Author: Brandon Morshedi, MD, DPT, NREMT (EM Resident Physician, UT Southwestern Medical Center / Parkland Memorial Hospital) // Edited by: Alex Koyfman, MD (@EMHighAK) & Justin Bright, MD (@JBright2021)
Airway management is one of the most challenging and critical skills that the emergency medicine physician must master. This is particularly true in the setting of the trauma patient, where the ABCs of trauma evaluation begin with establishing the patency of the airway and ensuring adequate oxygenation and ventilation before moving through the remainder of the trauma algorithm. It is well known that delays in adequate airway management are one of the most common causes of preventable death in both the prehospital and emergency department setting.1-2 Even for patients that are initially stable, a delay in intubation is associated with increased mortality from 1.8% to 11.8% in one study.3
The Eastern Association for the Surgery of Trauma (EAST), comprised of trauma experts in the fields of surgery, emergency medicine, and anesthesia, developed a set of practice management guidelines in 2003, and modified them in 2012 based on new available evidence and technology.4 The results of their guidelines, as well as additional evidence and pearls found in the literature are presented below to guide the emergency medicine physician in the management of the trauma patient’s airway.
How Do I Adequately Assess the Airway?
While many emergency intubations are routine, studies have found that as many as 0.3% to 2.7% result in “failed airways” in the setting of trauma.5,6 There are specific anatomic characteristics that may predict the potential for difficulty with using a bag-valve-mask (BVM), performing direct laryngoscopy, or performing a surgical airway. Some examples of characteristics that may make it difficult to use a BVM are the presence of facial hair, obesity, edentulous patient, advanced age, snoring, and oral-maxillofacial trauma.7 Some examples of characteristics which may make it difficult to perform direct laryngoscopy are obesity, short neck, small or large chin, buckteeth, high arched palate, and any deformity related to trauma, tumor, or inflammation.8
While no one disagrees that a thorough assessment is advised prior to performing airway management, there are no specific recommendations on which method is the best to assess the airway. The EAST guidelines currently make a Level 2 recommendation to use “a structured assessment tool” (i.e. LEMON), and to use neuromuscular blockade with caution when significant difficulty is anticipated.4
The LEMON mnemonic is one of the most commonly utilized airway assessment tools, and is recommended by the most recent Advanced Trauma Life Support (ATLS) guidelines.9 The mnemonic refers to the assessment of five predictors:
Look – Look for external features that are predictive of a difficulty airway
Evaluate – Evaluate airway geometry by using the 3-3-2 rule to predict the oral opening (3 fingerbreadths), the mentum to hyoid distance (3 fingerbreadths), and the mandible to thyroid cartilage distance (2 fingerbreadths).
Mallampati score – Perhaps the least useful in the setting of trauma due to the high prevalence of cervical collars; assess the degree to which the posterior pharynx is visualized as a way to loosely associate the ability to view the glottis.
Obstruction/Obesity – Determine the location of the obstruction, whether it is fixed or mobile, and how rapidly it is progressing.
Neck mobility – This will not be a useful assessment in the setting of trauma given that most patients will be in cervical spine immobilization.
Which Trauma Patients Should I Intubate?
Some prehospital providers may perform field intubation prior to arrival in the emergency department, while others may have placed supraglottic devices (i.e. King-LT, LMA, or Combitube) or may simply be providing assisted ventilations with a BVM with only an oropharyngeal airway in place. Regardless, when they arrive in the emergency department, the emergency medicine physician must perform an assessment of the airway and decide whether or not the patient requires a definitive airway in place. The EAST guidelines make a Level 1 recommendation for endotracheal intubation in trauma patients with the following traits:4
- Airway obstruction
- Persistent hypoxemia (SaO2 ≤ 90%) despite supplemental oxygen
- Severe cognitive impairment (GCS score ≤ 8)
- Severe hemorrhagic shock
- Cardiac arrest
Additionally, endotracheal intubation is indicated for patients experiencing smoke inhalation with any of the following traits:
- Severe cognitive impairment (GCS score ≤ 8)
- Major cutaneous burn (≥ 40%)
- Major burns and/or smoke inhalation with an anticipated prolonged transport time to definitive care
- Impending airway obstruction as follows:
- Moderate-to-severe facial burn
- Moderate-to-severe oropharyngeal burn
- Moderate-to-severe airway injury seen on endoscopy
Finally, a Level 3 recommendation was made for endotracheal intubation in trauma patients with any of the following traits:
- Facial or neck injury with the potential for airway obstruction
- Moderate cognitive impairment (GCS score 9-12)
- Persistent combativeness refractory to pharmacologic agents
- Respiratory distress (without hypoxia or hypoventilation)
- Preoperative management (i.e. patients with painful injuries or undergoing painful procedures before non-emergent operation)
- Early ETI is indicated in cervical spinal cord injury with any evidence of respiratory insufficiency (complete SCI or incomplete injuries C5 and above)
A specific discussion is warranted for trauma patients who the decision is made to intubate based on persistent combativeness. Sise et al.10 performed a retrospective review of 1,000 consecutive patients that were intubated after injury for reasons other than those listed in the Level 1 recommendations of the EAST guidelines in 2003. These “discretionary indications” are now listed as Level 3 recommendations in the new EAST guidelines. It was noted in Sise’s study that 12.6% of these patients who were intubated for these additional indications had a clinically significant head injury, and that intubation in these patients was not without risk. Although the emergency medicine physician often intubates the persistently combative patient in order to complete a thorough trauma evaluation, including imaging, endotracheal intubation in these patients will lead to a longer stay, an increased incidence of pneumonia, and poorer discharge status when compared with matched controls.11
I Want to Intubate… Now What?
The first priority after making the decision to intubate is to prepare the patient for intubation. This is accomplished by preoxygenating the patient for at least 3 minutes (it will take the nurses this long to pull the RSI medications that you want anyway) and placing them in the appropriate position to maximize the provider’s chance of first-pass success of the endotracheal tube.
To preoxygenate the apneic or hypoventilatory patient, use a BVM at 15LPM of supplemental oxygen and provide artificial respirations. The patient may also simultaneously have a nasal cannula with high-flow oxygen (10-12 LPM). To preoxygenate the spontaneously breathing patient, use a combination of high-flow oxygen through a nasal cannula and a non-rebreather mask at 15LPM. The ultimate goal is to replace nitrogen with oxygen in the alveolar spaces, which will create a reservoir that will prevent hypoxia in the setting of the brief apnea that will occur during the intubation.
Which Drugs Do I Use?
The use of rapid sequence intubation (RSI) is a Level 1 recommendation in the EAST guidelines, with the exception of the presence of potential markers of significant difficulty with intubation. In this case, it may be recommended to attempt delayed sequence intubation or awake intubation. The objectives of choosing a specific RSI drug regimen includes achieving adequate sedation and neuromuscular blockade with maintenance of hemodynamic stability, CNS perfusion, and adequate oxygenation, as well as preventing increases in intracranial hypertension and preventing vomiting and aspiration.
In the trauma patient where increased intracranial pressure is suspected due to a head injury, the stimulatory effects of direct laryngoscopy on the posterior oropharynx may cause increases in heart rate, blood pressure, and intracranial pressure, and prove to be detrimental to the patient. Patients who have lost cerebral autoregulation may also experience an increase in intracranial pressure due to direct laryngoscopy.
The method to prevent these effects is to pretreat with an agent that will theoretically blunt these responses. The traditional agents are lidocaine and fentanyl, with lidocaine at 1.5mg/kg being the more commonly used agent. The evidence to support the use of pretreatment agents is mostly anecdotal, and studies demonstrating a favorable effect on outcomes are lacking. The clinician must weigh the potential benefit from a relatively benign medication in a trauma patient against the lack of clear outcome data.
The EAST guidelines do not make any specific recommendations regarding an induction agent. Below is a review of the most commonly utilized induction agents for RSI in the trauma patient.
Etomidate – In many centers, etomidate has been the drug of choice for induction because of its rapid onset, hemodynamic stability, and extensive experience with its use. However, there has been some controversy in the literature surrounding its use. A study by Cotton et al.12 showed an association with adrenal insufficiency with single-dose etomidate in critically injured patients. Another study showed an increased risk of adult respiratory distress syndrome and multiple-organ dysfunction syndrome in this same patient population.13 However, despite these two retrospective studies, the evidence has not been strong enough to recommend against the use of etomidate as the adverse events described are usually not clinically significant. The circulating cortisol levels will be decreased for 12-24 hours after a single dose administration, but studies have shown that the cortisol level still remains within physiological normal parameters.14
Ketamine – Ketamine has also been a source of controversy as an induction agent in patients with traumatic brain injury due to the theoretical increase in intracranial pressure (ICP). Multiple reviews and editorials have questioned this historical bias.15-16 Additionally, while not specifically related to trauma, there have been published studies showing that ketamine actually causes small decreases in ICP.17-18 If, in fact, ketamine does cause slight increases in ICP, it may be preferential to use in a hypotensive or shock trauma patient for its gentle increase in cerebral perfusion pressure. Obviously, more studies need to be performed related to this effect from ketamine. Ketamine is also useful for the hypotensive or shock trauma patient because of its sympathomimetic effects on the blood pressure.
For additional discussion on the use of etomidate and ketamine and comparison of costs, advantages, and disadvantages of these and other specific induction agents in the trauma patient, including the use of remifentanyl, propofol, thiopental, and midazolam, please refer to the 2009 study by Fields et al.19
The decision to paralyze the trauma patient with pharmacologic neuromuscular blockade does not come without risks. First and foremost, once the patient has been paralyzed, a definitive airway is the only endpoint that can be reached with the patient, whether through endotracheal intubation or a surgical airway. So, paralytics should never be administered without all of the proper rescue equipment at bedside, including a scalpel.
While the EAST guidelines do not make any specific recommendations regarding an induction agent, they do recommend succinylcholine as the agent of choice for neuromuscular blockade in the absence of any contraindications (i.e. crush injuries, burns, prolonged immobilization, skeletal myopathies, ESRD patients, etc.). In the event of contraindications to succinylcholine, high-dose rocuronium is an acceptable alternative, with the caveat that the neuromuscular blockade may last up to 45 minutes as compared to 8-10 minutes with succinylcholine. This may prove to be a significant disadvantage if the patient is unable to be ventilated or intubated, and the extended duration of paralysis may make it very difficult for the neurosurgeon to perform a reliable and thorough exam on the trauma patient with a head injury.
Should I use Cricoid Pressure?
The use of cricoid pressure (CP) was a Level 1 recommendation by the EAST guidelines in 2003, but was removed in the new guidelines. The cricoid pressure pendulum has swung wildly since its introduction in the 1960s. It has fallen out of favor recently as the evidence was lacking regarding its utility in preventing aspiration on induction in patients at high risk of aspiration.20 Additionally, MRI studies have shown a degree of lateral displacement of the esophagus relative to the midline which is only increased by the application of cricoid pressure, although the application of cricoid pressure did indeed seem to compress the hypopharynx which in theory could still prevent aspiration.21
An additional argument against the use of cricoid pressure has been the theorized worsening of the laryngeal view upon its application. The study results have been contradictory. For example, one randomized study by Noguchi et al.22 determined that cricoid pressure significantly worsened the laryngeal view whereas a study by McCaul et al.23 determined that cricoid pressure actually improved the laryngeal view in both lateral and supine positions. Alternatively, Turgeon et al.24 concluded in their large, randomized, double-blinded, controlled trial that there was no effect on laryngeal view.
In conclusion, there is insufficient evidence to support or abandon the use of cricoid pressure to prevent passive regurgitation. If used properly, it is likely to prevent aspiration. However, the provider should be properly trained in its application to both prevent aspiration and obstruction of the airway, as well as be prepared to release cricoid pressure if there is any difficulty in either intubating or ventilating the patient.20
A popular alternative to CP may be the use of BURP (backward-upward-rightward pressure) on the thyroid cartilage, not the cricoid ring, which can enhance visualization of the glottis.25-26 A modification of this technique, called bimanual laryngoscopy, allows the intubator to manipulate the larynx with the right hand until optimal glottis visualization is achieved and then an assistant maintains the position.25
Okay, last question… DL or VL?
The EAST guidelines do not make specific recommendations regarding the use of direct laryngoscopy (DL) vs video laryngoscopy (VL) in the intubation of a trauma patient. The studies using VL have consistently supported an improved Cormack-Lehane graded view of the glottis27-29, decreased cervical spine motion30-33, decreased forces and pressures exerted on the airway34-35, and minimized hemodynamic responses.36 However, despite all of these proven advantages, the literature has still failed to show a significant improvement in intubation success rates with the exception of studies performed in cadaver models, simulation scenarios, and elective nontrauma patients; all performed by personnel well-trained with the use of these VL devices. Additionally, the studies that show a higher first-attempt success rate also show an increased time to completion with VL vs DL.37
VL may certainly show an advantage in patients with potentially difficult airways, as studies persistently show similar success rates with Cormack-Lehane grades I or II using DL vs VL, and an increased time to intubation with VL. However, further studies specifically looking at the use of VL for ETI in trauma patients need to be performed.
Ultimately, when a trauma patient with an unprotected airway rolls into the emergency department, the end goal is a definitive airway. That goal is reached through various algorithms and methods depending on the experience of the provider. It is important to adequately assess the patient prior to intervening, make a quick decision about whether or not the patient needs a definitive airway at this time, have all of the necessary equipment and medications at bedside, and have a very specific plan laid out in the event that the airway becomes increasingly more difficult to achieve. This plan is different for every provider depending on their resources and experience, and it may need to be modified on a case-by-case basis depending on the clinical scenario laid out in front of the provider, but it is important that everyone involved in the trauma resuscitation be aware of the plan and available to assist in the implementation of that plan in order to create the highest chances of success for providing the trauma patient with a definite airway.
- Esposito TJ, Sanddal ND, Hansen JD, et al. Analysis of preventable deaths and inappropriate trauma care in a rural state. J Trauma. 1995;39:955-962.
- Teixeira PGR, Inaba K, Hadijizacharia P, et al. Preventable or potentially preventable mortality at a mature trauma center. J Trauma. 2007;63:1638-1650.
- Miraflor E, Chuan K, Miranda MA, et al. Timing is everything: delayed intubation is associated with increased mortality in initially stable trauma patients. J Surg Res. 2011;170:117-121.
- Mayglothling J, Duane T, Gibbs M, et al. Emergency tracheal intubation immediately following traumatic injury: An Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg. 2013;73(5):S333-S340.
- Bair AE, Rilbin MR, Kulkarni RG, et al. The failed intubation attempt in the emergency department: analysis of prevalence, rescue techniques, and personnel. J Emerg Med. 2002;23:131-140.
- Stephens CT, Kahntroff S, Dutton R. The success of emergency endotracheal intubation in trauma patients: a 10-year experience at a major adult trauma referral center. Anesth Analg. 2009;109:866-872.
- Langeron O, Masso E, Huraux C, et al. Prediction of difficult mask ventilation. 2000;92:1229-1236.
- Vissers RJ, Gibbs M. The high-risk airway. Emerg Med Clin North Am. 2010:28;203-217.
- Kortbeck, JB, Al Turki SA, Ali J, et al. Advanced trauma life support, 8th edition, the evidence for change. J Trauma. 2008:64:1638-1650.
- Sise MJ, Shackford SR, Sise CB, et al. Early intubation in the management of trauma patients: indications and outcomes in 1000 consecutive patients. J Trauma. 2009;66:32-39.
- Muakkassa FF, Marlye RA, Workman MC, et al. Hospital outcomes and disposition of trauma patients who are intubated because of combativeness. J Trauma. 2008;65:1328-1332.
- Cotton BA, Guillamondegui OD, Flemin SB, et al. Increased risk of adrenal insufficiency following etomidate exposure in critically injured patients. Arch Surg. 2008;143:62-67.
- Warner KJ, Cuschieri J, Jurkovich GJ, et al. Single-dose etomidate for rapid sequence intubation may impact outcome after severe injury. J Trauma. 2009;67:45-50.
- Schenarts CL, Burton JH, Riker RR. Adrenocortical dysfunction following etomidate induction in emergency department patients. Acad Emerg Med. 2001;8(1):1
- Filanovsky Y, Miller P, Kao J. Myth: ketamine should not be used as an induction agent for intubation in patients with head injury. 2010;12:154-157.
- Sehdev RS, Symmons DA, Kindl K. Ketamine for rapid sequence induction in patients with head injury in the emergency department. Emerg Med Australas. 2006;18:37-44.
- Mayberg TS, Lam AM, Matta BF, et al. Ketamine does not increase cerebral blood flow velocity or intracranial pressure during isoflurane/nitrous oxide anesthesia in patients undergoing craniotomy. Anesth Analg. 1995;81:84-89.
- Bar-Joseph G, Guliburd Y, Tamir A, et al. Effectiveness of ketamine in decreasing intracranial pressure in children with intracranial hypertension. J Neurosurg Pediatr. 2009;4:40-46.
- Fields AM, Rosbolt MB, Cohn SM. Induction agents for the intubation of the trauma patient. J Trauma. 2009;67:867-869.
- Bhatia N, Bhagat H, Sen I. Cricoid pressure: Where do we stand?. J Anaesthesiol Clin Pharmacol 2014;30:3-6
- Rice MJ, Mancuso AA, Gibbs C, Morey TE, Gravenstein N, Deitte LA. Cricoid pressure results in compression of the postcricoid hypopharynx: The esophageal position is irrelevant. Anesth Analg 2009;109:1546-52.
- Noguchi T, Koga K, Shiga Y, Shigematsu A. The gum elastic bougie eases tracheal intubation while applying cricoid pressure compared to a stylet. Can J Anaesth 2003;50:712-7.
- McCaul CL, Harney D, Ryan M, Moran C, Kavanagh BP, Boylan JF. Airway management in the lateral position: A randomized controlled trial. Anesth Analg 2005;101:1221-5.
- Turgeon AF, Nicole PC, Trépanier CA, Marcoux S, Lessard MR. Cricoid pressure does not increase the rate of failed intubation by direct laryngoscopy in adults. Anesthesiology 2005;102:315-9.
- Levitan RM, Kinkle WB, Levin WJ, Everett WW. Laryngeal view during laryngoscopy: a randomized trial comparing cricoid pressure, backward-upward-rightward pressure, and bimanual laryngoscopy. Ann Emerg Med. 2006;47:548-555.
- Knill RL. Difficulty laryngoscopy made easy with a “BURP”. Can J Anaesth. 1993;84:419-421.
- Stroumpoulis K, Pagoulatou A, Biolari M, et al. Videolaryngoscopy in the management of the difficult airway: a compromise with the Macintosh blade. Eur J Anaesthesiol. 2009;26:218-222.
- Kaplan MB, Hagverg CA, Ward DS, et al. Comparison of direct and video-assisted views of the larynx during routine intubation. J Clin Anesth. 2006;18:357-362.
- Brown CA, Bair AE, Pallin DJ, et al. Improved glottis exposure with the video Macintosh laryngoscope in adult emergency department tracheal intubations. Ann Emerg Med. 2010;56:83-88.
- Malik MA, Maharaj CH, Harte BH, et al. Comparison of Macintosh, Truview EVO2, Glidescope, and Airwayscope laryngoscope use in patients with cervical spine immobilization. Br J Anaesth. 2008;101:723-730.
- Komatsu R, Kamata K, Hoshi I, et al. Airway scope and gum elastic bougie with Macintosh laryngoscope for tracheal intubation in patients with simulated restricted neck mobility. Br J Anaesth. 2008;101:863-869.
- Maruyama K, Yamada T, Kawakami R, et al. Randomized cross-over comparison of cervical spine motion with the AirWay Scope or Macintosh laryngoscope with in-line stabilization: a video-fluoroscopic study. Br J Anaesth. 2008:101:563-567.
- Maruyama K, Yamada T, Kawakami R, et al. Upper cervical spine movement during intubation: fluoroscopic comparison of the Airway Scope, McCoy laryngoscope, and Macintosh laryngoscope. Br J Anaesth. 2008;100:120-124.
- Carrasitia M. Force and pressure distribution using Macintosh and Glidescope laryngoscopy in normal and difficult airways: a manikin study. Br J Anaesth. 2012;108:146.
- Russell T, Lee C, Firat M, et al. A comparison of the forces applied to a manikin during laryngoscopy with the Glidescope and Macintosh laryngoscopes. Anaesth Intensive Care. 2011;39:1098-1102.
- Koyama Y. Comparison of haemodynamic responses to tracheal intubation using the Airway scope and Macintosh laryngoscope in normotensive and hypertensive patients. 2011;66:895.
- Platts-Mills TF, Campagne D, Chinnock B, et al. A comparison of Glidescope video laryngoscopy versus direct laryngoscopy intubation in the emergency department. Acad Emerg Med. 2009;16:866-871.