Nasopharynx

The upper airway examination begins with a quick assessment of nasal and oral cavities. When the FB is introduced through the nose, the inferior turbinate is seen laterally and the nasal septum is seen medially. The bronchoscope is then directed posteriorly into the pharynx. When viewing the nasal cavity, the bronchoscopist should assess for septal deviation, hypertrophy of turbinates, presence of polyps, and integrity of mucosa. Serosanguineous nasal drainage with severe crusting may be suggestive of Wegener’s granulomatosis. Isolated, large septal perforation with inflamed and crusty edges is highly suggestive of nasal substance abuse. Diffuse nasal crusting or a vasomotor-like appearance to the nasal mucosa can typify sarcoidosis. In appropriate clinical settings, nasal polyps may suggest cause for postnasal drip and reactive airway diseases, such as atopic asthma or vasculitides (e.g., Churg–Strauss syndrome). Nasal tuberculosis may show a red, nodular thickening, with or without ulceration. A rapidly progressive black, necrotic mass of tissue filling the nasal cavity, eroding the nasal septum, and extending through the hard palate characterizes mucormycosis.

Oropharynx and Hypopharynx

When the FB is introduced orally, it passes through the oropharynx and larynx and into the trachea. Beyond the base of the tongue, the bronchoscope is passed through the curvature of the oropharynx, which is bordered superiorly by the soft palate and extends to the tip of the epiglottis. The FB is then directed posterior to the tip of the epiglottis. The three major structures in the hypopharynx are the pyriform recess, the postcricoid region, and the posterior pharyngeal wall (Figure 4.2). Tongue size, tooth integrity, and temporomandibular joint mobility are important factors affecting the ease of introduction into the oropharynx. The space between the base of the tongue and the anterior surface of the epiglottis on either side constitutes the vallecula. The valleculae are separated by the median glossoepiglottic fold and bordered laterally on either side by the lateral glossoepiglottic folds. Valleculae are often locations for foreign body entrapment and upper airway obstruction.

Figure 4.2 Laryngeal anatomy.

Larynx

The bronchoscopist should assess the vocal cords for normal abduction on inspiration and adduction during phonation. Dysfunction of vocal cords can be either functional or organic, as seen in persistent gastroesophageal acid reflux, and can cause significant airway compromise. Paradoxical vocal cord motion is an inappropriate adduction of the true vocal cords throughout the respiratory cycle with the obliteration of glottic aperture except for a posterior diamond-shaped opening.

The glossopharyngeal nerve and the vagus nerve supply the motor and sensory pathways for the larynx. The superior laryngeal branch of the vagus nerve (SLN) provides sensory innervation to the glottis, the arytenoids, and the vocal cords. Stimulation of pathways of the SLN, including manipulation of pyriform recess, may result in protective closure of the glottis. Therefore, it is paramount that appropriate topical anesthesia to theses structures be applied prior to proceeding with bronchoscopy.

Trachea

The lower airway (trachea to conductive bronchi) begins at the cricoid cartilage (at about the level of the sixth cervical vertebra, C6). The adult trachea ranges from 16 to 20 mm in internal diameter and has 18–22 cartilage rings. The trachea tapers slightly and aims posteriorly as it divides at the carina, at the level of fifth thoracic spine to the left and right main stem bronchi. The horseshoe-shaped tracheal cartilage shapes the anterior part of the trachea, whereas the posterior part of the trachea consists of smooth muscles that joins the ends of the tracheal cartilage (Figure 4.3).

Figure 4.3 Carina with right and left main bronchus. (RMB, right main bronchus; LMB, left main bronchus)

Starting at the upper trachea, mucosal integrity should be examined, even when there are no gross endobronchial lesions. The presence of extrinsic tracheal deviation and compression due to paratracheal masses should be noted. Both the anterior cartilaginous and posterior membranous portions of the trachea are sometimes sites for dynamic airway compromise caused by tracheomalacia or excessive dynamic airway collapse. The distal trachea and main carina are important sites for examination because malignant diseases often metastasize to the surrounding mediastinal lymph nodes.

If a lesion is identified, both sides of the lungs should be examined completely before biopsies are taken. The importance of complete surveillance is that unexpected satellite airway pathologies can occur in up to 10 percent of primary bronchogenic carcinomas. After main pathology is visualized or diagnostic procedures are started, the bronchoscopist can become too distracted to return to a thorough and careful examination of the remainder of the airways. Furthermore, when the site of primary pathology is sampled, bleeding can degrade the quality of the FB image, and coughing and oxygen desaturation will limit the time to complete the procedure. There is also a danger that samples retrieved from a secondary site that appear abnormal and are found to contain malignant cells can actually represent contamination from cells dislodged during earlier examination of a primary malignant site. Such false-positive results may have a devastating effect of overstaging a potentially curable peripheral lesion.