Standardization of Extraglottic Airway Devices, Is It Time Yet?

To the Editor

Since the introduction of the laryngeal mask airway into clinical practice (1988),¹ the number and variety of extraglottic airway devices (EADs) has multiplied. Most manufacturers use a weight-based sizing system although some have introduced alternative recommendations based on a variety of patient variables (height, gender, age), including a “1 size fits all” (Table 1).

Table: No title available.

An appropriate size is critical to optimal use of an EAD, although predicting the “most” appropriate is not easy due to the inconsistent relationship between oropharyngeal geometry and the patient’s gender and body weight.² Furthermore, developing a sizing guide that fits all shapes of EADs is quite challenging due to the shape of the extraglottic anatomy.

The ultimate goal of designers of a new EAD is to match the natural curve of the EAD with the natural curve of the pharyngeal structures so that an optimal seal is obtained.³ Consequently, this necessitates great flexibility of the EAD.

Most of the research on EADs has been performed using Caucasian patients, although other races differ substantially in their physical stature and cephalometric proportions,^4–6 and hence, racial/ethnic differences may influence sizing of EADs.⁷

Several questions remain: (1) Will a patient who loses or gains substantial weight need a different EAD size?; (2) Is “gender-based” sizing more appropriate than “weight-based” sizing?; (3) Does a weight-based formula also apply to children?

According to the recent American Society for Testing and Materials standards adopted by the Supralaryngeal Airway Task Group, manufacturing sizing recommendations are inadequate and they stress the need for expert clinical judgment in selecting the size of an EAD.⁸ We encourage American Society for Testing and Materials and the manufacturers of EADs to develop a coherent and universal industry-wide standard sizing system to avoid the risk of improper EAD size selection by the clinician.

Tom C. R. V. van Zundert, MD

Department of Anesthesiology

Maastricht University Medical Centre

Maastricht, The Netherlands

[email protected]

Carin A. Hagberg, MD

Joseph C. Gabel Professor and Chair

Department of Anesthesiology

The University of Texas Medical School at Houston

Houston, Texas

Davide Cattano, MD, PhD

Department of Anesthesiology

Memorial Hermann Hospital-TMC

The University of Texas Medical School at Houston

Houston, Texas