Yao et al reported formulas for estimating the intubation tube depth for a Japanese adult. The authors are from Showa University in Tokyo.
These formulas are similar to those of Chula, Hunyady and Morgan.
Patient selection: >= 17 years of age
Parameters:
(1) height in cm
(2) designation marker (DM) length in cm (may vary with each product): the distance between the distal edge of the intubation guide and the tip (see Figure 6)
The oral upper airway is relative to the tip of the incisors and extends to the arytenoids.
The nasal upper airway is relative to the tip of the nostrils and extends to the arytenoids.
oral upper airway in cm =
= ((height) / 10) -3
oral upper airway for fixation in cm =
= ((height) / 10) -3 + (DM)
nasal upper airway in cm =
= ((height) / 10) + 1
nasal upper airway for fixation in cm =
= ((height) / 10) + 1 + (DM)
