Yamanaka H, et al. - Researchers determined the changes in the length of the trachea (t-length) and the distance between the nare and the vocal cords (n-v-distance) in patients aged 2-8 year undergoing dental surgery. They fixed the nasotracheal tube at the patient's nares following nasotracheal intubation. They measured the distance between the tube tip and the first carina by using a fibrescope with the angle between the Frankfort plane and horizontal plane set at 110°. Then, they checked the location of the tube in relation to the vocal cords and repeated these measurements at angles of 80° (flexion) and 130° (extension). They used these measurements to calculate the t-length and n-v-distance. They found that the main determinants of a change in the position of the tracheal tube tip in the trachea were the changes in t-length during paediatric dental surgery.