Endotracheal tube position on chest X‑ray

Written by the X-Ray Atlas editorial team from the sources listed below · Medical review pending · Updated 24 October 2026 · Level: Beginner

After intubation, a chest X-ray is often taken to check the depth of the endotracheal tube (ETT) and to look for complications. It answers one question well: is the tip at a safe height above the carina? It does not prove that the tube is in the trachea rather than the oesophagus. That is the job of waveform capnography at the bedside. A tube that is too deep enters a main bronchus and ventilates one lung; a tube that is too high can slip out or damage the vocal cords. This page covers the target position, how neck movement shifts the tip, the classic malpositions, cuffs and tracheostomy tubes.

1. How to look

Most post-intubation films are supine AP portable films on ICU or in the emergency department. Apply the usual systematic approach, but find the airway devices first:

1. Find the tube. An ETT is a wide, radiopaque-edged tube with a radiopaque line along its length. Trace it from the mouth down the neck into the chest.
2. Find the tip. The tip is usually bevelled and marked by the end of the radiopaque line. Some tubes have a "Murphy eye" side hole just above the tip.
3. Find the carina. Follow the tracheal air column down to where it divides into the two main bronchi. On a poorly penetrated or rotated film the carina can be hard to see; windowing helps. If it truly cannot be seen, the medial ends of the clavicles and the vertebral levels give a rough guide (see below).
4. Measure from the tip to the carina in centimetres, using the PACS calliper.
5. Check the head position if you can: is the chin flexed down onto the chest or extended?
6. Look for complications: collapse, pneumothorax, pneumomediastinum and surgical emphysema, and the position of every other device, especially the NG tube.

2. Target tip position

The target range exists because the tube moves. Coughing, turning the patient and moving the head can shift the tip by a few centimetres, so a tip placed in the middle of the trachea has room to move in either direction before it reaches the bronchus or the vocal cords.

3. The tip follows the chin

The tube is fixed at the mouth, so when the head moves, the tip moves relative to the carina:

• Neck flexion (chin down) moves the tip down, towards the carina, by up to about 2 cm.
• Neck extension (chin up) moves the tip up, towards the larynx, by a similar amount.

So a tip 3 cm above the carina on a film taken with the neck extended may sit almost at the carina when the head is flexed. When you report a borderline position, note the head position if it can be judged from the film, for example from the position of the mandible relative to the cervical spine.

4. Too low: endobronchial intubation

The right main bronchus is shorter, wider and more vertical than the left, so a tube that is advanced too far usually enters the right main bronchus. The consequences on the film:

• The tip lies beyond the carina, in line with the right main bronchus.
• Collapse of the left lung, which is not being ventilated: a white left hemithorax with volume loss and shift of the mediastinum to the left. See lobar collapse.
• The tube may also occlude the right upper lobe bronchus, which arises very close to the carina, causing right upper lobe collapse.
• The ventilated right lung may be over-inflated, with a risk of barotrauma and pneumothorax.

A tip that sits at, or within about 2 cm of, the carina should be reported as low, because it can enter a bronchus with neck flexion. The usual action is to withdraw it to the target range, then re-check clinically and, if policy requires, radiologically.

5. Too high

A tip at or above the medial ends of the clavicles, near the thoracic inlet, sits close to the larynx. Problems include:

• Accidental extubation with head extension or patient movement.
• The cuff lying at the level of the vocal cords, with risk of cord injury and an air leak.
• The tip sitting in the pharynx: the tube may be displaced completely. Look for gastric distension.

6. Oesophageal intubation and what the film cannot tell you

This is the most important limitation. The oesophagus lies directly behind the trachea, so on an AP film a tube in the oesophagus can project over the tracheal air column and look correctly placed. Clues that the tube is in the oesophagus include:

• The tube projects outside the margins of the tracheal air column, often to the left.
• A distended, gas-filled stomach, and gas in the oesophagus.
• The tube tip lies below the carina without following either bronchus.

None of these is reliable enough to exclude oesophageal intubation, and their absence does not confirm tracheal placement. The Royal College of Anaesthetists and the Difficult Airway Society are clear that placement in the trachea is confirmed by sustained waveform capnography, summed up in the campaign phrase "No trace = wrong place". A chest X-ray should never be used to decide whether a tube is in the trachea, and waiting for one in a deteriorating patient wastes time.

7. The cuff and complications

• Cuff size. The cuff should fill the trachea without bulging its walls. A classic rule of thumb is that a cuff diameter more than about 1.5 times the normal tracheal width suggests over-inflation, and a markedly bulging cuff or a tracheal outline that is distended around it should prompt concern about tracheal injury. Cuff pressure is measured at the bedside; the film is only a prompt.
• Barotrauma. Look for pneumothorax (on a supine film, the deep sulcus sign), pneumomediastinum and surgical emphysema. A new pneumothorax in a ventilated patient can rapidly become a tension pneumothorax.
• Aspiration around or before intubation: new consolidation, often in the dependent lower lobes or the right lower lobe. See consolidation.
• Tracheal injury after a difficult intubation: pneumomediastinum and surgical emphysema in the neck should prompt urgent senior review.
• Other devices: intubated patients usually have an NG tube, and often central lines. Check them all on the same film.

8. Tracheostomy tubes and children

Tracheostomy

A tracheostomy tube enters the trachea through the front of the neck. Its tip should lie roughly halfway between the stoma and the carina (around T3), and the tube should run parallel to the long axis of the trachea. A tube angled towards the anterior or posterior tracheal wall risks erosion. After a new tracheostomy, look for pneumothorax, pneumomediastinum and surgical emphysema. Position does not change much with neck movement, because the tube is fixed in the neck.

Children and neonates

The paediatric trachea is short, so the margin for error is small. Tip targets in children are commonly given as around T1–T2 on the film, or about 1–2 cm above the carina in neonates. Sources and units differ, and many neonatal units have their own targets. [VARIES] See the neonatal chest X-ray for the neonatal context.

Red flags: act now

What to focus on, by role

Role	Priorities
Medical student	Find the carina, measure to the tip, and know the 5 ± 2 cm rule and the right main bronchus as the usual too-deep position. Know that capnography, not the film, confirms tracheal placement.
Nurse	On ICU, note the tube length at the teeth or lips and compare with previous documentation. Report a changed length, a lost capnography trace, or asymmetric chest movement at once.
Junior doctor	Review every post-intubation film for tip height, collapse and pneumothorax, then check the NG tube and lines on the same film. Act on a low tube before the formal report.
Radiographer	Include the whole tube and the carina with adequate exposure, and keep the head neutral if it is safe to do so, so the tip height is meaningful.
Advanced / FRCR	Cuff over-distension, tracheal injury, double-lumen tubes, tracheostomy complications and paediatric targets.

Practise on lines and tubes films →

References

1. Radiopaedia. Endotracheal tube position. radiopaedia.org
2. Radiology Masterclass. Chest X-ray: endotracheal tube anatomy. radiologymasterclass.co.uk
3. Royal College of Anaesthetists and Difficult Airway Society. Capnography: No trace = wrong place. rcoa.ac.uk
4. Difficult Airway Society. Guidelines. das.uk.com

For education only. Not a substitute for a formal report, senior review or your local policy. Never use this page to make decisions about a real patient.