Comparison of the flexible and standard laryngeal mask airways

Reports of Investigation



To determine mucosal pressures, ease of insertion, mask position and oropharyngeal leak pressures for the flexible (FLMA) and standard laryngeal mask airway (LMA).


Forty anesthetized, paralysed adult patients were randomly allocated to receive either the FLMA or LMA. Microchip sensors were attached to the LMA or FLMA at identical locations corresponding to the base of tongue, hypopharynx, lateral pharynx, oropharynx, posterior pharynx and pyriform fossa. Mucosal pressure, oropharyngeal leak pressure (OLP) and mask position (assessed fibreoptically) were recorded during inflation of the cuff from 0–40 ml in 10 ml increments.


Ease of insertion and mask position were similar between devices. Mean OLP was higher for the LMA (22 vs 19 cm H2O), but the maximum OLP was similar (25 vs 24 cm H2O). Mean mucosal pressures were generally low (< 12 cm H2O) for both devices, but were higher for the LMA in the lateral pharynx (4 vs 1 cm H2O) and oropharynx (13 vs 3 cm H2O) and higher in the posterior pharynx for the FLMA (4 vs 2 cm H2O). The OLP for both devices increased with increasing intracuff volume from 0–10 ml and 10–20 ml, and from 20–30 ml for the FLMA.


We conclude that the LMA and FLMA perform similarly in terms of ease of insertion and mask position, but OLP and mucosal pressures are slightly higher for the LMA. Pharyngeal mucosal pressures for both devices are lower than those considered safe for the tracheal mucosa. The overall clinical performance between the two devices is similar.


Laryngeal Mask Airway Intracuff Pressure Posterior Pharynx Cuff Volume Pyriform Fossa 
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Déterminer les pressions exercées par la muqueuse, la facilité d’insertion, la position du masque et les pressions liées aux fuites oropharyngées concernant le masque laryngé flexible (MLF) et le masque laryngé standard (ML).


Quarante patients adultes, sous anesthésie, ont été répartis au hasard et ont reçu soit le MLF soit le ML. Des détecteurs électroniques ont été attachés au ML ou au MLF à des endroits identiques correspondant à la base de la langue, à l’hypopharynx, au pharynx latéral, à l’oropharynx, au pharynx postérieur et à la fosse piriforme. La pression de la muqueuse, la pression de fuite oropharyngienne (PFO) et la position du masque (évaluée par fibroscopie) ont été notées pendant le gonflement du ballonnet de 0–40 ml en incréments de 10 ml.Résultats: La facilité d’insertion et la position du masque ont été similaires pour les deux appareils. La PFO moyenne a été plus élevée avec le ML (22 vs 19 cm H2O), mais la PFO maximale a été similaire (25 vs 24 cm H2O). Les pressions muqueuses moyennes ont été généralement basses (< 12 cm H2O) pour les deux masques, mais plus élevées pour le ML dans le pharynx latéral (4 vs 1 cm H2O) et l’oropharynx (13 vs 3 cm H2O) et plus élevées dans le pharynx postérieur pour le MLF (4 vs 2 cm H2O). La PFO a augmenté avec le gonflement du ballonnet de 0–10 ml et de 10–20 ml pour les deux masques, et de 20–30 ml pour le MLF


Nous concluons que le ML et le MLF sont similaires quant à la facilité d’insertion et à leur position, mais la PFO et les pressions muqueuses sont légèrement plus élevées avec le ML. Les pressions de la muqueuse pharyngée, pour les deux masques, ont été plus basses que celles qu’on considèrent habituellement sans risque pour la muqueuse trachéale. Le bilan général est similaire pour les deux appareils.


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Copyright information

© Canadian Anesthesiologists 1999

Authors and Affiliations

  1. 1.Department of Anaesthesia and Intensive CareCairns Base HospitalThe EsplanadeAustralia

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