A The Clinical Challenge

Airway management in the trauma patient can be particularly challenging because of the presence of a difficult airway with the need for rapid action. The traumatized airway is often anatomically disrupted, obstructing direct laryngoscopy, and the presence of blood in the upper airway confounds attempts at fiberoptic intubation. Manual in-line stabilization of the cervical spine (C-spine) is required in most patients with blunt trauma, compounding the airway difficulties. Although trauma patients are often intubated outside the operating room (OR), usually in the emergency department (ED) resuscitation area, they can also present to the OR requiring intubation for emergency surgery. In the ED, trauma patients are intubated primarily by emergency physicians, but patients with direct trauma to the airway may be managed using a team approach, with emergency physicians, anesthesiologists, and surgeons working in concert to achieve the best possible results. In the OR or other units within the hospital, trauma airway management is typically the responsibility of the anesthesiologist, although surgeons may be called on to assist when the airway is disrupted.

Trauma patients needing airway intervention require a rapid evaluation for potentially difficult airway attributes, development of an airway management plan (including rescue techniques in the event of failure), and a willingness to act quickly with incomplete information. In most cases, the need to intervene is apparent, but certain situations can mislead the evaluating physician into thinking that an airway is not at risk. Many trauma patients initially appear to be stable; they maintain a patent airway and breathe spontaneously until some process causes them to deteriorate rapidly. Soft tissue swelling, hematomas, or subcutaneous air can cause dramatic and potentially lethal airway distortion, even though external findings remain unremarkable, until the patient suddenly decompensates. Any patient with a traumatized airway requires early assessment and decisive action. Delay or observation, although initially seeming prudent, can lead to catastrophic airway compromise and make airway intervention much more difficult than if it had been undertaken earlier.

B The Decision to Intubate

The decision to intubate is the most important resuscitative decision, but it is often the one with which the provider struggles the most. Trauma patients present anxiety-provoking situations because their airway difficulty is often exaggerated by C-spine immobility, direct airway trauma, overall physiologic compromise, and the propensity for clinical deterioration. Early definitive airway management must be performed in a logical and safe fashion to continue evaluation and resuscitative efforts for these patients. Decision making must be based on a consistent, reproducible series of principles that accounts for the patient’s current condition, likelihood of deterioration, planned diagnostic and therapeutic interventions (including transport), preinjury comorbidity, and the resources and expertise available in the resuscitation area.

Answers to three fundamental questions inform the decision to undertake emergency intubation:

Questions 1 and 2 are relatively straightforward in the setting of the trauma patient. Failure to maintain the airway is clinically obvious. Loss of airway protection usually occurs in the setting of depressed mental status caused by head trauma, hypovolemic shock, or ingestion of drugs or alcohol and is a condition with which the ED physician and anesthesiologist are familiar. Airway protection is best tested by evaluation of the patient’s ability to phonate (if possible). Phonation requires an unobstructed upper airway and the ability to execute complex, coordinated maneuvers. After phonation, the patient’s ability to swallow and handle secretions is assessed. 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 connotes airway protection. The gag reflex, long advocated as the test by which the need for intubation can be judged, should never be performed in a critically injured, supine, immobilized trauma patient. The wisdom of inserting a tongue blade or other device to stimulate the patient’s posterior oral pharynx in this state is questionable, because vomiting is easily provoked and difficult to deal with.

The gag reflex is much less reliable than phonation and swallowing, and it is absent in up to 25% of the normal adult population.³ The presence of a gag reflex does not equate to airway protection, nor does its absence indicate a need to intubate. The presence or absence of the gag reflex is better thought of as a neurologic evaluation (i.e., cranial nerves IX and X) rather than as part of an airway evaluation. The Glasgow Coma Scale is a better tool for predicting intubation.⁴

The ability of a patient to maintain appropriate oxygenation and ventilation can be assessed clinically and supported by pulse oximetry and capnography. Although arterial blood gas values are useful in evaluating the trauma patient with respect to identification of occult acidosis that may represent more severe shock than is clinically apparent, these determinations have little or no role in the decision to intubate. Evaluation of the patient’s respiratory effort and the overall sense of the patient’s injuries in the context of pulse oximetry readings are more important to the intubation decision than arterial blood gas values. Patients with compromised ventilation or oxygenation should receive high-flow face mask oxygen (O₂) with a reservoir, and all reversible issues should be addressed. Hemothorax, pneumothorax, flail chest, and opioid overdose are examples of reversible conditions that compromise oxygenation and ventilation. Most cases of hypoxemia or hypoventilation in multitrauma patients are multifactorial and do not respond to simple interventions. In these cases, early intubation usually is indicated.

Most trauma patients can maintain and protect their airways and exhibit adequate or correctable oxygenation and ventilation. For them, it is the anticipated clinical course that guides the decision to intubate. This is the most sophisticated and most important of the decisions facing the airway manager or trauma captain. 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 44) may present with a somewhat hoarse voice or a simple cough but has an otherwise patent airway. Failing to recognize the likelihood of progressive obstruction of the airway, which has been subjected 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 and protection, oxygenation, or ventilation, the likelihood of deterioration is alone sufficient to warrant airway intervention.⁵ It is the predictability of the deterioration that determines the decision to intubate. Alternatively, the upper airway can be examined by fiberoptic laryngoscopy, informing the airway manager of the stability or fragility of airway patency. Similarly, the patient with a crushed pelvis, 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 from behind the computed tomography (CT) scanner.

Consideration of the patient as a whole, of the individual injuries and how they interact, of the effects of these injuries on the patient and on the patient’s comorbidities, and of the need for interventions (including transport) frequently guides a prudent and rational decision to intubate, even when the patient does not have an immediate airway problem and when oxygenation and ventilation are adequate.

Preventing morbidity or mortality as it relates to trauma airway management refers to delaying intubation rather than to a mishap occurring during intubation. It is better to err on the side of intubating early and securing a potentially threatened airway than observing the patient with a false sense of security born from adequate oxygenation and ventilation at that moment. The purpose of observation is to see whether obstruction or airway failure ensues, but if either occurs, the results may be disastrous.

A Direct Airway Trauma

Direct trauma to the airway can be broadly classified as blunt or penetrating trauma. Each of these categories can be considered in the context of direct injury to the airway itself versus compromise or threat to the airway caused by the proximity of an injury in the neck. Injury to the airway can occur at one or more levels. Maxillofacial trauma can compromise the upper airway; direct injury to the neck can compromise the airway from the hypopharynx to the trachea; and injuries to the thorax can disrupt the lower trachea, main stem bronchi, or other smaller bronchi. The approach to airway management is dictated by the clinical presentation of the patient and the best judgment of the operator.

1 Penetrating Neck Trauma

Penetrating neck injuries range in scope from stab or other puncture wounds to major lacerations due to both low-velocity (e.g., BBs, pellets) and high-velocity (e.g., crossbows, firearms) projectile injury. The consequences of these various mechanisms can vary drastically. The overall mortality rate due to penetrating neck injuries is 2% to 6%, with a significantly lower mortality rate for low-velocity injuries.^7–9 The patient with a stab wound to the neck usually has identifiable anatomy and can undergo a planned airway evaluation and early intubation under controlled circumstances. Patients with high-velocity injuries often have significant vascular and hollow-structure injuries, and anatomic distortion can make airway management challenging.¹⁰ These injuries mandate urgent airway management, but the approach is confounded by the myriad injuries caused by the missile.¹¹

For the purposes of classification of penetrating injury, the neck is divided into three zones (Fig. 41-3). Zone 1 extends from the clavicles inferiorly to the level of the cricoid cartilage. Zone 2 extends from the cricoid cartilage to a line drawn through the angles of the mandible, and zone 3 is the area above the angles of the mandible. This classification is most useful for low-velocity penetration, such as from a stab or long-distance birdshot, but it has also been applied to high-velocity injuries, such as rifle wounds.¹⁰ These zones were designated because of their unique anatomic characteristics.¹² Zone 1 is dominated by the major vascular structures at the root of the neck, specifically the carotid arteries, internal jugular veins, subclavian arteries and veins, and innominate arteries and veins. The airway at this level is relatively inaccessible except by tracheotomy. Zone 1 injuries are relatively uncommon (<10% of penetrating neck injuries) but are often associated with major vascular injuries or injuries to the dome of the lung.¹³ Patients with zone 1 injuries often require emergency airway management because of direct airway compromise by hemorrhage or the anticipated clinical course predicted by the profound shock that typically develops. There is little literature to guide the selection of airway management techniques for zone 1 penetrating injuries. Most information is limited to small case series of subsets of larger series that are dominated by zone 2 injuries. The approach to airway management is dictated more by the nature of the threat to the airway than by the location of the inciting wound. The overall approach to airway management in penetrating neck injuries is outlined subsequently.

Figure 41-3 Zones of the neck.

Zone 2 is the most common location for penetrating neck injuries, accounting for most reported cases.¹⁴ Zone 2 injuries require emergency airway intervention in approximately one third of the cases, with a large proportion of the remainder undergoing subsequent intubation related to evaluation or surgical repair. The area of concern in zone 2 extends from the anterior margins of the paravertebral muscles bilaterally. In this area, major vascular structures (e.g., common carotid arteries, internal jugular veins) and their associated sympathetic ganglia and the hypopharynx, esophagus, larynx, and trachea are all at risk. The most common cause of airway compromise in zone 2 injuries is external distortion by hemorrhage related to vascular injuries or direct injuries to the airway.¹⁵

Zone 3 injuries are uncommon (<10% of all penetrating neck injuries) because of the very small area involved and the protection provided by the mastoid processes posteriorly, the mandible anteriorly, and the base of the skull superiorly. The area, however, is rich with major vascular structures (i.e., carotid arteries and internal jugular veins) and provides easy access to the pharynx. Surgical repair of injuries in this area is difficult, and most of these patients undergo extensive evaluation by angiography, with stenting of vascular injuries often the intervention of choice. Because zone 3 injuries involve the pharynx, direct airway compromise is uncommon except by hemorrhage into the airway from a through-and-through injury to the carotid artery. In these rare circumstances, immediate airway intervention is required and may be difficult because of the torrential hemorrhage. Orotracheal intubation is usually successful in these cases, however, particularly if the patient is positioned head down to prevent the blood from entering the operator’s view. After the airway is secure, the mouth can be packed tightly with gauze to control the internal hemorrhage while direct external pressure is simultaneously applied as the patient is transported to the OR.

The approach to the airway in the patient with penetrating neck trauma is guided by the same principles that were outlined earlier in this chapter. Compromised airway patency or protection because of hemorrhage, for example, is an indication for active airway management. Similarly, severe shock with overall obtundation of the patient and an inability to protect the airway or ventilate and oxygenate adequately makes the intubation decision fairly straightforward. The difficulty lies in the patient who has evidence of injury to the neck, but who does not have an obviously compromised airway at the initial evaluation. It is in these cases that judgment is most important and that most tactical errors are made.

The best approach is to consider two specific issues. The first is whether there is evidence of a direct injury to an air-containing structure in the neck. Subcutaneous air indicates injury to an air-filled structure in the neck,¹⁶ such as the airway (including the hypopharynx or pharynx) or the esophagus. In severe cases, particularly patients with injury to both vascular and air-filled structures, airway obstruction can occur rapidly, requiring emergency cricothyrotomy.¹⁷ In less threatening cases, it is virtually impossible to tell whether the esophagus or airway is involved, and early direct or fiberoptic examination of the airway is indicated. Sedation and topical anesthesia allows the operator to determine the severity and location of any airway injury. Preparation with a small to moderate-size endotracheal tube (ETT) (e.g., 6.0- to 7.0-mm inside diameter) mounted on the scope before initiating endoscopy facilitates prompt intubation if the injury is found to be significant. If the scope has been placed successfully distal to the injury, the patient can be gently intubated over the flexible fiberoptic bronchoscope (FFB), because it is best to secure the airway distal to the injury. This at least ensures that the patient is safe until he or she can be transported to the OR for further evaluation by an otolaryngologist or general surgeon. Although tracheostomy is often necessary, in these cases, temporary oral endotracheal intubation over an FFB ensures airway control and minimizes the subsequent leakage of air into the tissues, facilitating later repair.¹⁶ If no airway injury is identified and there is no evidence of increase in the subcutaneous emphysema in the neck during spontaneous or assisted ventilation, the injury can be presumed to be esophageal.¹⁸ If, however, circumstances change and subcutaneous emphysema begins to increase, even slightly, intubation is recommended since development of large amounts of subcutaneous emphysema can distort airway anatomy such that subsequent intubation or surgical airway management becomes difficult or impossible. As with all penetrating neck injuries, early intubation, even in patients who do not appear to immediately require it, is the most prudent course.

The second issue is whether there is evidence of significant vascular injury to the neck. All penetrating neck wounds have some external bleeding, although it can be surprisingly modest. The issue with respect to airway management is whether injury has occurred to any of the major vascular structures in the neck (e.g., carotid arteries, jugular veins). A hematoma of any size, external hemorrhage, or any evidence of displacement of the airway structures can serve as evidence of direct vascular injury. As soon as it has been established that direct vascular injury has occurred, active airway management should be undertaken.^19,20 Most of these patients present early in the course of their injuries, when anatomy is preserved and orotracheal intubation is likely to be relatively easy to achieve. Waiting to determine whether the hematoma is expanding is perilous, because most of the hemorrhage into the neck occurs into the deep tissue planes, distorting and displacing the airway without external evidence until a crisis occurs. The time-honored dictum that hematomas of the neck should be observed to see whether they are expanding is not rational, and any evidence of direct vascular injury to the neck is sufficient justification for intubation. Early intubation can proceed using a rapid-sequence intubation (RSI) technique if a careful examination for difficult airway attributes fails to identify problems and there is a sound rescue strategy planned in the event of intubation failure.²¹ Early intervention allows the operator to intubate in a controlled fashion rather than scrambling to secure an emergency airway later in the patient’s course, when airway obstruction is imminent or has already occurred.

If there is doubt regarding oral access, three approaches can be considered. The first option is to perform oral RSI under a double setup with preparations and personnel in place to perform immediate surgical cricothyrotomy if orotracheal intubation is not successful. This approach should only be undertaken only if the preintubation airway assessment indicates that orotracheal intubation, although potentially difficult, is still likely to be successful. Similarly, there must be confidence that bag-mask ventilation (BMV) will be successful in maintaining the patient’s oxygenation, if required. If visualization is suboptimal during conventional direct laryngoscopy, the use of a bougie or video laryngoscope can be considered.

The second option is to perform fiberoptic intubation under sedation and topical anesthesia, as described earlier. This allows the operator to use the FFB to identify and enter the airway, even if the anatomy has become distorted. If this is undertaken early in the patient’s course, there is typically sufficient time and control to yield a high success rate. However, a distorted and bloodied airway makes fiberoptic intubation technically challenging, and the most experienced operator should perform the procedure.

The third option is to proceed directly with a planned surgical cricothyrotomy. This requires that the airway be identifiable with clear landmarks to permit a surgical approach. Local anesthetic infiltration and direct transcricothyroid puncture for instillation of local anesthesia into the airway are likely to make the procedure easier to perform (see Chapter 31).

In all cases of penetrating neck trauma, early consultation with an otolaryngologist or general surgeon is essential. Initially innocuous injuries may lead to catastrophic consequences for the patient if not identified and managed early.²² Early airway intervention permits controlled resuscitation and prevents major morbidities related to penetrating neck injury, such as airway compromise with resultant hypoxia or anoxia.

3 Maxillofacial Trauma

Mandibular fractures are usually isolated injuries, but they can occur in the setting of multitrauma, particularly in unrestrained occupants in motor vehicle collisions and victims of severe assault. They rarely threaten the airway unless the anterior mandible is fractured, which allows the tongue to fall back and obstruct the airway. Usually, this obstruction is easily relieved by pulling the anterior segment of the mandible forward. This maneuver also remedies any interference with endotracheal intubation by the posteriorly displaced tongue. Patients with fractures of the angle of the mandible or the mandibular condyles often have limited mouth opening due to pain and to anatomic restriction. Because the deformity is bony, it is often not abolished by neuromuscular blockade (NMB). Although it is always important to establish the extent of mouth opening and whether it is adequate to permit intubation before administering NMB agents, this is especially true in patients with mandibular fractures.

Maxillary fractures usually occur in one of the classically described Le Fort patterns. Although the precise location of the Le Fort fracture pattern is sometimes difficult to remember, the Le Fort I, II, and III fractures can be thought of as follows (see Fig. 41-2). The Le Fort I fracture represents separation of the roof of the mouth from the face, with the fracture extending through the alveolar ridge to the base of the nose and separating the alveolar ridge and hard palate from the rest of the face. The Le Fort II fracture is separation of the central face from the rest of the face and cranium. The fractures extend from the base of the nasal bones through the medial orbits down through the maxilla to the posterior molars, effectively creating a free-floating central face fragment. The Le Fort III fracture is separation of the face from the skull. This fracture extends from the base of the nasal bones through the orbits to the lateral orbital rims and then through the zygomatic arch and down through the pterygoid plate.

Le Fort I fractures rarely cause airway compromise. If the fracture fragment has displaced posteriorly, it can easily be pulled forward by gripping the upper incisors or alveolar ridge. Le Fort II fractures similarly do not compromise the airway unless extensive hemorrhage is present. The fracture fragment, although free floating, rarely displaces posteriorly enough to compromise the airway. In the absence of hemorrhage, the mouth and oral pharynx are usually patent and functional. However, Le Fort III fractures can significantly compromise the airway due to posterior displacement of the entire central face, compromising the oral and nasal pharynx. Similarly, extensive swelling or hemorrhage related to the fractures may threaten the airway. In all cases, careful oral inspection and suctioning to determine the patency and adequacy of the oral cavity, followed by early intubation for airway protection and overall management of the patient, are advisable.

An uncommon but disastrous presentation of maxillofacial injury occurs when an attempted suicide fails because the gun (usually a shotgun) is oriented in such a way as to have the mass of the shot pass upward through the face rather than on a posterior trajectory through the brainstem. This often happens when the patient places a rifle or shotgun under the chin and then tries to reach downward for the trigger. This movement naturally leads to extension of the neck, and the trajectory of the missile is altered, causing it to pass upward through the face (Fig. 41-4). Although such injuries occur with massive facial distortion, airway management can range from easy to virtually impossible. Destruction of the mandible, tongue, palate, and nasopharynx often makes orotracheal intubation impossible, and hemorrhage is usually extensive. Primary surgical airway management is usually the method of choice. However, the injury can be predominantly anterior, sparing the airway, and the mandible and tongue can be displaced forward, permitting adequate oral access for orotracheal intubation. Nonetheless, efficient suctioning is usually required because the hemorrhage can be significant.

Figure 41-4 Facial trauma.

B Cervical Spine Injury

Unstable injury to the C-spine presents a particular hazard with respect to airway management because of the potential to cause or exacerbate spinal cord injury. C-spine injury usually occurs when there is high-energy transfer, such as in a motor vehicle collision, but it can occur with relatively minor trauma in patients with significant degenerative disease of the C-spine, such as rheumatoid arthritis or osteopenia. Motor vehicle collisions are the greatest cause of spinal injury, accounting for about 50% of these injuries, followed by falls, athletic injury, and interpersonal violence.²⁶

In the trauma resuscitation room, all patients who have been subjected to significant blunt trauma should be assumed to have a C-spine injury until it has been excluded. Penetrating trauma can also cause spinal injury, but creation of an unstable spinal injury without concomitant spinal cord injury is exceedingly rare. With penetrating injury, it is usually apparent whether spinal injury has occurred because the patient sustained a neurologic disability. Barring this finding, C-spine immobilization in a patient with isolated penetrating trauma is typically unnecessary and may even be harmful.^27–29

One of the significant challenges related to airway management in patients with blunt trauma is the inability to determine definitively whether the patient has a C-spine injury before intubation is required. Fortunately, most patients with a C-spine injury do not require intubation during the acute phase of resuscitation. However, those who have the most severe trauma are likely to require intubation, and this is the same population who is at highest risk for spinal injury.³⁰ It has been estimated that 2% to 14% of all patients with serious blunt trauma have a significant C-spine injury.^31,32

The decision about whether to obtain portable C-spine imaging before intubation must take into account two radiographic principles. First, a single, portable, lateral, cross-table radiograph is highly insensitive for significant C-spine injury. At least 25% of lateral C-spine radiographs fail to visualize the cervical-thoracic junction (C7-T1).³³ Even if the lateral radiograph is adequate, it should be considered no more than 80% sensitive for C-spine injury.³⁴ A complete three-view C-spine series fails to identify about 15% of significant C-spine injuries, and it is difficult to obtain adequately for patients in cervical collars.³⁵ In consideration of this information, no plain radiograph should be interpreted as indicating that the C-spine is free of injury and that movement can be undertaken with impunity during intubation.

Second, the severe limitations of portable C-spine radiographs question their value before intubation. Current guidelines recommend the use of CT for C-spine evaluation of patients with trauma.³⁶ Given the limitations of portable cross-table plain radiographs of the spine and the danger of remote imaging before airway management, it is prudent to presume a C-spine injury and intubate with in-line C-spine stabilization without imaging.

Only patients who will not be obtaining CT imaging before emergency surgical management should have a lateral C-spine radiograph in the trauma bay. In other words, C-spine injuries should be presumed for all patients with blunt trauma needing airway management (and precautions should be taken accordingly), with CT imaging obtained for those thought to be stable enough for the scanner. However, in patients proceeding directly to the OR after intubation, a lateral C-spine x-ray (along with portable chest and pelvis radiographs) can be obtained to screen for the presence of catastrophic C-spine injury. In these cases, however, only a positive C-spine radiograph can be considered to provide additional information. The incidence of a false-negative radiograph despite significant injury is high enough that no reassurance should be taken from a negative study result.

Airway management in the patient with C-spine injury must be undertaken with strict attention to C-spine immobilization. This is best performed by a second operator whose sole function is to maintain the alignment of the head, neck, and torso. The best immobilization technique is one that allows the person performing the immobilization to have direct contact with the head and the torso.

Two common methods of immobilization are described. In one method, the assistant approaches the head from the thorax, resting his or her forearms on the upper chest and clavicles and passing the wrists and hands up alongside the neck bilaterally, so that the hands (with fingers spread) can grip and immobilize the occipital-parietal area of the head. This allows the assistant to prevent and detect any change in the angle of the head on the neck or the neck on the body during laryngoscopy and intubation. The assistant must provide direct feedback to the intubator of any motion.

In another method, the assistant crouches below the operating table, usually to the intubator’s left side. The assistant then reaches up over the head of the table and immobilizes the base of the occiput with the heels of both hands. The fingers extend down alongside the neck to the top of the patient’s shoulders, permitting the assistant to immobilize the head and neck and allowing detection of movement.

Intubation should be performed with the anterior portion of the cervical collar open because it may limit laryngoscopy. Leaving the collar intact has not been shown to reduce significant C-spine movement during intubation, and is not a substitute for manual in-line stabilization.^37–39 Although cricothyrotomy can be performed through the openings in most cervical collars, it is often technically challenging, and it is preferable to remove the anterior one half of the collar before undertaking surgical airway management. The debate regarding nasotracheal intubation versus various awake intubation techniques versus RSI in the trauma patient is discussed in “Principles of Airway Management in the Trauma Patient.”

C Intracranial Injury

Intracranial injury commonly occurs with blunt and penetrating forms of trauma. In penetrating trauma, injuries are obvious because the penetration must occur proximate to the cranial vault. With blunt trauma, however, the presence of intracranial injury can be much more difficult to establish. Although the Glasgow Coma Scale (GCS) score is widely used in trauma, it is at best a crude instrument. However, in the absence of a reversible cause (e.g., opioid overdose), a GCS score of 8 or less indicates coma and mandates intubation on the basis of airway protection and anticipated deterioration. Any patient with a GCS score of 12 or less should be considered to have significant head injury until cranial CT scanning can prove otherwise. These patients may have elevated ICPs, and all patients with a GCS score of 8 or less should be presumed to have elevated ICPs with loss of cerebral autoregulation. This approach has some impact on the agents selected for intubation and, to a lesser degree, the methods used.

Airway management in the patient with intracranial injury is dictated by an often-conflicting series of choices between limiting the adverse responses in the brain related to intubation and maintaining overall management of the patient’s hemodynamic status and resuscitation. In patients with an elevated ICP, stimulation of the upper airway structures by a laryngoscope or other device results in an increase in the ICP.⁴⁰ The ICP appears to increase by two mechanisms: First, a release of sympathetic adrenergic transmitters results in elevation in heart rate and blood pressure, which translates to an elevation in ICP in the nonautoregulated brain.⁴¹ Second, a direct reflexive increase in ICP is caused by laryngeal stimulation, although the mechanism is not precisely defined.⁴²

Succinylcholine, which is the drug of choice for RSI of the multitrauma patient, is believed to cause an elevation in ICP, although this has been disputed.^43–45 The mitigation of these potential elevations in ICP is an important theme in the airway management of the trauma patient with presumed intracranial injury. Avoidance of hypoxia and hypercarbia and maintenance of adequate perfusion are vital for producing the best possible patient outcome.

Lidocaine has been studied in the context of prevention of the ICP response that is sympathetically mediated and the ICP response that is considered reflexive. Its use during RSI in the context of head injury continues to be controversial. Best-evidence reviews of patient outcomes and lidocaine use during airway management in head injured patients showed that no good evidence exists evaluating this specific issue.^46–48 Several small, randomized trials have found conflicting results with respect to the ability of lidocaine to attenuate spikes in ICP during laryngoscopy and intubation.^41,49–54 Overall, there is insufficient evidence to strongly recommend the use of lidocaine for the purpose of suppression of sympathetic discharge during intubation. However, lidocaine given intravenously at a dose of 1.5 mg/kg has been shown to blunt the direct ICP response to tracheal suctioning and laryngeal stimulation in hypocarbic patients with elevated ICP.^51,53 Lidocaine’s wide therapeutic margin, familiarity, safety profile, and ready availability make it a reasonable choice when administered at 1.5 mg/kg intravenously for 3 minutes before the induction agent when undertaking RSI of a patient with known or presumed elevated ICP. Used in this manner, lidocaine may have a beneficial effect on the direct ICP response to laryngoscopy and intubation.

The sympathetic response to intubation has been extensively studied, and synthetic opioids and beta-blockers have been shown to attenuate the reflex sympathetic response to laryngoscopy. Administration of a beta-blocker to a trauma patient may worsen hemodynamic instability and is rarely desirable, except in certain cases of isolated head trauma. Similarly, administration of full sympathetic-blocking doses of the synthetic opioids, such as fentanyl, can have adverse effects, particularly in patients with hypovolemia, who depend on sympathetic drive. Fentanyl, in a dose of 2 to 3 µg/kg as a pretreatment agent, has been shown to attenuate the reflex sympathetic response to laryngoscopy and should have minimal adverse cardiovascular effects.⁵⁵ Care must be used, however, to ensure that the fentanyl does not cause respiratory depression with resulting hypercarbia and that the patient has sufficient hemodynamic stability to tolerate even this small dose.

Competitive NMB agents, such as rocuronium, achieve intubating conditions almost as rapidly as succinylcholine, but without the attendant rise in ICP.^56,57 However, the duration of paralysis when 1.0 mg/kg of rocuronium is used for intubation is about 45 minutes.⁵⁸ For this reason, succinylcholine, with its ultrarapid onset and shorter duration of action, remains the drug of choice for emergency intubation of trauma patients, including those with elevated ICP. The exacerbation of the ICP elevation by succinylcholine, however, is clearly not desirable. Evidence is poor supporting the administration of a defasciculating dose of a nondepolarizing NMB before succinylcholine to attenuate an increased ICP and is not recommended.

In summary, when RSI is planned, and there is no contraindication, 1.5 mg/kg of intravenous lidocaine and 3 µg/kg of intravenous fentanyl should be considered before the administration of succinylcholine. Defasciculating doses of non-depolarizing NMB drugs should not be used until further study clarifies their role. Laryngoscopy and intubation should be as gentle and atraumatic as possible. There is evidence that minimizing laryngeal stimulation helps to reduce the hemodynamic and ICP responses to laryngoscopy and intubation. Several devices have been evaluated to see whether they are less traumatic than direct laryngoscopy. Intubations through a laryngeal mask airway (LMA) and with the use of the Trachlight stylet appear to be less stimulating than intubation by direct laryngoscopy.^59,60 Studies comparing intubation over a lighted stylet with direct laryngoscopy indicate that the placement of the ETT into the trachea is more stimulating than the laryngoscopy itself.⁶¹

D Intraocular Injury

Most patients with open globe injuries can be intubated in the OR under controlled conditions. Penetrating globe injuries usually are isolated and are caused primarily by implements (e.g., sticks, children’s toys) or by low-velocity missiles (e.g., BBs, pellets). Occasionally, open globe injury occurs in the context of multitrauma and requires intubation in the trauma bay. Decisions related to overall management of the patient’s multiple injuries should take precedence over management of the eye injury. Whether the intubation occurs in the trauma resuscitation bay or in the OR, the concern related to managing open globe injuries is whether succinylcholine, which causes a transient rise in intraocular pressure, may cause extrusion of intraocular contents.⁶² There has never been a single case report of vitreous extrusion after the use of succinylcholine in a patient with an open globe injury.⁶³ The paramount consideration therefore appears to be prevention of straining, coughing, or bucking during the intubation, arguing for RSI. It has been recommended that a defasciculating dose of a competitive NMB agent be given 3 minutes before administration of succinylcholine in patients with open globe injuries to mitigate the elevation of intraocular pressure, but this approach has never been subjected to study. It appears that defasciculation is appropriate for patients with open globe injuries receiving succinylcholine unless there is a contraindication, such as severe respiratory compromise.

E Thoracic Injury

Blunt and penetrating injuries can cause sufficient compromise of respiration or oxygenation to mandate intubation. The extent of injuries associated with penetrating trauma depends on the implement or missile used and the location and path of the object involved. High-velocity gunshot wounds to the chest are often fatal, causing disruption of the major vasculature, main stem bronchi, or the heart.⁶⁴ Lower-velocity gunshot wounds, especially those more peripherally placed, often cause much less blast injury to the chest, resulting in minor pulmonary contusions and a surprisingly low incidence of hemothorax or pneumothorax.⁶⁵ Pneumothorax is common in penetrating injury, whether caused by missile or implement, and cardiac injury with pericardial tamponade can occur. Blunt chest trauma tends to be more diffuse and is more often associated with pulmonary contusion, disruption of the chest wall with concomitant rib fractures, costochondral separation, hemothorax or pneumothorax, and if severe, disruption of a main stem bronchus or of the aorta.

In addition to a thorough physical examination and a determination of vital signs (including O₂ saturation), early, portable, anterior-posterior chest radiography is invaluable in assessing patients who are victims of thoracic trauma. However, obvious life-threatening conditions, such as tension pneumothorax, should be treated before radiographic confirmation. A patient presenting with external evidence of chest trauma (e.g., motor vehicle crash victim with multiple rib fractures and subcutaneous air) who has signs compatible with tension pneumothorax (e.g., hypotension, tachycardia, tachypnea, O₂ desaturation) should have immediate decompressive thoracostomy before radiographic studies. The finding of tracheal deviation occurs only in the final stages of tension pneumothorax when the patient is in extremis, and the presence of a midline trachea should never be used to exclude tension pneumothorax. If there are not sufficient personnel to manage all of the necessary tasks simultaneously, a needle thoracostomy can be done, pending insertion of the chest tube. Needle thoracostomy, however, is strictly a short-term temporizing measure, and tube thoracostomy with a 34-Fr or larger chest tube should be performed at the earliest opportunity. The objective is to release sufficient air such that diminished venous return and cardiac contractility are temporarily relieved. Release of tension pneumothorax also facilitates choice of the induction agent for intubation as hemodynamics typically improve significantly after needle or tube thoracostomy. Mitigation of the intrathoracic pressure helps to avoid the hypotension that may occur when positive-pressure ventilation is instituted after intubation.

Thoracic injuries have three effects on airway management. First, the intrathoracic injuries may be the primary reason for intubation. Pulmonary contusion, bilateral hemothorax, flail chest with respiratory compromise, pulmonary hemorrhage, and major life-threatening intrathoracic injury are all indications for early intubation.

Second, the thoracic injuries may compromise preoxygenation before intubation and promote rapid oxyhemoglobin desaturation after paralysis. Preoxygenation is essential when performing RSI, and patients with severe pulmonary injury may not preoxygenate well. It may be difficult to obtain O₂ saturations greater than 90%, even with high-flow O₂. Rapid oxyhemoglobin desaturation can be anticipated, and these patients may require BMV throughout the intubation sequence to maintain adequate oxygenation. This approach is particularly important in the patient with concomitant head injury.

Third, hypotension related to thoracic injuries may limit agent selection. Some induction agents, such as sodium thiopental and propofol, are potent venodilators and negative inotropes. When they are given to patients with hemodynamic compromise related to thoracic or multisystem injuries, the hypotension can be severe and prolonged. This effect often precludes the use of such agents or necessitates a significant reduction in dosage.

The intubation technique for patients with thoracic trauma is dictated by their overall status. Rarely does the thoracic trauma alone determine the technique. RSI usually is preferred, but care must be taken to preoxygenate the patient adequately and to maintain adequate oxygenation throughout the procedure. After the patient is intubated, positive-pressure ventilation may further compromise venous return and mean arterial blood pressure, and the mechanical ventilation should be adjusted to maintain adequate oxygenation with the least effective tidal volume until the patient-specific hemodynamic effects of the positive-pressure ventilation can be determined. Patients with pulmonary injury, such as pulmonary contusion, usually do better with modest amounts of positive end-expiratory pressure (5 to 10 mm Hg), but this has the potential to further compromise venous return and must be instituted with caution.

F Hemorrhagic Shock

The patient in profound hemorrhagic shock has significant metabolic debt, experiences rapid muscle fatigue, is susceptible to respiratory compromise and failure, and usually requires intubation with positive-pressure ventilation unless the underlying process can be reversed. In addition to contributing to the need for intubation, hemorrhagic shock greatly limits the choice of agents for intubation. Induction agents such as sodium thiopental and propofol have significant adverse hemodynamic consequences.⁶⁵ These agents should be used in greatly reduced doses or avoided altogether in patients with hemorrhagic shock. Ketamine releases catecholamines and is the most stable of the induction agents. Ketamine can be used in a reduced dose of 1 mg/kg, even in patients with significant hemodynamic compromise. In frank shock, however, ketamine, like every other induction agent, depresses myocardial contractility and must be used with extreme caution.^66,67 It has been implicated in transient elevations of ICP, but the evidence in this regard is highly conflicted.⁶⁸ In the context of head injury with significant hypovolemia, ketamine’s superior hemodynamic characteristics outweigh its potential to cause small, transient rises in ICP. Although caution is advised in administering ketamine to patients with head injury and to those in shock, it may be the least of all evils if given in a reduced dose in these patients.

Etomidate, an imidazole derivative, has remarkable hemodynamic stability.⁶⁹ In the induction dose of 0.3 mg/kg, it causes virtually no change in mean arterial blood pressure in normal and hypovolemic patients. In very large doses (two or three times the induction dose), etomidate consistently causes hypotension.⁷⁰ In morbidly obese trauma patients, dosing should be based on their lean body weight, not total body weight. For patients with frank shock, the dose should be reduced to between 0.15 and 0.2 mg/kg. Etomidate appears to have some cerebral protective effect and can significantly lower ICP without adverse effects on perfusion pressure.⁷¹ It is therefore a rational agent for use in patients with multisystem trauma and hypovolemic shock.

Midazolam is infrequently used as an induction agent in multitrauma patients. It exhibits many of the same adverse hemodynamic effects as propofol and Pentothal. If it is used, the dose should be greatly reduced to 0.1 mg/kg in patients in frank shock. However, compared with other readily available agents, midazolam has a slower onset and longer clinical half-life, and at greatly reduced doses, it may not provide adequate amnesia for the patient.⁷²

In addition to influencing the decision to intubate and the choice of agents, hemorrhagic shock greatly complicates overall management. Drug circulation times can be longer, and the physician may have to allow more time between the administration of succinylcholine and the first attempt at intubation. Succinylcholine itself is remarkably stable, although an increased or repeated dose may be required because of poor drug distribution in patients who have hemorrhagic shock. Pretreatment agents usually are avoided in hemorrhagic shock, with the exception of lidocaine for elevated ICP.

Isotonic fluid resuscitation must occur in parallel with preparation for intubation. The use of a high-flow blood-infusing unit can provide warmed packed red blood cells at a rate as high as 500 mL/min.⁷³ Care must be taken not to overshoot the resuscitation, particularly in the presence of penetrating injuries and those thought to be associated with ongoing bleeding. The goal is maintenance of an adequate perfusion pressure to support the brain and vital organs until surgical repair can be undertaken. There is no evidence that restoration of the blood pressure to a normal range is beneficial, and evidence suggests that permissive hypotension may instead be preferable.^74–76 Crystalloid can be infused as the first 2 L of fluid during resuscitation, but it should be rapidly replaced with blood if shock is ongoing. A urinary catheter may be helpful to monitor urine output, and lactic acid or base deficit values can help to monitor the overall treatment of shock.⁷⁷ If the patient is not going to be transported promptly to the OR, placement of an arterial line is highly advisable.

A Control of the Combative Patient

Trauma patients, particularly those who are intoxicated or who have sustained head injury, are frequently agitated or combative on arrival to the ED. In some cases, this agitation is a result of an overwhelming combination of confusing sensory inputs to the patient. Intoxication, head injury, disorientation, and severe pain can contribute to combative behavior. The patient’s mental status may be an extension of a medical condition that precipitated the injury. Hypoglycemia, stroke, syncope, and seizure should be considered when the patient’s mental status is significantly altered or when prehospital reports suggest a minor mechanism or minimal vehicular damage.

Initially, attempts should be made to reassure the patient and to help him or her orient to the chaotic environment of the resuscitation room. An agitated and confused patient may be helped by the physician placing his or her face relatively close to the patient’s and speaking in a clear, firm, reassuring voice. Although this may have some initial calming effect, physical and chemical restraints are often necessary to facilitate an orderly, efficient, and safe trauma assessment. These patients are often restrained on a long spine board with a cervical collar, tape, and sandbags, but these constraints are temporary, and the patient’s ability to move and to exert significant forces on the potentially injured spine often warrants further action.

The decision about whether to sedate a patient or to intubate for behavioral control should be made on the basis of the patient’s overall injuries. If intubation is inevitable, even without combative behavior, based on the patient’s injuries and expected clinical course, early intubation is the best approach. RSI allows protection of the C-spine, complete control of the patient, and treatment of multiple injuries without further disruption or pain. If the patient’s overall injuries are deemed to be relatively modest and intubation would not be indicated in the absence of the combative behavior, chemical restraint without intubation is the best approach. Repeated, titrated doses of a butyrophenone, such as haloperidol, can rapidly achieve control of the patient without compromising respiration or significantly altering the neurologic examination. In the hemodynamically stable patient, 5 mg of haloperidol can be given intravenously in repeated doses every 5 minutes, with observation for effect.⁷⁸ Most patients calm rapidly under the influence of the haloperidol, and management can then proceed in a more orderly fashion. Haloperidol has been rumored to lower the seizure threshold and therefore be contraindicated in patients with head trauma, but this is close to a medical fairy tale. There are no well-controlled studies proving this association, and the remainder of the literature is a heterogenous mixture of rat studies and case reports.⁷⁹ There is no human evidence to support this often-cited contraindication. Droperidol was equally effective and commonly used for this purpose before the U.S. Food and Drug Administration (FDA) issued a highly controversial black box warning about QT interval prolongation, which greatly curtailed its use.⁸⁰

Benzodiazepines are often used but have the potential for significantly more respiratory depression than haloperidol. Benzodiazepines must be used with great caution, particularly in patients with concomitant alcohol intoxication. The practice of using haloperidol in combination with benzodiazepines complicates matters by giving two drugs when one drug would do. Haloperidol has stood the test of time in trauma patients, who remain hemodynamically stable, and it can be given in large doses when necessary. Haloperidol does not alter the need to investigate the cause of the patient’s combative behavior with CT, neurologic examination, and metabolic testing, but it does rapidly help to achieve control of the patient and permit ongoing evaluation.

B Prevention of Aspiration

All trauma patients are considered to be at high risk for aspiration. Compromised airway protection from head injury or from intoxication, prone position, and a nonfasted state make aspiration a paramount concern. Reasonable precautions should be taken to prevent aspiration, particularly of gastric contents, during overall trauma management and particularly during airway management. The initial intubation method depends on the constellation of patient injuries, hemodynamic status, and the equipment and expertise available. Most patients, however, will undergo RSI. Induction and the use of NMB drugs that occurs during RSI place the patient at risk for passive regurgitation. Early and generous suction, particularly when hemorrhage exists, reduces the aspiration of blood.

Routine application of posterior cricoid pressure (i.e., Sellick’s maneuver) held throughout laryngoscopy was widely accepted dogma because it was thought to prevent aspiration through compression of the upper esophagus against the anterior cervical vertebral bodies. Although it seemed logical, it was never supported by firm evidence.^81,82 Misapplication of cricoid pressure is common among a variety of operators, and it can result in more difficult mask ventilation, direct laryngoscopy, and tracheal tube passage.^83–86 Moreover, regurgitation is often seen despite Sellick’s maneuver being applied.^87–90 Advanced imaging suggests the cervical esophagus is positioned lateral to the cricoid ring in many patients, a relationship that is exaggerated by posterior pressure rarely resulting in esophageal obstruction.⁹¹ C-spine motion may occur during cricoid pressure and introduce unnecessary risk for patients with known or suspected unstable C-spine injuries. If applied correctly however, Sellick’s maneuver may reduce gastric insufflation during BMV.^92–94 On balance, the best approach is to consider posterior cricoid pressure optional during laryngoscopy and intubation and to remove it immediately if the laryngeal view is poor or tube passage is difficult. It should be routinely performed during prolonged rescue BMV.

If the patient vomits while on the 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. Vomiting is an indication for early intubation in patients who require immobilization on a spine board and who may be relatively helpless to manage the vomitus after it is in the mouth. 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 is increased risk of aspiration because of the topical anesthesia of the supraglottic area and the vocal cords. Prompt suctioning and repositioning of the patient, if necessary, should help reduce this risk. There is no evidence that one particular device or technique is more likely to prevent aspiration than any other. RSI, developed as the cornerstone of emergency airway management because of its ability to reduce aspiration, has recently been challenged in this regard.⁹⁵

C Choice of Technique

The issues related to approach to the airway are discussed in detail in the individual sections earlier in this chapter. Overall, the choice of technique must balance the physiologic status of the patient, the nature of the injuries, predicted airway difficulty, the urgency of the airway intervention, and the availability of various devices and surgical backup. Historically, the Advanced Trauma Life Support (ATLS) course developed by members of the American College of Surgeons advocated blind nasotracheal intubation for patients with suspected C-spine injuries because it was believed to be less likely to cause C-spine movement. This belief was unfounded, and blind nasotracheal intubation has fallen out of favor as a method of airway management in the trauma patient because of slower intubation times, higher complication rates, and greater O₂ desaturation.^96–98 RSI is the preferred method for most intubations. There was early objection, however, due to suspicion of dangerous degrees of C-spine motion during unrestricted direct laryngoscopy and that residual muscle tone in nonparalyzed patients provided valuable splinting support. As a result of these two fundamentally incorrect beliefs, trauma intubations through the 1970s and 1980s were largely performed by awake intubation. Cadaver studies and those done in living patients have failed to support this contention. There is no evidence that careful laryngoscopy performed with in-line stabilization subjects the C-spine to any risk, although intubation should not be forceful or prolonged. There is good evidence that manual in-line stabilization combined with a careful oral laryngoscopy and RSI does not pose any risk to the cervical spinal cord.^99–101

Unrelaxed patients present the potential for significantly more C-spine motion as a result of coughing, bucking, gagging, or other movement during an awake intubation attempt. RSI has been successful and frequently used during trauma intubations. In a published report of almost 9000 ED intubations from phase II of the National Emergency Airway Registry showed that 82% of trauma patients underwent RSI and 11% were intubated with no medications; they were mostly patients in full arrest or near-full arrest who were completely unresponsive on presentation and underwent immediate direct laryngoscopy with intubation and manual in-line stabilization. Less than 1% of patients underwent unassisted nasotracheal intubation.¹⁰²

D The Difficult Airway

Trauma patients represent a group with high-risk, exceptionally difficult airways. Acquired characteristics, such as airway trauma, C-spine immobility, hemodynamic compromise, and other potentially life-threatening injuries, can exacerbate inherently difficult airway markers, necessitating clarity of thought and error-free decision making during intubation. An efficient but detailed difficult airway assessment is necessary before NMB in the multitrauma patient. Conventional assessments that occur during a preoperative visit may not be possible in the trauma bay. It is rarely possible to obtain a prior surgical anesthetic history from the patient. Creators of the national Emergency and the Difficult Airway Course: Anesthesia have developed a four-pronged rapid assessment tool that can be quickly applied to virtually any patient.¹⁰³ Portions of this tool have been externally validated in emergency populations, and it is currently subject to further validation in the third phase of the National Emergency Airway Registry multicenter registry.¹⁰⁴ The LEMON mnemonic is used as shown in Box 41-1 to identify one or more attributes of a difficult airway in a patient.

The tool is overly sensitive at the cost of specificity, but that is more desirable than the converse. If a difficult intubation is anticipated, physicians use an algorithmic approach that is dictated by how stable the patient is and how urgently he or she needs to be intubated (Fig. 41-5). The easiest surrogate is the best attainable O₂ saturation measurement, because it defines the time available to consider alternative approaches. If the patient is well oxygenated and is reasonably stable (i.e., does not need to be intubated in the next 2 to 3 minutes), a methodic stepwise plan can be made. If the patient is critically desaturated and highly unstable, it is probably necessary to proceed directly with some form of airway intervention promptly without the luxury of a planned approach to the difficult airway. In this scenario, a double-setup RSI, in which the anterior neck is prepared for a surgical airway as RSI drugs are administered, is most appropriate. RSI gives the operator the best chance of intubation success, and if a cannot intubate, cannot ventilate (CICV) scenario develops, a cricothyrotomy should be immediately performed. Primary cricothyrotomy may be the primary method used, usually when orotracheal and nasotracheal intubation is predicted to be difficult or impossible. Rarely, other devices such as the FFB or intubating LMA (ILMA) are useful.

Figure 41-5 Difficult airway algorithm. BMV, Bag-mask ventilation; BNTI, blind nasotracheal intubation; DL, difficult laryngoscopy; EGD, extraglottic device; FO, fiberoptic; ILMA, intubating laryngeal mask airway; RSI, rapid-sequence intubation; VL, video laryngoscopy.

(From Walls RM: Manual of emergency airway management, ed 3, Philadelphia, 2008, Lippincott Williams & Wilkins.)

When there is sufficient time (SaO₂ > 90%) to plan the intubation approach carefully, the patient should be evaluated for the likelihood of success with BMV and laryngoscopy. Predicted success with BMV is a necessary precursor to consideration of paralysis. The MOANS mnemonic (Box 41-2) contains a well-validated collection of patient attributes that contribute to difficult mask ventilation.¹⁰⁵ If it is the intubator’s judgment that the patient cannot be BMV successfully, a technique using NMB is out of the question unless it is part of a double setup with an immediate ability to move to a surgical airway if the first attempt at laryngoscopy is unsuccessful. Next, the operator must decide whether laryngoscopy and intubation are likely to be successful. If it is thought that the patient is likely to be successfully intubated by direct laryngoscopy despite the difficult airway attributes, taking into consideration that the patient should successfully undergo BMV, RSI can be planned with a surgical backup, as necessary. For example, the assault patient requiring strict C-spine precautions because of a dislocated jaw and active upper airway bleeding would be challenging or impossible to manage with direct laryngoscopy because of a severely reduced mouth opening, neutral head position, and airway bleeding. However, a normal-sized patient who was stabbed in the abdomen and was placed in a C-spine collar by emergency medical services but who has little likelihood of a neck injury would routinely warrant a laryngoscopic attempt. Both patients meet criteria for a difficult airway, but successful direct laryngoscopy is reasonable in the second patient but not in the first patient. With the advent of the video laryngoscope, traditional difficult laryngoscopy predictors may not apply, and what constitutes a difficult video laryngoscopic attempt has not been defined. As our knowledge and experience with video laryngoscopy develops, our threshold for NMB in these patients may change.

In most circumstances, difficult airway attributes are identified in trauma patients, but the operator can still be confident that BMV and direct laryngoscopy will be successful, thereby permitting RSI. If, however, in the opinion of the operator, BMV or direct laryngoscopy is unlikely to be possible, it is better to proceed with an awake technique. This involves administration of sedation and use of topical anesthesia to permit awake evaluation of the airway by a direct, video-assisted, or fiberoptic technique (see Chapter 11). Awake laryngoscopy is a common approach that has three possible outcomes: the cords are well visualized, and the patient is intubated; the cords are well visualized, and the decision is made that RSI is possible (in this case, awake laryngoscopy is terminated, and the patient undergoes RSI); or awake laryngoscopy determines that orotracheal intubation will likely be difficult or impossible, and an alternative approach is necessary.

If, after awake direct laryngoscopy, it is determined that the patient cannot be intubated orally, there are several alternative techniques, which are described elsewhere in this textbook. In the trauma patient, the most useful of these is video laryngoscopy. Although it is susceptible to soiling from airway secretions and bleeding, the mechanical limitations inherent in direct laryngoscopy virtually vanish with video laryngoscopy, and glottic visualization nearly always improves.^106,107 Surgical cricothyrotomy, flexible fiberoptic intubation, video laryngoscopy, a lighted stylet technique, and an ILMA may be useful in selected cases. Supralaryngeal or retroglottic airways, such as the LMA, King LT, and others, can be used as a rescue device in the setting of a failed airway, but they are rarely preferred as a primary management tool in trauma patients because of the uncertainty about their ability to protect against aspiration. The goal in managing the trauma patient, even with an identified difficult airway, is to achieve endotracheal intubation with an inflated cuff to protect against aspiration. Placement of a device that does not achieve this is normally considered only in circumstances in which there has been a failed airway or the patient has precipitously arrested and definitive airway management is not possible (see “The Failed Airway”).

E Pharmacologic Considerations

Injured patients are most often managed with RSI and several factors commonly observed for trauma victims should be considered when finalizing the pharmacologic menu. Rapidly selecting the appropriate induction agent, NMB agent, and pretreatment agents to secure the airway with the least likelihood of adverse effect is paramount.

Trauma patients are frequently hypovolemic, even if their initial mean arterial blood pressure is normal. Drug selection must go hand in hand with volume resuscitation and other appropriate interventions, such as tube thoracostomy, control of external hemorrhage, and pelvic stabilization. The individual decisions related to choice of pretreatment and induction agents are discussed throughout this chapter, but a few points should be emphasized.

Induction agents should be chosen to provide the best possible intubating conditions (used in conjunction with succinylcholine) with the least likelihood for adverse hemodynamic consequences. Etomidate, in a dose of 0.3 mg/kg, is remarkably hemodynamically stable, appears to provide some degree of cerebral protection, and has an onset-duration profile similar to that of succinylcholine. Although etomidate has been associated with adrenal cortical suppression, this is not clinically significant when a single dose is used for induction for intubation.¹⁰⁸ Its safety during RSI in trauma patients has been challenged, although these studies have fatally flawed methodology and low patient numbers, making the results hard to interpret and impossible to apply to clinical practice.^109,110 Etomidate can cause myoclonic jerks during its onset, but use of a rapidly acting NMB agent, such as succinylcholine, mitigates this effect substantially. Ketamine is an appropriate induction agent for hypotensive trauma patients. Ketamine’s role in head injury has been questioned because of its tendency to cause elevated ICP, but it is likely that the preservation of cerebral perfusion by maintenance of mean arterial blood pressure in hemodynamically unstable patients is more important than any theoretical risk to the brain caused by ketamine’s tendency to increase cerebral activity and ICP.^64,111 Other induction agents, such as propofol and pentothal, have much more tendency to cause hypotension and should be used in reduced doses and with caution in compromised or elderly trauma patients. Patients in shock with an immediate need for intubation should be given reduced (one-third to one-half) doses, regardless of the induction agent. Choice of a paralytic is not altered by the presence or absence of trauma. Succinylcholine and rocuronium are both appropriate and result in near-equivalent intubating conditions and first-pass success, depending on the dose used.^112,113

The choice of agents for sedation and awake intubation is influenced by the patient’s general status. It is advisable to use the agent with which the operator is most familiar for sedation. For example, if the operator typically sedates patients for painful procedures using propofol, it may be the best choice to sedate the trauma patient for awake laryngoscopy. In the absence of operator preference, ketamine may be ideally suited, especially when combined with an antisialagogue because of its ability to preserve respirations and hemodynamic status.¹¹⁴ Overall, familiarity with the drugs and the ability to titrate them carefully are probably more important than the drug’s pharmacodynamic characteristics.

F The Failed Airway

In managing the severely traumatized patient, it is important to have a clear definition of airway failure and a prepared action plan. The most widely accepted definition of a failed airway and the one used in the Emergency and the Difficult Airway Course: Anesthesia states that a failed airway exists when “(1) there have been three failed attempts by the most experienced operator, or (2) there has been one failed attempt by an experienced intubator combined with an inability to maintain adequate oxygen saturation despite airway adjuncts, maximal supplemental oxygen, and a bag and mask.”¹¹⁵

In either case, it is necessary to recognize that, with the current method and device being used, orotracheal intubation is not going to succeed, and the operator must move on to a rescue technique. If three attempts have failed, but oxygenation can be maintained with BMV, the operator should quickly evaluate why intubation was unsuccessful. Despite solid direct laryngoscopic technique, inadequate glottic exposure is often the culprit and results from the additive effect of poor C-spine mobility, reduced mouth opening, and oral secretions and blood. The modern difficult airway manager should have within his or her immediate reach a device designed to overcome these limitations and see around corners. Many options exist, although video laryngoscopy has shown the most promise, resulting in improved laryngeal views in almost every conceivable scenario in OR studies and ED populations.^{106,107,116,117} In the CICV scenario, the most appropriate rescue device is surgical cricothyrotomy. One parallel attempt at oxygenation may occur by rapid, blind insertion of a rescue supralaryngeal airway, such as a King LT or LMA, but only in concert with preparation for a surgical approach. If the patient’s oxygenation improves, other options can be explored. There should, however, be no hesitation for performing a cricothyrotomy if the slightest hint of supralaryngeal airway failure exists. An algorithm for managing a failed airway was developed for the Emergency and the Difficult Airway Course: Anesthesia and is shown in Figure 41-6.¹¹⁵ The theme of the algorithm is that decisions are driven by whether there is sufficient time to consider alternatives. If a CICV scenario arises at any time, the pathway leads to cricothyrotomy.

Figure 41-6 Failed airway algorithm. BMV, Bag-masic venfilation; ETT, endotracheal tube; I-LMA, intubating laryngeal mask airway; LMA, laryngeal mask airway; SpO₂, oxygen saturation measured by pulse oximetry.

(From Walls RM: Manual of emergency airway management, ed 3, Philadelphia, 2008, Lippincott Williams & Wilkins.)

G Rescue Techniques

The ultimate rescue technique for a failed airway in the trauma patient is surgical cricothyrotomy (see Chapter 31). When intubation has failed but ventilation is possible (i.e., cannot intubate but can ventilate scenario), several devices warrant consideration. They appear in the central box of the algorithm in Figure 41-6.

If direct laryngoscopy alone has been used, the operator should consider video laryngoscopy. The Glidescope video laryngoscope (GVL) and Macintosh video laryngoscope have been shown to improve laryngeal view compared with direct laryngoscopy in heterogeneous patient populations. Use of the GVL is associated with high levels of intubation success after failed direct laryngoscopy, although it may not be as effective in patients with significantly altered upper airway anatomy.¹¹⁸ Video laryngoscopy should be considered early as a backup or principal intubating device for significantly difficult trauma airways. Optically enhanced devices, such as the Airtraq, are understudied in trauma populations, although, early data suggest the Airtraq may be effective for patients requiring C-spine precautions.¹¹⁹

If these tools are not available, many supralaryngeal airways can be tried. The Combitube has been evaluated as a primary airway management device and as a rescue device. Numerous studies have shown that emergency medical technicians can successfully insert Combitubes with a high likelihood of success.^120,121 When studied in a cadaver unstable C-spine model, the Combitube produced more posterior C-spine displacement than the LMA or fiberoptic methods. This suggests that in-line stabilization is equally important during Combitube insertion as during direct laryngoscopy.¹²² Insertion with a cervical collar in place, however, has yielded mixed results. One study showed a high insertion success rate, and another reported successful blind insertion in only one third of patients with a semirigid collar on.^123,124 Ventilation with the Combitube, however, usually is highly successful.¹²⁴ The primary use of the Combitube is as a rescue device in the cannot intubate but can ventilate scenario in which other airway devices are thought unlikely to be successful. The Combitube is a less desirable choice because it does not place a cuffed ETT in the trachea when located in the esophageal position, but it usually suffices for ventilation and oxygenation. Another role for the Combitube is as a temporizing measure during preparations for cricothyrotomy. In this circumstance, only a single, expeditious attempt at placement is warranted.

Patients may arrive in the trauma bay with the Combitube inserted, inflated, and functioning. Because the Combitube does not provide a definitive airway (defined as a cuffed ETT in the trachea), it is advisable in most circumstances to intubate the patient and remove the Combitube. Details of insertion and use of the Combitube are discussed in Chapter 27, but there is a specific technique that must be used to intubate when the Combitube is in place. The Combitube has two cuffs, which are inflated through two separate channels. The proximal (pharyngeal) cuff is the larger of the two and is indicated by the blue filling valve. After ensuring that the patient is stabilized and adequately preoxygenated, this proximal cuff should be deflated. The Combitube should then be moved to the left corner of the patient’s mouth to permit access from the right side for laryngoscopy. Because the Combitube is almost always placed in the esophagus, it can remain in place while laryngoscopy proceeds. If difficulty arises, video laryngoscopy may be performed.¹²⁵ After the patient is intubated with the ETT cuff inflated and tube position confirmed by end-tidal CO₂ detection, the distal cuff on the Combitube can be deflated, and the Combitube can be removed. In the few cases in which the Combitube is inserted in the trachea, it can serve as a definitive airway, and tracheal placement is identified because successful ventilation and CO₂ detection are occurring through its second port. It has been recommended that a nasogastric tube be passed and the stomach decompressed before removal of the Combitube. It is possible for regurgitation to occur after removal of the Combitube, particularly if BMV occurred before placement of the Combitube in the prehospital setting.

In the ED and trauma resuscitation room, the ILMA is preferable to the Classic LMA. The ILMA is equally or more easily inserted and allows a conduit for subsequent intubation, with a significantly higher success rate than for the Classic LMA.^126,127 The ILMA has also been used to facilitate fiberoptic intubation and lighted stylet intubation.¹²⁸ The standard LMA and the LMA ProSeal have reasonable insertion success rates in the context of C-spine immobilization, but this situation has not been evaluated for the ILMA.¹²⁹ The ILMA has two main uses in the trauma patient. It can be used as the primary intubation method in a patient with an identified difficult airway. In the trauma patient, however, particularly one with an immobilized C-spine, the ILMA typically is not the first device selected. More commonly, the ILMA is used as a rescue device in a cannot intubate but can ventilate scenario. Placement of the ILMA allows ongoing ventilation with a very high success rate and facilitates endotracheal intubation. Like the Combitube, the ILMA can be placed as a temporizing measure during preparation for a cricothyrotomy in a CICV situation, as long as the placement and attempted ventilation through the ILMA do not delay initiation of surgical cricothyrotomy. Although less studied, the King LT shows promise as an effective rescue device and offers advantages of speed and success over the Combitube when used by prehospital providers.¹³⁰

The lighted stylet has not been studied specifically in trauma as a primary intubating device or as a rescue device. In controlled settings and experienced hands, the lighted stylet can have a high intubation success rate. However, the possible need for reduced lighting during a trauma resuscitation, the lack of supporting evidence in managing trauma, and the availability of more effective video devices make this tool an option best left on the shelf.