Do We Still Need Nonvisual Intubating Techniques?
For many decades, tracheal intubation under direct vision using a laryngoscope has been considered the standard technique of intubation. Unfortunately, this approach to intubation has limitations. Difficult and failed intubation employing this technique can be as high as 21%, particularly in emergency situations.1 Not surprisingly, studies have shown that considerable experience is required before a trainee becomes proficient in laryngoscopic intubation. Konrad and Mulcaster have constructed learning curves showing that a 90% probability of success requires between 47 and 57 laryngoscopic intubations.2,3
The high incidence of difficulty and failure, coupled with these kinds of learning curves for laryngoscopic intubation have driven the development of many alternative intubation devices and techniques, such as rigid and flexible endoscopes, video-laryngoscopes, and optical intubating stylets. All of these devices have gained a measure of popularity. Unfortunately, these devices are substantially more expensive than the Macintosh laryngoscope. Furthermore, the cleaning and sterilization processes of some of these devices, such as the flexible bronchoscope, require an average of 50 to 60 minutes to complete, hindering their availability and practicality in emergency airway management and in pre-hospital care (i.e., they may be “context” driven).
The challenge of visual techniques employing optical stylets and video scopes is visualization of laryngeal anatomy and the passage of the ETT through the glottic opening in the face of fogging or the presence of blood, secretions, and vomitus in the upper airway. It is precisely these kinds of difficulties that have motivated the search for nonvisual techniques using a variety of devices, such as intubating guides, light-guided intubation using the principle of transillumination, blind nasal intubation, digital intubation, and retrograde intubation, all of which have proven to be effective, safe, and simple techniques.
INTUBATING STYLETS OR GUIDES
What Is the Eschmann Tracheal Tube Introducer? How Does It Facilitate the Placement of an Endotracheal Tube?
In 1949, Macintosh4 reported the use of an introducer (gum-elastic bougie) to facilitate orotracheal intubation under direct laryngoscopy. Using the concept of the introducer, Venn5 designed the Eschmann Introducer (Eschmann Tracheal Tube Introducer, Portex Limited, Hythe, UK), a tube like core woven from polyester threads and covered with a resin layer. The Eschmann Introducer (EI) is 60 cm long, with a J (coudé) tip (a 35-degree angle bend) at the distal end to facilitate advancement anteriorly underneath the epiglottis into the trachea and to provide tactile tracheal confirmation (Figure 12–1A). Centimeter markings designate the distance from the tip. The EI is often referred to as the “gum-elastic bougie” or “bougie.” However, to avoid confusion, historically the “gum-elastic bougie” has been used to refer to a shorter urinary catheter made of different material and without a curved tip.6
Intubating guides: (A) the Eschmann Introducer with a coudé tip at the ...