Knowledge regarding normal upper airway anatomy is essential for airway management and is required to prevent malpositioning of endotracheal tubes. We evaluated the length of the upper airway in Korean children and adults who had no abnormality of the upper airway using a fiberoptic bronchoscope.

Eighty seven patients aged 5 to 81 years undergoing noninvasive elective surgery were included in this study. After induction of anesthesia was complete, we measured the distance from the upper incisor to various components of the upper airway by fiberoptic bronchoscopy.

In adults, the mean length between the upper incisor and midtrachea was found to be 21.8 ± 1.8 cm in males and 19.9 ± 1.3 cm in females, while the mean length of the trachea was 10.1 ± 1.3 cm in males and 10.3 ± 1.6 cm in females. The length between the upper incisor and midtrachea (IT) were correlated with height both in children (IT [cm] = 2.531 + 0.109 × height [cm]) and adults (IT [cm] = 0.167 + 0.127 × height [cm]), which shows that they differ from the western standard (length of tube [cm] = 5 + 0.1 × height [cm]).

In adults and children, the length from the incisor to the midtrachea was significantly different when compared with western standards. Therefore, re-evaluation of the proper and precise depth of endotracheal tube in Koreans should be considered.