Decision Making in Difficult Airway Management

Tara Knizner

Cynthia Wells

Management of the airway is one of the primary responsibilities of anesthesiologists and physicians caring for critically ill patients. There are multiple clinical scenarios in which intubation of the trachea is indicated. In the operating room, intubation is necessary in order to ensure patency and protection of the airway in a patient rendered unconscious by anesthesia. When a patient is in acute respiratory distress or requires resuscitation, there is a requirement to maintain oxygenation and ventilation.

Complications related to airway management are one of the most frequently cited adverse outcomes associated with anesthetic delivery. These complications include death, brain injury, unnecessary tracheostomy, airway trauma, and damage to teeth (see Chapter 55).¹ Many of these catastrophic outcomes result from inability to secure the airway during attempts at management of difficult ventilation and/or intubation. In order to standardize management of the difficult airway, practice guidelines were developed by the American Society of Anesthesiologists (ASA) Task Force in 1993 and later revised in 2003. Since their implementation in the United States, morbidity, mortality, and claims related to airway management in the operating room have fallen significantly.²

When following the ASA Difficult Airway Algorithm, the two primary components of the initial patient assessment involves determining whether one may face difficulty with mask ventilation or tracheal intubation. As described in the previous chapter, there are multiple physical criteria used by physicians to identify patients that are at high risk (see Table 12-1).¹ Additional consideration must be given to whether the patient may have difficulty cooperating with awake attempts at intubation or whether one may face a difficult tracheostomy in an emergency setting. Furthermore, the airway examination may reveal the presence of severe airway anatomy or pathology that warrants an initial surgical approach. Other management options include maintenance of spontaneous ventilation versus attempting intubation after the induction of general anesthesia. Most often, if it is determined that there would be difficulty with ventilation or intubation, the option of an awake intubation is considered for the cooperative patient in order to maintain spontaneous ventilation. This technique increases the threshold of safety if problems are encountered with securing the airway. Table 12-2 lists techniques for management in these situations.¹

One of the greatest challenges in airway management is the patient who does not demonstrate the above characteristics but presents difficulty in ventilation or intubation after being rendered unconscious. Therefore it is the responsibility of the anesthesiologist OR OTHER AIRWAY PROVIDER to always be prepared to manage the unanticipated difficult airway. Prior to the induction of every anesthetic, various airway tools should be readily available, including multiple rigid laryngoscope blades of various sizes, a gum elastic bougie, oral airways, laryngeal mask airways (LMAs), a 14G angiocatheter, and a functional manual jet ventilator.

If an attempt at intubation after induction of anesthesia is undertaken in a patient who has an airway exam that is less than ideal, the anesthesiologist should have additional tools for airway management immediately available. These, may include a rigid fiberoptic laryngoscope (eg, Glidescope), a fiberoptic bronchoscope, AN intubating LMA, A lightwand or a difficult airway cart that is equipped with various tools that can be used in the event of difficulty with intubation. The importance of being familiar with these tools and having them immediately available in the event of an unanticipated difficult airway cannot be overstated because prediction of the difficult airway is unreliable.

The ASA difficult airway algorithm specifically addresses the course of action to take in the event a difficult airway is encountered after the induction of general anesthesia (Fig. 12-1).¹ If initial attempts to intubate the patient are unsuccessful, then the anesthesiologist should consider calling for help, returning the patient to spontaneous ventilation, and/or allowing him/her to awaken provided that a short-acting anesthetic and muscle relaxants have been administered. The ability to call for assistance varies depending on the type of institution in which the anesthesiologist is practicing as well as the time of day. This situation changes dramatically if the anesthesiologist is the lone provider or is on call at night where he/she may be the only trained airway provider available. Similarly, intensivists, hospitalists, and emergency physicians who provide airway management services may find themselves
unable to call upon “back up” because the settings and times of day that are involved often preclude this.

Table 12-1 Components of the Preoperative Airway Physical Examination

Airway Examination Component		Nonreassuring Findings
1.	Length of upper incisors	Relatively long
2.	Relation of maxillary and mandibular incisors during normal jaw closure	Prominent “overbite” (maxillary incisors anterior to mandibular incisors)
3.	Relation of maxillary and mandibular incisors during voluntary protrusion of cannot bring	Patient mandibular incisors anterior to (in mandible front of) maxillary incisors
4.	Interincisor distance	< 3 cm
5.	Visibility of uvula	Not visible when tongue is protruded with patient in sitting position (eg, Mallampati class greater than II)
6.	Shape of palate	Highly arched or very narrow
7.	Compliance of mandibular space	Stiff, indurated, occupied by mass, or nonresilient
8.	Thyromental distance	Less than three ordinary finger breadths
9.	Length of neck	Short
10.	Thickness of neck	Thick
11.	Range of motion of head and neck	Patient cannot touch tip of chin to chest or cannot extend neck
This table displays some findings of the airway physical examination that may suggest the presence of a difficult intubation. The decision to examine some or all of the airway components shown in this table depends on the clinical context and judgment of the practitioner. The table is not intended as a mandatory or exhaustive list of the components of an airway examination. The order of presentation in this table follows the “line of sight” that occurs during conventional oral laryngoscopy.
From Practice guidelines for management of the difficult airway: an updated report by the ASA task force on management of the difficult airway. Anesthesiology. 2003;98:1269-1288, with permission.