LARYNGEAL MASK AIRWAY POSITION AND THE RISK OF GASTRIC INSUFFLATION

A potential risk of the laryngeal mask airway (LMA) is an incomplete m ask seal causing gastric insufflation or oropharyngeal air leakage. Th e objective of the present study was to assess the incidence of LMA ma lpositions by fiberoptic laryngoscopy, and to determine their influenc e on gastric insufflation and oropharyngeal air leakage. One hundred e ight patients were studied after the induction of anesthesia, before a ny surgical manipulations. After clinically satisfactory LMA placement , tidal volumes were increased stepwise until air entered the stomach, airway pressure exceeded 40 cm H2O, or air leakage from the mask seal prevented further increases in tidal volume. LMA position in relation to the laryngeal entrance was verified using a flexible bronchoscope. The overall incidence of LMA malpositions was 40% (43 of 108). Gastri c air insufflation occurred in 19% (21 of 108), and in 90% (19 of 21) of these patients, the LMA was malpositioned. Oropharyngeal air leakag e occurred in 42%, and was independent of LMA position. We conclude th at clinically unrecognized LMA malposition is a significant risk facto r for gastric air insufflation. Implications: Routine placement of lar yngeal mask airways does not require laryngoscopy. In our study, fiber optic verification of mask position revealed suboptimal placement in 4 0% of cases. Such malpositioning considerably increased the risk of ga stric air insufflation.