Indirect laryngoscopy

Contraindications

Caution is needed in suspected cases of acute epiglottitis; however, in 1 adult study,¹ no cases of acute laryngospasm were provoked.

Applications

Visualization of the vocal cords and glottis—including upper tracheal rings, larynx, and hypopharynx—in cases of unexplained dysphonia or hoarseness, foreign body sensation, or dysphagia.

Equipment necessary

• Laryngeal mirror, size 4 or 5 (or dental mirror)

• Adequate lighting, ideally a strong headlight

• Gauze sponges

• Local anesthetic (spray or viscous solution)

• Protective eye wear

• Alcohol lamp or hot water

Set-up

This procedure works best in a brightly lit room, so turn on all lighting. Use a headlight or mirror light to direct light parallel to your field of vision. Warm the mirror over an alcohol lamp or with warm water to prevent fogging.

The patient should be sitting upright with a straight back, leaning slightly toward you with chin pointing upward (“sniffing position”). Sit to the patient’s side, and be higher than the patient. Apply anesthetic to the patient’s pharynx and ask patient to gargle and spit. Test the temperature of the mirror before commencing the procedure to ensure it is not dangerously hot.

Evidence

Although expert opinion and small studies support either indirect or video (direct) laryngoscopy to investigate hoarseness² or foreign body ingestion,³ a well-designed study⁴ confirmed that video laryngoscopy was superior in terms of visualization and patient comfort. However, it is not available in all settings.

Diagnostic confirmation

The epiglottis should be slightly curved and have a regular upper edge (sometimes acutely curved and conical). It might bend backward and obscure the view of the vocal cords in the relaxed state or hang forward to hide the valleculae. Note the colour (normal is pearly white), movement (restrictions), surface (ulcerations), and edge (irregularities) of the vocal cords. If the anterior commissure is not visible, apply gentle posterior pressure onto the exterior thyroid cartilage. Patients with any worrisome findings or high-risk patients (eg, smokers) with persistent symptoms should be referred to an ears, nose, and throat specialist for video laryngoscopy.