We learned in Chapter 1, ‘Why airway management matters’ that the three core actions for airway management in the critically ill are to assess for potential difficulty, plan and prepare for that potential difficulty, and recognize and manage failure. Chapter 5, ‘Airway evaluation for anatomic difficulty’ explored the first core action—assessing for difficulty. Chapter 3, ‘The decision to intubate’ discussed when to intubate, including patients on noninvasive respiratory support. In this chapter, we will discuss how to use your assessment for airway difficulty to develop a strategy that accounts for these patient characteristics to give you the best chance of successful intubation without complications.

The general framework for developing a strategy is outlined in Fig. 9.1 and starts with the difficult airway assessment. The first step is to assess for anatomic characteristics that will make it difficult or impossible for you to intubate, ventilate with a bag and mask or supraglottic airway device (SAD), or do a cricothyrotomy.

Every patient can have a difficult airway assessment, although some will likely be abbreviated based on available time (i.e., an apneic or periarrest patient). However, the sicker the patient, the more imperative it is to have a good strategy that accounts for the difficulties predicted by your assessment. Many poor outcomes arise from airway management in sick patients without an airway assessment, or a strategy, and assigning the “crash airway” label. This is rushing right into failure, and hopefully, by the end of this chapter, you will have a firm grasp on developing a strategy for any situation.

Almost every patient has some profile of difficult airway characteristics that would potentially make laryngoscopy, tube placement, mask ventilation, supraglottic airway placement, or cricothyrotomy difficult. Each characteristic lies on a spectrum of severity, and the contribution from a combination of minor characteristics may be as difficult as someone on the extreme end of one characteristic. That does not mean every patient will be difficult or that every patient will require an awake intubation. On the contrary, many patients with a predicted difficult airway are successfully intubated with rapid sequence intubation (RSI).¹ The question is not if there are any predictors of difficulty, but rather what can you do to overcome their specific profile of difficult airway characteristics (Fig. 9.2).

For laryngoscopy and tube placement, the answer to this question involves device selection (i.e., direct laryngoscopy (DL), video laryngoscopy (VL), blade size, blade geometry) or combination of devices (e.g., DL or VL + flexible endoscope or optical stylet, supraglottic airway + flexible endoscope, etc.), stylet (rigid, malleable) or bougie selection, tube size, and a focus on appropriate positioning to align the anterior ear with sternal notch.

For mask ventilation, is there a better preoxygenation option to delay needing mask ventilation? Can apneic oxygenation limit your need to mask ventilate for rescue oxygenation? Ensuring you have a positive end-expiratory pressure (PEEP) valve, appropriately sized adjuncts (nasopharyngeal [NPA] and oropharyngeal [OPA]), optimal positioning for maintaining an open airway, ensuring waveform capnography and availability of a supraglottic airway for rescue ventilation should all be considered for every patient with predicted difficulty of BMV.

For supraglottic airway placement and ventilation, this involves choosing the right supraglottic airway (cuff vs. cuffless, size according to patient’s mouth opening and anatomy), availability of lubrication depending on the SAD, head of bed (HOB) elevated (in obese patients to remove the weight of abdominal contents on the diaphragm), and quick access to a PEEP valve in case high airway pressures are required during rescue oxygenation.

For surgical airway, the use of preintubation ultrasound can identify the necessary landmarks of cricothyrotomy, which may be unexpectedly altered or off midline in the setting of tumors or prior surgeries.

After optimizing all your equipment, preoxygenation strategies, and positioning for the profile of difficult airway characteristics for that patient, the next series of questions will start to inform your plans within your strategy.

If you proceed with RSI, can you see the airway and place an endotracheal tube? What are the obstacles for this patient and what tools do you have to overcome those? There are some anatomic characteristics that, when severe, will always make laryngoscopy difficult. If someone has no neck mobility or is unable to tolerate neck manipulation, either through immobilization (e.g., cervical fixation, halo) or through pathogenic disease (severe rheumatoid arthritis, ankylosing spondylitis), aligning the visual axes of the airway will be difficult. Similarly, if someone has limited or no space in the mouth, either through pathogenic disease (e.g., muscle spasm/tetany, angioedema, Ludwig’s, severe temporomandibular disease), or surgical fixation, aligning the visual axes and having space in the mouth for the laryngoscope and tube will be difficult. A soiled airway, either through blood or vomit, will potentially make visualization of the airway difficult no matter which approach you choose.

Lastly, will intubation be difficult even if you can see the airway? Arytenoid sclerosis, supraglottic tumors, abscesses, hemangiomas, glottic swelling (e.g., anaphylaxis, hematoma), and subglottic or tracheal stenosis will make tube placement difficult. You may need more information after your airway exam to determine if intubation will be difficult or impossible, and which route will most likely be successful—through the mouth or through the nose. Radiographic imaging can be helpful, particularly CT imaging, and point-of-care ultrasound of the airway can evaluate the glottic opening and upper airway in patients who cannot lay flat (Chapter 10, Applied airway ultrasound). Nasopharyngoscopy can be invaluable in evaluating the airway, particularly the lower airway, to guide strategy, especially in patients with stridor or obstructing masses.

Hyperangulated VL is designed to visualize the airway in patients with profiles of difficulty related to an inability to align the visual axes of the airway, such as those with a large tongue or minimal submental space to displace the tongue with a standard geometry blade, and in patients with cervical immobility. Hyperangulated VL combined with a flexible endoscope can overcome extremes of cervical immobility and difficult airway characteristics in the upper and lower airways (aiding in both airway visualization and placement of an endotracheal tube), but this approach requires a patient with adequate preoxygenation and enough safe apnea time to tolerate a more prolonged attempt.

Airway management in patients with airways soiled from vomit or blood presents a particular challenge. Ongoing aspiration makes oxygenation and hemodynamics more difficult, adding a time pressure to secure the airway. Soil in the airway obscures the airway view, no matter how you attempt to see the airway. VL risks contamination of the camera if the operator pushes through a pool of soil, but still provides a higher chance of success than DL.^2,3 In cases with massive vomiting or upper GI bleeding, airway decontamination becomes critical.

Can you open the airway, get a mask seal, and elevate the chest wall? If anatomic characteristics are obstacles to any of those three requirements then mask ventilation may be challenging or difficult. Proper positioning, adjuncts for opening the airway (NPA or OPA) and a PEEP valve should be used to overcome those obstacles if possible. If they are not predicted to overcome those obstacles, then mask ventilation will be difficult or impossible and the strategy needs to be adjusted accordingly.

Can you get a SAD in the mouth? Will it seat, and will it elevate the chest wall? Can you identify neck anatomy and palpate the cricothyroid membrane? Difficult airway characteristics for mask ventilation can potentially be overcome with a SAD. However, you must be able to get the supraglottic airway in and get it to seat. If a SAD is likely to be difficult, your only rescue oxygenation option at that point is a cricothyrotomy, which may be difficult in patients with distorted anatomy or a history of neck radiation. In patients with difficult landmarks to palpate, point of care ultrasound can be helpful for identifying the cricothyroid membrane but the ultrasound needs to be done during the airway assessment, not when the cricothyrotomy is needed.

After you have done your assessment and answered the four Key Questions above, the next step is to pick a path, generally RSI or “awake” intubation. Most patients will benefit from RSI, which is associated with increased first-attempt success,^4,5 fewer intubation-related complications,⁶ and fewer laryngeal injuries.⁷ Despite clear evidence for RSI, there is lingering debate about neuromuscular blocking agents because of fear of an inability to mask ventilate. The fear is that if intubation is not rapidly successful, the paralyzed patient could precipitate a “can’t intubate-can’t oxygenate” (CICO) emergency.^8,9,10,11 However, evidence suggests that neuromuscular blocking agents either improve, or at worst have no effect on, the ease of mask ventilation,^12,13,14,15 and should be given (if not already) in a CICO situation.^{9,11,12,13,15,16,17,18,19,20,21,22}