Can Imaging Techniques Contribute to the Proper Insertion of Double-lumen Tubes?

Ultrasound measurements will be made with a 5-10 MegaHertz linear probe positioned in the horizontal plane at the midline of the anterior neck. After identifying the vocal cords as paired hyperechoic linear structures, the probe was moved caudally to visualize the cricoid arch. The transverse air column diameter was measured at the lower border of the cricoid cartilage.