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Laryngoscopy

Laryngoscopy is a method of examining the larynx through the oral cavity. There are two types of laryngoscopy - indirect, or mirror, and direct, or autoscopy. Indirect laryngoscopy is performed using round mirrors attached at an angle of 120 ° to the metal rod. Laryngeal mirrors have a different diameter - from 15 to 30 mm. For convenience, the mirror is inserted into a special handle. In indirect laryngoscopy, the doctor and the patient sit opposite each other; the light source is placed to the right of the patient at the level of the ear, somewhat posterior to it. The patient opens his mouth and sticks out his tongue; the doctor with the help of a gauze napkin holds the patient's tongue with his left hand, and with the right hand he inserts a laryngeal mirror into the pharynx, directing a beam of light at him, reflected from the frontal reflector (Fig. 1). Immediately before using, the guttural mirror is slightly warmed up on a spirit-lamp or in hot water, always checking the degree of heating, touching the back of his hand with a mirror. To determine the mobility of the larynx and the closure of the vocal cords, the patient is offered to inhale alternately and to utter the sound “e” or “i” in falsetto. During laryngoscopy, the tongue and soft palate are slightly moved back by the mirror to the back and up.

indirect laryngoscopy
Fig. 1. Indirect laryngoscopy

It is impossible, however, to touch the back wall of the pharynx and the root of the tongue with a mirror so as not to cause a gag reflex.

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The mirror picture of the larynx does not coincide with the actual location of its parts: what is in the larynx is in front (epiglottis, anterior ends of the vocal cords), is reflected in the upper part of the mirror, what is in the larynx in the back (articular cartilage, posterior ends of the vocal cords), reflected in the mirror below.

In those cases when a mirror examination of the larynx is somehow impossible (for example, in young children) or insufficient (when removing foreign bodies, tumors), direct laryngoscopy is used.

For a direct examination of the larynx, it is necessary to straighten the angle formed by the horizontal axis of the oral cavity and the vertical axis of the larynx.

This is achieved through special spatulas or tubes.

direct laryngoscopy
Fig. 2. Direct laryngoscopy:
1-3 - successive stages with appropriate endoscopic pictures.

Direct laryngoscopy is performed under local anesthesia: the mucous membrane of the larynx is smeared with a 2% solution of dikain. The introduction of the spatula into the larynx consists of three points (Fig. 2): 1 — carrying the spatula to the epiglottis; 2 — bending around the edge of the epiglottis with the tip of the spatula and holding it to the entrance to the larynx; scaly-like cartilages and posterior divisions of the vocal cords appear in sight ; 3 - squeezing the root of the tongue anteriorly and transfer the spatula to a vertical position; while in the field of view appear the back wall of the larynx and the upper part of the trachea , the true and false vocal cords.

Direct laryngoscopy can only be performed by a specialist with relevant experience.

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Laryngoscopy can be performed by means of laryngeal mirrors (Fig. 30) and with the help of special tools (bronchoscope, Undritsa directoroscope, Tikhomirov spatula, etc.). You can also use the laryngoscope used for intratracheal anesthesia.


Fig. 30. Laryngeal mirror.

Laryngeal mirrors come in various sizes. Sterilized with rubbing alcohol to avoid amalgam damage. Protection of the guttural mirror from fogging at the time of inspection of the larynx is achieved by preheating it on an alcohol lamp or in hot water, or over a match flame. Before producing laryngoscopy (Fig. 31), you should check the degree of heating of the mirror on your arm, which protects the mucous membrane from burns. With laryngoscopy, the anterior parts of the larynx are projected in the guttural mirror above and the rear ones below. The right and left sides of the larynx do not change. Laryngeal mirror with laryngoscopy should be in the oropharynx with an inclination of 45 ° to the horizontal axis. The tongue is raised with the back and up. The patient opens his mouth wide and sticks out his tongue, the tip of which, through the gauze napkin, examines the patient with his thumb and middle fingers of his left hand. You can hold your upper lip with your index finger. The mirror is taken with the right hand and inserted in such a way that the handle is located in the left corner of the patient’s mouth, and the mirror does not touch the hard palate and tongue.


Fig. 31. Laryngoscopy.

In the laryngeal mirror, when it is advanced into depth, it is possible to see first the display of the root of the tongue, and then the epiglottis, the false and true vocal cords and the sub-connective space (Figure 32). In the lateral position of the mirror, pear-shaped pits are inspected.


Fig. 32. Laryngoscopic picture.
a - true vocal cords converge; b - the glottis has the shape of an isosceles triangle.

Initially, the larynx is examined during normal breathing. Then they offer the patient to utter the sound “e” and observe the character of the convergence of the vocal cords. Finally, the patient is offered to take a deep breath, the glottis is visible while widely gaping, which allows us to consider the anterior wall of the trachea. True ligaments differ sharply from the rest of the mucous membrane in their color and brilliance; their color is white, and the color of the entire mucous membrane of the larynx is pink.