CHAPTER 3: Preparation for Awake Intubation

INTRODUCTION

Case: A 60-year-old female with carcinoma of the colon is scheduled for laparoscopic colon resection. She has hypertension, obstructive sleep apnea (OSA), and is morbidly obese with a body mass index (BMI) of 41 kg·m⁻². She provides a history of difficult airway management at another institution 10 years previously at cholecystectomy. Records are not available. Examination of her airway reveals mouth opening of 3 cm (approximately 2 fingerbreadths), full dentition with prominent upper incisors, and a receding mandible. Mandibular mobility is poor and she is unable to bite her upper lip with her lower incisors. Her neck is short and has a circumference of 44 cm. Her cricothyroid membrane (CTM) is difficult to identify. Her neck extension is unremarkable and she has a Mallampati score of IV.

This patient has predictors of difficult facemask ventilation, difficult direct laryngoscopy, difficult video-laryngoscopy (VL), difficult supraglottic device, and difficult surgical airway. An awake flexible bronchoscopic intubation is an appropriate airway management plan. Alternative techniques include awake intubation using a video-laryngoscope or an optical stylet.

What Are the Fundamentals of an “Awake, Bronchoscopically Facilitated” Intubation?

Awake bronchoscopic intubation can be performed rapidly with minimal patient discomfort. The technique requires familiarity with the airway anatomy, adequate regional anesthesia of the airway, and bronchoscopic dexterity. Optimal regional anesthesia of the airway requires a thorough knowledge of the pharmacology of the local anesthetics employed and the techniques of administration. The primary requirement for successful awake intubation is effective regional anesthesia of the airway.¹

AIRWAY ANATOMY

Why Is Knowledge of Upper Airway Anatomy Beneficial in Airway Management?

Knowledge of the structure, function, and pathophysiology of the upper airway permits the practitioner to anticipate potential life-threatening problems and better utilize the full spectrum of airway management techniques.² Functionally, the upper airway can be considered to consist of the nasal cavities, pharynx, larynx, and trachea (see Figure 3–1).³ The oral cavity provides an alternate access route to the pharynx.

The Nose

Anatomically, the nose can be divided into an external component and the nasal cavity.⁴ The external nose consists of a bony vault posteriorly and superiorly, a cartilaginous vault anteriorly, and the lobule at its inferior-anterior aspect (see Figure 3–2).³ The cavity of the nose is divided into bilateral compartments by the nasal septum and continues about 3 inches (7.6 cm)⁵ posteriorly from the nostrils (nares), to communicate with the nasopharynx at the posterior aspect of the septum (the choanae) (see Figure 3–3).³ The nasal lobule includes the tip of the nose, the U-shaped lower lateral cartilages, the fibrofatty alae, the vestibule, and the columella.^6...