After endotracheal intubation is performed, the location of the endotracheal tube (ETT) is confirmed followed by assessment of ETT depth. Physical examination can be unreliable and chest radiographs can lead to delayed recognition. Ultrasound may facilitate rapid determination of ETT depth at the bedside; however, the ideal technique is unknown.

This was a randomized trial comparing the static versus dynamic technique for ETT depth assessment using a cadaver model. The ETT was randomized to correct versus deep placement. Seven physicians blinded to ETT location assessed the location using static (direct visualization of an inflated cuff) versus dynamic (active inflation of the ETT cuff) visualization. Outcomes included diagnostic accuracy, time to identification, and operator confidence with subgroup analyses by physician ultrasound experience.

420 total assessments were performed. The static technique was 99.1% (95% CI 94.8%–100%) sensitive and 97.1% (95% CI 91.9%–99.4%) specific. The dynamic technique was 100% (95% CI 96.7%–100%) sensitive and 100% (95% CI 96.7%–100%) specific. Time to identification was faster for the static technique (6.6 s; 95% CI 5.9–7.4 s) versus the dynamic technique (8.7 s; 95% CI 8.0–9.5 s). Operator confidence was lower for the static technique (4.4/5.0; 95% CI 4.3–4.5) versus the dynamic technique (4.7/5.0; 95% CI 4.6–4.8). There were no differences in the findings when assessed among expert or non-expert sonographers.

There was no statistically significant difference in the accuracy of ETT depth identification between the static or dynamic technique. However, utilizing the dynamic technique showed a statistically significant improvement in sonographer confidence and a concomitant increase in time to identification.