care can be provided before the injured person bleeds out. Newer tourniquets consist of personalized cuffs, limb protection sleeves, and instruments that minimize the risk of tourniquet-related injury by varying the pressure applied.
Some tourniquet systems contain microcomputers that allow accurate and automatic pressure control, plus other safety features. There is general agreement that the tourniquet should not be used for longer than 90 minutes without being released for a short time.
A number of pneumatic, or inflatable, tourniquets have been developed for military and civilian use, based on surgical designs shown to be safe over many years. Such pneumatic devices have been used in Afghanistan and Iraq and in other pre-surgical emergency settings. Although pneumatic military tourniquets are more commonly used by medics than by individual soldiers in combat, both these and non-inflatable types can be designed for rapid, one-handed self-application in the field.
In a 2020 review of prehospital tourniquets in civilians, the authors from the University of Oslo, Norway, explain that trauma in the civilian setting may differ from trauma in the military, ‘but the last decades’ terrorist attacks and mass-casualty events worldwide have made penetrating injuries more similar in the two settings than before’.
They describe the different settings as follows: civilian settings in which a patient is treated by non-military personnel, such as emergency medical service personnel, doctors, laymen, fire constables, and law enforcement in a civilian environment. In military settings, military personnel and civilians are treated by military personnel (medics, soldiers, and military hospitals) in a warfare environment.
The authors concluded: “Despite relatively low evidence, the studies consistently suggested that the use of commercial tourniquets in a civilian setting to control life-threatening extremity hemorrhage seemed to be associated with improved survival, reduced need for blood transfusion, and few and transient adverse effects.”
In an interview with AirMed&Rescue, Dr Ross Davenport, Senior Lecturer in Trauma Sciences at Queen Mary University of London, outlined recent progress in clinical research. He agreed there is 'good evidence that modern tourniquets work and save lives', adding: “Most services will be able to get a patient to hospital within a timeframe that means tourniquet injury risk is low, since in-hospital management will prioritize rapid definitive control of hemorrhage and restoration of blood flow.”
TXA reduces mortality from major bleeding
The evidence on TXA is strong, he confirms. It is the primary anti-fibrinolytic drug that prevents early clot breakdown and is affordable, at GB£0.10p to £0.15p per vial. “There is good evidence that it has a significant impact on reducing mortality from major bleeding,” Dr Davenport said.
He pointed to the well-known CRASH-2 trial, a large placebo-controlled trial that aimed to determine the effect of the early administration of TXA on death and transfusion needs in bleeding trauma patients. It randomized over 20,000 patients in 40 countries to receive TXA or placebo. The results, published in 2010, reported a significant risk reduction in 28-day mortality of 1.5 per cent, and 0.8 per cent in death from hemorrhage among those receiving TXA. The greatest reduction in death from hemorrhage occurred if TXA was given within one hour of injury.
As for changes in the use of TXA, Davenport says there is some ongoing research into increasing the dose for a greater benefit – however, this is being weighed against the possible risks – and the possibility of administering TXA intramuscularly rather than intravenously.
RePhill and blood products
In terms of blood products, a range is currently in use. Davenport explains that all four components of blood – RBCs, plasma, platelets, and the coagulation factor fibrinogen – play a role in stopping bleeding. However, the logistics of carrying the four components make it impossible to transfuse all elements prehospital.
Major of East Anglian Air Ambulance explained that his organization took part in the national RePHill trial, which finished a year or so ago. “This trial has not reported yet, but is currently under peer review in The Lancet medical journal,” he said.
The RePhill (Resuscitation with Pre-Hospital Blood Products) trial was a national clinical trial, funded by the National Institute for Health Research and coordinated by the University of Birmingham. It was the first trial of its kind and aimed to determine whether giving RBCs plus plasma in a prehospital environment improves patient outcomes in a trauma setting. Four UK air ambulances participated in the trial, starting in 2018 and ending in January 2021. Collectively, 432 trauma patients
Major added: “We have several ongoing research and development projects looking at bleeding and our last Trauma Audit Research Network data (the five years up to 2019) show we have a high number of unexpected survivors in our trauma patient group. We haven’t had any outcome data yet for our patients who received blood as we are waiting for RePhill to publish its results.
“We continue to use TXA for bleeding and packed RBCs and lyoplas, and are expecting to continue to use these products. We are not currently looking at any additional or other blood products. We keep under review the evidence base and utility of REBOA (Retrograde Endovascular Balloon Occlusion of the Aorta) for bleeding patients within the east of England but don’t currently deploy this on our services.”
New clinical trial using whole blood
Davenport told AirMed&Rescue of a new clinical trial (SWiFT: Study of Whole blood in Frontline Trauma) due to start this year examining the use of a whole blood product including platelets, developed by NHS Blood and Transplant (NHSBT).
Outcomes will be compared against patients treated with the current standard of care, usually either RBCs alone or together with plasma. Around 850 patients will be recruited in this trial, which is a collaboration between NHSBT, 10 air ambulances and the Defence Medical Services, an organization within the UK’s Ministry of Defence.
Miller at Air Methods explained: “Hemorrhage management is at the forefront of issues we prepare and train for. Every patient care guideline and equipment choice at Air Methods is based on evidence and data. We started the endeavor of adding blood products in 2013. This was not fast and early on was very challenging and slow. At that time there was limited prehospital published research on blood, which added to our challenge of finding blood centers to work with us.
Reviewing the data
“We reviewed military data, in-hospital data, and also the information on current technology to support safe storage in order to make the decision. Once we added prehospital blood products, we closely monitored the impact on our patient receiving center arrival conditions compared to those who did not carry blood. In limited samples we saw improved hemodynamics and acid base status on arrival.
“As we continued to monitor our patients and research provided by studies such as PAMPer, which we had aircraft participate in, we decide to aggressively expand our program. TXA was also added to our Patient Care Guidelines in 2013 and the decision largely attributed to the CRASH-2 study initially.
“In our community-based system, outcome data proves to be difficult. We have over 160 community-based aircraft delivering patients to thousands of hospitals each year. We have seen patients arriving at receiving centers more hemodynamically stable after suffering from uncontrolled hemorrhage using the tools we have (tourniquets, hemostatic gauze, TXA, and blood products). We have just recently had a breakthrough, which is allowing us to exchange data with receiving centers on a large scale. We hope this provides us the ability to take the next step in our quality assurance and research program with large-scale visibility into outcome data.
“We at Air Methods are constantly monitoring changes in management strategy of all patient populations. Trauma, which includes the majority of our hemorrhage control patients, accounts for around 34 per cent of the over 100,000 transports we were involved in during 2021. So, while we do not have any significant change in practice on the horizon, we are set up to quickly move where the evidence points us in our care.”
Trauma, which includes the majority of our hemorrhage control patients, accounts for around 34 per cent of the over 100,000 transports we were involved in during 2021.
Combat trauma care
Turning to the requirements in military medicine, the approaches vary due to a higher likelihood of injury inflicted by improvised explosive devices (IEDs).
Dr Sean Keenan, MD, an independent consultant on trauma care policy for the US Defense Health Agency, shared his knowledge with AirMed&Rescue.
He explained: “In general, the military has made great strides to standardize the approach to combat trauma using Tactical Combat Casualty Care (TCCC). Most combatants who have deployed to war in the last 20-plus years received TCCC training.
“Because military medicine is very trauma-focused, TCCC exclusively deals with trauma management, with hemorrhage control being paramount to any of the protocols. The Committee for TCCC, under the Joint Trauma Service, meets semi-annually to consider relevant research and observations from the field, and issues annual updates.”
Keenan, who retired from the US Army Medical Corps in 2018, added: “With the higher prevalence of IED injuries, and ‘dismounted IEDs’ (combatants on foot triggering IEDs), the addition of things like pelvic binders incorporated those observed injury patterns. The basic protocol, however, covers both penetrating, blunt and blast/combined trauma.
“Flight medics and paramedics are similarly trained in TCCC principles and we saw the introduction of blood (fresh whole blood) and blood products in rotary wing use on or about 2011 with resultant better survivability in those patients that received blood or blood products within about 30 minutes from time of injury (early and far forward principle of Damage Control Resuscitation or DCR).
“All of these findings trickle down into civilian practice, but generally take time. Also, civilian Emergency Medical Service, in general, is more medical emergency-focused rather than pure trauma, so civilian practice tends to be less protocol-focused on trauma.
“Military research is similarly focused on operational subjects, with hemorrhage control being among them. Things like hemorrhage-control gauze, which quickly followed the wholesale adoption of tourniquets in the early 2000s, were spearheaded through military research.
“Currently, there is a focus on non-compressible, torso hemorrhage and although things like REBOA are being explored, there still is no real solution for non-compressible hemorrhage besides rapid evacuation to a surgical trauma team."
Looking to the future of prehospital bleeding control, Miller at Air Methods reported: “We feel the prehospital environment is better suited now than ever to combat uncontrolled hemorrhage. We also recognize that room for improvement and innovation remains in this patient population. We at Air Methods look forward to being part of those improvements and the innovations that continue to raise the bar in hemorrhage control.”
Major bleeding following severe trauma continues to represent a global public health issue
Major bleeding following severe trauma continues to represent a global public health issue, and mortality in trauma patients remains substantial. A number of guidelines and initiatives aim to improve the management of major bleeding in patients treated in a variety of prehospital situations.
Improvements have been made in the management of the heavily bleeding trauma patient, with state-of-the-art clinical practice minimizing blood loss and stabilizing the patient. Nevertheless, the appropriate management of patients with massive bleeding remains a major challenge and multidisciplinary is key to further improving patient outcomes.