Do mask aperture bars of extraglottic airway devices prevent prolapse of epiglottis causing airway obstruction? A randomized crossover trial in anesthetized adult patients.

STUDY OBJECTIVE: The study objective is to determine whether extraglottic airway devices (EADs) with or without mask aperture bars (MABs) result in similar anatomical positions in patients undergoing surgery.

DESIGN: Prospective, randomized, crossover comparison of four extraglottic airway devices.

SETTING: Operating theatre at a large teaching hospital.

PATIENTS: Eighty consenting patients scheduled to undergo surgery with general anesthesia.

INTERVENTIONS: Patients were randomly allocated to receive anesthesia with one of four tested EADs. Two versions of each EAD were inserted in random order; one with and one without MABs.

MEASUREMENTS AND MAIN RESULTS: Endoscopic evaluation did not demonstrate any difference between the EADs with or without MABs. Contact between MABs and arytenoids (n=15) and herniation of arytenoids (n=7) was restricted to the Cobra-group patients. In nine patients the epiglottis made contact with a MAB, although this contact was very limited and often unilateral.

CONCLUSION: This study demonstrated that the anatomical position of the four tested single-use EADs is similar with or without mask aperture bars. We therefore question whether MABs have a protective role in prevention of airway occlusion and whether MABs are essential components. In the overall majority of EADs with MABs, the latter did not prevent contact with the epiglottis. Contact and herniation of the laryngeal structures are seen more frequently when more than two MABs are present.