CHAPTER 9: Direct Laryngoscopy

INTRODUCTION

In this day and age with video laryngoscopy (VL) rapidly becoming more freely available for orotracheal intubation (OTI) one might ask if there is still a need for a chapter on direct laryngoscopy (DL). However, while VL is gaining ground on DL, particularly in countries with developed economies, VL has yet to replace DL as the most common device employed worldwide to facilitate OTI. Proficiency with DL remains a vitally important skill for difficult and failed intubation rescue, and in parts of the world that cannot afford or do not have access to VL.¹

What Is the History and Evolution of Direct Laryngoscopy?

In the modern era, DL is usually associated with tracheal intubation, even though the procedure was initially developed for diagnosing and treating laryngeal pathology. Following the development of mirror laryngoscopy in the 1800s by Garcia, Tuerck, and Czermak,² Kirstein reported the first use of DL in 1895.³ Over the next twenty years, the basic tenets of the procedure were refined by surgeons interested in laryngeal examination and surgical exposure.

A step-wise approach, the focus on epiglottoscopy, recognition of posterior laryngeal landmarks, optimal positioning for laryngeal exposure, and the benefits of external laryngeal manipulation and head elevation, etc. were all detailed by Chevalier Jackson in his 1922 text, “Bronchoscopy and Esophagoscopy, a Manual for Peroral Endoscopy and Laryngeal Surgery.”⁴

With the evolution of modern anesthesia, the straight laryngoscope designs developed by ear, nose, and throat (ENT) surgeons gave way to instruments specifically designed for tracheal intubation, such as the straight Magill (1930),⁵ Miller blades (1941),⁶ and the curved Macintosh blade (1943).⁷ It was also during this time that the design of a detachable blade and battery handle became commonplace.

Between the 1930s and 1970s many different laryngoscope blades were designed to facilitate intubation (e.g., Wisconsin, Phillips, Guedel, etc.), but the Magill, Miller, and Macintosh models (albeit with some modifications) remain universally used, and in most settings, are the only laryngoscope blades available.

The development of flexible fiberoptics, with subsequent attachment of fiberoptics to rigid blades (Bullard laryngoscope,⁸ WuScope,⁹ etc.), and more recently video laryngoscopes (GlideScope, McGrath, Storz Video MAC, etc.)¹⁰ have spawned a wide array of indirect visual devices for both diagnostic imaging of the larynx and tracheal intubation, leaving a narrowed clinical role for standard, line-of-sight (LOS), DL. Alternative devices are being increasingly deployed for both routine and anticipated “difficult laryngoscopy.”

EQUIPMENT

What Are the Principal Design Components and Function of Laryngoscopy Blades?

Laryngoscope blade design, light, and battery systems affect procedural performance due to their impact on illumination, laryngeal exposure, and endotracheal tube (ETT) delivery. Laryngeal exposure is achieved by managing the oral opening and teeth, the tongue and epiglottis, all of which interpose ...