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Transtracheal ultrasound to confirm tracheal intubation in cardiopulmonary arrest

Three Part Question

In [adult patients in cardiopulmonary arrest], is [transtracheal ultrasonography] reliable at [confirming tracheal tube placement]?

Clinical Scenario

A 40-year-old man is brought into the emergency department in cardiopulmonary arrest. It is agreed by the cardiac arrest team that endotracheal intubation is now appropriate to manage the airway. You usually use end-tidal CO2 (ETCO2) waveform analysis to confirm tube placement—but are aware that it is not so reliable during cardiac arrest. You wonder if transtracheal ultrasonography is a good tool to confirm endotracheal intubation in this situation.

Search Strategy

Medline using OVID up to September week 1:

Embase using NHS Evidence 16 July 2014:

The Cochrane Library Issue 6 of 12 June 2014:

Medline using OVID up to September week 1: [[exp Intubation, Intratracheal/ OR ( AND { or exp Intubation/})] AND [ OR Ultrasonography/)R ultrasonograph$.mp]] LIMIT to [english language and humans].

Embase using NHS Evidence 16 July 2014: [exp ultrasound] AND [exp endotracheal intubation/ OR “intratracheal intubation”, ti, ab] AND [exp capnometry OR capnography, ti. ab].

The Cochrane Library Issue 6 of 12 June 2014: Transtracheal ultrasound in Title, Abstract, Keywords.

Search Outcome

Two hundred and sixty papers found of which one was relevant to the clinical question and of sufficient quality for inclusion. This paper is shown in the table.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Chou et al,
89 adult patients in cardiopulmonary arrest. Severe neck injury, neck tumour and neck surgery (including tracheostomy) were exclusions. Gold standard for intubation was end-tidal CO2 >4 mm Hg after 5 breaths with typical waveform AND bilateral breath sounds. Tracheal ultrasonography performed by 3 trained senior EM residents Diagnostic cohort studySensitivity100%(94.4–100)US results are dependent on the sonographer's experience and skills. Very few oesophageal intubations (7 ex 89)
Specificity85.7% (42–99.2)


The utility of transtracheal ultrasonography in determining tracheal placement by looking for evidence of a single comet-tail artefact is well established. This paper looked at its utility in the real-world situation of cardiac arrest where standard techniques such as ETCO2 waveform and quantification are less effective. Other ultrasound techniques (diaphragmatic movement, lung slide) are not evaluated.

Clinical Bottom Line

Transtracheal ultrasonography may be a supplementary tool for establishing the correct tracheal tube placement in cardiac arrest. Further work is needed.


  1. Chou HC, Chong KM, Sim SS et al . Real-time tracheal ultrasonography for confirmation of endotracheal tube placement during cardiopulmonary resuscitation. Resuscitation 2013;84:1708–12.