Proper depth of placement of nasotracheal tubes in adults prior to radiographic confirmation

Objective: To determine the optimal initial depth of tube placement in nasotracheal intubation (NTI) of adult patients, measured at the naris, prior to obtaining a chest radiograph (CXR). Methods: Part 1: A prospective, observational study was performed to compare the initial depth of NTI, measured at the naris, with the observed height of the endotracheal tube (ETT) tip above the carina on the initial CXR. Optimal depths were predicted by gender. Part 2: Results from Part I were prospectively validated by measuring the frequency of adequate placement when ETTs were placed to this depth. ETT placement was considered adequate if the tip was at least 2 cm above the carina and below the larynx on the CXR. Results: Part 1: The mean depth measured at the naris was 27.5 ± 1.5 cm in women (n = 50) and 27.8 ± 1.0 cm in men (n = 74). The mean distance of the tip of the ETT to the carina was 3.9 ± 2.7 cm in women and 6.4 ± 2.2 cm in men. Initial tube position was adequate in 39 (78%) of the women and 72 (97%) of the men. It was determined that if a depth of 26 cm had been used in the women and 28 cm in the men, 45 (90%) of the women and 70 (95%) of the men would have had adequate tube placement, resulting in statistically significant improvement of placement in the women (p < 0.05; McNemar x²). Part 2: These calculated depths (26 and 28 cm) were then prospectively applied in 26 women and 52 men. Twenty-five (96%) of 26 women and 51 (98%) of 52 men had adequate placement, with a mean height above the carina of 4.5 ± 1.4 cm in women and 5.6 ± 1.8 cm in men. Conclusion: Initial placement of NTI at 26 cm in women and 28 cm in men, measured at the naris, resulted in adequate initial placement for most adult patients.