title: The anatomical position of three extraglottic airway devices in patients with clear airways.
abstract: We tested the hypothesis that, in patients with clear airways, the anatomical position of three single-use extraglottic airway devices is similar. The airways studied were: the laryngeal mask airway unique (LMA-U), the Softseal laryngeal mask airway (SS-LM) and the Cobra perilaryngeal airway (Cobra-PLA). Three hundred spontaneously breathing patients were randomly allocated to have their airway managed using one of these three supraglottic airway devices. A rigid endoscope was passed down the airway tube and the following anatomical assessments were made: position of the epiglottis; position of the glottis; and position of the cuff. The epiglottis was more frequently visible with the LMA-U than with the SS-LM (76 vs 57%, p = 0.006) and with the LMA-U than with the Cobra-PLA (76 vs 46%, p < 0.0001). The epiglottis was in contact with the mask aperture bars in 25% of patients, and in 34% of these, the epiglottis was seen to be herniated through the aperture bars. Herniation of the epiglottis through the mask aperture bars occurred more frequently with the Cobra-PLA than the LMA-U (8 vs 3%, p = 0.008). The vocal cords and arytenoids were more frequently visible with the LMA-U and SS-LM than with the Cobra-PLA (both p < 0.006). Herniation of the arytenoids through the mask aperture bars was more frequently seen with the Cobra-PLA than with the LMA-U (8 vs 0%, p = 0.004). The position of the cuff was optimal for the LMA-U and SS-LM in 90% and 93% of patients, respectively. The cuff was more frequently in the midline with the LMA-U than with the SS-LM (p = 0.002). We conclude that the anatomical position of the LMA-U and SS-LMA is superior to that of the Cobra-PLA in patients with clear airways. The mask aperture bars probably have no anatomical utility and predispose to herniation of the pharyngeal structures.
authors.affiliation: Deparmtent of Anaesthesiology, Intensive Care and Pain Therapy, Catharina, Hospital--Brabant Medical School, Eindhoven, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: van Zundert
authors.forename: J
authors.initials: J
authors.lastname: Brimacombe
authors.forename: R
authors.initials: R
authors.lastname: Kamphuis
authors.forename: M
authors.initials: M
authors.lastname: Haanschoten
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001193:Arytenoid Cartilage / Q000033:anatomy & histology; D004209:Disposable Equipment; D004825:Epiglottis / Q000033:anatomy & histology; D005260:Female; D005931:Glottis / Q000033:anatomy & histology; D006547:Hernia / Q000209:etiology; D006801:Humans; D007818:Laryngeal Diseases / Q000209:etiology; D017214:Laryngeal Masks / Q000009:adverse effects; D007830:Larynx / Q000033:anatomy & histology*; D008297:Male; D008875:Middle Aged