“Airway management” may be defined as the application of therapeutic interventions that are intended to effect gas exchange in patients who are unable to do it for themselves. Gas exchange is fundamental to this definition.¹ A number of devices and techniques are commonly employed in health care settings to achieve this goal. These include the use of bag-mask-ventilation (BMV), extraglottic devices (EGDs), oral or nasal endotracheal intubation (ETI), and invasive or surgical airway techniques.

The failure to adequately manage the airway has been identified as a major factor leading to poor outcomes in anesthesia, critical care, emergency medicine, hospital medicine, and emergency medical services (EMS).^2,3 Adverse respiratory events constituted the largest single cause of injury in the ASA Closed Claims Project.⁴ The 4th National Audit Project (NAP4) conducted in the United Kingdom over a 1-year period of time identified major airway management complications in the operating room (OR), critical care units, and emergency departments leading to death, brain damage, emergency surgical airway, or unexpected ICU admission.^5,6 NAP4 reinforced the findings of the National Reporting and Learning System in the United Kingdom that found 18% of 1085 airway management complications in ICU over a 2-year period (2005 to 2007) were directly related to the act of intubation.⁷

It is critically important to recognize that the single most important factor leading to a failed airway is the failure to predict the difficult airway.^3,4,8 Other factors that can make airway management challenging are human factors as described in Chapter 6. Screening tests intended to predict difficult or impossible BMV and laryngoscopic intubation are unable to predict success or failure with any degree of certainty in otherwise normal patients. For this reason, the terms “reassuring” and “non-reassuring” have been coined to describe one’s summative assessment of the various operations associated with airway management (e.g., BMV, EGD, laryngoscopy and intubation, and surgical airway).⁹ It is because of this “reliability gap” that airway practitioners need to be prepared to manage an airway predicted to be difficult appropriately (e.g., awake technique) and to resort to surgical airway management in the event that nonsurgical techniques fail.^9–11

The fundamental dilemma facing the airway practitioner is to predict if the airway is “reassuring” or “non-reassuring.” The task is to identify non-challenging versus challenging airways employing tools with poor predictive value alone and in combination. As mentioned above, the ASA Guidelines have used the terms “reassuring” and “non-reassuring.” Huitink and Bouwman¹² have recently advanced the proposition that a trained practitioner should be able to manage a patient with a reassuring airway (they use the term “basic airway”) employing basic airway management techniques (BMV and ETI) after proper training. Even more advanced airway rescue techniques (e.g., EGD) in these patients are expected to be relatively easy because the anatomy is normal. Conversely, they maintain that the less reassuring the airway, the greater the need to prepare for failure. A very common sense approach!

This chapter deals with the identification of the difficult and failed airway, particularly in an emergency, in which case evaluation and management must be done concurrently in a compressed time frame and canceling the case or delaying airway management is not an option.

Successful airway management is generally governed by four intertwined factors that constitute the “context” in which that airway is managed (see Chapter 7):

• 
  

  A clinical situation of varying urgency, venue, and resources

  
  
• 
  

  Patient factors including airway anatomy and vital organ system reserve

  
  
• 
  

  Available airway resources

  
  
• 
  

  Skills of the airway practitioner

Because the airway practitioner must choose a method of airway management from an array of techniques, precision of language and communication is essential. Success or failure to effect gas exchange in an apneic patient may occur with any single method:

• 
  

  Bag-mask-ventilation

  
  
• 
  

  Extraglottic device ventilation

  
  
• 
  

  Direct laryngoscopy or DL (e.g., straight or curved laryngoscope blades)

  
  
• 
  

  Indirect laryngoscopy (e.g., video-laryngoscopy [VL], flexible endoscopy)

  
  
• 
  

  Emergency oxygenation and ventilation techniques (e.g., Ventrain™ or Manujet™)

  
  
• 
  

  Invasive surgical airway (e.g., cricothyrotomy)

Airway practitioner may find any of these methods “difficult,” and difficulty with one does not necessarily indicate that another will be difficult though there tends to be a relationship.^13,14 Strategies to identify difficult BMV, difficult ventilation employing an LMA, difficult DL and intubation, difficult VL, and difficult surgical airway will identify predictors unique to the method (e.g., surgical airway would be difficult in a patient with an anterior neck hematoma or tumor mass), and predictors associated with some of the other methods (e.g., male sex) or all of the other methods (e.g., history of neck and upper airway radiation therapy or the application of cricoid pressure). This expands on the definition of difficult as promulgated by the American Society of Anesthesiologists (ASA) beyond difficult BMV and intubation to include the complete array of methods that may be employed to manage an airway.¹⁰

Any method may fail in which case the terminology “failed BMV,” “failed ETI,” or “failed EGD” may be employed. Conventionally, if all of these methods fail the airway is called a “failed airway,” and is equated with a “cannot intubate, cannot oxygenate” (CICO) airway.¹¹ In the past, this situation has been called “cannot intubate, cannot ventilate” (CICV), though CICO is more accurate and currently more commonly employed.

For more clarity, a failed intubation defined narrowly as the failure to intubate the trachea on three attempts^9,15 (the DAS 2015 Guidelines permit one additional attempt by an expert: 3+1)¹¹ may not constitute a failed airway if one is able to affect gas exchange with BMV or with an EGD. However, intubation failure ought to conjure a sense of urgency and mandates the airway practitioner to rapidly switch to a failed airway management sequence or drill because such a situation may become life-threatening if gas exchange cannot be provided expeditiously and adequately by other means. Furthermore, the alternative airway technique employed must have the highest degree of success in the practitioner’s skill set. It is inappropriate to make random disorganized attempts to manage the airway in the hope that one of the airway techniques might work. Rather, one should have a planned strategy (see the algorithms in Chapter 2) including invasive techniques such as cricothyrotomy.^11,16,17

This assumes that the practitioner acts on the prediction and selects the most appropriate technique.

How Common Are the Difficult and Failed Airway?

Bag-mask-ventilation, the use of EGDs, ETI, and surgical airway management constitute the four primary avenues by which gas exchange is provided in the event patients are unable to do so adequately for themselves. In each category, difficulty and failure may be encountered. Failure of all four, ordinarily, leads to death or brain damage.

Until recently, the success or failure of airway management has been defined in terms of BMV and orotracheal intubation. The introduction of EGDs and the heightened profile of cricothyrotomy have broadened such concepts. Fortunately, tracheal intubation is usually straightforward, particularly in the elective setting of the OR, though it should be realized that tracheal intubation can be performed in many different ways with direct or indirect techniques and each technique has its own complication and failure rates. The same cannot be said for venues outside of the OR where airways are often anything but “straightforward.”

Airways that are difficult to manage are fairly common in anesthesia, emergency medicine, critical care, and EMS practice, with some estimates as high as 20% of all emergency intubations.^{9–12,18–21} However, the incidence of intubation failure is quite uncommon (ranging 0.5% to 2.5%), and the disastrous situation of being unable to intubate or ventilate rarely occurs (0.1% to 0.05%).^2,18–26 This translates to a “can’t intubate, can’t oxygenate” failure rate of about 1:1000 to 1:2000 patients in a general surgical population. The incidence is strikingly higher in the parturient undergoing cesarean section (1:280), an almost tenfold increase.^27–29 Further, the gold standard awake flexible bronchoscopic intubation also has a defined failure rate as high as 13%.³⁰

How Do We Avoid Airway Management Failure?

Although circumstances can vary widely, the expectation is the same: timely, effective airway management executed without patient injury. In circumstances of multiple trauma, facial or airway swelling, abnormal upper airway anatomy, upper airway hemorrhage, or a myriad of other difficult airway scenarios, intubation may be difficult, or even impossible, and even BMV can fail. Many other “contextual” factors can make airway management challenging such as location, human factors, available resources, and experience of the medical team. Nevertheless, the goal remains that the patient’s airway be promptly secured and oxygenation be maintained.

Responding to an identified need to reduce the incidence of airway management failure, the American Society of Anesthesiologists (ASA) issued guidelines and an algorithm for management of the difficult airway in 1993, with subsequent revisions in 2003 and 2013.^9,10,31 The guidelines stressed the importance of performing an airway evaluation for difficulty prior to inducing anesthesia and paralyzing the patient. Planned awake intubation, awakening the patient in the presence of a failed airway, and acquiring skills in alternative airway management techniques are hallmarks of the 1993 guidelines. The 2003 guidelines reemphasize the importance of the airway evaluation and incorporate the laryngeal mask airway (LMA) as a discrete step in the algorithm, should failure occur. In the 2013 guidelines VL is incorporated as a first airway management plan. The DAS have come up with simplified guidelines for management of the unanticipated difficult intubation in adults in 2015 emphasizing emergency oxygenation and ventilation techniques.¹¹

Unfortunately, the ASA and DAS guidelines are less useful outside the OR, especially in circumstances in which tracheal intubation must be accomplished quickly and awakening the patient is not an option. Even in the OR setting, explicit guidelines for the rapid evaluation of an airway for occult difficulty and the prioritization of rescue maneuvers in the event of a mandated immediate intubation are not well handled by the ASA or DAS guidelines and algorithms (see Chapter 2). Furthermore, these guidelines do not take into consideration patients who are uncooperative (e.g., young children or mentally challenged patients) or different patient populations (e.g., pediatrics and near term parturients [see Chapter 51]).

Further complicating this issue are the many new, effective, and safe airway devices that have been introduced to assist with difficult and failed airway management. Flexible endoscopic and video-intubating bronchoscopes have become more portable and easier to use and have been joined by a collection of rigid optical devices and stylets (e.g., Shikani Optical Stylet™, Bonfils Stylet™, Levitan FPS Scope™, Clarus Optical Stylet™, etc.), hybrid devices employing cameras or fiberoptics, such as video-laryngoscopes (e.g., GlideScope^®, McGrath^® Series 5 video-laryngoscope, McGrath^® MAC, King Vision^®, AirTraq^®, Storz CMAC^®, see Chapter 11), and disposable camera tubes (Vivasight, ET View Medical).

The LMA and intubating laryngeal mask airway (ILMA or LMA Fastrach™) have assumed a distinct role in the management of both the difficult and the failed airway. In the prehospital setting the iGel (Intersurgical) and Air-Q (CookGas) have assumed a more prominent role for initial airway management, and rescue during rescucitation.³² The Combitube™ had been used in the past as a lifesaving rescue device, though now largely replaced by the King Laryngeal Tube airway (Ambu Medical) and the EasyTube. Lighted stylet methods may permit light-guided (transillumination) intubation in situations in which the vocal cords cannot be visualized, but in the era of vision guided intubation aids, there is a decrease in use of this device. With the realization that airway rescue techniques should be done quickly, the so called “one second intubation technique” employing disposable camera tube devices (ET VIEW Vivasight^®) are gaining popularity when used in combination with an EGD such as the iGel or Air-Q. Certain airways are impossible to manage by any means other than cricothyrotomy, a procedure that all airway practitioners ought to be competent to perform. Several techniques have been advocated, including the “no drop” cricothyrotomy and the “fast surgical airway” technique, a 4-step bougie-scalpel-tube technique^11,33 (see Chapter 14).

The challenge for any airway practitioner is to be able to accurately predict when a difficult airway is present, to immediately recognize when an intubation failure has occurred, and to reliably and reproducibly ensure continuous gas exchange in both of these unnerving circumstances.

Is There a Prevailing Standard of Care in Managing the Difficult and Failed Airway? How Is It Defined?

The growth in knowledge and evidence related to the practice of airway management is relentless. Advances in airway management over the past two decades have significantly improved patient outcome with a reduction in the incidence of death and disability.³⁴ The challenge for the practitioner is to keep abreast of new information and new techniques to practice within the standard of care.

Black’s Law Dictionary³⁵ defines the “standard of care” as:

This definition incorporates several important features:

• 
  

  Average degree of skill

  
  
• 
  

  Same or similar locality

  
  
• 
  

  Present state of knowledge

Taking these into consideration, the standard of care is the conduct and skill of an average and prudent practitioner that can be expected by a reasonable patient. A bad result due to a failure to meet the standard of care is generally considered to be malpractice. There are two main sources of information as to exactly what is the expected standard of care:

• 
  

  The beliefs and opinions of experts in the field.

  
  
• 
  

  The published scientific evidence, standards of care, practice guidelines, protocols.

Driven by the complex nature of this clinical dilemma and the need for successful solutions that are easily learned and maintained (and cost-effective), the standard of care in airway management is exceedingly dynamic. Continuing evolution of new devices and techniques, or ways of thinking, modify the existing standard of care on an ongoing basis. It is incumbent on practitioners to keep abreast of new devices and techniques and remain facile with existing rescue techniques. They can do so by continually perusing the literature and attending educational programs related to airway management.

What Is the Role of Professional Organizations in Establishing the Standard of Care?

International, national, regional, and local professional organizations generally address issues relevant to airway management in a variety of ways. Most national societies, such as the ASA, the Difficult Airway Society (DAS-UK), the American College of Emergency Physicians (ACEP), the Canadian Anesthesiologists’ Society (CAS), and others, engage in crafting practice guidelines.^{10,11,16,17,36}

In the event of an untoward outcome, the reasonable patient expects the published guidelines to be observed by the prudent practitioner. Organizations that craft and publish such practice guidelines are careful to stipulate that such guidelines do not constitute the standard of care.^10,11,16 Unfortunately, guidelines are often perceived as the standard of care, particularly in a medical–legal context.

Professional organizations often provide educational initiatives to ensure that their members practice at the prevailing standard. The ASA, DAS, CAS, ACEP, and the Society for Airway Management (SAM) are good examples. SAM, DAS, and European Airway Management Society (EAMS) are organizations committed to advancing knowledge and improving the quality of airway care to all patients no matter who cares for them. These societies blend the expertise of anesthesiology, otolaryngology, head and neck surgery, critical care, and emergency medicine to the airway management debate. They also serve as sounding boards for new devices and techniques and those wishing to challenge traditional dogma to advance new frontiers. Those with a specific interest in airway management are well advised to become involved in these organizations.

How Can We Integrate the Standard of Care into Our Clinical Practice?

Despite all these initiatives, the standard of care remains elusive, particularly when applied to the management of the difficult and failed airway. It means different things to different practitioners and is situation dependent. For example,

• 
  

  To the plaintiff’s attorney, it must be precisely defined in minute details

  
  
• 
  

  To the practitioner, it is what they do every day

  
  
• 
  

  To the defendant practitioner, it is consistent with their actions

It is perhaps easier to articulate what it is not:

• 
  

  It is neither much better nor much worse care than that delivered on average by one’s peers.

  
  
• 
  

  It is not the same as the care provided by experts managing difficult and failed airways every day.

  
  
• 
  

  It is not what ivory tower academic experts think it ought to be.

  
  
• 
  

  It is not a single study published in a reputable journal last week, or a position advocated by experts in an editorial in a similarly reputable journal.

We do know that the standard of care is dynamic and our patients expect to receive it at a minimum.

Perhaps the best test with respect to difficult and failed airway management is to ask a specific question: “Should the average, reasonable, and prudent practitioner…”

• 
  

  Be able to recognize and manage an anticipated difficult airway?

  
  
• 
  

  Be able to manage an unanticipated difficult airway?

  
  
• 
  

  Be able to use a flexible bronchoscope to intubate the trachea of a patient?

  
  
• 
  

  Be able to recognize and manage the failed airway?

  
  
• 
  

  Be facile with one or two rescue devices or techniques in the face of a failed airway?

  
  
• 
  

  Be able to work in a team, communicate clearly, and be able to perform under stressful circumstances?

  
  
• 
  

  Be able to perform a surgical airway? Or at the least, trans-tracheal oxygenation and ventilation?

It is reasonable to expect that most practitioners charged with managing airways would answer yes to all of these questions and thereby define the standard of care.

How Did the Design of Direct Laryngoscopes and the Basic Technique of Oral Laryngoscopy Evolve?³⁷

Herholdt and Rafn are generally credited with first describing blind oral intubation in 1796. Subsequently, Desault described blind nasal intubation in 1814. Although Sir William Macewen described direct vision oral intubation in 1880, it is generally accepted that the first description of laryngoscopic-aided oral intubation was by Kirsten in 1895. By 1907, Chevalier Jackson, an ENT surgeon of considerable renown, introduced distal lighting to the laryngoscope, and Janeway in 1913, innovated the insertion of electric batteries into the handle of a laryngoscope to facilitate the procedure. Magill and Rowbotham engineered the straight Magill blade in the 1920s by cutting a wedge out of the side of the blade of the ENT surgeon’s anterior commissure laryngoscope to facilitate intubation (Figure 1–1). Across the Atlantic, this design (with minor modifications) became known as the Miller blade in the 1940s. The Macintosh blade was also introduced in the 1940s by Sir Robert Macintosh.

Magill is credited with introducing the “retro-molar” or “paraglossal” approach, reasoning that placing the blade as far to the corner of the mouth as possible when attempting to bring the glottis into view (as opposed to being in the midline) ought to minimize the distance to the glottis and enhance the degree to which it is visible. This technique has been resurrected by Henderson who developed the Henderson blade™ (Karl Storz Germany).³⁸

How Did the Design of Endotracheal Tubes Evolve?

It was also Sir Ivan Magill (circa 1914) who recommended a left-sided bevel (Magill bevel) be created on the distal tip of an endotracheal tube (ETT) (Figure 1–2). At that time, blind nasal intubation using a non-beveled, gum-elastic tube was popular. Magill observed that, as the right nostril is usually largest and most anesthesia practitioners are right handed, nasotracheal intubation was usually first attempted through the right nostril. The natural tendency for a tube introduced through the right nostril was to deviate leftward as it transited the nasopharynx and oropharynx and to deflect off the left glottic structures into the left pyriform recess. Magill reasoned that the left-sided bevel would deflect the ETT into the glottis.³⁹ Left-side bevel ETTs continue to be the most commonly used tubes to this day.

Curare was first used in the 1940s and succinylcholine was introduced into anesthetic practice in 1952. These drugs led to the need for positive pressure ventilation through a tube with a tracheal seal being achieved by packing gauze (at times oil soaked) around the glottic opening. A more effective seal could be obtained by incorporating a balloon (initially rubber, thick walled, high pressure, and removable) onto the ETT. However, the possibility that the beveled orifice of the distal tip could rest against the wall of the bronchus in the event of a right mainstem intubation permitting positive pressure inspiration but not passive expiration was noted. This led to the creation of the Murphy eye opposite the bevel orifice (i.e., facing the right side).

The bulk of the ETT and balloon hindered its passage through the channel of laryngoscope blades, and this led the Eschmann Corporation to develop a tracheal introducer (invented by Sir Robert Macintosh) to facilitate a Seldinger-type intubation over the introducer in 1949.⁴⁰

How Has Our Understanding of How the Difficult Airway Might be Predicted Developed Over the Years?

The use of neuromuscular blockade to facilitate orotracheal intubation followed the introduction of curare into anesthetic practice in the early 1940s and succinylcholine in the late 1940s. Up until that time, orotracheal intubation was largely performed with the patient breathing spontaneously under inhalational anesthesia. The consequence of a failed intubation was mitigated by the fact that the patient continued to breathe spontaneously. The threat of failure to intubate in the face of neuromuscular blockade and apnea required anesthesia practitioners to evaluate the airway for difficulty, leading to a landmark publication by Cass in 1956.⁴¹ This study identified those anatomical features that might predict difficult laryngoscopic intubation. Thus, the clinical use of neuromuscular blocking agents became inseparable from the ability to perform an airway evaluation and the ability to rescue the airway in the event of failure. Many practitioners still fail to recognize a difficult airway when one exists or they overlook the evaluation altogether.^4,9

The literature regarding the difficult airway was relatively quiet until the mid-1980s when Patil offered the proposition that a thyromental distance of less than 6 cm was associated with orotracheal intubation difficulty.⁴² During the 1990s, Savva did the same by using the sternomental distance.⁴³ The importance of Patil’s dimension rests not in the distance described, or in its lack of sensitivity, specificity, or positive predictive value with respect to airway management difficulty, but in the fact that it alludes to the geometry of the airway. The thyromental line constitutes the hypotenuse of a right angle triangle (Figure 1–3). The axis is length of the floor of the mouth (a dimension of the mandibular space), and the abscissa locates the larynx in relation to the base of the tongue. The length of the oral axis affects the ease with which the glottis is exposed during conventional laryngoscopy: the glottis cannot be visualized beyond the horizon of visibility if it is too long; the larynx is shielded by the base of the tongue (anterior larynx) if it is too short. Likewise for the location of the larynx in relation to the base of the tongue: it is beyond the visible horizon if it is too far down the neck; it is tucked up under the base of the tongue if it is too high in the neck. Furthermore, the dimensions of the mandibular space (length, width, and depth; or volume) have important implications. The volume of the mandibular space must accommodate the tongue, as it is displaced into this space during laryngoscopy to bring the glottis into view.

Mallampati in 1983 and 1985 created a scoring system^44,45 modified by Samsoon in 1987,⁴⁶ that identified oral and pharyngeal access as an issue of importance in airway management (Figure 1–4). Although the score by itself had poor sensitivity, specificity, and positive predictive value, the notion that access is important became cemented.

It was during this time that Cormack and Lehane proposed their laryngeal view grade scoring system in an effort to provide some structure to the discussion of difficult laryngoscopy (Figure 1–5).⁴⁷ Although found to be subject to considerable interobserver variability, the scale has been embraced as a valid measure of difficulty; with Grades 3 and 4 views being equated with difficult laryngoscopy. By the late 1990s, other models with more reproducible scoring systems, such as Levitan’s percentage of glottic opening (POGO) visible, were proposed.^48–50 However, widespread adoption of these systems over the Cormack/Lehane (C/L) system has yet to occur (Figure 1–6).

By the late 1980s, it had become apparent that airway management failure was the most important contributor to poor patient outcome in anesthesia practice, lawsuits, and financial settlements.⁴ The question facing airway practitioners became: Who should you not paralyze? A variety of investigators pursued univariate and multivariate systems of analysis that attempted to answer this question, but none with reliable success⁵¹:

• 
  

  Wilson (1988) (Wilson Risk Sum): Employed a weighted scoring system 0 to 2 incorporating body weight, head and neck movement, jaw movement, receding mandible, and prominent (buck) teeth.⁵²

  
  
• 
  

  Bellhouse (1988): Used x-rays to evaluate for difficulty.^53–57

  
  
• 
  

  Rocke (1992): Evaluated 1500 parturients using a combination of Mallampati, short neck, receding mandible, and buck teeth.⁵⁸

  
  
• 
  

  Savva (1996): Identified a sternomental distance less than 12 cm as a risk for difficulty.⁴³

  
  
• 
  

  Tse (1995): Combined Mallampati, head extension, and thyromental distance.⁵⁹

  
  
• 
  

  El-Ganzouri (1996): In a large study of 10,507 patients looked at mouth opening, Mallampati, neck movement, mandibular protrusion, body weight, and a positive history of airway management difficulty.⁶⁰

  
  
• 
  

  Karkouti (2000): Evaluated 461 patients (38 difficult) and correlated mouth opening, chin protrusion, atlanto-occipital extension.⁶¹

Between 2000 and 2015 studies identified factors that reliably predicted impossible bag mask ventilation and intubation such as head and neck radiotherapy.^{13,14,62–67} Kheterpal and others identified risk factors for failed video-laryngoscopic intubation such as airway pathology from previous surgery, a local mass, or radiotherapy to the head and neck.^13,14

Hot on the heels of the “Who should you not paralyze?” question is the dilemma: “How is the airway best rescued in the event that intubation and/or ventilation is impossible, that is, a failed airway?” In the past, BMV was viewed as the most commonly performed fallback technique. This technique, difficult to teach, learn, and perform, is being supplanted by more user friendly and easily performed EGDs. This has led to a reframing of the way we think about airway management: In the event laryngoscopy and intubation fails, is it likely that gas exchange can be maintained by BMV or one of these EGD devices? Furthermore, the recognition that while aspiration is undesirable, it is not usually a deadly occurrence, serves to emphasize the primacy of gas exchange over intubation and airway protection.

There has also been a substantial change in our thinking with respect to surgical airway management. In the past, it was left to the practitioner as to whether to perform a Seldinger technique or an open cricothyrotomy. In fact, it was taught that anesthesia practitioners ought to preferentially select a Seldinger technique as using a needle as opposed to a scalpel was felt to be psychologically more acceptable. However, it has become apparent that fellowship trained and certified anesthesiologists cannot reliably locate the cricothyroid membrane in elective surgical patients, particularly if they are female or obese.^5,6,68–70 The report from NAP4 identified that needle techniques were unsuccessful and open techniques were successful. So it is currently recommended that an open cricothyrotomy be performed in the CICO situation.¹¹

Cricothyrotomy employed in the setting of a failed airway has become emblematic of airway management failure. It is now taught that if the airway manager considers a CICO airway even remotely possible that the cricothyroid space be identified by manual palpation or with ultrasound (Chapter 14) and the incision line marked preemptively. In other words, should a cricothyrotomy be needed, it is a deliberate “part of the plan” as opposed to “emblematic of failure.” The psychology of this approach is compelling in motivating individuals to move earlier to a cricothyrotomy as soon as a CICO airway is identified. Peterson³⁴ and NAP4 both identified delay in performing cricothyrotomy as substantial issues leading to poor outcomes.

As noted earlier, this chapter explores the concepts of the difficult and the failed airway. The premise is that the pre-procedure recognition and management of the difficult airway should minimize the occurrence of a failed airway. Furthermore, recognizing the failed airway promptly ought to optimize the chances that failing techniques will be abandoned and replaced by techniques reasonably anticipated to succeed.

The Difficult Airway

When one is presented with a patient that requires tracheal intubation, the first decision is whether or not this airway needs to be managed immediately. If so, immediate action is indicated.

As discussed above, unlike the failed airway the difficult airway is not so easily defined. Rather than a definition, in concept, the difficult airway has several dimensions¹⁵:

• 
  

  Difficult BMV

  
  
• 
  

  Difficult DL

  
  
• 
  

  Difficult VL

  
  
• 
  

  Difficult intubation

  
  
• 
  

  Difficult placement of a EGD

  
  
• 
  

  Difficult cricothyrotomy