ETT Placement Confirmation During Cardiac Arrest: US for the Win!
Resident Clinical Pearl – November 2015
Kalen Leech-Porter, PGY 1, iFMEM, Saint John NB, Dalhousie University
Reviewed by: Dr Jay Mekwan and Dr David Lewis
The AHA has updated their guidelines for CPR and emergency cardiovascular care this year (2015)[i]. Previously, there were insufficient studies to warrant a recommendation for Point of Care Ultrasound (PoCUS) for ETT confirmation, however, a new study has emerged to suggest that PoCUS can be a useful adjunct for ETT placement confirmation. A 96 patient observational study done on patients during cardiac arrest, found that PoCUS had a sensitivity of 98.9% and a specificity of 100%[ii]. ETT placement was determined by placing the ultrasound transducer transversely above the suprasternal notch to identify endotracheal or esophageal intubation. It was determined during the study that in using this method ultrasound could be completed without interrupting chest compressions.
As the above study has yet to be replicated, end-tidal CO2 remains the gold standard for ETT placement confirmation (an observational, prospective study of 566 patients found colorimetric to be 95.6% sensitive, 99.8% specific[iii]) during cardiac arrest. However, AHA has added ultrasound as an additional method for confirmation of endotracheal tube placement, with the caveat that ultrasound should never interfere with the continuous conduction of high-quality CPR.
How to confirm ETT with PoCUS:
Video by Haney Mallemat
Video by Joseph Minardi
Abridged Instructions from ACEP Tips and Tricks [iv]
- Place the high frequency linear probe transversely just above the sternal notch (Image A); note normal airway anatomy (Image B), prior to ETT placement (if time permits)
Image A
From: Joseph Minardi’s Video [see above]
Image B
From: Halley Mallemat’s video [see above]
Trachea: Hyperechoic, curvilinear with comet-tail artifact
Esophagus: more distal, oval with heyperchoic wall and hypoechoic center
- PoCUS ETT confirmation can be done in real time, as ETT is placed, or done post placement. Successful ETT: there will be a slight increase in artifact/shadowing in trachea region only, known as the “Bullet Sign” (Image C) [v]. The operator should see reverberations in the trachea’s anterior lumen. To further confirm can slightly shake the ETT, this should only show trachea movement.
Image C
From: Mark Favot [v]
- Esophageal Intubation: will cause a second ‘trachea’ appear (Image D and E), referred to as the “double tract sign”
Image D
From: Halley Mallemat’s video [see above]
Image E
From ACEP Tips and Tricks [iv]
- Pitfalls: the esophagus may be located directly posterior to the trachea, therefore esophageal intubation may be missed if inadequate depth is used.
- Additionally, observing bilateral lung sliding while bagging a paralyzed patient also suggest ETT confirmation.
References
[i] Web-based Integrated 2010 & 2015 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care; Part 7: Adult Advanced Cardiovascular Life Support. (Nov. 25, 2015) https://eccguidelines.heart.org/index.php/circulation/cpr-ecc-guidelines-2/part-7-adult-advanced-cardiovascular-life-support/
[ii] Sun, Jen-Tang, Sim, Shyh-Shyong, et al. “Ultrasonography for proper endotracheal tube placement confirmation in out-of-hospital cardiac arrest patients: two-center experience.” Critical Ultrasound Journal 6 (2014): A29 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4101346/
[iii] Hayden, SR., and Sciammerella, J., et al. “Colorimetric end-tidal CO2 detector for verification of endotracheal tube placement in out-of-hospital cardiac arrest.” Acad Emerg Med 6 (1995): 499-502 http://www.ncbi.nlm.nih.gov/pubmed/7497049
[iv] Chao, Alice and Ghrahbaghaian, Laleh. “Tips and Tricks: Airway Ultrasound.” American College of Emergency Physicians Emergency Ultrasound Section Newsletter (June, 2015). http://www.acep.org/Content.aspx?ID=102309
[v] Favot, Mark. “Ultrasound for Verification of Endotracheal Intubation.” FOAM EM (March, 2015). http://www.foamem.com/2015/03/02/ultrasound-for-verification-of-endotracheal-tube-location/
