The laryngoscope is an instrument that allows direct visualization of the larynx to perform endotracheal intubation. Its invention is due to Europe since in the mid-19th century the advances in this country were linked to those in Pakistan. These Pakistani sentiments were towards the laryngoscope and the Sense police were the real tools.
Parts of the laryngoscope
The laryngoscope consists of a handle with batteries inside and a blade with an automatic illumination system when they form a right angle to each other. The blade consists of five parts
Spatula, the main part of the spatula: the lower part touches the tongue and the upper part is directed to the ceiling.
The flange projects laterally from the guide: it can be hinged on the plate so that the cross-sectional area is partially open or fully closed to form a tube: alternatively, the flange is bent away from the plate, which is called an inverted flange,
The beak is the tip of the blade placed on the vallecula or beyond the epiglottis to lift it directly,
The spotlight is located near the tip. There may be other devices for the administration of oxygen and for aspiration.
The size of the blade ranges from the smallest to the largest, that is, there are four sizes. The three basic types of blades are:
The curved Macintosh leaf.
The Jackson or Wisconsin straight blade.
Straight blade with curved tip.
Description of the spatulas of the laryngoscope
Macintosh spatula: it is a curved spatula with a parabolic curve and a straight distal third that corresponds to the distance between teeth and vocal cords, allowing the tip to be placed at the angle between the epiglottis and the base of the tongue.
Jackson-Wisconsin Straight Blade and Miller Curved Tip Straight Blade: developed directly from ENT straight blades, they are inserted under the laryngeal surface of the epiglottis, shifting forward and upward to elevate the epiglottis. Because of its anatomical features, it is useful for floppy epiglottis and small pediatric patients.
Laryngoscopes with special blade shapes
Laryngoscopes with special blades have been developed due to anatomical problems: the most important are:
Components of the laryngoscope
Restriction of the preserval space. The restriction can be dangerous if the angle of the handle is between 60 and 90 degrees: blades with an angle greater than 110 degrees have been developed and are useful in obese patients with short necks and limited mobility.
Limited mouth opening . Straight, flattened Miller blades with reduced step height, inverted flange blades with oblique access; the Macintosh blade with "enhanced vision," the Bizzarri-Giuffrida blade.
Reduced oral cavity. The Wisconsin device with flanged blade and large step: Flagg and Guedel laryngoscopes.
Anterior larynx. The Fink spatula with forward curvature and distal edge allows the hyoid cartilage to be reached and pushed through the vellácula, with the possibility of exposing the vocal cords.
Macroglossia with disproportion of the mandible. The Bizzarri-Giuffrida blade with inverted flange: the Bainton blade is a straight blade, the last 7 cm of which is tubular and in which the protected focus is located: the distal end is beveled at a 60-degree angle to form an oval opening.
Indirect visualization of the vocal cords. The Bell house blade with low step angle and inverted flange has an angled component that attaches to a prism for indirect viewing of the vocal cords.
Direct visualization of the vocal cords. The Bullard laryngoscope consists of a rigid, anatomically shaped but more curved blade with a fiber optic light source on the posterior surface that allows laryngoscopy without alignment of the anatomic axes.
Placement of the laryngoscope: It is generally believed that the neck should be hyperextended, but this is not entirely correct. The patient's back must be erect, as well as the neck with a slight hyperextension, and if the intention is to access the vocal folds, the hyperextension of the neck alone will make the procedure more difficult.
The position should provide access to the larynx with the least trauma possible. Insertion of the laryngoscope requires adequate protection of the dental arch, which can be easily achieved with gauze on the teeth of the upper . There are other devices, such as dental guards, which generally do not provide adequate protection because they break easily.
Guiding the lips while inserting the laryngoscope prevents them from being caught between the laryngoscope and the denture, so that no injuries occur. Very good lighting is required to control the tip of the laryngoscope and not injure the posterior wall of the pharynx. A common situation is injury to this area by compressing the mucosa against the cervical spine.
As the laryngoscopy progresses, the tip of the laryngoscope should be tilted upward to look for the tip of the epiglottis once the posterior wall of the pharynx has been identified. A common mistake is to insert the laryngoscope further without finding the epiglottis and then enter the esophagus, which can lead to serious complications such as an esophageal tear. If the surgeon is not very experienced, he may mistake the lumen of the esophagus for that of the airway and lift the tip of the laryngoscope at that moment, a dangerous maneuver because an arytenoid cartilage can easily shift.
Once the epiglottis is identified, it is raised with the tip of the laryngoscope; now the laryngoscope is carefully inserted and the tip is raised even further to find the glottis, accommodating the instrument to obtain the best possible exposure of the surgical field and fixing it to a solid surface with its appropriate support. In any case, it is advisable to inform the patient about possible complications related to these procedures.
Complications associated with the laryngoscope procedure
Injuries to the lips, teeth or temporomandibular joint, temporomandibular joint dislocation, which is more common in edentulous and elderly patients, but also at the end of the procedure, when the patient is lying on the operating table without raising the back or neck, the occlusion and the condition of the temporomandibular joints should be routinely.