**1. Introduction**

Although the use of general anesthesia (GA) has been largely replaced by neuraxial anesthesia, there are certain clinical situations in which the administration of GA is most appropriate [1, 2]. GA is frequently preferred in emergent cases (e.g., fetal bradycardia, massive hemorrhage, maternal coagulopathy, uterine rupture, maternal trauma) as it has a rapid onset and allows for airway ventilation and hemodynamic control [2, 3]. Airway-related complications remain a leading cause of anesthesiarelated maternal mortality [2–7], with approximately 2.3 per 100,000 GAs versus 1 per 180,000 GAs in the general population. Although advanced airway devices (e.g., supraglottic airways, flexible bronchoscopes, and video laryngoscopy) have been increasingly available for difficult airway management, the incidence of failed tracheal intubation in obstetrics cases has remained unchanged over the past 40 years. A 2015 systematic review reported that the incidence of failed intubation for all obstetric procedures was 1 in 390 [8]. The rate of failed obstetric intubation is approximately eight times higher compared with non-obstetric procedures [9]. Significant anatomic and physiological changes of pregnancy have been considered to explain the increased difficulty in obstetric airway management [2–4]. Several suggestions have been proposed to reduce the difficulty of maternal airway management [10, 11].
