Tracheal intubation in children requires expertise to prevent inadvertent esophageal or bronchial intubation. This is particularly true in the child requiring cardiopulmonary resuscitation, presenting with a difficult airway anatomy and in small children in whom tracheal intubation is more delicate. Numerous devices have been described to verify tracheal tube position with the vast majority relying on indirect measurements.8–13
Auscultation is commonly considered the first step to confirm tracheal intubation. Sensitivity and specificity are variable and lower in tracheal tubes with a Murphy eye.2 Auscultation may also be misleading in patients with low lung compliance or cases of severe bronchospasm.
Transmission of light through the tissues of the neck has also relied on an intense and circumscribed midline glow of light in the region of the anterior neck, just below the thyroid prominence. However, these devices are not suitable for tracheal tube size with an inner diameter of 6 and 4.5 mm for Trachlight (Laerdal Medical, Armonk, NY) and SURCH-LITE (AARON Medical Industries, St. Petersburg, FL), respectively. Alternative methods, such as aspiration of air from the lungs (TubeChek: Ambu, Linthicum, MD) and acoustic reflectometry, are currently not widely used12,17 or are unsuitable in small children.18
Direct visualization of the glottis and passing the tracheal tube under direct vision is not always possible in cases of difficult intubation in a child with distorted anatomy or pathological conditions.
Fiberoptic control of tube placement is generally considered by anesthesiologists and intensivists to be the gold standard for confirmation of correct tube placement. Observation of the tracheal rings and carina is generally easy and unmistakable but requires availability of a fiberscope and may be complicated by misting, blood and secretions. The use of the fiberscope may also be limited by the inner diameter of the tracheal tube.
A standard chest radiograph is commonly used to determine tube position in intensive care patients, but it is time consuming and therefore not realistic in the operating room environment. It may be only suitable for follow-up in intensive care.19
No studies are available assessing the use of US imaging for real-time confirmation of tracheal tube position in children. This current study demonstrates that US readily detected tracheal intubation in all but one patient in whom esophageal intubation was diagnosed immediately upon insertion of the tube into the esophagus. This study reports characteristic US findings suggesting a set of criteria for confirming tracheal intubation in children. However, it must be remembered that all clinicians involved in this study were experienced in US and none of the studied children presented with difficult airway management. The addition of an indirect sign, such as movement of the chest wall VPPI, may also be useful to confirm successful ventilation. This sign is more easily observed in the apneic or paralyzed patients.
This technique is likely to be used for routine tracheal intubation. However, US confirmation of correct tracheal tube placement may be beneficial for circumstances in which capnography is unreliable, such as cardiac arrest. Other situations include airway trauma or difficult intubation. In these situations, it might be useful to be able to confirm passing of the tracheal tube through the vocal cords and correct tracheal tube placement in real-time. However, this will need to be confirmed in future studies.
US is now more commonly available in the operating room due to its increased use for securing vascular access. The place for its use in real-time airway management has yet to be established in adults and children, and further studies are required to assess sensitivity and specificity of this technique based on the suggested US criteria.
We conclude that US of the pediatric airway can be easily used to assess correct tracheal tube position and to detect esophageal intubation.
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