BACKGROUND: : Although the estimated risk of life-threatening adverse respiratory events during supraglottic airway device use is rare, the reported rate of events leading to failure of the airway device is 0.2-8%. Little is known about the risk-adjusted prediction of Laryngeal Mask Airway failure requiring rescue tracheal intubation and its impact on patient outcomes. METHODS: : All adult patients in whom a laryngeal mask airway (LMA Unique[TM], uLMA[TM]; LMA North America, Inc., San Diego, CA) was used in ambulatory and nonambulatory anesthesia settings were included. The primary outcome was uLMA[TM] failure, defined as an airway event requiring uLMA[TM] removal and tracheal intubation. The secondary outcomes were the incidence of difficult mask ventilation and unplanned hospital admissions. RESULTS: : Of the 15,795 cases included in our study, 170 (1.1%) experienced the primary outcome of uLMA[TM] failure. More than 60% of patients with uLMA[TM] failure experienced significant hypoxia, hypercapnia, or airway obstruction, whereas 42% presented with inadequate ventilation related to leak. Four independent risk factors for failed uLMA[TM] were identified: surgical table rotation, male sex, poor dentition, and increased body mass index. A 3-fold increased incidence of difficult mask ventilation was observed in patients with uLMA[TM] failure. Among outpatients with uLMA[TM] failure, 13.7% had unplanned hospital admission, 5.6% of whom needed intensive care for persistent hypoxemia. CONCLUSIONS: : The study supports the use of the uLMA[TM] as an effective supraglottic airway device with a relatively low failure rate. However, there are clinically relevant consequences of uLMA[TM] failure, as evidenced by the high rate of acute respiratory events and need for unplanned hospital admissions. [ABSTRACT FROM AUTHOR]