The laryngeal mask airway(LMA) is a new type of airway that has many advantages compared with the tracheal tube, but its potential problem might be pulmonary aspiration. This study therefore was designed to investigate the risk of pulmonary aspiration during general anesthesia using LMA.

We studied 101 patients who received general inhalation anesthesia with LMA and mechanical positive pressure ventilation for gynecological operations. Methylene blue was poured into the oropharynx after the LMA was placed, and the presence or absence of the dye staining of the larynx, tracheal and main stem bronchi with fiberoptic bronchoscope through the LMA shaft lumen was observed one and/or two hour(s) after LMA placement.

In two out of 101 patients there was staining of the larynx with methylene blue dye. One was one hour after and the other was stained two hours after LMA placement.

Dye staining of the larynx suggests that even mechanical positive pressure ventilation with LMA placement have the risk of pulmonary aspiration. Therefore LMA is contraindicated if the stomach is not emptied.