EMS Trauma Stabilization and Transport: A Comprehensive Review

AUTHORS

Brian L. Springer, MD, FACEP, Director, Division of Tactical Emergency Medicine, Wright State University Department of Emergency Medicine, Dayton, OH

Steven J. Repas, MD, Wright State University, Department of Emergency Medicine, Dayton, OH

Eric Kretz, MD, Wright State University, Department of Emergency Medicine, Dayton, OH

PEER REVIEWER

Howard A. Werman, MD, FACEP, Professor Emeritus of Emergency Medicine, The Ohio State University, Columbus

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It is essential that acute care providers have an awareness of the prehospital system — strengths, scope of practice, different transport modalities (strengths and limitations) — to optimize patient outcomes.

— Ann M. Dietrich, MD, Editor

Introduction and Background

Prehospital transportation of sick and injured persons has a long and rich history. The desire to get patients to professional medical care as fast as possible is not a novel idea. The emergency medical services (EMS) lineage can be traced to the Napoleonic Wars. Since then, a variety of medical and non-medical personnel have been entrusted with transporting the ill and injured to hospitals and other treatment facilities.

The modern history of triage and transport of traumatically injured patients began with Dominique Jean Larrey’s fundamental work with the French army during the French Revolution and as Napoleon Bonaparte’s military physician. Larrey’s innovative strategy was to take the injured soldiers to the battlefield surgeon as fast as possible. To accomplish this vision of expeditious and proximal medical care, he designed the “flying ambulance.” The system used small and highly mobile horse-drawn carriages kept close to the field of battle. From there, they could rapidly reach injured troops and initiate care, as well as facilitate rapid evacuation to field hospitals. With his appointment as a commander of the Legion of Honor, he was able to use his military position to bolster the expansion of his flying ambulance units with direct support from the non-medical military command.

Half a century later in America, Major Jonathan Letterman was appointed as medical director of the Army of the Potomac. Under his direction, the Army Medical Corps was able to create a dedicated ambulance corps based on Larrey’s model to rapidly evacuate injured soldiers to close medical support. Although initially successful in moving patients from the point of injury to treatment, Letterman recognized that without higher medical coordination, mismatches between the patient’s location and medical supplies/personnel were compromising outcomes. Over the course of various battles from Antietam to Fredericksburg, he redesigned the system to establish a structured medical command throughout the army. Morbidity and mortality were high by today’s standards, but Letterman’s system offered a chance at survival previously unknown to trauma patients in military conflict.¹

From the time of the Civil War to the mid-20th century, America’s medical system underwent an immense and rapid modernization as medicine and surgery turned the corner toward contemporary standards. Antibiotics, vaccines, and radiography, along with pioneering abdominal, orthopedic, neurological, and cardiovascular surgery, pushed the envelope for longevity and survival of acute illness. However, trauma care lagged significantly behind other fields. In 1966, the Committee on Shock, Trauma, and Anesthesia of the National Academy of Sciences spent 36 months studying and researching this gap, which resulted in the publication of Accidental Death and Disability: The Neglected Disease in Modern Society. This landmark work was meant as a call to action. Many technological, cultural, educational, and enterprise-wide deficiencies were identified. Among them were a lack of broad basic education in layperson first aid; medical professionals inadequately trained in cardiopulmonary resuscitation (CPR); no national EMS structure and a lack of interagency collaboration; inadequate EMS financing; and a paucity of prehospital and trauma research. Over the ensuing 50-plus years, many systemic changes came about.²

Following the publication of Accidental Death and Disability, the 1966 Highway Safety Act created the National Highway Traffic Safety Administration with the purpose of mandating that all 50 states create an ambulance system. In 1971, the first educational standards for emergency medical technicians (EMTs) were established, and in 1977 the national curriculum for EMT-paramedic was developed. In 1971, the University of Cincinnati graduated the first emergency medicine resident in a then-new and soon-to-be-growing field. Other important publications like the EMS Agenda for the Future and EMS Agenda 2050 (released in 1996 and 2019, respectively) laid out guiding principles for EMS involvement in trauma care. At the same time, the American College of Surgeons (ACS) was walking in step with EMS. Immediately after the publication of Accidental Death and Disability in 1966, the ACS began creating a system of standardized, supervised, and coordinated trauma care across the nation and developed the National Trauma DataBank as a means of gathering information and generating research on trauma care and outcomes. In 1976, the ACS released their first Optimal Hospital Resources for the Injured Patient, and it has continued this publication over several editions, most recently as the 2017 Optimal Resources for Surgical Quality and Safety. This landmark document defined Trauma Center Levels of Care as we know them today.³

Level I and Level II Trauma Centers have identical standards for the clinical care of traumatically injured patients. The differences between them are patient volume requirements, the presence of a dedicated surgical critical care service, and time invested in training, education, outreach, injury prevention, and trauma research. Level III and Level IV Trauma Centers serve as the entry points into the trauma chain of survival. Level III centers must maintain the capability to provide the initial clinical care and management of injured patients with pre-established transfer agreements to Level I and II centers. Level III centers have 24-hour immediate coverage by emergency physicians, with the availability of rapid general surgery coverage; Level IV trauma centers are responsible for having an emergency physician or mid-level provider coverage for trauma patients, with surgery and critical care services provided if available. The principle that guides the trauma chain of survival is rapid access to trained medical professionals, along with pre-established protocols to facilitate transfer to higher echelons of care based on patient needs.

Another major change with a lasting impact occurred in 1986 when the United States Congress passed the Emergency Medical Treatment and Active Labor Act (EMTALA). This law states that any patient presenting to an emergency department (ED) is to be stabilized and treated independently of their ability to be covered by insurance or pay out of pocket for their care.⁴ Three main tenets exist under EMTALA for all Medicare-participating hospitals:

• All patients presenting to the ED must be screened for a life-threatening emergency without a delay for inquiring about their financial or insurance status;

• Appropriate emergency treatment care must be provided to patients within the capabilities of that facility regardless of their insurance or ability to pay, and they must be transferred to higher levels of care if additional care is needed;

• Hospitals with advanced and specialist/subspecialist capabilities are required to accept transfers from hospitals without such services.

As noted, EMTALA applies to trauma patients coming from the field or being transported from one ED to another. If an unstable patient is being transferred to another facility, the benefits must outweigh the risks. Ongoing care must be provided until the time of transport, and the receiving hospital must confirm that it has the ability to provide the needed care. Patients must be transported with the appropriate staff and equipment, along with medical documentation of their care up to that point.⁵

Pathophysiology and Patient Assessment

Blunt Trauma Mechanism

Every year in the United States, there are an estimated 6 million motor vehicle collisions (MVCs), generating significant morbidity and mortality and causing numerous injury patterns. In 2020 in the United States, there were more than 40,000 deaths from MVCs, leading to 110 deaths/day and more than $430 billion in healthcare costs. In the same year, there were 2,100,000 ED visits for injury/suspected injury from an MVC.^6,7 Patients present with blunt injuries from a multitude of other causes: falls from standing or height, farm accidents, struck-by injuries, and assault. Information about the trauma scene that was encountered by EMS often is the hospital provider’s first and best window into events of the incident, the mechanisms of trauma, and the injuries to anticipate.

Penetrating Trauma Mechanisms

Gunshot wounds (GSWs) are a common cause of penetrating trauma injuries, with an average of 85,649 ED visits per year for nonfatal wounds and 34,538 deaths (76.6% of which are prehospital deaths).⁸ GSWs can be deceiving, since the external appearance of the wound and initial patient appearance may not reflect the severity of the internal injury. Accurate assessment and identification of wounds by the prehospital provider can help the receiving trauma team anticipate possible injuries. While GSWs have significant morbidity and mortality, knife wounds greatly outnumber GSWs at an average of 400,000/year (both accidental and intentional).⁹ Knife-related injuries vary greatly depending on the knife size, shape, and location of the injury. Comparing head-to-head, GSWs had 33% mortality vs. stab wounds, which had 7.7% mortality. Penetrating injuries also can come from any object that can pierce the body, to include environmental objects (sticks, pipes, animal teeth and claws, and other sharp objects), accidental or intentional explosions, and everyday objects as results of falls or other accidents.

The range of injury secondary to blunt and penetrating trauma varies from minor to immediately life-threatening. Triage, treatment, and disposition should be individualized to the patient since no two traumatic injuries are identical. Injuries are influenced by mechanism, body region, age, and gender.¹⁰ (See Table 1.)

Assessment

Injured patients encountered by EMS for transport generally will fit into the category of blunt or penetrating trauma. Ultimately, both patterns of injury can lead to hemorrhagic, obstructive, or neurogenic shock. Trauma patients will be assessed initially at or near the point of injury by the EMS team. Providers first must determine scene safety and identify possible threats to themselves and patients. Once on scene, they must estimate the number of patients, don proper personal protective equipment (PPE), determine the need for backup resources, recognize the mechanism of injury, and consider the need for spinal immobilization. If there is more than one patient, triage is critical. In 2021, a multi-organizational working group created the national guideline for civilian field triage, specifically in non-mass casualty events.¹¹ (To view the guideline, visit https://bit.ly/3ARYVma.)

The first step of individual patient assessment is the primary survey. The ACS guidelines for Advanced Trauma Life Support (ATLS) and the prehospital trauma programs Prehospital Trauma Life Support (PHTLS) and International Trauma Life Support (ITLS) (based on ATLS) all recommend an ABCDE primary survey: airway, breathing, circulation with hemorrhage control, disability (assessment of neurologic status), and exposure with protection from environmental factors. The assessment can be performed rapidly by asking a patient their name and what happened to them. The patient’s response allows the provider to assess the airway by the patient’s verbal response, breathing by assessing their air movement, circulation by observing for blood loss and palpating a carotid and radial pulse, and disability by their presenting level of consciousness.¹⁰

The approach to a traumatically injured patient in a tactical/military setting is different than that proposed by ATLS. Starting as a Navy Special Warfare initiative in 1993, Tactical Combat Casualty Care (TCCC) has become the foundation for combat trauma care. TCCC organizes its primary survey with an emphasis on hemorrhage control. The assessment begins with massive hemorrhage, followed by airway, respirations, circulation, and hypothermia prevention (MARCH). The emphasis on hemorrhage control comes from decades of military data that demonstrate up to 25% of battlefield trauma deaths could have been prevented if a tourniquet had been placed.¹² With TCCC fully integrated into combat units, there was a demonstrated mortality benefit. Over the course of 2001-2010, the 75th Ranger Regiment with more than 8,000 combat missions had a total of 28 deaths, with 0 of those deemed as preventable.¹³ The unit’s successful adoption of TCCC and focus on hemorrhage control directly saved lives on the battlefield.

Treatment and Transport

Expeditious treatment and rapid transport of trauma patients are of the highest priority for an EMS crew. On-scene and en-route treatment is focused on direct life-saving interventions that do not delay arrival to a treatment center. For penetrating trauma patients, every minute increase of on-scene time correlates with a 1% increase in mortality.¹⁴

Trauma patients may require intervention for any of the components of the primary survey. Penetrating and blunt injuries can lead to massive internal or external hemorrhage. Prehospital interventions for internal bleeding are limited, and definitive control is obtained by quick transport to a facility with surgical capabilities. External bleeding can result from a compressible injury, such as a GSW, stab wound, large laceration, amputation, partial amputation, or open fracture, or from non-compressible injuries, such as closed femur fracture or torso/junctional bleeding. On-scene and en-route direct pressure, wound packing, hemostatic agents, and tourniquets (to include extremity and junctional) mitigate bleeding and reduce morbidity and mortality.

As noted earlier, scene information from the EMS crew is useful to hospital providers, but it should be noted that it is difficult to assess volumetric blood loss.¹⁵ When tested in controlled settings, both emergency physician and paramedic estimates of traumatic blood loss ranged from half to two times the actual blood loss. Depending on the provider level of training and transport times, tranexamic acid (TXA) may be administered for massive hemorrhage. TXA has demonstrated a 7.6% mortality risk reduction at 48 hours and 14.4% reduction at 30 days when studied in combat injuries, concordant with data found in the civilian population, with a 1.5% mortality reduction at four weeks.¹⁶ TXA is most effective when administered within one to three hours of injury, making its use during transport a consideration in rural areas far from definitive trauma care hospitals.¹⁷

During EMS transport, a trauma patient may become hemodynamically unstable. Hemorrhagic shock may result in tachycardia and hypotension depending on the degree of blood loss. The best replacement for traumatic blood loss is whole blood, followed by blood products 1:1:1, then packed red blood cells (PRBC) and plasma. In a study of combat trauma patients with traumatic limb amputation and abnormal vital signs (heart rate [HR] > 120 beats per minute [bpm] or systolic blood pressure < 90 mmHg), administering blood products in the prehospital setting or within less than 15 minutes of injury had a 24-hour and 30-day mortality benefit when compared to delayed or no blood transfusion.¹⁸ When whole blood is unavailable for prehospital resuscitation, the highest mortality benefit is with the administration of PRBC and plasma. Plasma and PRBC administered alone both offer mortality benefits as well, while crystalloid transfusion alone actually increases mortality in trauma patients.¹⁹

Overall blood replacement should correlate with blood loss. Classic teaching is to target a mean arterial pressure (MAP) of 65, although on meta-analysis permissive hypotension (target MAP of 50) may offer a survival benefit.²⁰ Crystalloid fluids often are the most abundant resuscitation fluid for basic and advanced life support units. Given the demonstrated risk of mortality with their administration, a prehospital shift targeting a MAP of 50 may save lives with preference to whole blood > blood products > crystalloid.^{12,15,17,18,21,22,23}

Significant head or face trauma can lead to depressed mental status or airway compromise that requires the prehospital provider to perform airway intervention. Jaw thrust, chin lift, and positioning often are sufficient to improve oxygenation and ventilation in the field. Patients who do not respond to repositioning should be managed with airway adjuncts, such as nasopharyngeal and oropharyngeal airways, applying nasopharyngeal airways cautiously when facial trauma is present. When more advanced airway support is required, a supraglottic airway, oral endotracheal intubation, or cricothyroidotomy all are considerations, although no consensus exists on the ideal prehospital trauma airway. Different practice settings will dictate the most appropriate prehospital airway intervention in trauma. For example, a definitive airway may be more appropriate in a rural setting prior to a long transport, compared to urban settings with short transport times.

Patients who experience chest trauma can have up to a 20% to 50% chance of developing a pneumothorax depending on the mechanism of injury.²¹ Pneumothoraces are classified as simple pneumothorax, tension pneumothorax, or open pneumothorax. A simple pneumothorax is a collection of air between the visceral and parietal pleura. A tension pneumothorax occurs when a pneumothorax occupies enough space to create mediastinal shift to the opposite direction of the pneumothorax, resulting in obstructive shock with cardiopulmonary compromise. Tension pneumothorax requires prompt intervention with needle or digital thoracostomy. Older teaching was needle thoracostomy at the midclavicular line in the second intercostal space. However, patient body habitus and improper needle length result in more than two-thirds of needle decompressions not entering the pleural space.²⁴ Current ATLS and TCCC have adopted the fifth intercostal space in the anterior axillary line as an option for initial needle thoracostomy.^10,25

Open pneumothorax occurs as a result of penetrating injury to the chest wall above the diaphragm. The downward movement of the diaphragm during spontaneous negative pressure ventilation causes ambient air to take the path of least resistance and enter the thorax through the hole in the chest wall caused by the patient’s injury. With each ventilation breath, more air is sucked into the pleural space, creating a “sucking chest wound” until an airtight seal is applied and negative intrathoracic pressure is restored. Prompt recognition and treatment can reduce respiratory distress and limit the risk of hypoxia-driven cardiopulmonary collapse.

Commercial chest seals are adhesive-backed occlusive dressings designed for rapid application against bare skin. Vented chest seals are created with a one-way valve system not only to prevent ambient air from entering the chest in inhalation, but to allow excess air in the pleural space to exit the chest and limit the risk of developing a tension pneumothorax. Lung parenchyma injury will continue to leak inhaled air into the pleural space, worsening a pneumothorax even after chest seal placement. Frequent reassessment for worsening pneumothorax and developing tension pneumothorax must be performed after chest seal placement.

ALS/BLS Trauma Considerations

Cervical Spine Collar and Spine Board

The best approach to selecting which patients might benefit from spinal immobilization after a trauma looks at the patient, the mechanism of injury, and the initial exam findings. Upon approaching a trauma scene, the prehospital provider should consider potential cervical spine injuries and the need for manual and cervical collar stabilization even before starting the primary and secondary surveys. Providers should act within their local protocols established by their medical directors.

The National Registry of Emergency Medical Technicians (NREMT) recommendations on which patients should be immobilized are based on the NEXUS Criteria and the Canadian C-Spine rules.²⁶ These two clinical decision instruments were originally created to help ED providers determine if cervical spine imaging is needed for trauma patients.

Using NEXUS Criteria begins with ensuring that the patient does not have altered mental status or a language barrier that could limit the ability for further assessment. Any of the following criteria would lead to cervical motion restriction with a collar: spinal tenderness or deformity, Glasgow Coma Scale score < 15, signs of intoxication from alcohol or drug use, presence of distracting injury, or neurologic deficit. If none of the criteria are met, the patient does not require cervical spine imaging. If any one of the criteria is met, a patient should undergo cervical spine imaging to rule out traumatic pathology.²²

Using Canadian C-Spine rules begins with determining three criteria: age, extremity paresthesia, and mechanism. If the patient’s age is > 65 years, extremity paresthesias are present, or a dangerous mechanism was encountered (fall > 3 feet, axial load, high-speed MVC, or bicycle or recreational vehicle collision), then a patient’s cervical spine should be imaged. After determining these initial criteria, other low-risk criteria need to be met to forgo imaging: the patient is ambulatory at the scene or any time since, the patient can sit upright spontaneously, no midline tenderness is present, and neck pain is delayed or gradual in onset.²⁷

Based on these clinical decision instruments, the NREMT recommends patients who have experienced blunt trauma due to a significant mechanism and with the following criteria be placed in cervical spine immobilization:

• altered level of consciousness;

• drug or alcohol intoxication;

• inability to communicate;

• spinal column pain or tenderness;

• neurologic complaints (numbness or motor weakness);

• anatomic deformity of the spine;

• distracting injuries (injuries so severely painful that the exam of the neck is unreliable, such as severe thoracic trauma, long bone fractures, crush injury, or large burns).²⁶

In 2018, the ACS, the National Association of EMS Physicians, and the American College of Emergency Physicians created a joint position with similar criteria for both cervical spine and full spinal motion restriction.²³ NREMT does not use the same criteria for the use of a long spine board; instead, the decision is based on the individual patient’s mechanism of injury and physical exam. For patients with penetrating trauma, NREMT only recommends spinal motion restriction in those who have abnormal neurologic findings on exam.

Both cervical spine collars and long spine boards carry risks to the patient. It has been demonstrated that reducing the use of long spine boards does not increase the incidence of spinal cord injury or worsen outcomes. Patients who present to EDs on long spine boards rarely have clinically unstable thoracolumbar injuries, and EMS crews may use a spine board as the easiest mode of transport rather than for immobilization. Some of the complications of long spine board use include the risk of pressure sores, respiratory compromise secondary to impairment of normal physiologic ventilation, unnecessary pain, and unnecessary radiation exposure, since these patients are more likely to have spinal imaging without other indications.^28-32

While prehospital trauma care moves away from long spine boards, there still is a select role for cervical collars, since 3.7% of all trauma patients will have acute cervical spine injury, with 41% of those injuries resulting in operative fixation or prolonged external stabilization.³³ The prehospital space allows for a more individualized approach to the methodology of cervical spine immobilization. Prehospital crews may use equipment of opportunity, such as pillows, rolled blankets, vacuum pillows, etc., in combination with a cervical collar to successfully achieve spinal motion restriction. Cervical collars pose a risk of pressure ulcers, nosocomial pneumonia secondary to restriction in normal physiologic ventilation, jugular vein compression with potential for intracranial pressure (ICP) elevation, and unnecessary pain and ED radiologic imaging.^34-40

Implication of ALS vs. BLS

EMS protocols and scope of practice vary between cities and states in the United States, along with differing use of a basic life support (BLS) or an advanced life support (ALS) crew. Generally speaking, BLS providers are able to tend to external wounds via splinting, apply bandages and tourniquets, apply oxygen, conduct CPR with defibrillation if necessary, and transport patients to the hospital.⁴¹ ALS has a much broader scope of practice, which can include advanced airway management; obtaining vascular access via intravenous (IV) or intraosseous catheter; administration of medications to include IV fluids, pain medication, and blood products; and other technical procedures, such as needle decompression.²³

The ideal scope of practice for prehospital providers managing trauma is controversial. Conceptually, ALS squads would be optimal, with a skill set allowing for most ACLS and ATLS interventions, more standardized initial care, and improved patient outcomes.⁴² There is a significant shortage of ALS squad availability in the United States, most prominently in rural communities and regions where volunteer EMS is the primary service.³⁴ The increased geographic area and subsequent prolonged transport time, coupled with BLS limitations on scope of practice, could worsen outcomes.³⁵ If a BLS squad is all that is available for a critical trauma patient, other resource requisition may be warranted, such as helicopter EMS or meeting an ALS squad en route to a trauma center.³⁶

As noted earlier, diminished scope of practice could worsen outcomes, but not necessarily. The single most important intervention EMS can provide is prompt transportation to a trauma center.²⁸ Outcomes are significantly improved with faster transport times. Although stabilization and treatment in the field are important, there is a delicate balance when it comes to on-scene time to treat vs. speeding up the transportation process. Rappold et al compared ALS vs. BLS mortality outcomes in penetrating trauma patients in an urban setting. In their review, they noted significantly longer ALS on-scene times. Additionally, patients with an injury severity score of less than 30 showed an increased odds of mortality when patients were treated and transported by ALS.³⁷ This finding was corroborated by Kondo et al, who demonstrated no significant mortality benefit between ALS and BLS crews who transported trauma patients.²⁸ Definitive care at the trauma hospital is sometimes a necessity to reverse the pathology that the initiating trauma caused. This is especially true when it comes to traumatic wounds to the chest, abdomen, and pelvis. Any level EMS provider is only able to give temporizing measures in the field, so timely transport is of the utmost importance.

EMS Transport

Ground transportation is used by the majority of EMS crews to move trauma patients to definitive care. Based on the 911 system, when an emergency call is placed, the dispatcher sends the closest ambulance to respond. This simultaneously brings emergency medical personnel to the scene to triage and treat patients while also providing a vehicle for transportation once the crew is ready to move the patient. Ground-based ambulances generally are less expensive and more readily available than aircraft, but they have certain limitations. Ground transportation is limited by road conditions, distance to a trauma center, traffic, and crew capabilities.³⁸ An estimated 1,500 EMS ambulance crashes are recorded each year per NHTSA, reflecting significant risk when driving at high speeds to scenes or to the hospital.³⁹ While transport time is a crucial metric for patient survival, excessive speed can endanger both the patient and crew. Ambulances failing to yield at intersections, whether a green or red light is present, also has demonstrated an increased risk for motor vehicle accidents.⁴⁰ If an EMS ground vehicle does crash, the risk of injury and death to crew members is higher than to passengers in other ground vehicle accidents. Risk of crew member fatality is increased further in emergent ambulance transports compared to non-emergent ambulance transports.²⁹ Much of this risk can be attributed to the fact that less than 50% of EMS crews in the patient compartment use seat belts.³⁰ These statistics emphasize a renewed need to prioritize safety when using this transportation modality.³¹

Private vehicles are used to transport a significant amount of penetrating trauma patients directly to the trauma centers in urban areas within the United States.³² This amount varies between cities but can range anywhere from 13% to 39%.³² Bystanders on the scene often can reach and transport victims in less time than EMS. Reducing the time from injury to hospital delivery decreases trauma patient mortality, even when those transporting the victim lack medical skills, and private vehicle transport of penetrating trauma patients has shown decreased mortality compared with ground EMS.^32,43 Law enforcement (LE) vehicles are another nontraditional means of transporting trauma patients. Wandling et al conducted a retrospective review of the National Trauma Database between 2010 to 2012. In this time frame, 2,467 patients were transported to trauma centers by LE. When compared to EMS transport, police transport had a similar mortality risk for transporting trauma patients even without advanced medical intervention.⁴⁴ Another study showed that the LE “scoop and run” trauma transport method had a similar mortality rate compared to EMS ground transport.⁴⁵

EMS air transport can include both helicopter emergency medical services (HEMS) and fixed-wing transport. Each modality has associated risks and benefits. Helicopters can land in more austere areas compared to fixed-wing aircraft, but they are limited by distance (compared to fixed-wing aircraft) and inclement weather. HEMS differs from ground EMS and varies from agency to agency with different crew profiles, credentialing, training, protocols, and scope of practice. One major difference is the use of prehospital nurses and physicians in flight medicine, who are rarely part of a ground crew. HEMS offers many advantages for critically ill trauma patients, such as advanced practice crews, rapid transport time, and timely access to remote locations. Similar to ground transport, HEMS also frequently is used to perform interfacility transports to higher echelons of care. Fixed-winged aircraft tend to be used for transporting patients between distant regional trauma centers or across state or international lines. Fixed-wing aircraft can go incredible distances, generally are faster than helicopters, especially for long distance transports, and are cheaper to maintain.⁴⁶ The major limitation is the need for a formal runway and airport to launch and land, along with the need for ground transport to get the patient to and from the aircraft.

Over the last several decades, there has been increasing use of HEMS. HEMS has shown up to a 15% mortality improvement when used to transport select critically ill trauma patients.⁴⁶ Colnaric et al directly compared penetrating trauma patient mortality rates of ground EMS and HEMS using the National Trauma Data Bank. They showed HEMS had a greater than 6% mortality reduction for transport times ranging from 31 to 60 minutes. Interestingly, there was no significant mortality benefit between ground EMS and HEMS if transport time was less than 30 minutes.⁴⁷ The mortality improvement on the longer transports stems from a faster scene-to-hospital delivery time for longer transports paired with HEMS personnel who usually possess an expanded skill set and critical care experience. It takes a fair amount of time to requisition and deploy a HEMS unit to the scene. This is because of safety checks, mobilization of the crew, and limited launch points of HEMS units; therefore, in shorter distances (0-30 minutes), it is faster for a ground EMS unit to transport immediately compared to waiting for a HEMS unit. This notion is supported by Chen et al, who demonstrated that HEMS had nearly a 13-minute longer total prehospital time compared to ground EMS.⁴⁸

With the use of HEMS comes a very large incurred cost of operation to both the healthcare system and the patient. It is necessary not to overuse this resource since it also has been shown to aid in mortality benefit only in specific trauma patient populations and distances.⁴⁹ When comparing HEMS to fixed-wing aircraft, there was no significant mortality difference when transporting patients less than 100 miles. The larger difference, both economically and mortality-wise, came in distances greater than 100 miles. Fixed-wing aircraft had better outcomes because of speed, ability to carry more medical staff and equipment, and ability to fly in adverse weather conditions.⁵⁰ Additionally, fixed-wing aircraft more often are able to take bariatric patients because they have fewer weight restrictions when compared to HEMS.⁵⁰

Overall, the largest consideration is the modality that will best serve the patient. There are guidelines and triage tools to help EMS personnel and dispatchers know when to use which transportation modality.^44,51 These guidelines take into account the 2013 joint statement on HEMS from Air Medical Physician Association (AMPA), American College of Emergency Physicians (ACEP), National Association of EMS Physicians (NAEMSP), and American Academy of Emergency Medicine (AAEM) stating that HEMS should be used, first, to have a meaningful shortening of time to delivery of definitive care to patients with time-sensitive medical conditions; second, to provide necessary specialized medical expertise or equipment before or during transport; and third, to provide transport to patients who are inaccessible by other means of transport.⁵²

Special Populations

Pediatric Patients

Penetrating trauma now is the leading cause of death in patients younger than 18 years of age, followed closely by blunt accidental trauma.^53,54 Pediatric patients differ from adults in ways that affect prehospital needs and interventions. Pediatric patients have a smaller, more collapsible airway, a larger relative head-to-body ratio, and increased fragility of their skeleton and other internal organs.⁵⁵ Pediatric patients also initially compensate for shock better than adults and may not become hypotensive until a substantial blood volume has been lost.⁵⁶ These differences can confound crews and dispatchers alike on whether transport to a dedicated pediatric trauma center is needed.⁵⁷ Clinical decision tools like the Pediatric Trauma Score can help risk-stratify patients.⁵⁸ The mechanism of injury, age, and trauma center capability all factor into EMS transport decisions.^59,60 Many protocols require at least the consideration of HEMS use for any patient younger than 12 years of age with significant trauma, especially in a rural setting since there tend to be fewer dedicated pediatric trauma centers in these areas.⁶¹

Fortunately, dedicated pediatric trauma centers are becoming more common in the United States and are the best prepared to handle these patients in regard to experience, resources, and availability of specialty personnel.^62,63 Although transport to such a facility should be considered the gold standard, initial care at adult trauma centers results in similar outcomes and metrics.⁶⁴ Huang et al showed that adult trauma surgeons were able to perform surgery and stabilize older children at a non-pediatric trauma center with close collaboration with the nearest pediatric trauma center. Once stabilized at an adult trauma center, pediatric patients then can be transferred to the nearest pediatric specialty hospital.

Pregnant Patients

Trauma from MVC or assault is the most common cause of non-obstetric death in pregnant patients.⁶⁵ Pregnant trauma patients have differing physiological parameters when compared to non-pregnant trauma patients. Increased blood volume, decreased blood pressure, lower functional reserve capacity in the lungs, and increased cardiac output along with other hemodynamic changes make this population at higher risk for trauma-related mortality.^66,67 The average blood volume increase is nearly 50% in pregnant women, delaying signs of shock even after significant blood loss and warranting a higher volume of initial resuscitation fluids.⁶⁵ The gravid uterus has a compression effect on the underlying vasculature that will lead to symptomatic hypotension when supine. Compression of the inferior vena cava (IVC) by the uterus can decrease venous return by nearly 30%.⁶⁵

En route to the hospital, several special techniques can be employed to optimize stabilization in this patient population. Placing a pregnant patient in the left lateral decubitus position, placing a Cardiff wedge, or displacing the uterus to the left of the body if the patient must be kept supine can help increase venous return. Moderate or significant trauma in a pregnant patient warrants consideration of HEMS transportation.⁶¹ Dispatch and crews need to consider the distance from a trauma center and distance to a hospital with OB/GYN capabilities, weather, and HEMS response time to the scene.⁶¹ While transportation modality decisions are complex with this patient population, all pregnant patients should be taken to a trauma center if possible, since even minor trauma can cause placental abruption.

Prehospital providers also need to consider medication effects on pregnancy. For example, pain management in a pregnant patient changes depending on the current trimester. Nonsteroidal anti-inflammatory drugs (NSAIDs) and short-term opioids for mild to moderate pain are acceptable prior to the third trimester; however, they are contraindicated and considered a level C pregnancy risk once a woman is in her third trimester.⁶⁸

Geriatric Patients

According to the U.S. Census, it is expected that 1 in 5 Americans will be older than the age of 65 years by 2040.⁶⁹ The number of geriatric trauma calls also is increasing exponentially.⁷⁰ This population may decompensate sooner because of declining physiological capacity, stunted compensatory responses due to polypharmacy, and statistically an increased number of comorbidities. As a result, elderly patients historically have been under-triaged following traumatic injury.⁷¹ Generally, patients older than 70 years of age should be evaluated at a trauma center regardless of perceived severity of trauma.⁷² Some guidelines are even more stringent, recommending that any trauma patient older than the age of 65 years with either a systolic blood pressure less than 110 mmHg or a heart rate greater than 90 bpm be taken to a trauma center.⁷³

Considerations while transporting geriatric trauma patients include increased suspicion for c-spine injury balanced with increased vulnerability of harm from spinal immobilization, increased risk of traumatic brain injury warranting frequent reassessment of neurologic status and early initiation of resuscitation due to limited physiological compensation capabilities, again while acknowledging increased vulnerability to volume overload.^74-76

Burns

The American Burn Association reports more than 450,000 burn-related emergency visits per year.⁷⁷ Burn patients can deteriorate very quickly at any time because of airway compromise, hypovolemia, and hypothermia. In a prehospital setting, the single most important initial step is to stop the burning process.⁷⁸ This involves removing clothing, extinguishing active flames, or irrigating chemical burn sites. Once the burning source has been contained, attention should be placed on the airway. Burn patients are at risk for airway compromise because of swelling and inhalation injury.⁷⁹ Intravenous access with prompt fluid administration is paramount to improve burn patient outcomes.⁸⁰ For temperature control, use warm blankets, keep the ambulance warm, and use warm intravenous fluids. Burn patients should be transported to a specialized burn center, which results in improved outcomes.^79,81 Given the complexity of management, transport of burn patients should be done by the highest scope of practice providers available, whether by ground or HEMS. While all patients with burns ideally should be transported to a burn center, HEMS should be considered for several criteria of burn patient. This includes but is not limited to electrical burns, inhalation burns, greater than 20% total body surface area (TBSA), and burns to the face, hands, genitals, and feet.⁶¹

Rural

The U.S. Census Bureau defines rural as any population, housing, or territory with less than 2,500 people.⁶⁹ Although various definitions are used when considering “rural” EMS, this paper defines “rural” as greater than 60 minutes to the nearest Level I or Level II trauma center.⁸² In the United States, a large majority of Level I trauma centers are located in dense urban areas. Rural EMS providers have incredibly large geographic areas to cover with limited access to trauma centers.⁸³ This greatly increases average response time both to the scene of a trauma and transport times to a trauma center.^84,85 Planning and well-established lines of communication have been shown to improve outcomes within the rural areas.

Given the increased response and transport distance, HEMS or even fixed-wing transport should be considered in patients with significant traumatic injury.^86,87 Another issue is a lack of rural ALS squad availability.³⁴ ALS squads may be preferred to transport trauma patients for distances longer than 30 minutes.⁸⁸ As a result of distance adversity, making a decision to transport to a trauma center actually may confer higher mortality rates.⁸⁹ Elkbuli et al showed large mortality discrepancies in Level I and II trauma centers located in Southern and Western states when compared to the Northeast and Midwest. They associated this with the higher concentration of rural areas in the South and West and the increased times to reach and to transport those patients.

Sometimes, transporting critically ill patients to a Level III or non-trauma center may confer the best chance of initial survival.⁹⁰ Rapid definitive care and stabilization buys time until transport to a tertiary or quaternary center.⁹¹ Other data show contradictory outcomes when looking at differing population densities.^35,92 Newgard et al found no significant difference in trauma patient mortality when comparing urban and rural EMS; Ryb et al found a higher likelihood of trauma mortality in the rural setting and suggested prehospital care is the reason for this disparity. These conflicting opinions warrant further research into rural vs. urban EMS disparities to elucidate possible causes and solutions.

Tactical

Tactical-based trauma management is becoming more common in the United States. With the recent increase in mass shooting events, LE personnel are responding at higher frequencies and often are the first on scene capable of rendering medical care.⁹³ In most active killer situations, the primary cause of injury is penetrating wounds from firearms. It is important for public safety agencies to plan for these situations to mitigate preventable casualties.⁹⁴ LE must notify hospitals and EMS systems quickly that an active killer event is either happening or could develop.^95,96

In addition to planning and communication efforts, training LE personnel in TCCC and Tactical Emergency Casualty Care can speed up the time from wounding to initiation of lifesaving treatment.⁹⁷ Basic hemorrhage and airway control during the post-injury “platinum” five minutes (via tourniquets, wound packing, and positioning) can stabilize casualties long enough to facilitate transport to an appropriate trauma center.⁹⁸ The mode of transport will vary depending on the situation and the ability of EMS to access casualties. If scene safety issues limit the use of ambulances, consideration should be given to using LE vehicles to move casualties to the nearest appropriate hospital.

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