CHAPTER 1: Evaluation of the Airway

INTRODUCTION

“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 ...