Ron M. Walls
The Clinical Challenge
The trauma patient poses several unique challenges with respect to airway management. Conflicting priorities may arise because of multiple system injuries, and resuscitation often requires a team response. Success demands excellent assessment skills, an understanding of the physiology of injury, a thorough knowledge of airway pharmacology, and strong leadership. Fundamentally, though, the principles of trauma airway management are no different than those applied to management of the airway in other complex medical situations. A consistent approach and a reproducible thought process help create a successful outcome.
Approach to the Airway
Although many trauma intubations turn out to be straightforward and routine, systematic application of the airway algorithms and difficult airway mnemonics is essential. At the outset, all intubations performed in the injured patient should be considered at least potentially difficult. During the primary survey, the presence of multiple severe injuries can combine with distracting presentations (external hemorrhage, combative behavior) to create information overload for the treating clinician, impeding data gathering and impairing decision making. This underscores the importance of applying the main airway algorithm (see Chapter 2) and using the difficult airway mnemonics (LEMON, MOANS, SHORT, and RODS; see Chapter 7) in orderly fashion while assessing the patient:
1. L: Look externally: Injury to the face, mouth, or neck may distort anatomy or limit access, making the process of intubation difficult or impossible. The integrity of the mask seal may be impaired by facial hair, external bleeding, pre-existing physiognomy, or anatomical disruption (MOANS). Injury to the anterior neck, such as by a clothesline mechanism or hematoma, may preclude successful cricothyrotomy (SHORT) or extraglottic device (EGD) placement (RODS).
2. E: Evaluate 3-3-2. In blunt trauma, the cervical spine is immobilized, and a cervical collar is usually in place at the time that airway decisions must be made. A cervical collar is not particularly effective at limiting cervical spine movement during intubation, but greatly impairs mouth opening, limiting both laryngoscopy and insertion of an EGD (RODS). The front portion of the collar should be opened to facilitate the primary survey and removed entirely during intubation. Other injuries, such as mandibular fractures, may either facilitate or impair oral access, and mouth opening should be assessed as carefully as possible.
3. M: Mallampati. The trauma patient is rarely able to cooperate with a formal Mallampati assessment, but the airway manager should open the patient's mouth as widely as possible and inspect the oral cavity for access, using a tongue blade, or the laryngoscope blade, which has the advantage of illumination. At this time, potential hemorrhage or disruption of the upper airway may also be evident (RODS).
4. O: Obstruction, Obesity. Obstruction, usually by hemorrhage or hematoma, can interfere with laryngoscopy, BMV (MOANS), or EGD placement (RODS). Obesity in the trauma patient presents the same challenges as for the nontrauma patient.
5. N: Neck mobility. The majority of trauma patients, including all those with blunt trauma and certain patients with penetrating trauma, require manual inline stabilization to prevent cervical spine movement during intubation. The role of cervical spine immobilization during penetrating injury is controversial. Spinal instability caused by penetrating injury (usually gunshot wounds) is extremely rare in a patient presenting without neurological deficit. In other words, when these high-energy injuries create spinal instability, they also cause injury to the spinal cord or emerging nerve roots. Therefore, cervical spine immobilization in such patients is based on the location and mechanism of the wound, the physical (especially neurological) findings on examination, and the urgency and difficulty of the airway intervention. Patients with penetrating injury can be subjected to secondary injury, as from falling down a flight of stairs, and these patients should be immobilized as for their blunt injury. Patients with gunshot injury to the head and neck may have brain injury that confounds spinal assessment. In general, though, an intact neurological examination in the context of penetrating injury argues strongly against the possibility of spinal instability. If spine immobilization is preventing successful intubation, it is advisable to relax the spine immobilization to permit completion of the intubation. This may expose the patient to a tiny risk of spinal cord injury, but the likelihood of brain injury from hypoxemia because of the failed intubation is manyfold greater. Similarly, even for blunt injury with intact neurological examination, if strict cervical spine immobilization is preventing intubation and hypoxemia is developing, judicious relaxation of the degree of immobilization to an extent just sufficient to permit intubation may be necessary, depending on the judgment of the airway manager.
6. Other factors: Pre-existing comorbidities and certain other injuries can complicate both the decision making and execution of trauma airway management:
a. A patient with heart failure or chronic obstructive pulmonary disease, for example, may desaturate rapidly, requiring bag-mask ventilation during rapid sequence intubation (RSI).
b. Injuries to the chest may create conflicting priorities between tube thoracostomy and intubation.
c. Hypotension or marginal hemodynamic stability may influence the choice of pretreatment and sedative agents for RSI. For example, the brain injured patient with hypotension is not a good candidate for fentanyl pretreatment, despite the presence of central nervous system injury or presumed elevated intracranial pressure (ICP), because of the likelihood of further lowering the mean arterial blood pressure. Similarly, the patient's circulatory status may influence selection of the sedative agent, with etomidate and ketamine providing much greater hemodynamic stability than propofol or midazolam, for example.
d. Specific illness or injury may require consideration as for the uninjured patient. For example, the trauma patient with asthma may receive lidocaine pretreatment.
Evaluation of the trauma patient follows the primary/secondary survey as described within the Advanced Trauma Life Support course. During the “A” phase of the primary survey, assess the integrity of the airway by observing the patient's air movement during respiration; quickly inspect and palpate the anterior neck (with cervical collar open); have the patient phonate (“What is your name?”); and inspect the oral cavity for disruption, dental or tongue injury, hemorrhage, or pooling secretions. A patient whose eyes are open and who is phonating (even nonsensically) likely has an adequate airway at that moment in time. If an oral or nasal airway is required to maintain airway patency, the patient is likely not able to protect the airway, and early (but not necessarily immediate) intubation is indicated. Next, inspect and feel the chest wall for injury, and listen for breath sounds. Although much is made about palpating the trachea to ensure it is in the midline, this is not a reliable finding for pneumothorax, and the presence or absence of tracheal deviation should not be considered to diagnose or exclude pneumo- or hemothorax. Careful palpation for subcutaneous air in the red alerts the examiner to the possibility of direct airway violation, which may render tracheal intubation difficult and BMV ineffective.
During this phase of examination, the pulse oximetry, blood pressure, and pulse are assessed in concert with auscultation of the chest. Presence of suspected pneumo- or hemothorax with hemodynamic compromise can create a dilemma with respect to the sequence of tube thoracostomy versus intubation. On the one hand, the patient may be so critically ill that immediate intubation seems necessary. Consideration of the effects of the hypotensive effect of the sedative agent and positive-pressure ventilation, however, may argue strongly for tube thoracostomy before intubation, in hopes that relief of the pneumothorax will improve the blood pressure. In general, if the airway is patent and functioning (i.e., immediate intubation is not required), and patient factors do not prevent insertion of a chest tube, it is preferable to perform tube thoracostomy first and then to intubate. The improved hemodynamics after tube thoracostomy may expand the choices for RSI drugs and also improve the safety of the intubation. However, the patient may be restless or combative, and thoracostomy may be difficult unless it is delayed until after the patient is sedated and paralyzed. Striking the right balance can be challenging and is one of the most difficult decisions facing the trauma leader. Options include (a) when a trauma team is present, the patient may be induced for RSI, and then the tube thoracostomy is performed by one team member while another intubates; or (b) when resuscitation is by a single provider or small team, a needle thoracostomy may be performed, followed immediately by intubation, and then by tube thoracostomy.
Specific Clinical Considerations
The trauma airway is one of the most challenging clinical circumstances in emergency care. It requires knowledge of a panoply of techniques, guided by a reproducible approach (the airway algorithms), sound judgment, and technical expertise. The principles common to the various clinical scenarios in trauma airway management are discussed previously. In this section, we describe the considerations unique to certain specific presentations.
Cervical Spine Injury
All severely injured blunt trauma patients have cervical spine injury until proven otherwise. In the vast majority of cases, the patient will be immobilized by prehospital providers in the field. Although this step is essential to prevent further spinal injury, it can create several problems as well. Intoxicated or head injured patients typically become agitated and difficult to control when strapped down on a backboard. Physical and chemical restraint may be required. Aspiration is a significant risk in the supine patient with traumatic brain injury or vomiting. In this position, ventilation may be impaired, especially in the presence of chest injury. High-flow oxygen should be provided to all patients, and suction must be immediately available.
If urgent airway management is needed, there is no purpose served by obtaining a crosstable-lateral cervical spine x-ray before intubation. This single view is inadequate to exclude injury, with a sensitivity of 80% at best, even with a technically perfect film. Waiting for the x-ray will expend precious time and give the operator a false sense of security when the film is interpreted as “normal.” Instead, all patients must be assumed to have cervical injury, and inline stabilization must be maintained at all times. The preintubation neurological status of the patient and the use of inline manual immobilization of the cervical spine during intubation should be clearly documented in the medical record. The intubation itself is performed as gently as possible, with inline cervical stabilization by a second provider and optimal preoxygenation. Although most trauma intubations present some degree of difficulty, as described previously, RSI is often the best method for intubation, provided that the operator is confident about the likelihood of success and of the effectiveness of bag-mask ventilation or EGD placement, if intubation is unsuccessful. As experience with video laryngoscopy increases, it is likely that these devices will provide superior glottic views with less cervical stress than is possible by conventional laryngoscopy.
Disrupted Airway Anatomy
Here, the very condition that mandates intubation may also render it much more difficult and prone to failure. Direct airway injury may be the result of
· Maxillofacial trauma
· Blunt or penetrating anterior neck trauma
· Caustic ingestion
In cases of distorted anatomy, the approach must be one that minimizes the potential for catastrophic deterioration. Although some authors recommend a period of expectant observation, waiting to see if the nearly obstructed airway becomes completely obstructed can be disastrous. Theoretically, a short period of observation determines that the situation is deteriorating, and intubation is then undertaken. It is often not possible, however, to determine whether the airway threat is increasing; for example, expansion of a deep hematoma may not be clinically obvious. In such cases, deterioration may not be evident until a crisis occurs, at which time the patient's airway is nearly or completely obstructed, hypoxemia rapidly ensues, and intubation is difficult or impossible because of the extreme anatomical distortion. In these cases, neither bag-mask ventilation nor insertion of an EGD is possible, and the window of opportunity for cricothyrotomy has also often passed, with devastating consequences.
Airway disruption may be marginal or significant, real or potential. In either case, the guiding principle is to secure the threatened airway early, while more options are preserved, and the patient's stability permits a more deliberate approach. As for any other anatomically distorted airway, application of the difficult airway algorithm will often lead to a decision to perform an awake intubation. In patients with signs of significant airway compromise (e.g., stridor, drooling, respiratory distress, voice distortion), both the urgency of the intubation and the risk of using neuromuscular blockade are high. When symptoms are more modest, there is more time to plan and execute the airway intervention, but in neither case is delay advisable. Application of the difficult airway algorithm will lead the clinician through the evaluation of the patient's oxygenation (i.e., “Is there time?”), and then help determine whether RSI is advisable, possibly under a double setup, even though the airway is difficult. This will depend on the clinician's confidence about the likelihood of success of bag ventilation and intubation by direct laryngoscopy (see Chapters 2 and 7). Often, the best approach is to attempt awake intubation by fiberoptic laryngoscopy with sedation and topical anesthesia (see Chapters 8 and 12). This permits both examination of the airway and careful navigation through the injured area, even when the airway itself has been violated. When the airway is disrupted and the scope is used to traverse the disruption, the endotracheal tube should be as small as possible so it closely follows the fiberoptic scope when advanced, minimizing the likelihood of catching on the pathological breach in the airway. No other method of intubation allows the airway to be visualized both above and below the glottis. Although “awake” direct laryngoscopy is also a reasonable technique, using either a conventional or a video laryngoscope, this does not permit visualization of the airway beyond the glottis, so the intubation itself is “blind” with respect to the infraglottic trachea.
Smoke Inhalation
Smoke inhalation can present on a spectrum from mild smoke exposure to complete airway obstruction with death. Exposure to the toxic products of combustion usually does not cause direct thermal injury to the airway, and the ensuing edema is caused by tissue toxicity of the constituents of the smoke. Initially, the patient presents with evidence of smoke exposure (history of closed space fire) and physical findings suggestive of inhalation (singed nasal hairs, perinasal or perioral soot, carbon deposits on the tongue, hoarse voice, carbonaceous sputum.) When evidence of airway involvement is present, direct examination of the airway, often with intubation, is mandatory. This is usually, and best, done with fiberoptic laryngoscopy, which permits evaluation of the airway and simultaneous intubation, if indicated. Identification of supraglottic edema should be considered an indication for intubation, even if the edema is mild, because progression can be both rapid and occult. If examination of the upper airway identifies that the injury is confined to the mouth and nose, and the supraglottic area is spared (and normal), then intubation in not indicated, and subsequent examination can be at the discretion of the operator. If erythema or edema is identified, gentle intubation, either by direct laryngoscopy or over the fiberoptic scope, is indicated. The patient may well be extubated 24 or even 12 hours later without any evidence of intervening airway swelling, but that cannot be predicted at the time of initial examination, except by the presence of a normal upper airway. If doubt exists, the patient can be observed, but with a plan for a repeated upper airway examination in 30 minutes, even if symptoms do not develop or worsen. Observation in lieu of airway examination can be hazardous because the airway edema can worsen significantly without any external evidence, and by the time the severity of the situation is apparent, intubation is both immediately required and extremely difficult or impossible.
Chest Trauma
Chest injury, such as pneumothorax, hemothorax, flail chest, pulmonary contusion, or open chest wound, impairs ventilation and oxygenation. Preoxygenation may be difficult or impossible in these patients, and rapid desaturation following paralysis is the rule. In addition, the positive pressure delivered via the endotracheal tube may convert a simple pneumothorax to a tension pneumothorax. Refer to the previous discussion in this chapter regarding the clinical dilemma that often ensues when a patient has evidence of severe chest injury with hemo- or pneumothorax and is in need of immediate intubation.
Hypotension
Patients suffering significant injury may have obvious or occult hypotension from many different sources. Shock in the multiply injured patient can be broadly classified as hemorrhagic (e.g., external, intrathoracic, intra-abdominal, retroperitoneal, long bone) or nonhemorrhagic (e.g., tension pneumothorax, pericardial tamponade, myocardial contusion, spinal shock). As the causes of shock are elucidated and corrected, airway management choices must consider the loss of hemodynamic reserve in these patients. Mechanical causes of shock, such as tension pneumothorax or hemothorax, are addressed early and almost simultaneously with airway management (see previous discussion). Pericardial tamponade is rare in blunt trauma, but may be the most critical element destabilizing the patient with penetrating thoracic or upper abdominal trauma. Induction, intubation, and initiation of positive-pressure ventilation in a patient with untreated pericardial tamponade may precipitate cardiovascular collapse and arrest. Accordingly, the tamponade must be relieved before intubation. If this is not possible, a minimal dose of the most hemodynamically stable induction agent should be used (e.g., 0.5 mg/kg of ketamine). Rapid fluid administration is used to maximize filling pressure. The heart rate is maintained, and minimum effective tidal volumes are used to mitigate the inhibition of venous return to the thorax. Redistributive shock (spinal shock) is treated with fluids and, as necessary, pressors, with the constant caveat that spinal shock, in isolation, is not to be diagnosed until hemorrhagic shock has been excluded. Administration of crystalloid and blood will improve the hemodynamic tolerance for intubation and mechanical ventilation in patients with blood loss.
Traumatic Brain Injury
The principles of management of the patient with traumatic brain injury (TBI) fall within those discussed in Chapter 28 for patients with elevated ICP. The technique chosen is one that will optimize cerebral perfusion pressure by preserving systemic mean arterial blood pressure and minimize the extent and duration of hypoxemia. In the past, aggressive hyperventilation was advocated as a means to reduce ICP, and this, in itself, was considered an indication for intubation. This approach has long since been discredited, and hyperventilation is now known to worsen, not improve, the outcome in severe TBI. Hypercapnia is undesirable, however, because it causes cerebral vasodilation, and PCO2 should be maintained at 35 torr. Certain sedative induction agents are believed to be more “cerebroprotective” because of their ability to decrease cerebral blood flow or oxygen demand. Etomidate, because of its balance of preservation of hemodynamics and modest cerebroprotective properties, is often the agent of choice. Formerly, it was widely believed that ketamine was contraindicated in head injury, but the evidence in this regard is scant and contradictory. Ketamine may be the drug of choice in the hypotensive TBI patient, as an alternative to etomidate. Because of its tendency to release catecholamines, ketamine is not advised for normotensive or hypertensive TBI patients.
Technique
Paralysis versus Rapid Tranquilization of the Combative Trauma Patient
The combative trauma patient presents a series of conflicting problems. The causes of combative behavior in the trauma patient are numerous and include head injury, drug or ethanol intoxication, pre-existing medical conditions (diabetes, in particular), hypoxemia, shock, anxiety, personality disorder, and others. The priority is to rapidly control the patient so that potentially life-threatening causes can be identified and corrected. Controversy exists as to whether such patients ought to undergo rapid tranquilization with a neuroleptic agent or sedative, or whether immediate intubation with neuromuscular blockade is appropriate. Rapid tranquilization using haloperidol is well established as a safe and effective means for gaining control of the combative trauma patient who cannot be settled by other means. Haloperidol can be used intravenously in 5- to 10-mg increments every 5 minutes until a sufficient clinical response is achieved. There is extensive literature supporting the safety of this approach. Recently, concerns have been raised about the potential for intravenous haloperidol to worsen QT prolongation or cause Torsades Des Pointes. If possible, obtain a pre-administration monitor strip to assess QT interval length, but the patient's behavior often precludes this. Haloperidol has minimal effect on the CO2response curve, so does not depress respirations, although, occasionally, the additive effect of haloperidol to another general anesthetic agent, such as ethanol, can cause hypoventilation. Opioids, such as morphine or fentanyl, although indicated for pain control, are not primary sedative agents, and should not be used for this purpose because of their profound respiratory depressant effects.
The decision to use rapid tranquilization rather than RSI with neuromuscular blockade depends on the nature of the patient's presentation and injuries. If intubation is required based on the patient's injuries, independent of the combative behavior, then immediate intubation is indicated. If, however, the patient is presenting primarily with control problems and does not appear have injuries that would mandate intubation, then rapid tranquilization is appropriate. In many situations, the decision will not be clearcut, and judgment will be required. In either situation, control of the patient is an essential step in overall management, whether this is achieved through intubation with sedation and paralysis or through rapid tranquilization.
Choice of Pretreatment Agents
Pretreatment agents for the multiply injured patient are the same as those for other patients requiring intubation (see previous discussion), with a few important caveats. Fentanyl is indicated when the catecholamine surge, which accompanies intubation, is undesirable, such as in traumatic cerebral hemorrhage and penetrating injury, particularly involving a great vessel. In the trauma patient, however, sympathetic tone is often maximized to preserve blood pressure in the face of blood loss, and administration of an agent to reduce sympathetic tone is not desirable. In such patients, although there may be a theoretical reason to administer fentanyl, it should not be given because of the potential to greatly worsen hemodynamic compromise. In cases of isolated head injury without hypotension, though, fentanyl is indicated, as is lidocaine. There are no particular traumatic contraindications to lidocaine, when it is otherwise indicated for pretreatment (see Chapter 17).
Choice of Neuromuscular Blocking Agent
Succinylcholine (SCh) is the drug of choice for RSI in the trauma patient because of its rapid, reliable onset and brief duration of action. Although patients with spinal cord injury, extensive burns, or severe crush injuries are at risk for SCh-induced hyperkalemia, the receptor upregulation that causes the hyperkalemia takes several days to develop and is not an issue in the context of acute injury. SCh is contraindicated in these patients beginning 5 days post injury, though, and extending for 6 months or until the burns are healed (see Chapter 19).
SCh also has been implicated in the elevation of ICP in the patient with traumatic brain injury. We no longer recommend the use of a defasciculating agent in this setting, however, and elevated ICP is neither an absolute nor relative contraindication to the use of SCh (see Chapters 19 and 28). SCh's short duration of action permits ongoing postintubation sedation using a propofol infusion, without paralysis, in many cases of traumatic brain injury, thus facilitating ongoing neurological evaluation.
Choice of Sedative Induction Agent
Table 27-1 provides a summary of recommendations for RSI sedative induction agent selection based on the particular clinical situation. In most circumstances, etomidate is the drug of choice, based on its hemodynamic stability and familiarity. The controversy regarding the use of etomidate in shock, related to suppression of the adrenal axis, is discussed in Chapter 18. This controversy has related primarily to septic shock, and there is currently no evidence to support abandoning this reliable, proven, and hemodynamically stable agent in trauma. Overall, the preservation of hemodynamic status and cerebral perfusion pressure outweighs considerations of theoretical transient suppression of the adrenal axis.
Failed Airway
When a failed airway situation develops in the trauma patient, the failed airway algorithm is followed, just as for the nontrauma patient. The trauma patient has a higher incidence of upper airway distortion that may render oral approaches impossible, necessitating cricothyrotomy, and cricothyrotomy is required over four times more often in trauma than in medical cases. Careful application of the LEMON, MOANS, RODS, and SHORT mnemonics during the preintubation assessment will ensure that the devices chosen are appropriate for the patient's particular injuries, and that transition from the primary method selected (e.g., RSI) to the rescue technique (e.g., intubating LMA [ILMA]) in the event of a failed airway is as smooth as possible. Cricothyroidotomy equipment should always be readily available, and the operator must be familiar with both the technique and the cricothyroidotomy kit contents.
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Table 27.1 RSI Sedative Induction Agent Selection in the Trauma Patient |
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Tips and Pearls
1. Most considerations related to intubation of the multiply injured patient follow the same principles as for the medical patient, and the primary challenge for the intubator is to avoid being distracted by the patient's obvious external injuries, combative behavior, or the intrinsic anxiety that accompanies care of the severely injured, often young, trauma patient.
2. Resist the temptation to observe the patient with upper airway injury or smoke inhalation. Delay can lead to disaster, and, at the least, the upper airway should be examined fiberoptically to ensure that there is adequate airway patency and time.
3. The hemodynamically compromised trauma patient may be much more severely injured than is apparent. Young patients, in particular, can preserve a reasonably normal blood pressure in the face of significant blood loss. The occult hypotension may be suddenly unmasked by the administration of sedative agents, initiation of positive-pressure ventilation, or both.
Evidence
1. Are there any large series of intubation of trauma patients? In an evidence-based literature review, Dunham et al. (1) provided a comprehensive overview (demographics, airway management techniques, success rates) of trauma patients requiring emergency airway management. Although most of these patients were critically ill, the degree of injury was highly variable; the mean Injury Severity Score was 29 (range 17–54), and the mean Glasgow Coma Scale was 6.5 (range 3–15). On average, 41% of patients died (range 2%–100%). They reported death more frequently when airway management was delayed, difficult, or unsuccessful, but a lack of randomization makes these findings difficult to interpret. In the multicenter National Emergency Airway Registry (NEAR) project, analysis of more than 2,000 trauma intubations identified head trauma as the single largest indication. RSI was the most common airway management method used, and the RSI success rate was more than 97% (2). Cricothyrotomy is required in approximately 2.5% of all trauma patients, almost always as a secondary, or “rescue,” technique (3). Cricothyrotomy, when required, has a high success rate and a low rate of adverse events (3). More detailed analysis of trauma intubations by the NEAR investigators is forthcoming.
2. Has inadequate or inappropriate airway management been linked to preventable death? When 629 trauma deaths in the state of Montana were reviewed to determine the rate and cause of preventable mortality and “inappropriate” care by a panel of physicians and prehospital care providers, the overall preventable death rate was judged to be 13%. The most common cause of inappropriate care was inadequate management of the airway in either the prehospital setting (6.8% of cases) or emergency department (5.4% of cases) (4). This argues for proper airway training, as well as the availability of adequate equipment and drugs for trauma airway management, in the context of a comprehensive quality program.
3. Is oral endotracheal intubation safe in cervical spine injury? A prospective study of airway management practice and associated neurological outcome in 150 patients subsequently diagnosed with cervical spine injury used a standardized neurological examination that was performed before and after intubation, which was performed using inline stabilization. Twenty-six (32%) of 81 patients without a neurological deficit required intubation on presentation, and none manifested a subsequent neurological deficit. Twenty-nine (42%) of 69 additional patients with high cervical injury required intubation, and no patient exhibited neurological deterioration (5). A retrospective review was conducted of 150 patients with known cervical spine injuries who were electively intubated: 50 patients (33%) had preoperative neurological deficit, 83 patients (55%) were intubated after induction of general anesthesia, and 67 patients (45%) were intubated awake. Cervical immobilization with inline stabilization was documented in 86 patients (57%). Two patients (1.3%) developed new neurological deficits. The study size was insufficient to determine whether awake intubation versus general anesthesia conferred any potential benefit (6). A retrospective study of 73 out of 393 patients with traumatic cervical spine injuries who underwent RSI with inline stabilization within 30 minutes of presentation (36 patients) or between 30 minutes and 24 hours (37 patients) found no neurological sequelae as a result of the intubation (7).
A retrospective analysis of patients undergoing tracheal intubation for surgical fixation of cervical spine injuries compared results when awake fiberoptic intubation was used with those obtained using general anesthesia and neuromuscular blockade. Sixteen of the 45 patients had preoperative neurological deficit. Cervical traction was used to stabilize the spine for all intubations. None of the 45 patients sustained a new or worsened neurological injury (8). A similar retrospective review of 113 patients with cervical spine fractures requiring operative repair, of whom 33 (30%) had a partial neurological deficit, found no new neurological deficits among the 86 (76%) who underwent nasal intubation or the 27 (24%) who underwent oral intubation with inline stabilization (9).
There are no guarantees that any particular approach is safe, but there is solid evidence that a controlled intubation using manual inline cervical stabilization protects the patient against neurological injury.
4. Are the ILMA and Combitube safe in cervical spine injury? A prospective study of radiographs taken before, during, and after intubation using the ILMA versus direct laryngoscopy in patients with normal cervical spines found that the ILMA intubation took about twice as long (39 seconds vs. 21 seconds), but that the cervical spine movement was significantly less with the ILMA (p <.008) (10).
Although the Combitube (CT) airway has been recommended as a device for airway rescue when RSI fails, it may be more difficult to place in patients with immobilized cervical spines. When CT placement was attempted in 15 patients (mean age, 32 years) with Philadelphia collars on during anesthesia for elective surgery, blind insertion was possible in only 5 patients; in the remaining 10, the investigators were unable to advance the device through the mouth into the hypopharynx and required laryngoscopy. Once placed, the CT functioned effectively. These results cast doubt on the use of the CT in the immobilized trauma patient (11).
5. Do alternative methods create more or less cervical spine movement than direct laryngoscopy? In a study of cervical spine movement during intubation in 24 healthy volunteers, the Shikani optical stylet (see Chapter 13) caused 55% less cervical spine movement in three of the four cervical spine segments studied than did intubation with the MacIntosh laryngoscope. Intubation took an average of 28 seconds with the SOS versus 17 seconds with the MacIntosh (12). The same researchers subsequently compared intubations with the lighted stylet, GlideScope, and MacIntosh laryngoscope in 36 elective anesthesia patients (13). Compared with direct Macintosh laryngoscopy, the Trachlight (see Chapter 11) reduced motion by 49%, 72%, 64%, and 41% at four studied cervical segments, and the GlideScope reduced motion by 50% at the C2–C5 segment, but did not affect other levels. Time to successful intubation was similar with the Trachlight and MacIntosh laryngoscope (14 and 16 seconds), but was significantly longer with the GlideScope (27 seconds). (See also Chapters 14 and 15.)
References
1. Dunham MC, Barraco RD, Clark DE, et al. Guidelines for emergency tracheal intubation immediately after traumatic injury. J Trauma 2003;55:162–179.
2. Brown CA, Walls RM. National Emergency Airway Registry (NEAR III): an initial report of 3,342 emergency department intubations [abstract]. Acad Emerg Med 2004;11(5):491.
3. Collins JJ, Brown CA, Walls RM. Surgical airways in emergency department patients: a report of 75 cases from the National Emergency Airway Registry (ii) [abstract]. Acad Emerg Med 2004;11(5):522–523.
4. Esposito TJ, Sanddal ND, Hansen JD, et al. Analysis of preventable trauma deaths and inappropriate trauma care in a rural state. J Trauma 1995;39(5):955–962.
5. Shatney CH, Brunner RD, Nguyen TQ. The safety of orotracheal intubation in patients with unstable cervical spine fracture or high spinal cord injury. Am J Surg 1995;179:676–679.
6. Suderman VS, Crosby ET, Lui A. Elective oral tracheal intubation in cervical spine-injured adults. Can J Anaesth 1992;39:516–517.
7. Criswell JC, Parr MJ, Nolan JP. Emergency airway management in patients with cervical spine injuries. Anaesthesia 1994;49(10):900–903.
8. McCrory C, Blunnie WP, Moriarty DC. Elective tracheal intubation in cervical spine injuries. Irish Med J 1997;90:234–235.
9. Holly J, Jorden R. Airway management in patients with unstable cervical spine fractures. Ann Emerg Med 1988;18:1237–1239.
10. Walti B, Melischek M, Schuschig C, et al. Tracheal intubation and cervical spine excursion: direct laryngoscopy vs. intubating laryngeal mask. Anaesthesia 2001;56:221–226.
11. Mercer MH, Gabbott DA. Insertion of the Combitube airway with the cervical spine immobilized in a rigid cervical collar. Anaesthesia 1998;53(10):971–974.
12. Turkstra TP, Pelz DM, Shaikh AA, et al. Cervical spine motion: a fluoroscopic comparison of Shikani optical stylet vs MacIntosh laryngoscope. Can J Anesth 2007;54(6):441–447.
13. Turkstra TP, Craen RA, Pelz DM, et al. Cervical spine motion: a fluoroscopic comparison during intubation with lighted stylet, GlideScope, and MacIntosh laryngoscope. Anesth Analg 2005;101(3):910–915.