Airway length in adults: estimation of the optimal endotracheal tube length for orotracheal intubation

Abstract

Study objective: To estimate the optimal endotracheal tube (ETT) length in orotracheally intubated patients.

Design: Prospective study.

Setting: Operating room of a medical center hospital.

Patients: 293 ASA physical status I and II patients (150 male and 143 female), requiring general anesthesia and orotracheal intubation.

Interventions: We used fiberoptic bronchoscope within the ETT to identify the carina and vocal cords.

Measurements: The length from carina to vocal cords, vocal cords to right mouth angle (corner), and carina to right mouth angle were measured. The optimal ETT tip was defined as 5 cm above the carina. Patient's height and sternum length were recorded.

Main results: The correlation between airway length and body height was significant. By linear regression, a formula was obtained to estimate the optimal ETT length in orotracheally intubated patients: the length from 5 cm above carina to right mouth angle (cm) =< body height (cm)/5> - 13.

Conclusion: The optimal insertion length of the ETT for orotracheally intubated adult patients with the head placed in a neutral position is correlated with body height. The proposed formula can provide a useful guide to determine the optimal ETT tip position in most of the patients who required orotracheal intubation.