Accuracy of Bedside Ultrasound for Confirming Endotracheal Tube Tip Position in Critically-Ill Emergency Department Patients

Romulo Iii Babasa, Janna Elyza Olivera


To compare the accuracy of point-of-care airway ultrasound (POCUS) versus post-intubation chest x-ray in identifying proper ETT tip placement and location following emergency intubation using capnography as reference standard.



This was a prospective, single-blinded, single center, cross-sectional diagnostic accuracy study of patients emergently intubated by direct laryngoscopy.

POCUS of suprasternal window was performed on all patients, recording artifacts such as “double trachea” (esophage-al intubation), “double lumen” (endotracheal intubation) and “saline bubbling” (ET cuff saline filling).

Subsequently, post-intubation chest radiograph and capnography were done.

Outcomes measured were sensitivity and specificity of POCUS and chest x-ray in identifying proper endo-tracheal tube placement and location.


For our required sample size of 33, computed at 95% CI with 5% margin of error, we recruited a total of 35 patients into the study.

All 35 patients were successfully intubated on the first attempt with no esophageal intubations recorded. Both chest x-ray and POCUS (double lumen sign) were able to confirm endotracheal placement of ETT in all cases, as correlated with capnography.

POCUS was able to confirm ideal ETT tip position much better than chest x-ray as evidenced by its higher sensitivity of 81.82% and positive predictive value of 93.10% correlated with the capnography reference standard.

The accuracy of POCUS at 77% is also better to that of chest radiography, which was at 65%.

The kappa coefficient between the 2 modalities at 0.42 (moderate agreement) was acceptable


Point-of-care ultrasonography of the suprasternal notch to detect the “double lu-men” and “saline bubbling” artifacts after intubation is a highly sensitive and accurate test compared to chest radiography in confirming endotracheal placement of the ETT as well as location of the ETT tip above the tracheal carina.

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