What Is a Laryngoscope?

Due to the deep position of the larynx and the complex physiological structure, it cannot be directly seen. During the larynx examination, some special inspection methods are needed, such as indirect laryngoscope, direct laryngoscope, fiber laryngoscope, electronic laryngoscope, stroboscope, Ultra-high-speed movie photography, sound or glottis.

Basic Information

English name: laryngoscope

Visiting department: Functional Inspection Division

Laryngoscope indirect laryngoscope

Indirect laryngoscopes are the most commonly used method of laryngoscopy. The indirect laryngoscope is a round flat mirror with a handle. The mirror surface intersects with the handle at 120 degrees. The diameter of the mirror surface is different. The indirect laryngoscope should be selected according to the condition of the examinee's pharynx.

The subject was sitting on a chair during the examination, leaning forward, opening his tongue, covering the first third of the tongue with clean gauze, pulling the tongue forward and down, heating the indirect laryngoscope but not putting it in his mouth In the pharynx, the examinee is asked to take a deep breath, make a "clothing" sound, move the root of the tongue forward, and lift the epiglottis. When placing an indirect laryngoscope, place the mirror face down and place it on the soft palate quickly and securely at 45 degrees to the horizontal surface without touching the tongue, hard palate, and tonsils, so as not to cause nauseous reflexes and prevent inspection. If the subject's pharyngeal reflex is too heavy to cooperate, a small amount of 1% decaine can be sprayed on the pharynx and examined again. Because the mirror is tilted 45 degrees downwards, the laryngeal image seen in the mirror and the actual laryngeal position are upside down and left and right. Due to the limitation of the mirror size of the indirect laryngoscope, the entire larynx cannot be seen at the same time, so the mirror should be slowly rotated and the larynx should be inspected one by one.

This method has the advantages of simple and easy operation, easy to master, and small patient pain. Its limitations include: patients with sensitive pharyngeal reflex cannot tolerate; patients with hypertrophic tongue base and poor epiglottic lifting are not satisfied with laryngeal examination; Features of anatomic development are difficult to observe in the throat ^[1] .

Direct laryngoscope

Direct laryngoscopy requires direct laryngoscopy to lift the root of the tongue and epiglottis directly. It is not a routine examination method of the larynx, because this examination is an invasive examination method for laryngoscopy. The patient is anesthetized on the mucosal surface. It is generally difficult to tolerate and usually requires hospitalization under general anesthesia. Direct laryngoscope can understand the abnormalities of the laryngeal structure in detail, clarify the location and scope of the lesion, and biopsy the lesion tissue if necessary. Direct laryngoscopy cannot obtain functional indicators of the larynx. Since the development of fiber laryngoscopes and electronic laryngoscopes, direct laryngoscopes have become less and less widely used as an examination method, but they have been widely used in clinical practice as a surgical method.

There are many types of direct laryngoscopes according to their uses, such as thin-film laryngoscopes (straight and curved pieces, generally used in anesthesia), ordinary direct laryngoscopes, lateral laryngoscopes, and anterior laryngoscopes Support laryngoscope and suspension laryngoscope. According to their size, there are laryngoscopy for infants, children and adults. If special equipment is added, such as microscope, laser system, endoscope system, camera and camera system, etc., it is more convenient for inspection, surgical treatment and teaching ^[2] .

Indication

(1) If the indirect laryngoscopy and fiber laryngoscopy are unsuccessful, or the visual field exposure of the indirect laryngoscopy and fiber laryngoscopy is not satisfactory, the direct laryngoscopy can be used.

(2) Take a laryngeal tissue biopsy specimen, or directly swab the throat secretion for examination.

(3) Treatment of laryngeal lesions, such as benign tumor resection (such as vocal cord polyps, small benign tumor removal of the larynx). Laryngeal scar stenosis, electrocautery, local medication, and removal of foreign objects from the upper end of the larynx, trachea, and esophagus.

(4) Those who are not easy to get off the tube during endotracheal anesthesia or bronchoscopy can be assisted by direct laryngoscope.

(5) Used for endotracheal intubation, for anesthesia intubation and rescue laryngeal obstruction patients.

(6) For bronchoscopy in children, the glottis can be exposed with a lateral laryngoscope and then introduced into the bronchoscope ^[3] .

Contraindication

Cervical spine lesions, such as dislocation, tuberculosis, and trauma, are not suitable for this operation. Serious illness, severe weakness, and late pregnancy are not absolute contraindications, but caution should be exercised.

3. Inspection method (except support laryngoscope and suspension laryngoscope)

Direct laryngoscopy under mucosal surface anesthesia. The surgeon holds the scope in his left hand, puts a thick layer of gauze to protect the upper teeth, and pushes his upper lip with the finger of his right hand to avoid being injured by the scope pressure on the teeth. Back to the entrance cavity, transfer to the middle line and go straight to the root of the tongue. When the epiglottis is seen from the laryngoscope, the right thumb and the index finger assist in holding the tube from the front and back respectively. Tilt the laryngoscope proximally upwards (tilt forward when seated), and point distally toward the posterior pharyngeal wall, but do not touch it. Continue to enter the mirror beyond the free edge of the epiglottis. After seeing the epiglottic nodules, lift the laryngoscope with the left hand with parallel upward force, pressurize the epiglottis and lift it completely to expose the laryngeal cavity. At this time, if laryngeal spasm occurs and the glottic fissure is tightly closed. When the glottic fissure cannot be seen, the laryngoscope should be fixed in place. Wait for a while to wait for the laryngeal spasm to contact the laryngeal spasm. If the laryngoscope is too deep and touches the mucosa of the laryngeal cavity to cause reflex spasm, the laryngoscope should be withdrawn a little. After the laryngeal spasm is resolved, the observation should be made again. Use your right hand to perform all necessary operations.

If the subject's neck is short and thick, and the front vocal cord is not easy to expose, the head must be raised, the left hand should be used to lift up the laryngoscope, the thumb of the right hand should be pushed upward from below the laryngoscope, and the remaining fingers of the right hand should be held on the right side of the patient. The teeth listed above support the epiglottis in concert. This method is unsuccessful, you can ask the assistant to press down the thyroid cartilage or use an anterior laryngoscope. The anterior combined laryngoscope can not only clearly see the anterior vocal cord, but also can be inserted into the glottis to check the subglottic cavity. When examining young children, in order to prevent laryngeal edema after this operation, the laryngoscope tip may not compress the epiglottis. Just raise the tongue root to the premise, and the epiglottis will be erected to expose the laryngeal cavity.

4. Complications

It rarely happens. In young children, especially those with spasticity, severe or even life-threatening laryngeal spasms can occur during surgery. During the operation, the movement should be as gentle as possible to reduce the damage to the pharyngeal and laryngeal mucosa and reduce the chance of hematoma, bleeding or secondary infection.

Laryngoscope fiber laryngoscope

Fiber laryngoscope is currently the most widely used fiber-optic fiberscope in ENT. Fiber laryngoscope makes use of the flexibility of light-transmitting glass fiber, strong fiber beam brightness and the ability to guide light in any direction to make a thin and soft laryngoscope. The light source is a cold light source with a halogen lamp. The fiber laryngoscope system is composed of a lens body, a cold light source, and an accessory. It can be inserted through the anterior nostril to inspect the nasopharynx, oropharynx, laryngo-pharynx, and larynx. There are different types and specifications of fiber laryngoscopes. The commonly used fiber laryngoscopes have an effective body length of more than 300mm, and the distal end can be bent upwards by 90-130 degrees, downwardly by 60-90 degrees, and the viewing angle is 50 degrees. At present, the external diameter of fiber laryngoscope commonly used in clinical is 3.2mm ~ 6mm, which can be used for the examination of children and adults. At the same time, the fiber laryngoscope has a lumen in it, which can be put into forceps for biopsy and surgery. Negative pressure suction and local administration through the larynx. Fiber laryngoscope can be connected with camera system and computer system, and can use computer to process recorded images and videos.

Indication

It is basically the same as direct laryngoscopy. Because the fiber laryngoscopy has a soft and flexible lens body and strong brightness, it can be inserted through the nasal cavity for examination. Therefore, it is overly sensitive to the pharynx, the teeth are closed, the mouth is difficult to open, the cervical spine is rigid, the neck is short, the tongue Excessive indirect laryngoscopy and direct laryngoscopy are particularly suitable for reasons such as excessive body height, short tongue bands, and epiglottis covering the throat entrance. Because the fiber laryngoscope can approach the examination site and enlarge it through the display, it can find hidden lesions and early tiny lesions, and can perform local lesion biopsy and surgery on smaller vocal nodules and polyps. Equipped with a video recording system can still dynamically observe the development of the lesion.

Contraindication

Fiber laryngoscopes have no clear absolute contraindications. For those with acute inflammation of the upper respiratory tract with dyspnea, severe heart and lung lesions, allergic to dicaine, and severe laryngeal obstruction of unknown cause can be regarded as relative contraindications.

3. Inspection method

Anesthesia of the mucosa of the nasal cavity and throat is usually required before the examination. Anesthesia is usually sprayed with 1% dicaine. For nasal examinations, ephedrine spray should be used to contract the nasal cavity. The total dose of dicaine for mucosal facial anesthesia in adults should not exceed 60 mg.

Fiber laryngoscopes can be performed nasally or orally. The nasal cavity and the nasopharynx can be observed at the same time through the nasal examination. The lens body is easy to fix. When the fiber laryngoscope is inserted along the posterior pharyngeal wall, the pharyngeal reflex is light, without the interference of the tongue, and it is easy to operate. However, if you encounter a deviated nasal septum, inferior turbinate hypertrophy, nasal polyps or new organisms, those who have recently had repeated nosebleeds or pus may be examined by mouth. Usually hold the operating part of the lens in the left hand, hold the distal end of the lens in the right hand, and enter the nasopharynx along the bottom of the nasal cavity or middle nasal passage. Adjust the curvature of the lens and bend downward to observe the root of the tongue and epiglottis (lingual and laryngeal surfaces). , Epiglottis, piriform fossa, sacral mucosa and intercondylar area, ventricular zone, vocal fold, anterior joint and subglottic mucosa. Pay attention to the color and shape of the laryngeal mucosa, ulcers, congestion and new organisms. Observe the sound The size of the door fissure, the movement of the acoustic chamber band, and the symmetry. If you need to observe the laryngo-pharynx, you can instruct the patient to close the lips tightly for air blowing. When the entrance of the esophagus is opened, the situation of the piriform fossa and the posterior ring area can be observed.

4. Advantages

(1) The lens body is soft and flexible, the patient does not need special posture, the pain and trauma are small, and the patient with neck deformity, difficulty in opening mouth, and weak and critical patients can be examined.

(2) The operation is simple, which is more conducive to examining various lesions of the larynx in the state of natural pronunciation.

(3) The end of the mirror tube is close to the anatomical part, especially for patients with short neck, hypertrophy of tongue, narrow pharyngeal cavity and infantile epiglottis.

5. Disadvantages

The objective lens has a small mirror surface and a long lens tube, which produces a fish-eye effect, the image is easily distorted and the color fidelity is low ^[4] .

Laryngoscope electronic laryngoscope

The appearance of electronic laryngoscope is similar to that of fiber laryngoscope, and it is also a tube fiber endoscope, which has been widely used in clinic in recent years. The electronic laryngoscope endoscope image system is equipped with a CCD chip at the endoscope end. As an ultra-small camera, the obtained image is converted into points and transmitted after the signal. An electronic guidance system is used to replace the light guide fiber bundle. At the same time, a digital image processing system can be connected. Get higher definition images. The electronic guide system includes a screen display, a video recording device, etc., and is assembled into a fiber endoscope. Through the computer connected to the electronic laryngoscope, the electronic laryngoscope image can be processed by the computer. Its indications, advantages and disadvantages, and examination methods are the same as fiber laryngoscopes.

/ Laryngoscope dynamic laryngoscope / strobe laryngoscope

The vibration characteristics of the vocal cords reflect the vocal function of the larynx, which is an important subject of noise medical research. Dynamic laryngoscope / strobe laryngoscope is the main inspection method to study the function of larynx.

Dynamic laryngoscope

Dynamic laryngoscopy is also called stroboscopic laryngoscopy, which is mainly used to observe the vocal cord vibration characteristics during vocalization. It is the only inspection that can see the vocal cord mucosal wave movement mode. It can observe the vocal cord vibration law, provide an objective basis for the diagnosis of vocal cord diseases (such as vocal cord cysts, early vocal cord cancer) and comparison before and after vocal cord surgery. With the advancement of electronic technology, the analysis of the images of dynamic laryngoscopes by electronic computers has been implemented so that the dynamic laryngoscopes exclude subjective factors and develop quantitatively. Therefore, dynamic laryngoscopy is of great significance in the fields of laryngology, voice medicine and art noise medicine.

(1) Principle The frequency of vocalization is high, and the vocal cords vibrate quickly. It is difficult for the naked eye to observe the true condition of vocal cord vibrations. Therefore, in order to observe the real situation of vocal cord vibration in detail, some method is needed to slow down the rapid vibration of the vocal cord. This method is a dynamic laryngoscope inspection method. The basic principle of a dynamic laryngoscope is: After a fast-moving high-frequency wave is filtered by a low-frequency scintillation wave, the fast-moving high-frequency wave will become a slow, moving waveform and easy to observe. Talbot's law: For a series of images with a time interval less than 0.2 seconds, the human eye perceives a continuous dynamic picture.

(2) Inspection method The inspection method of the dynamic laryngoscope is basically the same as that of the straight tube magnifying laryngoscope. The difference is that the light source is an intermittent flash light source, that is, the straight tube magnifying laryngoscope and the cold laryngoscope light source are connected through an optical fiber. The camera system can record the real vibration state of the vocal cord at the eyepiece end of the straight tube laryngoscope, and then carefully observe the vibration of the vocal cord and the pathological changes of the larynx through video playback. According to clinical needs, check dynamic phase, static phase, and phase from 0 to 360 degrees, the morphology of vocal cords when real, false, low-pitched, high-pitched, weak, and strong sounds are recorded, and video is recorded as needed.

(3) Observation index or parameter of dynamic laryngoscopy Symmetry of vocal cord vibration The symmetry of vocal cord vibration is judged with reference to the phase of vocal cord opening and closing and the width of lateral vocal cord offset. If the vocal cords are symmetrical, they appear as symmetrical, mirror-image movements; if the motion of a certain phase is asymmetric, the motion of one side vocal cord exceeds the expected phase or a follow-up motion of another vocal cord appears This is an important feature of vocal cord movement. Periodic vocal cord vibration The normal vocal cords vibrate regularly. If the vibration loses its regularity, it means aperiodic vibration. When the dynamic stroboscopic light is synchronized with the fundamental frequency, the static picture of the vocal fold is visible. In this synchronized state, if any movement of the vocal cords is visible, a non-periodic vibration of the vocal cords is prompted. Amplitude of vocal cord vibration The amplitude of vocal cord vibration can reflect the tension of the vocal cord itself, and it is an objective index reflecting the effective vibration of the vocal cord. If the vocal cord vibration part shrinks, the thickness and hardness increase, the amplitude decreases; if the vocal cord tension decreases, the amplitude increases. Variations of vocal fold mucosa Mucosal waves directly reflect the histological changes of the vocal fold double vibrator, so it is a sensitive indicator of no pathological changes in the vocal fold. Glottic closure degree Because the vocal cords vibrate extremely fast when vocalizing, it is not possible to determine the true closed state of the glottis with ordinary laryngoscopes, which can only be determined under dynamic laryngoscopes. Various lesions of the vocal cords cause changes in the vocal cord vibration pattern, resulting in abnormal vocal function.

(4) Significance of dynamic laryngoscopy Diagnosis of subtle lesions By observing the condition of mucosal waves, it is helpful to find lesions that are difficult to find under ordinary light sources, such as vocal sulcus, micro cysts in the vocal cords, and vocal cord scars. Defining the extent of lesions For lesions below or below the free edge of the vocal cords, such as wide basal polyps, vocal cord ridges, etc., the width of the base of the lesion can be understood by observing the mucosal wave, which guides the extent of surgical resection. In terms of noise surgery, according to the vocal cord vibration and mucosal wave conditions, it is possible to identify proliferative lesions with similar morphology or find changes in the fine structure of the vocal cords to determine the surgical method. Dynamic observation of the progress of lesions. Superficial lesions of the vocal folds only affect mucosal waves. When the lesions develop to the deep layer, they have an effect on mucosal waves and vocal cord vibration.

2. Super high-speed movie photography

Ultra-high-speed movie photography allows more detailed observation of vocal cord vibration. The videos produced at super high speed can provide details of the complex vibration process, frequency and intensity of the vocal cords in each vibration cycle, and can also capture non-verbal larynx functions such as coughing, crying, sputum and other actions.

(1) Principle and instrument

The ultra-high-speed throat camera system consists of a xenon lamp, a set of optical systems that can reflect the examined throat light to the camera, a super-speed camera, an electronic system that operates the light source and the camera, and a time display Pulse motors and other components.

The shooting of ultra-high-speed vocal cord vibration is controlled at 1000-5000 frames per second, which is 20-30 times faster than the normal vocal cord vibration frequency. For example, when someone makes a sound, the frequency of the vocal cord vibration is 125Hz, the speed of recording it should be 3000 frames per second, that is, about 25 frames of images should be taken per vibration cycle. When this vibration mode is projected at a normal speed of 24 frames per second, the sound of the sound on the film appears very slowly, and the projected image is also enlarged by a factor of 125. Beneficially, the acoustic signal can also be recorded on the film at the same time, in order to compare the sound and the vocal cord vibration image.

(2) Application

Due to the high cost of the ultra-high-speed laryngeal photography system, the data accumulation process is very time-consuming, inoperable on some patients, and the inspection costs are high. Factors such as it have not been widely used in clinical practice, but in acoustic research and teaching, High-speed photography is quite useful. Although ultra-high-speed photographic examination is not suitable as a conventional method for diagnosing voice obstacles, it can provide the number of times the glottis are opened during the vocal cord vibration cycle, and can quantitatively evaluate the vibration of each vocal cord. This information is important for understanding the vocal cords. The vibration characteristics and vibration mechanism have certain value. Because ultra-high-speed photography can record images of vocal cord movement and can be screened multiple times, it can study the physiological functions of the larynx and its abnormal phenomena, find early larynx lesions, track and observe patients with larynx diseases, and perform larynx surgery. The comparison between front and back has great value.

Laryngoscope sonogram

An acoustic image is a tracing pattern obtained by recording the sound signal emitted by the larynx and converting it after electrical processing. Based on this image, the sound and speech are analyzed. The sound atlas recorded by the instrument reflects the physical characteristics of the sound. It is an objective inspection method and cannot replace the physiological role of humans in identifying the sound timbre and loudness of the sound. Therefore, the sonogram inspection should be combined with the subjective inspection method. .

Instrument composition

The sonograph is mainly composed of three parts: a recording device that records the original acoustic signal on a magnetic tape; a heterodyne frequency analysis device that performs spectrum analysis of the recorded signal at 45Hz (narrowband) or 300Hz (broadband); display The device displays the analysis results on a fluorescent screen or records on a special recording paper. There are two types of displayed graphics: one is a three-dimensional continuous graphic of time, frequency, and intensity; the other is a two-dimensional graphic of an instantaneous signal at a certain time section.

2.Principle

The sonograph uses acoustic instruments and methods to extract common and unique parameters in various voices, such as the fundamental frequency, intensity, duration, abnormalities of each formant, etc., and then compares these parameters with the clinical and find The relationship. By analyzing wave patterns and data, objective conclusions and judgments are made.

3. Analysis of sound maps

The sound signal is burned by voltage and current after being processed by the frequency analysis device. The graph drawn on the electrosensitive recording paper is the sound map. The ordinate represents the frequency distribution and the abscissa represents the passage of time. The depth of the recording paper being burned. The degree represents the strength of the sound signal, which can usually be divided into several levels from shallow to deep.

The sound map of normal vowels is regular, neat and clear. In various hoarse sound patterns, it can be seen that the noise component increases and is proportional to the degree of hoarseness.

4. Application

Sonograms have been available for more than 40 years and are now widely used in clinical departments, especially laryngology. Its practical value is: identification of vocal patterns of normal people; analysis of the characteristics of various pathological noises, combined with clinical aids in diagnosis; used as objective records to compare the effects of various surgical or non-surgical treatments; Sound quality; used in various areas of speech defects, speech correction and speech medicine; sound maps are an important means of identification in forensics.

Laryngoscope glottis

The glottis is a curve obtained by measuring the dynamic changes of the glottis through special equipment and computer systems. It cannot directly measure the glottis area dynamically, but it can indirectly reflect the change of the glottis area. It is an important method to study the physiology and pathology of noise and the diagnosis of laryngeal diseases of singing voice.

1. principle

Human tissues have good electrical conductivity, as if they consist of a single resistor, and their physical characteristics conform to Ohm's law, that is, current is proportional to voltage and inversely proportional to its own resistance. When a current passes through human tissue, the voltage formed is proportional to its resistance. This is the principle of the use of electro-glottic diagrams.

2. Detection method

Electroglottic examination is to place two metal electrodes on both sides of the neck and throat of the subject, which is equivalent to 1/3 of the bilateral thyroid cartilage plate corresponding to the glottis, and adjust the electrode placement area appropriately to make the amplitude of the map It is advisable to reach the maximum. When testing, please ask the subject to naturally vowel / ae / or / a: / for three seconds. After A / D conversion, the electrogram waveform and Electro-glottic parameters.

3. Clinical application

As a laryngeal function tester, the electro-glotograph can detect the regularity of the vocal cord vibration, the open and closed states of the glottis, and different vibration modes of the vocal cord without affecting the vocalization. As a clinical examination instrument, it can particularly reflect the state of the lower edge of the vocal cord and the closed phase of the vocal cord, thereby making up for the lack of endoscopy, and is especially suitable for children who are uncooperative with laryngoscopy and patients who are not suitable for laryngoscopy. Using the electro-glottic waveform and its parameters to analyze the vibration and closure of the vocal cords is helpful for the diagnosis, treatment and acoustic research of laryngeal diseases. Clinically, electroacoustic imaging is used to study vocal cord polyps, vocal cord nodules, vocal cord paralysis (unilateral), laryngeal cancer, and vocal cord leukoplakia.

References:

1. Li Xuepei. Otorhinolaryngology [M]. Beijing: Peking University Medical Press, 2003: 155-159.

2. Huang Xuanzhao, Wang Jibao, Kong Weijia. Practical Otorhinolaryngology Head and Neck Surgery 2nd Edition [M]. Beijing: People's Medical Publishing House, 2008: 2008: 405-418.

3. Han Demin, Xu Wen. Voice Medicine. Beijing: People's Medical Publishing House, 2007: 61-62.

4. Yu Ping, Wang Rongguang. Voice diseases and voice surgery. Beijing: People's Military Medical Press, 2009: 53-59.