Patient-specific depth of endotracheal intubation-from anthropometry to the Touch and Read Method

Objective: Knowledge of accurate airway length (AL) enables safer placement of the endotracheal tube (ETT) in the trachea. Our objective was to check the safety of a new formula (Touch and Read method) to determine ETT depth.

Methods: AL was measured in 176 patients. Patients were divided into a normal group (AL >25 cm in men, >23 cm in women) and a risk group (AL ≤25 cm in men, ≤23cm in women). A control test (Conventional method) was performed in which the ETT was secured at a depth of 23 cm from the central incisor in men and 21 cm in women. In the experimental test (Touch and Read method), the ETT was secured at a depth equal to the distance from the angle of the mouth to the epiglottis tip plus 12.5 cm in men and 11.5 cm in women. The mean distance from the tube tip to the carina and that from the vocal cords to tube cuff were compared between the control and experimental tests in each group.

Results: The two distances were similar between control and experimental tests in the normal group, but differed in the risk group (Women: mean distance from tube tip to carina, 1.2 cm and from vocal cords to cuff, 2.7 cm [control test]; 1.9 and 2.0 cm, respectively [experimental test]. Men: 0.7 and 3.5 cm, respectively [control test]; 2.0 and 2.3 cm, respectively [experimental test]).

Conclusion: Touch and Read method enables safer placement of the ETT in the trachea than the conventional method in the risk group.