Endotracheal Tube at the Carina: Radiographic Pitfalls and Clinical Implications

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 Endotracheal Tube at the Carina: Radiographic Pitfalls and Clinical Implications



Figure 1. Endotracheal tube at the carina. In this example, the tip of the ETT (yellow arrow) is too close to the carina (orange arrow), and is at the origin of the right main bronchus. In this position, there is a risk of overventilation of the right lung and underventilation of the left.

Introduction

Endotracheal intubation is a cornerstone of airway management in critical care and emergency settings. Proper placement of the endotracheal tube (ETT) is crucial for effective ventilation and the prevention of potentially life-threatening complications. Radiographic evaluation of tube position, particularly using chest X-ray, is the most common and immediate method for confirmation after intubation.

This article delves into a critical case scenario where an ETT was placed at the level of the carina, outlining its clinical significance, radiographic characteristics, and the potential complications associated with malposition. The content is inspired by the case study published by St. Vincent’s University Hospital Radiology Department [1].

Radiographic Anatomy and Ideal ETT Position

The trachea bifurcates into the right and left main bronchi at the carina, which typically lies at the T4-T5 vertebral level. For adult patients, the recommended ETT tip position is approximately 5–7 cm above the carina when the neck is in a neutral position. This allows for slight movement with neck flexion or extension without risking bronchial intubation or accidental extubation [2].

If the ETT tip is at or near the carina (as in Figure 1), there is a significant risk of bronchial intubation—most often into the right main bronchus due to its wider diameter and more vertical course.

Clinical Case Overview

The referenced case involved an ICU patient post-intubation whose portable chest radiograph revealed the ETT tip directly at the carina. While technically within the trachea, such positioning is considered malpositioned due to its proximity to the bifurcation, where even minimal tube advancement could lead to endobronchial intubation.

Key Radiographic Features

  1. Tube Positioning: The ETT tip should ideally lie between the thoracic inlet and 5 cm above the carina on inspiration.

  2. Neck Movement Influence: Flexion can lower the ETT by as much as 2 cm, while extension can elevate it.

  3. Single-lung Ventilation Risk: If the tube enters the right main bronchus, it may result in left lung atelectasis and hypoxia.

Potential Complications of Carinal Placement

  • Unilateral Lung Ventilation: Right mainstem bronchus intubation can lead to left lung collapse.

  • Barotrauma: Overinflation of a single lung.

  • Hypoxia: Due to impaired gas exchange.

  • Delayed Diagnosis: Without proper imaging, these complications may remain unnoticed.

  • Accidental Extubation: Particularly during patient movement or transport.

Management Recommendations

  • Radiographic Confirmation: Obtain a chest X-ray immediately after intubation.

  • Tube Repositioning: If the tip is at the carina, withdraw 2–3 cm and recheck placement.

  • Ultrasound/Capnography: Adjunct tools for verification.

  • Continuous Monitoring: Especially during transfers and head movement.

Quiz

1. What is the most appropriate action when a chest X-ray reveals that the endotracheal tube tip is located at the carina?

A. Leave it in place
B. Advance the tube 1–2 cm further
C. Withdraw the tube 2–3 cm and re-check position
D. Replace the tube with a double-lumen tube

2. Which of the following complications is most likely if an ETT is advanced too far into the right main bronchus?

A. Bilateral pneumothorax
B. Left lung collapse
C. Pulmonary embolism
D. Vocal cord injury

Answer & Explanation

1. Answer: C. Explanation: The carina is the anatomical bifurcation of the trachea. To ensure safe and effective ventilation, the ETT tip should be at least 5 cm above the carina. If placed at the carina, even minor movements can result in endobronchial intubation.

2. Answer: B. Explanation: Right mainstem bronchus intubation typically results in poor ventilation of the left lung, leading to collapse (atelectasis) and hypoxia.

Conclusion

Correct placement of the endotracheal tube is not only critical for effective mechanical ventilation but also for preventing dangerous complications. Radiographic evaluation is indispensable in confirming proper tube location, particularly in unstable or unconscious patients. As shown in this case, an ETT tip at the carina is a radiologic red flag requiring immediate correction to avoid one-lung ventilation and associated complications.

Always consider radiographic landmarks, clinical context, and tube depth when interpreting ETT positioning. Awareness and vigilance can significantly enhance patient safety in the ICU and emergency settings.

References

[1] St. Vincent’s University Hospital Radiology. Endotracheal Tube at Carina. [Online]. Available: http://www.svuhradiology.ie/case-study/endotracheal-tube-at-carina/

[2] A. Benumof, “Evaluation and management of the difficult airway,” Anesthesiology Clinics of North America, vol. 16, no. 1, pp. 1–27, 1998.

[3] R. H. Schwartz, et al., “Chest radiographic evaluation of endotracheal tube position,” Chest, vol. 103, no. 2, pp. 416–420, 1993.

[4] R. P. Kline and J. F. Lee, “Positioning the endotracheal tube,” Critical Care Clinics, vol. 12, no. 4, pp. 849–862, 1996.

[5] L. Y. Chen, et al., “Chest X-ray for endotracheal tube placement: A teaching tool,” Journal of Intensive Care Medicine, vol. 32, no. 3, pp. 179–183, 2017.

[6] A. Y. Nordin, “Radiographic signs of malpositioned ETT in the ICU,” Journal of Radiology Case Reports, vol. 12, no. 4, pp. 12–19, 2019.

[7] C. M. Roberts and P. N. Black, “The pitfalls of tube misplacement in ventilated patients,” BMJ, vol. 314, pp. 182–185, 1997.

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