The laryngoscope is by definition an instrument which allows to observe the larynx and the pharynx. Its use is strictly reserved for specialist physicians and is performed in the operating room under general anesthesia.

The laryngoscope is used for two types of procedures: direct rigid laryngoscopy and orotracheal intubation.

Composition

The laryngoscope consists of two parts, which are assembled only at the time of use:

• the blade: this is the part of the instrument which is introduced into the patient’s mouth and inserted up to the epiglottis. It has at its end a lighting system, by bulb or optical fiber, which allows the user to be guided. There are several blade sizes numbered from 0 to 4 depending on the patient’s build. The shape chosen also depends on the age of the patient: curved blades (Mac Intosh type) for adults and flat blades (Miller type) for children. The blades are reusable or single use;
• the handle: it is used to hold the laryngoscope and contains the power supply system for the light source (batteries or rechargeable battery).

There are now video laryngoscopes, which are equipped with a linked screen, or deported (connected by wire or wifi). The most revolutionary models even make it possible to visualize the larynx on a mobile phone or tablet thanks to a dedicated application. The downside is the price which is multiplied by 10 at least.

The laryngoscope is best known for performing intubations in the context of surgeries, respiratory emergencies or resuscitations. But they are also used by ENT doctors for performing laryngoscopies.

Laryngoscopie

A laryngoscopy looks at the back of the throat (or pharynx) and the larynx with the vocal cords. This examination may be recommended for various reasons:

• persistent voice disorder;
• persistent pain in the ENT sphere;
• chronic cough;
• difficulty swallowing;
• presence of a suspicious mass in the neck;
• presence of a foreign body to be removed;
• performing a biopsy to analyze throat or vocal cord tissue.

Laryngoscopy can be:

• or indirect, if it consists in making an observation of the back of the throat with the naked eye using a light and a mirror held at the back of the throat;
• either direct flexible, if it consists of illuminating the back of the throat using a bundle of optical fibers inserted through a flexible tube passed through the nose;
• or direct rigid, if it is performed using a laryngoscope under general anesthesia on an outpatient basis in the hospital.

Laryngoscopy can highlight:

• the presence of polyps or nodules on the vocal cords or larynx;
• injury or infection of the larynx;
• vocal cord paralysis;
• gastroesophageal reflux disease;
• a tumor.

Intubation orotrachéale

The main function of the laryngoscope is to clear the epiglottis in the back of the throat so that the patient’s vocal cords can be viewed. This allows the endotracheal tube to be inserted into the trachea without the risk of passing it into the esophagus. The patient can then be connected to an artificial respirator.

Concerned public

Respiratory intubation is performed in several situations:

• in the context of “heavy” surgical procedures requiring significant general anesthesia, resulting in the blocking of the respiratory muscles;
• in the event of respiratory distress;
• in unconscious or coma patients to prevent them from choking on inhalation of gastroesophageal reflux.

The stages of operation

• The patient’s head is tilted back to allow access to the airways;
• Dentures must be removed;
• The anesthetist holds the handle of the laryngoscope in the left hand and the blade in the right hand (for a right-handed person);
• The blade is gradually introduced through the patient’s mouth: it lowers the tongue and clears the soft palate up to the epiglottis. The doctor is guided by the light located at the end of the blade;
• Once the vocal cords are visible, the trachea is involved;
• If it is an intervention or a resuscitation, the anesthetist can insert the breathing probe;
• If it is a laryngoscopy, the ENT doctor can examine the vocal cords, the glottis, the surrounding tissues, and take samples for a biopsy.

And after?

The use of a laryngoscope, whether for therapeutic purposes or for intubation, can cause some pain after its removal. Having a sore throat or hoarse voice after intubation is quite common and should not be a concern. However, more annoying side effects are sometimes observed: infection, lesions, bleeding, inflammation, ulcer, spasm of the vocal cords.

Precautions to take

Laryngoscopy is a delicate medical procedure to perform which requires a great deal of precision and dexterity. One wrong move can injure the throat, glottis or vocal cords.

During the preoperative examination, the anesthetist examines the patient’s mouth to identify possible intubation difficulties and provide, if necessary, alternative means of ventilation. Except in the case of disposable slides, these must be cleaned and sterilized in an autoclave at 134 ° C. The handle should also be disinfected according to the supplier’s recommendations (with alcohol or autoclave).

The different models

Laryngoscopes are distinguished by their type of blade (curved or flat), their light source (bulb or optical fiber), and whether or not they are connected to a screen (video laryngoscopes); Conventional laryngoscopes can be sold in a box containing a handle and a selection of several blades.

Standards

Laryngoscopes are medical devices and must therefore meet certain safety criteria: CE marking and ISO 7376 standard (anesthesia and respiratory resuscitation equipment). The slides must not present any roughness where liquids or organic tissue could be retained.

Who invented the laryngoscope?

In 1854, Manuel Garcia, singing teacher and baritone singer, invented the laryngoscope during his research on vocal functions. Subsequently, the Austro-Hungarian doctor Johann Czermak, passionate about phonetics, improved it and adapted it for medical use.