Predictors and clinical outcomes from failed Laryngeal Mask Airway Unique™: a study of 15,795 patients.

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™, uLMA™; LMA North America, Inc., San Diego, CA) was used in ambulatory and nonambulatory anesthesia settings were included. The primary outcome was uLMA™ failure, defined as an airway event requiring uLMA™ 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™ failure. More than 60% of patients with uLMA™ failure experienced significant hypoxia, hypercapnia, or airway obstruction, whereas 42% presented with inadequate ventilation related to leak. Four independent risk factors for failed uLMA™ 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™ failure. Among outpatients with uLMA™ 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™ as an effective supraglottic airway device with a relatively low failure rate. However, there are clinically relevant consequences of uLMA™ failure, as evidenced by the high rate of acute respiratory events and need for unplanned hospital admissions.