Laryngoscopy is a procedure used to view the inside of the larynx (the voice box).
A patient undergoing a laryngoscopy should be assessed for allergies to local anesthetics or other pharmacologic agents in order to prevent possible allergic reactions.
Patients may have fears concerning this procedure. Prior to laryngoscopy, the physician should explain the procedure in detail and assure the patient that he or she will be closely monitored for respiratory or other problems.
Two methods of laryngoscopy allow the examiner to view the structures of the larynx and the surrounding areas. A light and lens affixed to a surgical viewing instrument called an endoscope are used in both methods.
Indirect laryngoscopy, the simplest form of laryngeal examination, involves the placement of a small, angled mirror at the back of the throat, allowing the examiner to reflect light onto the larynx and view its major structures. However, since the mirror must remain in the back of the throat, examination of the larynx during normal speech is hindered. Also, a strong gag reflex in some patients may limit the usefulness of this procedure.
A rigid endoscope may also be used to perform an indirect laryngoscopy. An examination using a rigid scope involves placement of the tip of the instrument through the mouth and into the back of the throat. A prism at the tip allows the examiner to view the larynx. This type of exam provides clear and highly magnified images of the vocal cords and allows better examination of the larynx during phonation (the production of vocal sounds). Another advantage to these instruments is that photographic or video recordings can be made through the endoscope for future review, also allowing more than one person to observe the laryngeal area.
In direct laryngoscopy, a flexible, fiber-optic endoscope is threaded through the nasal passage and down into the throat. This procedure is used to detect or remove
Aspirate—To draw by suction.
Biopsy—The removal of a sample of tissue for study under the microscope.
Endoscope—An instrument used for visualizing the interior of a hollow organ such as the larynx.
Epiglottis—The lid-like appendage that covers the glottis during swallowing.
False cords—The protective valves of the larynx that prevent food from entering the trachea.
Laryngectomy—The surgical removal of the larynx.
Larynx—The organ of sound production, sometimes called the voice box. The larynx is made of cartilage and muscle.
Phonation—The production of vocal sounds. Examination of the larynx may be facilitated by asking the patient to produce a high-pitched "e-ee" sound, since this lifts the epiglottis.
True cords—Also called vocal cords, these are two small shelves of muscular tissue within the larynx. They supplement the protective valves of the larynx that prevent food from entering the trachea. Their main function is to vibrate against each other and generate a sound tone.
lesions or foreign bodies in the larynx, or to diagnose cancer by removing tissue for biopsy or samples for culture. Once the instrument is inserted, flexible glass fibers illuminate the laryngeal area and transmit the image to the external part of the scope. From this position, an image of the larynx and vocal folds (including their movement and position during respiration and speech) can be clearly obtained.
Bronchoscopy is a similar, but more extensive procedure in which the tube is continued through the larynx and down into the trachea and bronchi.
Patients should not eat for several hours before the examination.
Patients undergoing indirect laryngoscopy should sit in an upright position and breathe normally. The patient should be leaning slightly forward, with the head lifted. This facilitates the passage of the laryngeal mirror into the mouth and facilitates the procedure.
Topical anesthetics, such as lidocaine or dyclonine, may be used during laryngoscopy to suppress the gag reflex. The patient should be warned that the agent may taste bad and that the effects may be unpleasant. Anesthetized patients may feel as if their swallowing mechanism is impaired, and many experience an illdefined sense of insecurity. Patients who are receiving anesthesia should be warned about these side effects and reassured throughout the procedure.
The gag reflex can also be reduced in the adult by the intravenous injection of diazepam (Valium). The typical dose is 10 mg. Diazepam may be used as an alternative for patients who are allergic to local anesthetics or who require both agents to allow adequate examination. Diazepam should be injected slowly into a large vein, and is only appropriate for healthy adults.
This procedure carries no serious risks, although the patient may experience soreness of the throat or cough up small amounts of blood until the irritation subsides. After the procedure, the patient should ingest nothing by mouth until the gag reflex returns. Once the reflex returns, fluid intake should be encouraged because it promotes the expectoration of secretions, and lozenges or gargles may be used relieve a sore throat.
Vital signs should be assessed frequently for 24 hours to detect bleeding or complications such as difficult or labored respiration (dyspnea).
A normal result would be the absence of signs of disease or damage.
Health care team roles
A nurse plays an important role in explaining the procedure to the patient, preparing the patient for the procedure, and assisting the physician in conducting the procedure. A nurse also assists patient recovery after the procedure, administering fluids and lozenges once the gag reflex returns, and monitoring vital signs.
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American Board of Otolaryngology, 3050 Post Oak Blvd., Suite 1700, Houston, TX 77056. (713) 850-0399. <http://www.aboto.org>.
National Institute on Deafness and Other Communication Disorders, 31 Center Dr., MSC 2320, Bethesda, MD 20892-2320. <http://www.nidcd.nih.gov>.
Jennifer F. Wilson