Advancing Airway Management: Laryngoscopy

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Airway management is often undertaken by a variety of practitioners, with a wide array of skills and experience. Individual practitioners develop habits and preferences for the class and types of devices used in airway management based on those devices that are available, supported by protocol as applicable, used with some degree of frequency, and with which proficiency has been achieved.

The challenge is when new airway management devices are brought in for evaluation. Terminology alone can be very confusing—direct, indirect, video, optical, fiber optic, lighted, flexible, rigid, intubating, etc.—making it difficult to choose which class of device, much less a specific device, may work for an individual practice. With this article we hope to help practitioners wade through the sea of names, and understand each class of device and how they work. The airway practitioner can then assess differences between devices within the same class to make knowledgeable decisions about the type to evaluate and use. To guide us through this journey into the nomenclature of airway devices, let’s first take a look at the history of laryngoscopy.

The most common class of laryngoscopy devices, and one that has been in use for over 100 years—since 1895, is the direct laryngoscope (DL) class. First developed and used by the German Alfred Kirstein (1863–1922), this class of laryngoscope used a modified esophagoscope to directly visualize the glottic structures. This class of scopes went through a rapid growth phase and by 1913 Chevalier Jackson proved placement of an endotracheal tube could be obtained with a high rate of success using this technique. In 1919, Sir Ivan Magill in the U.K. introduced the straight blade, modified by Robert A. Miller in 1941, which is still in use today. Sir Robert Macintosh introduced the “curved” blade DL in 1943, which remains in common practice 60-plus years later.

Each device in the DL class utilizes a light source at the distal tip of a (generally) removable locking blade with a handle. The airway practitioner creates a view of the glottic structures by lifting the tongue and other oropharyngeal structures out of the way. Consequently this class of laryngoscopes is extremely dependable and applicable to patients of all sizes and most clinical conditions.

Over the past several decades a newer class of devices known as indirect laryngoscopes (IL) has emerged. An indirect laryngoscope utilizes different methods to look “around” the corner, so the airway practitioner is not required to obtain a direct line of site with the glottis. This is advantageous for those patients in whom manipulating their anatomy into position for the view is impractical or not possible. We begin by discussing the video-assisted indirect laryngoscope, or video laryngoscope.

The video laryngoscope utilizes a small camera, often located midway down the device’s shaft, to view the glottic structures distal to the camera. The camera then sends a video image up the device shaft to a video screen. Examples of this class of device include the GlideScope® series, the C-MAC, the McGRATH®, the Pentax-AWS and the King Vision laryngoscopes. Each device in this group is similar in that there is not the need to move the tongue and oropharyngeal structures out of the way in order to “see” the glottic opening.

Another group of indirect laryngoscopes are the indirect optical devices, or optical laryngoscopes. Optical devices existed even before the DL method, beginning in 1854 with Manual Garcia, a Spanish voice teacher who was the first person in recorded history to view the functioning glottis of a living person. These devices employ an integrated light source and a series of mirrors to transmit the view from the distal lens to a proximal lens that the airway practitioner looks into, and thus provide indirect visualization of the glottis rather than a direct line of site. Two optical laryngoscopes currently available commercially include the Airtraq and the Truview PCD video laryngoscope devices. The Truview is included in this category because it uses an optical blade that incorporates a video feed at its proximal end in order to enlarge the view for the clinician on a separate screen.

Still another device group of indirect laryngoscopes are the fiberoptic stylets, both rigid and semi-rigid. The Shikani Optical Stylet and the BONFILS intubation endoscope are representative of this group. Each device utilizes bundles of glass fibers tucked within a rigid or semi-rigid stylet, which capture light and images on one end and pass this along the length of the fibers to a viewing port on the opposite end. An endotracheal tube is advanced over the stylet and into the glottis once visualization of appropriate structures is obtained.

Fiberoptic stylets have evolved to incorporate video technology. Examples of such video intubating stylets are the Clarus Video System and the Video RIFL. Devices in this class have a video camera located in the distal tip of the stylet connected to a video screen at the proximal viewing end. Just as in the fiber optic stylet class, the endotracheal tube is slid over the stylet once an appropriate view of the glottis is obtained.

The last class of devices utilized in laryngoscopy is the flexible endoscopic class. The flexible bronchoscope and the AMBU aScope illustrate how this class of devices works. Each scope is carefully guided either orally or nasally by the airway practitioner using finger controls at the proximal end of the scope. Visualization occurs either through an eyepiece and/or a video camera and monitoring system. Once the glottic structures are located, an endotracheal tube is advanced over the scope, securing the patient’s airway.

Obtaining the appropriate view and placing an endotracheal tube within the airway is the ultimate goal of laryngoscopy. Knowing the terms used to describe the different classes of devices is crucial to making informed decisions on which class to evaluate for use. In future articles we will delve into the peculiarities of a particular class and discuss the research supporting its use in an emergency.

Kevin Franklin, CFRN, EMT-P, is a flight nurse with West Michigan Air Care in Kalamazoo, MI. He is also utilization review coordinator for Air Care. He is an adjunct lecturer in the Department of EMS at Kellogg Community College in Battle Creek, MI, and is co-owner of Airway Authority Education, LLC, a company developed for initial and continuing education of EMS and other professional emergency providers. He is southeast regional course director for The Difficult Airway Course: EMS.

Jan Eichel, CFRN, BA, EMT-P, is director of clinical operations and a flight nurse with West Michigan Air Care. She has over 20 years of clinical experience in critical care and air medicine. She is active in the Air and Surface Transport Nurses Association and was a contributing author for Transport Nurse Advanced Trauma Course, 4th edition (2006) and 5th edition (2010). She is southeast regional course director for The Difficult Airway Course: EMS.