INTRODUCTION CHAPTER 23 Non–Laryngeal Mask Airway Supraglottic Airway Devices 467 Nothing is more fundamental to the practice of general anesthesia than the maintenance of a clear upper airway. The choice of device depends on several factors, including access to the airway, duration of surgery, and risk factors for aspiration. After placement, the cuffed ETT provides a secure airway and protects against aspiration, but placement and removal of an ETT require training and judgment. Although ETTs typically are used without incident, complications ranging from trivial to lifethreatening can occur.1 Advanced airway management depends on many airway devices, several of which have been included in the American Society of Anesthesiologists (ASA) difficult airway algorithm.2 The Classic laryngeal mask airway (LMA Classic, LMA North America, San Diego, CA) was introduced into clinical practice in 1988. Since then and particularly in the past 10 years, there has been an explosion of supraglottic airway devices (SADs) designed to compete with the LMA Classic, especially single-use devices. The introduction of single-use devices has been driven by concern about the sterility of cleaned, reusable devices (e.g., elimination of proteinaceous material, risk of transmission of prion disease) and the inability to recycle the device enough to be cost-effective. More than 20 manufacturers produce single-use LMs. Other designs of SADs have been introduced, and they are the main focus of this chapter. II. NOMENCLATURE The term supraglottic airway device (SAD) is used to describe a group of airway devices designed to establish and maintain a clear airway during anesthesia. SADs have several roles, including maintenance of the airway during spontaneously breathing or controlled-ventilation anesthesia, airway rescue after failed intubation or out of the hospital, use during cardiopulmonary resuscitation, and use as a conduit to assist difficult tracheal intubation. Brimacombe recommended that the term extraglottic airway be used, because many of these devices have components that are infraglottic (i.e., hypopharynx and upper esophagus).3 This textbook describes all airway devices that have a ventilation orifice or orifices above the glottis as supraglottic and those that deliver anesthetic gases or oxygen below the vocal cords (e.g., transtracheal jet ventilation, cricothyrotomy) as infraglottic. Other terms and acronyms include supraglottic airway (SGA), extraglottic airway device (EAD), and periglottic airway device (PAD), but SAD is more widely accepted and is used in this chapter. Brimacombe and Miller suggested there should be a classification system for this increasingly complex family of devices. Miller4 described three main sealing mechanisms: cuffed perilaryngeal sealers, cuffed pharyngeal sealers, and cuffless, anatomically preshaped sealers. Further subdivision can be made by considering whether the device is single use or reusable and whether protection from aspiration of gastric contents is offered. The practical value of this type of classification is uncertain. Chapters 22 and 27 review the LMA, its variants, and the Combitube. The acronym LMA is a protected term and should be used to refer to any laryngeal mask airway produced by the manufacturers of the LMA Classic (LMA North America and associated international companies). The acronym LM refers to a laryngeal mask manufactured by anyone other than the original manufacturers. First-generation SADs are devices that can be considered simple airway tubes. They include the LMA Classic, a flexible LMA (LMA Flexible), and all LMs. They also include the Laryngeal Tube and the Cobra perilaryngeal airway (CobraPLA). They may or may not protect against aspiration in the event of regurgitation, but they are not specifically designed to lessen this risk. Second-generation SADs have been designed with safety in mind, and they incorporate design features that aim to reduce the risk of aspiration.5 They include the ProSeal LMA (PLMA), i-gel, LMA Supreme, Laryngeal Tube Suction II (LTS-II), disposable version of the LTS (LTS-D), the Streamlined Liner of the Pharynx Airway (SLIPA), and the Baska mask. The efficacy of several of these designs has not been proven. III. LIMITATIONS OF THE CLASSIC LARYNGEAL MASK AIRWAY Prior to 1988, choices of airway devices essentially were limited to the face mask and endotracheal tube (ETT). The LMA Classic was designed by Archie Brain in the United Kingdom in the early 1980s, and it was introduced into anesthetic practice in 1988. Its introduction revolutionized airway management (Fig. 23-1). It was soon recognized to be a suitable device to use for many cases that previously were managed with a face mask or an ETT, because the LMA Classic had many advantages over both devices.6 It has been used in approximately 200 million episodes of anesthesia globally. More than 2500 1988