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 (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.