Airway Management in Trauma

Challenges in the Emergency Department or Trauma Resuscitation Unit

Victims of trauma present with a spectrum of injuries, ranging from minor, localized injuries to catastrophic, multisystem trauma, and present unique challenges for the individual providing airway support and management. Although many of these patients do not require intubation outside of the OR, those requiring intubation in the emergency department (ED) or trauma resuscitation unit (TRU) can be some of the most challenging airway cases because of limited time for evaluation, immobilization, combativeness, direct airway trauma, presence of blood or vomit, or a combination of these factors. Emergency intubations outside the OR are generally associated with a higher frequency of difficult intubation and an increased complication rate, ^, and, in many cases, the usual paradigms of airway management used in elective perioperative care are not applicable. Care of the acute, severely injured trauma patient is best done using a team approach with a clearly designated team leader, who controls the decision-making, sequence, and flow of the entire resuscitation to include airway management considerations.

In the late 1990s, anesthesiologists performed the majority of trauma airway management in the United States both inside and outside the OR, with emergency medicine (EM) physicians handling the majority of nontrauma cases in the ED. More recently, multiple studies examining the impact of transitioning to a primarily EM-based airway management system for trauma have shown no adverse impact on complication or success rates. Currently in the United States, trauma patients are intubated primarily by EM physicians, although patients with direct trauma to the airway or with obvious signs of a DA may be managed best using a team approach, with EM physicians, anesthesiologists, and surgeons working in concert to achieve the best possible results. This includes determining algorithm-based backup plans and the appropriate location to proceed with advanced airway techniques in complex cases. Internationally there is considerable variation in the primary airway providers and capabilities available for the trauma patient.

An emergency trauma intubation in the ED generally requires more assistance than an intubation performed under controlled conditions. Multiple providers are required to ventilate the patient, hold cricoid pressure (CP) if applied, administer medications, and provide manual in-line stabilization (MILS) of the cervical spine, as necessary. Fig. 34.1 is an illustration of this approach. In addition, more assistance may be required to control a patient who is combative because of intoxication, traumatic brain injury (TBI), or other causes of altered mental status associated with agitation. The immediate presence of a surgeon or other physician who can expeditiously perform a surgical airway is also desirable. Even if a surgical airway is not required, additional experienced hands may prove useful during difficult intubations. The surgeon may wish to be present during laryngoscopy if there has been trauma to the face or neck or to personally visualize the upper airway when video-assisted laryngoscopy (VAL) is employed. Alternatively, the views obtained during intubation can frequently be recorded with most VAL devices and reviewed later by the managing surgical service.

Indications for Airway Management

Airway management decisions in the trauma patient are frequently driven by considerations beyond identification of the need for an operative intervention. The decision regarding when and how to control a patient’s airway is based on a complex series of considerations related to the patient’s specific injuries and overall condition, the likelihood of clinical deterioration, and the need for transport to locations in the hospital where airway control is desirable based on these and other factors (e.g., interventional radiology suite). Although the need for emergent or semiurgent intubation is obvious in many patients, it is less intuitive in others. The Eastern Association for the Surgery of Trauma (EAST) has published practice management guidelines addressing emergency tracheal intubation following traumatic injury, including indications for intubation; this information is summarized in Table 34.1 . The main indications for emergent intubation can be addressed by asking the following questions during the initial and subsequent evaluations:

• Is there a failure to maintain or protect the airway?

• Is there a failure of oxygenation or ventilation?

• Is there a need for intubation based on the anticipated clinical course?

The requirement to proceed with intubation, based on a failure to maintain an airway, will be clinically apparent in most cases. In some patients, however, the potential for rapid loss of an initially intact airway may drive the decision to intubate. Examples of this include a penetrating neck injury with an expanding neck hematoma or an inhalational injury with anticipation of progressive airway edema. The need to proceed with intubation for airway protection, however, may be less clear. Loss of the ability to protect the airway can occur because of several mechanisms, including altered mental status secondary to TBI, hemorrhagic shock, or ingestion of drugs or alcohol. When determining need for intubation, consideration should be given to possible effects of prehospital medications such as ketamine, opioids, and naloxone. For example, patients who receive relatively large doses of ketamine in the field will likely exhibit altered mental status and increased secretions despite maintaining airway reflexes, and these signs may factor into a decision to intubate. One of the most common approaches to determining the ability of a patient to maintain his or her airway is to calculate the patient’s Glasgow Coma Scale (GCS) score. A GCS score of 8 or lower in the absence of a rapidly reversible cause has been used as an indicator of coma and a general requirement for intubation in the setting of trauma. This cutoff has been promulgated through the Advanced Trauma Life Support (ATLS) program, although patients with a higher GCS score may still require intubation in the setting of an altered neurologic assessment. In a retrospective review of 1000 consecutive patients intubated after injury, Sise and colleagues found that twice as many patients were intubated for the discretionary indication of altered mental status (GCS score >8) than those with a GCS score of 8 or less, suggesting that other factors contributed to the decision to establish a definitive airway.

Basic testing for the presence of adequate airway protection in the initial assessment can be accomplished by asking the patient to phonate. Phonation requires an unobstructed upper airway and the ability to execute complex, coordinated maneuvers. Observation of the patient’s ability to swallow and handle secretions is also useful during the primary survey. The ability to sense the pooling of secretions in the posterior pharynx and to perform the coordinated series of neurologic and muscular maneuvers to swallow requires a high degree of function and demonstrates a greater likelihood of airway protection. Hospitalized patients with secretions pooling in the back of their mouths and demonstrated swallowing dysfunction are known to be at greater risk for aspiration and pneumonia although this has not been studied in the acute trauma setting.

The loss of the gag reflex may seem like a reasonable test as another indicator of inadequate protective airway reflexes and indication for intubation; however, it should not be assessed in a critically injured, immobilized trauma patient. Insertion of a tongue blade or other device to stimulate the patient’s posterior oral pharynx can cause the muscles of the soft palate and pharynx to contract collectively because of the reflex, and vomiting is easily provoked with potential aspiration of gastric contents. This can be made worse by vocal cord paralysis or depression of the gag reflex by sedatives where the glottis does not completely close with stimulation of the reflex. Additionally, the gag reflex is much less reliable than phonation and swallowing, and it is absent in up to 25% of the normal adult population. Generally, the presence of a gag reflex does not equate to airway protection, and its absence does not necessarily indicate a need to intubate.

The ability of a patient to maintain appropriate oxygenation and ventilation can be assessed clinically and evaluated by pulse oximetry and capnography. Although arterial blood gas analysis can be useful in evaluating the trauma patient with respect to adequacy of resuscitation efforts in the setting of severe shock, it will have little or no role in the decision to intubate during the acute resuscitation. Evaluation of the patient’s respiratory effort and magnitude of injuries in the context of pulse oximetry readings is more important to the intubation decision than arterial blood gas values. Patients with compromised ventilation or oxygenation, particularly those with suspected brain injury, should receive supplemental oxygen (O ₂ ), and all reversible issues should be addressed. Hemothorax, pneumothorax, and opioid overdose are examples of potentially reversible conditions that compromise oxygenation and ventilation. However, most cases of hypoxemia or hypoventilation in multitrauma patients are multifactorial and do not respond to simple interventions. In these cases, early intubation is typically indicated.

Most trauma patients will maintain and protect their airways and exhibit adequate or correctable oxygenation and ventilation during their initial assessment. In these cases, it is the anticipated clinical course that guides the decision to intubate. A patient may appear stable at the time of evaluation, but deterioration can be predicted as a natural course of the injuries. For example, the patient with burns from a closed-space fire with significant inhalation of superheated air (see Chapter 35 ) may present with a somewhat hoarse voice or a simple cough but an otherwise patent airway. Failing to recognize the possibility of progressive obstruction of the airway attributed to toxic and thermal insults and to intervene in a timely fashion can lead to disaster. Although the patient may not meet the criteria for emergency intubation related to airway maintenance, oxygenation, or ventilation at admission, the likelihood of deterioration may be sufficient to warrant intervention, including intubation and/or direct examination via fiberoptic nasoendoscopy. It is the predictability of the deterioration that determines the decision to intubate. Similarly, the patient presenting with multitrauma, complicated pelvic fracture, open femur fracture, and hypotension is inevitably intubated, even though there is no immediate threat to airway patency or oxygenation. The need for advanced imaging, aggressive pain control, and operative repair of obvious injuries dictates that the patient be intubated early and in a more controlled fashion than trying to manage a chaotic intubation in the computed tomography (CT) scanner.

Trauma patients may be aggressive, threatening, or combative because of anxiety, pain, fear, intoxication, TBI, or some combination of these. Attempts should be made when reasonable to determine and address the cause of the behavior both pharmacologically and nonpharmacologically, prior to consideration of induction and intubation. Induction and intubation are typically performed if the patient is at risk for self-harm or harming others due to their behavior when more conservative measures have failed. Similarly, if patient behavior prevents further work-up of life-threatening injuries, then intubation may be required. For example, a patient who will not remain still for a necessary CT scan despite conservative measures may need induction and intubation. Apart from patient behavior posing a risk of self-injury, injury to others, or prevention of a needed timely work-up, intubation is rarely required for behavior alone and every attempt should be made to control behavior without intubation where possible. Management of the combative patient is discussed in further detail in the section Management of the Combative Patient later in this chapter.

The decision to intubate is a critical resuscitative decision and can greatly influence subsequent management. Airway management in trauma patients can provoke anxiety because airway difficulty is often exaggerated by the need for cervical spine immobility, presence of direct airway trauma, compromise of hemodynamic status, and propensity for clinical deterioration. Early definitive airway management must be performed in a logical and safe fashion to support evaluation and resuscitative efforts for these patients. Decision-making must be based on a consistent series of principles that accounts for the patient’s current condition, likelihood of deterioration, planned diagnostic and therapeutic interventions (including transport and surgery), preinjury comorbidity, as well as the resources and expertise available in the resuscitation area.

Prevention of Aspiration

All trauma patients are at higher risk for aspiration given intoxication, trauma-induced reduction or absence of gastrointestinal motility, and unknown time of last food intake. Additionally, pharyngeal hemorrhage because of maxillofacial trauma, secretions, and foreign bodies may increase the risk. Reasonable precautions should be taken to prevent aspiration of gastric contents during overall trauma management and airway procedures. The initial intubation method depends on the constellation of patient injuries, hemodynamic status, and available equipment and expertise. Most patients, however, will undergo rapid sequence induction and intubation (RSI) with the intent of mitigating the risk of vomiting and aspiration during the procedure and securing the airway in a rapid, controlled fashion.

The application of CP held throughout laryngoscopy to prevent passive aspiration remains a controversial component of RSI. The use of CP was widely accepted dogma in trauma for many years based on the belief that it could prevent aspiration via passive regurgitation through compression of the upper esophagus against the anterior cervical vertebral bodies. More recently, this belief has been challenged. Advanced imaging suggests the cervical esophagus is positioned lateral to the cricoid ring in many patients and may not be compressed during application of CP. This relationship is exaggerated by posterior pressure, although the hypopharynx posterior to the cricoid ring may still be compressed by CP. Misapplication of CP is common and can result in more difficult mask ventilation, direct laryngoscopy (DL), supraglottic airway (SGA) placement, and tracheal tube passage, although a recent meta-analysis suggests CP may overall have little impact on intubation outcomes. Cervical spine motion may also occur during application of CP, although cadaveric work suggests that movement is relatively limited and can be reduced further with posterior manual support.

Controversy regarding the risk-benefit assessment for the continued use of CP in patients undergoing RSI is reflected in published guidelines from multiple organizations that have recommended eliminating its use or considering it an optional measure. The use of CP in the trauma patient was recently addressed in the EAST practice management guidelines for emergency tracheal intubation immediately following traumatic injury. Based on evidence that CP may worsen the laryngoscopic view, impair bag-valve-mask (BVM) ventilation efficiency, and not reduce the incidence of aspiration, the use of CP was removed as a level 1 recommendation. Similarly, the Scandinavian Society of Anaesthesiology and Intensive Care Medicine in its Clinical Practice Guidelines on General Anaesthesia for Emergency Situations determined that the use of CP is not mandatory and leaves its use up to individual judgment. This trend has continued in other areas of emergent airway management with the 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care recommending against the routine use of CP during laryngoscopy and BVM ventilation. These recommendations are reflected in recent surveys of anesthesiologists, emergency medicine physicians, and surgeons showing significant variability in the use of CP during RSI of patients requiring emergent intubation. ^{, , ,} In a recent national survey of teaching hospitals in the United States, however, 91% of participants indicated the continued use of CP as part of their modified RSI technique. In support of CP, the most recent guidelines of the American College of Surgeons’ ATLS course and the Difficult Airway Society 2015 unanticipated difficult intubation guidelines in adults include CP as a component of RSI. ^,

Although there is no universal agreement on the role of CP for aspiration prevention during RSI in the trauma patient, application of CP by trained personnel can still be useful during airway management. Correctly applied CP has been shown to reduce gastric insufflation during BVM ventilation ^, and may provide tactile feedback during endotracheal tube (ETT) placement. The most recent Cochrane Collaboration review concludes that the lack of randomized controlled trials addressing this question provides no strong evidence for or against the assumption that CP protects against aspiration; however, nonrandomized controlled trials suggest that CP may not be necessary for safe RSI performance. If the decision is made to use CP, it should be altered or removed to facilitate ventilation, laryngoscopy, or ETT/SGA placement if they are noted to be difficult. Securing the airway and providing ventilation should take precedence over the potential risk of aspiration in the trauma setting given the current level of evidence for CP during RSI.

In addition to the risk of aspiration during trauma RSI, other factors including patient positioning and other airway manipulation may influence the chance of aspiration. Placing patients in a 20- to 40-degree head-up position during RSI is theorized to capitalize on gravitational forces to reduce passive regurgitation above the upper esophageal sphincter. Caution must be exercised, however, in extreme shock states, as this positioning can decrease preload. If the patient vomits while immobilized on a spine board, the patient and the board should be rolled together into the right lateral decubitus position to permit suctioning and evacuation of the vomitus from the mouth. Recurrent vomiting is a relative indication for early intubation in patients who require immobilization and may be unable to manage the vomitus attributed to alterations in swallowing or level of consciousness. Because most patients may only require immobilization during transport, early evaluation should allow for discontinuation shortly after arrival at the ED. When applying awake intubation techniques, adequate sedation and topical anesthesia should be used to prevent gagging and emesis. If the patient vomits during awake intubation, there may be an increased risk of aspiration because of supraglottic and vocal cord topical anesthesia. Prompt suctioning and repositioning of the patient, if necessary, should help reduce aspirate volume.

Pharmacologic Considerations

In the trauma patient, use of RSI remains the most employed approach to facilitating intubation. As previously described, the primary objective of this technique is to minimize the time interval between loss of protective airway reflexes and tracheal intubation with a cuffed ETT. Following preoxygenation adjusted as needed for urgency and patient condition, rapid-acting induction and neuromuscular blocking (NMB) agents are administered to facilitate the procedure. Some providers, including the authors, routinely perform modified RSI (gentle mask ventilation after rapid sequence induction) in nearly all acute trauma patients as hypoxia and hypercarbia may be more detrimental to the patient condition than the risk of aspiration. This can be particularly important in patients with significant hypoxia prior to induction or in patients with suspected TBI due to difficulties with establishing adequate preoxygenation. The optimal medications for RSI in the setting of trauma would include the following properties: rapid onset and short duration of action, negligible hemodynamic effects, minimal side-effect profile, and rapid reversibility. Unfortunately, the perfect combination of drugs does not exist, leaving the provider with the necessity to make decisions based on specific drug considerations and patient factors. A lack of randomized controlled trials in the trauma population provides no additional insight into the best induction agent for specific subpopulations.