Ultrasound guided positioning of laryngeal mask airway in children

Abstract

Objective To evaluate the efficacy of ultrasound-guided laryngeal mask airway (LMA) in children. Methods ASA Ⅰ and Ⅱ children (aged 1 to 6 years) scheduled for orthopedic surgery of limbs were recruited in this study. A LMA was inserted after induction of general anesthesia. After mechanical ventilation for 5 minutes, the air-filled cuff was deflated and then inflated with saline. Ultrasonography was then performed by a high frequency linear-array transducer to confirm the correct placement of the LMA. Results The LMA can be easily recognized on the transverse view of the thyroid cartilage notch, appearing as a circle around the glottis, which was called the dumbbell sign. On the sagittal view of the thyroid cartilage, the LMA has an archlike appearance which ended below the thyroid cartilage. Oblique scan over the cricoid cartilage shows the tip of LMA is located at the upper portion of the esophagus. Conclusions Filling the LMA cuff with saline instead of air allows better LMA visualization by ultrasound. This method enhances correct positioning of the LMA, which is crucial to ensure safe ventilation. Key words: Ultrasonography; Laryngeal masks; Position