Optimal size selection of the classic laryngeal mask airway by tongue width-based method in male adults.

BACKGROUND: Proper size selection is crucial to the effective use of a laryngeal mask airway (LMA). The current choice of LMA size is based on body weight; in addition, the sex-based selection has also been suggested. However, the relationship between body weight, sex, and the dimension of hypopharynx where the LMA is positioned are inconsistent. Here we examined a tongue width-based method to determine the optimal size for the classic LMA (cLMA). METHODS: The enrolled patients had two different cLMA size selections, determined by both weight-based formula and tongue width-based method. Twenty-one male patients were studied. For the tongue width-based method, we made four rulers of different widths that corresponded to the four different cLMAs (Nos. 2.5, 3, 4, and 5) The patient was asked to open his mouth and protrude his tongue; the optimal size of cLMA was determined by the corresponding ruler which had the same tongue width of the patient. Two insertions with different-size cLMAs were randomly performed in every patient. Five parameters - frequency of insertion attempts, the presence of cuff in the mouth, end-tidal CO2 shown on monitor, oropharyngeal leak pressure, and fiberoptic score - were measured following each cLMA insertion. RESULTS: For all of the five measured parameters, the tongue width-based method was better than weight-based formula in determining optimal cLMA size selection. CONCLUSION: The tongue width-based method is a convenient and efficacious alternative for selecting an optimal cLMA size in male adults.