Prehospital Trauma Care

Introduction

• Traumatic injury is characterized by a primary (mechanical) insult, followed by diverse pathophysiological changes that may lead to secondary (biomechanical) damage. Trauma care is time-critical to correct physiological disturbances resulting from the injury as early as possible to avoid resulting morbidity and mortality.
• Prehospital providers play a vital role in assessing injuries at the scene of the trauma, providing resuscitative efforts, and transporting the patient to a trauma center where appropriate care can be offered.

Team Composition

• Prehospital care teams vary greatly in composition between regions. Most emergency medical systems use a tiered response with multiple levels. Lower-acuity accidents are assigned basic life support (BLS) teams of 2 emergency medical technicians. Higher acuity emergencies are answered by both a BLS and an advanced life support (ALS) team. ALS teams can consist of advanced paramedics, nurses, advanced practice providers, or physicians.
• The level of training of these responders and the materials they carry determine the level of care that can be provided at the scene. Prehospital vehicles are typically organized in a standardized manner to ensure all materials are readily accessible when needed (Figure 1). Team roles are assigned before arrival on scene, based on each provider’s skills and competencies.
• Prehospital teams routinely work closely together, knowing each other’s working practices and strengths. Teams often spend time at base simulating cases to develop sequences and standard operating procedures.

Initial Approach and Primary Survey

• All medical personnel responding to an incident should be aware of their surroundings and ensure they can approach the patient safely. Prehospital providers should first take the time to analyze potential hazards on scene and coordinate their approach with Fire, Police and other Rescue services.
• The prehospital approach to the trauma patient follows the treatment algorithm described in advanced trauma life support. It consists of a primary survey with concurrent treatment and transport to an appropriately equipped facility.¹ The primary survey follows a predetermined order of sequential clinical assessments, aimed at excluding potential lethal pathology in order of urgency associated with each clinical entity: “treat first what kills first.”
• The primary survey follows a structured xABCDE (eXsanguinating hemorrhage – Airway – Breathing – Circulation – Disability – Exposure) approach. As the primary survey is largely clinical, with only minor technical investigations to support clinical decisions, it can be conducted in the field with minimal equipment and time. Below, we discuss some of the unique aspects of prehospital trauma care as they may be encountered during a primary survey.

X – eXsanguinating External Hemorrhage

• Providers first look for uncontrolled and external exsanguinating hemorrhage. This is carried out by a rapid, targeted clinical examination focused on diagnosing massive external bleeding that is immediately life-threatening. Bleeding is treated with hemorrhage control measures aimed at occlusion of arterial flow to the injury: local pressure, occlusive dressings, or tourniquet application. In some countries, nonmedical providers such as police officers or teachers are trained to provide this care before the arrival of emergency medical services, and tourniquets are stocked at public locations¹ (see OpenAnesthesia “Stop the Bleed” section of the Hemorrhagic Shock in Trauma summary for further details).

Airway with Cervical Spine Protections

• Identifying and treating an acute airway obstruction is the next priority. Providers examine the airway for foreign bodies and fluids that obstruct airway patency by inspection, palpation (airway movement), and listening for obstructive breathing. Obstructed airways are treated by removal of foreign bodies, aspiration of the upper airways, and by definitive airway control by insertion of an endotracheal tube, if indicated.
• Patients who are unconscious in the setting of trauma may have limited reflexes protecting their airway patency.² Therefore, when a patient has a patent airway but a Glasgow Coma Scale (GCS) score of less than 9, the airway is routinely secured to prevent aspiration and maintain adequate oxygenation and ventilation throughout the primary survey and transport to definitive care.
• Advanced airway management during transport can be especially challenging: ALS providers are buckled in for their own safety, and vehicle movement can limit precision with airway instrumentation, posing risks of airway damage or failed intubation. Prehospital providers may thus electively intubate a trauma patient when concern exists of potential clinical decline during transport. Airway instrumentation in the prehospital setting can present challenges not typically encountered in the hospital, including outdoor lighting conditions, adverse weather, patient positioning, entrapment, and limited materials for difficult airway management.
• Before intubation, prehospital providers should discuss a plan with the team caring for the patient, as some of the first responders on-scene may not be familiar with (advanced) airway management. Tasks should thus be allocated in advance, and closed-loop communication should be used to ensure that everyone understands their role. The airway plan should address contingencies such as failure to intubate or oxygenate. Ideally, a definitive airway with a cuffed tracheal tube placed below the vocal cords should be used. Supraglottic airways have a role in prehospital trauma care as a rescue option for difficult airway management. Many prehospital services now carry video laryngoscopy devices and have adopted a bougie-first strategy to improve first-pass airway success rates.³
• In the case of an inaccessible airway (facial fractures, laryngeal fractures or failed intubation), a surgical airway or front-of-neck access (FONA) may offer a definitive airway. Use of a scalpel, bougie, and endotracheal tube technique for FONA is most common. Needle cricothyrotomy is reserved for younger children and may be combined with jet ventilation. Secure fixation of the endotracheal tube is essential to prevent dislocation during transportation.
• During examination and management of the airway in the trauma patient, the cervical spine of the patient should always be protected against movement, as airway instrumentation can worsen alignment of c-spine injuries.⁴
• In awake patients, clinical decision tools such as the Canadian Cervical Spine Rule or the National Emergency X-Radiography Utilization Study criteria may be used to determine whether further cervical spine immobilization is indicated. Neck immobilization may be performed manually via in-line stabilization (MILS; Figure 2) or by applying a rigid cervical collar, head blocks, or both. During airway instrumentation, it is more practical to rely on MILS provided by an experienced provider than attempting airway instrumentation with a rigid collar or headblocks in place.⁵

Rapid Sequence Induction and Drugs

• Careful selection and titration of induction drugs are necessary for the induction of emergency prehospital anesthesia, as all shock in severely injured patients is presumed to be hemorrhagic until proven otherwise. A rapid sequence induction is carried out to limit the risk of aspiration, and mobilization of the cervical spine, with basic airway maneuvers, such as bag-mask ventilation, placement of airway adjuncts, being avoided. The selection of an appropriate induction drug may be subject to local protocol. Prehospital providers should be aware of the limitations of some induction drugs in the setting of hypovolemic shock. Etomidate and midazolam have the least influence on vasomotor tonus,⁶ ketamine may be suitable in some cases, but the negative inotropic effect may predominate in profound or longer-existing hypovolemic shock.⁷
• Anesthesia should be maintained during transport to the hospital by intermittent bolus or continuous drip of hypnotics. Inhalational anesthetics are not routinely used in the prehospital setting. Methoxyflurane is commercially available as an inhaler for prehospital analgesia when intravenous (IV) access is unobtainable (currently an off-label use in the United States, as it is not Food and Drug Administration-approved).

Breathing

• Assessing breathing is the next priority of the primary survey. Similar to airway assessment, clinicians rely on targeted clinical examination to exclude certain life-threatening chest injuries. This can be done by assessing the symmetry of breath sounds on auscultation, inspecting chest movement, and noting the presence of specific wounds or findings. Important entities to be excluded clinically during the Breathing assessment of the primary survey include simple, open, and tension pneumothorax, hemothorax, flail chest, and lung contusion. Depending on the level of the prehospital service, diagnosis of pneumothorax may be aided by portable ultrasound as part of an extended focused abdominal sonography for trauma (eFAST).
• The presence of a clinically significant pneumothorax should trigger prompt decompression. Both needle and finger thoracostomy (Figure 3) may be used to attempt decompression. However, current evidence suggests finger thoracostomy in the 4th-5th intercostal space at the anterior to mid-axillary line is more reliable and durable. Some prehospital services may elect to place a chest drain after finger thoracostomy, but the focus lies in the decompression as a lifesaving intervention.
• Patients with chest injury should be subjected to frequent reassessment during transport, as pneumothoraces may recur, expand, or be complicated by bleeding. Especially in the setting of positive-pressure ventilation, air medical transport at significant altitude or with pressurized cabins, prehospital providers should decompress smaller pneumothoraces in anticipation of potential volume expansion.⁸

Circulation

• The aim of evaluating circulatory stability during the primary survey is to determine whether significant bleeding is present and to control it in anticipation of definitive (surgical or angiographic) care. Prehospital providers look for bleeding in 5 major places: abdominal, chest, pelvis with retroperitoneum, long bone fractures, and external bleeding. Massive exsanguinating hemorrhage is a top priority and should be managed at the very beginning of the primary survey (see above “x”). Clinicians rely on physical examination and may use portable ultrasound to perform eFAST. Ultrasound may reveal free fluid in the abdomen, chest or pericardium and can help plan interventions or triage the patients to an appropriate level of care.
• Providers attempt to control bleeding by applying direct pressure, occlusive dressings, tourniquets, aligning and splinting long bone fractures, and stabilizing the pelvis with a pelvic binder. Parallel to that, rapid large-bore vascular access is gained, and volume resuscitation of patients in hemorrhagic shock is started. When IV access is not rapidly achieved, intraosseous access is obtained. Limited crystalloid administration (10-20mL/kg of balanced isotonic solution) is usually the first step. Achieving specific blood pressure targets can be challenging, as noninvasive blood pressure readings are often unreliable during transport due to patient or vehicle movement. The administration of tranexamic acid 1gram IV is standard practice within the first 3 hours after injury with presumed hemorrhage to mitigate potential hyperfibrinolysis.⁹ Colloids have not proven useful in this setting.¹⁰ However, the administration of blood products in the prehospital setting, ranging from packed red blood cells, freeze-dried and liquid plasma to whole blood, has proven to be a safe intervention that improves survival in trauma patients with longer transport times to adequate care.¹¹ Prehospital blood product administration requires specialized equipment, including a blood fridge or cooler, a fluid warmer, and separate IV tubing and pressure bags capable of handling pressure differences during air medical transport. The exact modalities of transfusion may vary between regions and services.
• Some physician-led prehospital teams carry out advanced resuscitation techniques in patients with hemorrhagic shock, such as resuscitative thoracotomy. This procedure is indicated in case of loss of cardiac output with potential intrathoracic injuries, when other lifesaving actions (airway management, chest decompression, volume resuscitation) have already been carried out, or eFAST demonstrated evidence of tamponade. Especially in regions with a high incidence of penetrating trauma, resuscitative thoracotomy in the prehospital setting may improve outcome by limiting the time of low flow to essential organs (see OA summary “Anesthesia for Thoracic Trauma” for more details: Link)
• Although solid evidence supporting its use is lacking, resuscitative endovascular balloon occlusion of the aorta can be used in the field to limit blood loss below the diaphragm and redirect blood flow to the heart and brain. Prehospital teams have successfully placed balloon catheters in the aorta using anatomical landmarks with ultrasound guidance.
• Advanced resuscitation techniques can be time- and resource-consuming. Prehospital providers should carefully assess whether the time gained by early delivery of therapy outweighs the risk of increased time and effort on scene, which could delay transport.

Disability

• After ensuring airway patency, adequate oxygenation/ventilation, and appropriate cardiac output, the patient’s neurologic status can be evaluated. Prehospital providers can only rely on clinical examination to assess the patient’s neurological condition. Technical investigations, such as ultrasound measurements of the optic nerve to diagnose increased intracranial pressure (ICP), are not routinely used.
• Traumatic brain injury (TBI) remains one of the most determining injuries in the outcome of trauma patients. Diagnostics and interventions are aimed at limiting secondary damage caused by physiologic responses to injury. First, the GCS is determined to assess consciousness, followed by an assessment of pupils and of symmetry of movement in all limbs. Both central nervous system function and spinal cord integrity are assessed.
• Trauma patients with blunt injury should have spinal motion restriction during primary survey and for transportation. Current evidence does not support immobilization of the spine in patients with isolated penetrating trauma.¹ Without solid evidence to support clinical decisions, immobilization modalities are subject to local preferences and protocols.
• If the clinical examination raises suspicion of moderate to severe TBI, the prehospital team should take measures to limit secondary brain injury. This can be done by ensuring airway protection with adequate (often mechanical) ventilation, maintaining normocarbia via end-tidal CO₂ monitoring. Next, perfusion pressures should be optimized to maintain a mean arterial pressure greater than 80 mmHg by ensuring adequate, hemostatic volume resuscitation in hemorrhagic shock and by titrating vasopressors when adequate volume resuscitation has been achieved or neurogenic shock is present.
• In severe TBI and suspected ICP rise, hyperosmolar therapy has a place. In the prehospital trauma setting, both mannitol (0.5-1 g/kg IV bolus) and hypertonic saline (3 mL/kg IV bolus of 3% sodium chloride) are feasible. Although solid clinical evidence is lacking, many clinicians prefer the use of hypertonic saline over mannitol, as the latter may exacerbate delayed hypovolemia through diuresis.¹²

Environment/Exposure

• The primary survey concludes with a full-body assessment of the patient, exposing all areas to ensure no critical injuries are missed. This means log-rolling the patient to inspect and examine the back. When time is limited due to a critical need for transportation, “exposure” may be limited to a back sweep, in which the prehospital provider makes a sweeping gesture from the axilla to the hip to look for obvious bleeding or lacerations on the back of the patient, without the need to roll the patient.
• The ’E’ also stands for environment, where it is critical to cover the patient and to make every effort to prevent hypothermia; ideally, warm the patient if needed.

Summary: Primary Survey (xABCDE)

• The primary survey is a brief clinical assessment, supported by limited technical exams (if available), to identify immediate life-threatening injuries in a predetermined order of urgency. During this survey, urgent clinical conditions are identified and treated promptly to prevent patient deterioration. In the prehospital setting, where resources are limited, treatment focuses on stabilizing the patient for transport to an appropriate level of care. The receiving center is contacted prior to transport to ensure they can care for the patient. At the trauma center, the patient is handed over to the trauma team using a standardized briefing tool, such as ATMIST (Age – Time – Mechanism – Injuries – Signs & Symptoms – Treatment). Standardized briefing may help ensure no essential information is lost.

Special Considerations

• At the scene of an accident, two strategies are evident in prehospital trauma care: providers may expedite transport to a trauma center, limiting interventions to strictly necessary steps to avoid time loss and reduce the interval to specialized trauma care. This strategy is often called “scoop and run” and may be used for shorter transport distances or penetrating trauma with severe bleeding. Indeed, minimal interventions may result in faster transport times but could still delay time to delivery of certain critical interventions such as intravenous access, fluid resuscitation or blood product administration.¹³ Alternatively, prehospital crews may conduct a more thorough survey at the scene, stabilize injuries, and initiate appropriate resuscitation before transporting the patient. This strategy, called “stay and play,” could be particularly beneficial in settings with longer transport times, where providing certain time-critical interventions may improve stability during transport and increase the likelihood of survival. Despite resuscitation efforts, patients may succumb to their injuries on scene. Prehospital services should have local protocols in place to deal with the death of a patient as well as activation of forensic services and police when necessary.
• In a mass-casualty incident (MCI), where the number of victims overwhelms local response capacity, priorities shift. As resources are too scarce in the case of MCI, prehospital providers will shift from a single-patient primary survey approach to a triage service, rapidly assessing the largest possible number of patients in the shortest possible time. This helps direct patients to local and regional centers with adequate resources for individualized care, rather than investing limited resources in a single patient and precluding therapy for others. MCI care prioritizes directing available resources to save the greatest number of lives.