The following is the summary of “Diagnostic accuracy of ultrasound to confirm endotracheal tube depth” published in the December 2022 issue of Emergency medicine by Gottlieb, et al.
The Emergency Department is a popular setting for the administration of endotracheal intubation. Estimates and confirmations of the endotracheal tube (ETT) depth made using conventional methods may be erroneous or cause delayed recognition. At the bedside, an ultrasound could provide a quick method of confirming the ETT depth. Here, a randomized clinical experiment tested ultrasound’s diagnostic accuracy in verifying ETT depth. A random order was used to intubate 3 cadavers, with the ETT either inserted high (immediately below the vocal cords), moderately (2 cm above the carina), or deeply (ETT at the carina). Ultrasound measurements of ETT depth were made by 7 blindfolded sonographers. Sonographer identification, diagnostic accuracy, identification time, and operator ETT confidence were measured as outcomes.
Diagnostic accuracy was broken down into several groups according to operators’ levels of self-assurance. A total of 441 evaluations were carried out (154 high, 154 middle, and 133 deep ETT placements). There was an overall accuracy of 84.8% (95% CI: 81.1% to 88.0%). It took an average of 15.3 s (95% CI 13.6-17.0) and an average operator confidence of 3.9/5.0 (95% CI 3.7-4.1) for an ultrasound to identify a target when positioned high, with a sensitivity of 82.5% (95% CI 75.5% to 88.1%) and a specificity of 92.3% (95% CI 88.6% to 95.1%). With the ETT centered, ultrasound had a sensitivity of 83.8% (95% CI, 77.0% to 89.2%), specificity of 92.3% (95% CI, 88.6% to 95.1%), a time to identification of 16.7 seconds (95% CI, 14.6-18.8%), and an operator confidence of 3.7/5.0 (95% CI, 3.5-3.9).
In patients with a deep ETT placement, ultrasonography had a sensitivity of 88.0% (95% CI 81.2% to 93.0%), specificity of 92.2% (95% CI 88.6% to 94.6%), a mean time to identification of 19.0 s (95% CI 17.3-20.7), and an average operator confidence of 3.4/5.0 (95% CI 3.2-3.6). When sonographers reported a higher confidence score, they were much more accurate. When sonographers were confident in their visualization, ultrasound detected the ETT location with a moderate degree of accuracy in a cadaveric model. Combining transtracheal ultrasonography with lung sliding and other adjustments to increase accuracy should be investigated further in future studies.