Confirming tracheal intubation: should airway ultrasound become the third check?

We read with interest the editorial by Lyons on the double-way check for confirming correct tracheal tube placement [1]. He revisits recent guidelines recommending checks through sustained waveform capnography and direct visualisation of the tracheal tube passing through the vocal cords, ideally using videolaryngoscopy. Although waveform capnography remains the gold standard for excluding oesophageal intubation, it may not detect malposition within supraglottic or bronchial structures. The editorial supports integrating capnographic and visual confirmation to enhance the reliability of confirming tracheal intubation. Clinical evidence suggests that airway ultrasound may represent a valuable adjunct for rapid confirmation of tracheal tube placement, particularly when capnography is unreliable or when uncertainty persists despite visual confirmation [2]. Airway ultrasound allows dynamic visualisation of the tracheal tube crossing the vocal cords and immediate confirmation of its position within the trachea. The direct method consists of real-time visualisation of the tracheal tube passing through the vocal cords during laryngoscopy and assessment of tracheal positioning at the suprasternal notch. In cases of oesophageal intubation, ultrasound may reveal the characteristic ‘double-tract’ or ‘double-line’ sign, produced by the simultaneous visualisation of the trachea and oesophagus. The indirect method is based on the assessment of bilateral lung sliding and the ‘seashore sign’ on thoracic ultrasound, which may also help detect inadvertent endobronchial intubation. The combination of direct airway imaging and thoracic ultrasound appears to improve the sensitivity and specificity of the examination [3]. Beyond tracheal tube position confirmation, airway ultrasound may also contribute to a more comprehensive airway strategy by identifying anatomical features associated with difficult laryngoscopy and difficult facemask ventilation. A prospective observational study showed that increased anterior neck soft-tissue thickness, particularly the distance from skin to the hyoid bone, was associated with difficult facemask ventilation and difficult laryngoscopy [4]. These findings suggest that airway ultrasound may provide predictive and confirmatory information before and after tracheal intubation. The widespread availability of ultrasound equipment makes this approach increasingly feasible in everyday practice. In a recent Nordic survey, 380 (96%) respondents reported using ultrasound daily or weekly, and most departments had ultrasound devices available whenever needed. However, only a minority of clinicians reported formal ultrasound training or competency assessment, highlighting the need for more structured education in airway ultrasound [5]. Growing evidence suggests that airway ultrasound is rapid, easy to perform and readily available in highly specialised clinical settings such as the operating theatre and intensive care unit. In this context, it is reasonable to consider a third confirmatory step, particularly in equivocal or high-risk situations. Airway ultrasound could represent a valuable adjunct to waveform capnography and videolaryngoscopic visualisation, providing immediate bedside confirmation of tracheal tube position when uncertainty persists despite conventional checks.