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Endotracheal Tube (ETT)

The optimal position of ETT can be assessed with CXR. The idea is that you want the tip to be just in between the carina and the vocal cord. Most sources recommend to position the tip of the ETT about 5-7 cm from the carina. Although personally, I try not go higher than 5 cm.

If it too low, there is risk of endobronchial intubation

If it too high, there are risk of the cuff sitting at the level / above the level of vocal cord + risk of accidental extubation.

So, do you really need 5 cm space between the tip and the carina? Well, turn out that when the patient moves their neck, the ETT move too. A neck flexion can cause the tip to move as much as 2 cm downwards and a neck extension can cause the tip to move as much as 2 cm upwards. Hence, where the recommendation comes from.

In some cases when you can’t see the carina clearly from the CXR, you can use the vertebral body as a guide. The carina is at approximately at the level of T5 – T7. 5 cm from level of T5 is at the level of T2 which is correlates to the level of sternoclavicular joint.

This is a good alternative if you can’t truly see the carina on the CXR. Although I need to remind you that this method is much more prone to error. Patients may have kyphosis or chest wall abnormality so this method would not be reliable.

 

Some interesting images for more context.

Image 1: The tip of ETT at the ideal level, about 5cm-ish from the carina

Image 2:  The tip of the ETT (green line) is positioned slightly higher than the desirable level (above the sternoclavicular joint).

Image 3:  The tip of the ETT (green line) is positioned slightly lower than the desirable level (at the right main bronchus).

Key Points:

  • The ideal position for the tip is about 5 to 7 cm from carina
  • The tip can move with neck flexion / extension
  • Consider using vertebral body as guide if you can’t locate the carina on CXR
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