Esophageal intubation refers to the incorrect placement of an endotracheal tube in the esophagus. Within minutes its consequences can be catastrophic with the seriousness of its outcome depending largely on the timeliness of its diagnosis.
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Epidemiology
Accidental esophageal intubation can happen with any experienced anesthesiologist. It is more common with difficult intubations and in the emergency setting. In the critical care setting, esophageal intubation occurs in 8% of total intubation attempts 1.
Clinical presentation
Esophageal intubation is traditionally considered a clinical rather than a radiological diagnosis. Common clinical tests recommended for confirming correct endotracheal tube placement include 2:
- visualization of the endotracheal tube passing through the vocal cords
- auscultation of the chest and epigastrium
- observation of chest movement
If any of these tests are not consistent with correct endotracheal tube placement, there should be a high suspicion for esophageal intubation.
The Australian and New Zealand Committee on Resuscitation (ANZCOR) recommend that physical examination should be used with wave form capnography to confirm endotracheal tube placement as the gold standard 2.
Radiographic features
Plain radiograph
Projection of the endotracheal tube tip being lateral or posterior to the trachea is a sure sign of malpositioning and likely esophageal intubation 3. As the esophagus is leftwardly-displaced in most patients, a right posterior oblique view or turning the head to the right can increase the accuracy of the diagnosis 3,4.
While it is possible for the diagnosis to be made with a standard portable anterior-posterior film, it has proved to be difficult and unreliable, owing to the endotracheal tube often projecting over the tracheal air column 3.
Esophageal air and gastric distension (especially in the presence of a nasogastric tube) can also suggest esophageal intubation 3.
Ultrasound
The role of ultrasound in confirming endotracheal tube placement is a relatively novel idea. Studies have demonstrated that it has a sensitivity and specificity that rivals that of the current ANZCOR gold standard 5-7. The major advantage of ultrasound is that, unlike physical exam or wave capnography, it does not require lung ventilation or pulmonary blood flow which is particularly important in resuscitation scenarios 7,8.
Transtracheal scanning is performed with the transducer being placed transversely over the suprasternal notch 7. In this view, the trachea can be identified as a hyperechoic air-mucosa interface with comet tail artefact. Esophageal intubation is defined as when a second air-mucosa interface appears, often posterolateral to the trachea. This finding seems to suggest a second false airway and is therefore referred to as the “double tract sign” 7.
Transthoracic or intercostal scanning has also been shown to be an effective tool for detecting esophageal intubation 6. In this view, bilateral absence of the “lung sliding sign” would suggest esophageal intubation.
Treatment and prognosis
Esophageal perforation is the most serious complication and should be evaluated for on plain film 3.
Differential diagnosis
For ultrasound appearances, consider:
- local anatomical variants owing to previous neck trauma, neck tumors, previous surgery or tracheotomy
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