A 14-year-old girl is scheduled to have an excision of a mandibular mass in a hospital in Kigali, Rwanda. She is otherwise healthy, takes no medications, and has no allergies. She weighs about 42 kg and is 144 cm tall (BMI 20.3). On examination, she appears to be nervous, but cooperative. She has a large right mandibular mass restricting her mouth opening (3 cm) (Figures 7–1 and 7–2). She has a Mallampati IV score and jaw protrusion is limited, but, the range of motion of her cervical spine is normal. She agrees to have an awake intubation with some reluctance. Routine monitors (noninvasive blood pressure monitor, ECG, and pulse oximeter) are placed on her upon arrival at the operating room (OR). Intravenous (IV) access is established and a judicious amount of IV ketamine (bolus of 10 mg) is administered for sedation. Topical anesthesia is achieved with lidocaine sprays alone. Since a flexible bronchoscope is unavailable, the following plans are prepared to secure her airway and communicated to everyone involved in her care. Plan A: blind nasal intubation using a BAAM (Beck Airway Airflow Monitor) whistle¹; Plan B: orotracheal intubation using a video-laryngoscope (C-MAC); and Plan C: a surgical airway. Unfortunately, blind nasal intubation is not successful after a number of attempts as the endotracheal tube (ETT) repeatedly enters the esophagus. Tracheal intubation using the C-MAC is also difficult with poor visualization of the glottis, particularly when the posterior aspect of the tongue begins to bleed. With ongoing suction around the bleeding site, an attempt with direct laryngoscopic intubation also fails. It becomes obvious that the appropriate course of action is for the otolaryngologist to perform an awake tracheotomy under ketamine sedation and local anesthesia. With oxygen supplementation through a face mask (8 L·min⁻¹) and repeated boluses of IV ketamine (10 mg), tracheotomy is secured while oxygen saturation remains above 90% during the procedure. Anesthesia is induced with thiopental and anesthesia is maintained with 1 to 1.5 MAC of halothane. The otolaryngologist excises the mandibular mass and the patient is transferred to the intensive care unit in stable condition at the conclusion of the surgical procedure with ventilation maintained through the tracheostomy tube.

The fundamental goals of airway management are the maintenance of adequate ventilation, oxygenation, and protection from aspiration. In the majority of clinical settings, these three goals are achieved in tandem, usually via orotracheal intubation using a conventional direct laryngoscope. As the location, time of day, skill set of the practitioner, and the devices available (i.e., the “context”) change, the practitioner must be prepared to modify his or her approach and employ alternative techniques as appropriate. Continuous oxygenation by whatever method possible takes precedence, particularly in emergency situations.

What Is Context-Sensitive Airway Management?

The concept of “context-sensitive” airway management represents a paradigm shift in the approach to airway management. The skilled practitioner is less focused on specific devices and techniques, and is more aware of the context in which the patient presents and how that context influences the approach to airway management.

The “context-defining” questions can be conceptualized as the “who, what, when, where, why, and how” which are unique to each airway management encounter. These questions, or context modifiers, influence the decision making of a skilled airway practitioner. In a more pragmatic sense, examples of these contextual factors might include:

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  the urgency of the case,

  
  
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  availability of equipment (in the case presented, the practitioner attempts blind nasal intubation because a flexible bronchoscope is unavailable),

  
  
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  the expertise of an assistant or assistants,

  
  
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  the time of day (influences the availability of additional skilled airway practitioners),

  
  
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  the skill sets and personal experience of the practitioners (in the presented case, the skill set of the practitioner in blind nasal intubation, intubation using C-MAC, and the creation of a surgical airway),

  
  
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  the location in which the patient encounter occurs (in the presented case, resources such as airway equipment, drug availability, infusion pumps, etc. are limited in Rwanda).

Patient factors, such as anatomy and physiology and the degree to which the patient can cooperate, conspire to influence the context of the situation. In the case presented, the 14-year-old girl is anxious, but cooperative. If she had been uncooperative, an awake intubation may not have been possible and her airway management would be quite different. Although a mask seal may be challenging in this patient, some practitioners may have considered inhalation induction of anesthesia or deep sedation using IV anesthetics maintaining spontaneous ventilation while performing tracheal intubation or tracheotomy, although caution in choosing this technique was recommended by the 4th National Audit Project of the Royal College of Anaesthetists of Great Britain and Ireland and the Difficult Airway Society (NAP4).²

Which Technique Does the Context of the Case Presented Suggest That Should be Used to Provide Ventilation and Oxygenation to a Pediatric Patient with a Difficult Airway?

The case presentation demonstrates how airway management by its nature, is context-sensitive. “Who, what, when, where, why, and how” are all context-defining questions that affect the way the airway management is best approached. In the case presented, the airway was successfully managed by a surgical tracheotomy, an option that may not have been considered by the same team in a different environment. In other words, the context has changed.

Traditionally, bag-mask-ventilation (BMV) has been advocated as the initial approach to a patient unable to independently sustain adequate gas exchange. Indeed, among the four domains of airway management (BMV, extraglottic device use, tracheal intubation, and surgical airway), BMV has been the most common initial maneuver employed by most airway practitioners. Unfortunately, mounting evidence and opinion suggest that BMV is a difficult skill to master, particularly in the hands of nonexpert practitioners.^3–6 In many cases, BMV is performed poorly with ineffective oxygenation and ventilation, and with gastric insufflation being the end result. In the case presented, the use of BMV may be difficult because of altered anatomy (large mandibular mass) with disfiguration of the face. As extraglottic devices (EGDs) continue to improve in quality and ease of use, many experts agree that the placement of an EGD ought to supplant BMV as the initial technique of choice for the airway management of an unconscious and apneic patient, particularly by nonexpert airway practitioners.⁷ In the case presented, it may also be difficult to use an EGD as the device may not seat properly above the hypopharynx due to the altered anatomy.

Clearly, no single device or technique can be relied upon as the sole modality for airway management by any practitioner. The choice of device and technique depends on the context of the situation. The airway management encounter in the case presented was likely to result in a failure of gas exchange using BMV or EGD, or any oral intubation approach. The practitioner elected to employ nasal route options such as blind nasal intubation (in this case using a BAAM Whistle), nasal bronchoscopic-assisted intubation, or nasal intubation using a lightwand while at the same time preparing for surgical options. Unfortunately, neither a flexible bronchoscope nor a lightwand was available. A blind nasal approach is therefore reasonable with a surgical airway as an alternative plan.

How Has Increasing Appreciation of the Context-Sensitive Nature of Airway Management Guided Technological Advances Leading to Improved Airway Management Tools?

Technological advances over the past two decades have dramatically improved the quality and clinical utility of many airway management tools, including:

1. 
   

   The manufacturing and marketing of newer and improved EGDs for use in a variety of situations.^8,9 Gone are the days where the LMA-Classic™ was the only, or even the preferred, EGD for use in difficult or failed airways. In the United Kingdom, the iGel (Intersurgical Ltd.) has been the EGD of choice for pre-hospital airway management since 2010.¹⁰ The airway practitioner now has the option of choosing among devices that serve as tracheal intubation conduits in addition to those that have been shown to be effective rescue oxygenation devices in situations where intubation is not possible.¹¹

   
   
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   Advances in video resolution and LCD monitor technology, combined with high-quality color fidelity and optics have led to the development of several video-camera endoscopic-based devices. These include the Glidescope^® (Verathon Medical, Bothell, WA), the Video Macintosh Intubating Laryngoscope System (C-MAC, Karl Storz Endoscopy Co., Culver City, CA), and the McGrath^® Series 5 and McGrath MAC Video-Laryngoscope (Aircraft Medical, Edinburgh, UK). These devices remain subject to limitations due to fogging, and obscuration of glottic visualization in the presence of blood, vomitus, or secretions.¹² Their utility remains questionable in these contexts (see Chapter 11). Nonetheless, video-laryngoscopy continues to be an evolving field with intriguing possibilities in the absence of bodily fluids that may obscure their optics.

   
   
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   Improved portability of sophisticated airway management devices, coupled with the introduction of disposable variants, has broadened their utility. Devices are becoming more lightweight, portable, and robust in construction. Battery-powered flexible endoscopes and compact video-laryngoscopes, such as the McGrath^® Series 5 and McGrath^® MAC, and the Glidescope^® Ranger Video-Laryngoscopes, can be carried to the patient regardless of location and irrespective of external power sources or large video displays.

   
   
4. 
   

   Enhanced light intensity of some airway instruments. The transillumination technique employed by lightwand devices, such as the Trachlight™¹³ in the past, and new lightwand devices on the horizon, substantially improved with the use of high-intensity LED bulbs.¹⁴ Adequate transillumination is often possible under ambient lighting conditions, obviating the need to dim the lights or darken the room when these devices are being used. One study involving 950 patients demonstrated that nearly 88% of Trachlight™ intubations were effectively accomplished under ambient light with or without simple shading of the neck.¹⁵

   
   
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   Reduction in cost in some of the newer video-laryngoscopes. While video-laryngoscopes have been shown to improve the laryngoscopic view and tracheal intubation success rates in patients with both normal and difficult airways, the cost of some of the devices is high and may be a barrier to their routine use. With the retail costs falling, some of the newer video-laryngoscopes (e.g., the King Vision and the AirTraq) may become more affordable even for centers with limited resources (see Chapter 11).

In What Contexts Are Blind Intubating Techniques Indicated?

Over the years, direct laryngoscopic intubation has been shown to be an effective and safe technique that is relatively easy to perform. It has become the standard method of tracheal intubation in ORs, intensive care units, hospital wards, emergency departments, and in the field. Unfortunately, even in the hands of experienced laryngoscopists, the rapid and accurate placement of an ETT remains a significant challenge in some patients. This is particularly true in unprepared patients, or in situations where resources are limited, such as “austere” environments (see Chapter 59) in which blind or nonvisual techniques may be more practical and successful.

Flexible bronchoscopic intubation has gained a measure of popularity as an alternative intubation technique over the past several decades. While effective and reliable, this technique requires expensive equipment, and special skill and training. Additionally, bronchoscopic intubation can be difficult in emergency situations in which unprepared or uncooperative patients may have copious secretions, blood, or vomitus in the upper airway. One large study involving more than 1600 bronchoscopic intubations recorded a success rate of approximately 94% in all comers.¹⁶

The limitations of laryngoscopic intubation under direct vision, particularly under emergency conditions, have fostered the development of blind techniques using a variety of devices such as intubating guides and light-guided intubation using the principle of transillumination which have proven to be effective, safe, and simple.

Would It Not be Safer to Place a Tracheal Tube Using a Technique That Is Under Direct or Indirect Vision?