Flexible Endoscopic Intubation

INTRODUCTION

Flexible endoscopic intubation (FEI) is an invaluable technique for difficult airway management. Unlike other intubation devices, a flexible endoscope can be advanced through the vocal cords and into the trachea without applying significant pressure to the base of the tongue, vallecular, or other upper airway structures, which makes it one of the best choices for awake intubation.

The demographics concerning the incidence, success rates, procedural duration, and complication rate for FEI are not well described in the ICU setting, but have been described in the operating room (OR) and emergency department (ED) settings. The incidence of awake intubation in both the OR and ED settings is low, about 1%, and in the vast majority, a flexible endoscope is used.¹^,²^,³^,⁴^,⁵^,⁶ In both the OR and ED settings, the success rate of awake FEI is greater than 90%.¹^,³^,⁴^,⁵^,⁶ A large retrospective review by Joseph et al. showed that in the OR setting awake endoscopic intubation took only 8 minutes longer than standard induction and intubation.⁶ Finally, complication rates for awake FEI are low (2% to 5%) despite the fact that this technique is used almost exclusively for the most difficult airways.¹^,³^,⁴^,⁵^,⁶ One of the most common and serious complications, which occurred in 5% of patients in a large review by Law et al, is respiratory compromise during application of topical anesthesia to the upper airway.⁵

FEASIBILITY OF INTUBATING WITH A FLEXIBLE ENDOSCOPE

Most critical care providers are proficient at using a flexible endoscope for bronchoscopy, but many don’t perform FEI because they think it is a difficult and complicated procedure. However, FEI is a relatively simple procedure that is easy to learn. The key to the procedure is good topical anesthesia (see Chapter 16, Topical anesthetics and anesthesia for awake intubation) so that the patient can stay awake and cooperative. It is important for critical care providers to be able to perform this procedure themselves since many anesthesia providers are not experienced or confident with this procedure.

Additionally, disposable endoscopes are more widely available and have eliminated the equipment limitations of FEI. Early versions of single-use endoscopes had blurry optics and suboptimal controls, but modern versions are nearly identical to traditional bronchoscopes for the purpose of endoscopic intubation.⁷ A recent study in the ICU setting showed that 65% of operators preferred the Ambu® aScope™ 4 over a traditional bronchoscope for endoscopic intubation.⁸

LEARNING CURVE FOR FLEXIBLE ENDOSCOPIC INTUBATION

The mechanics of handling and steering a flexible endoscope are straightforward and can be learned and practiced on a simple low-fidelity manikin. This chapter will detail the mechanics of using the endoscope and the process of getting the scope and ETT into the trachea. Chapter 16 describes optimal techniques for topical anesthesia of the upper airway—which is equally important for successful awake FEI.

INDICATIONS AND CONTRAINDICATIONS

Indications for FEI are: (1) the anatomically difficult airway and (2) the physiologically difficult airway in which decreased respiratory drive or blood pressure cannot be tolerated. Examples include the following:

Inadequate oral access, recognized as a very limited interincisal distance, is a strong predictor of difficult or impossible orotracheal intubation via conventional means. Examples include
wired mandible, trismus, temporomandibular joint disease, and tongue and oral floor space-occupying lesions (i.e., angioedema, hematoma, oral infection).
Distorted upper airway anatomy, particularly obstructing upper airway pathology, often precludes visualization by direct or video laryngoscopy and prevents appropriate seating of blind extraglottic devices. Examples include pharyngeal abscess, neck or posterior oropharyngeal trauma or hematoma, angioedema, and base of tongue or perilaryngeal tumor.
Laryngeal trauma or suspected tracheal disruption. In these cases, intubation with continuous visualization without neuromuscular blockade is recommended.
Cervical spine immobility or deformity, particularly if the airway is predicted to be difficult based on additional features. Rigid cervical collar and halo brace immobilization are the most common examples. Severe cervicothoracic kyphosis is another example.
A patient who is severely hypoxic on maximum noninvasive support, who is likely to crash during RSI and you don’t believe you can oxygenate via BMV or an EGD.
Fragile right ventricular failure.

Contraindications to endoscopic intubation are relative and may include the following:

Excessive blood and secretions in the upper airway have the potential to obscure the indirect view of FEI.
Endoscopy in the context of high-grade laryngeal or tracheal obstruction, as with foreign bodies, supraglottitis, or malignancy, may precipitate complete airway obstruction. Patients with high-grade upper airway obstruction may deteriorate during application of topical anesthetic. Having a low threshold to transition to an emergency cricothyrotomy or performing a primary cricothyrotomy should be considered in these patients.

PREPARATION CHECKLIST

Specialized items: Flexible endoscope (ideally multiple sizes), 5.0- and 6.0-mm flex-tip microlaryngeal ET tubes (which are 35 cm long, so ideal for nasal intubation) (Fig. 25.1), Williams airways (9 and 10 mm) for oral intubation. MADgic laryngotracheal mucosal atomizer (see Chapter 16) (Fig. 25.2).