Confirmation of endotracheal tube placement during general anaesthesia by ultrasonography.

The cornerstone of airway management and resuscitation of patients is ‘rapid and accurate endotracheal tube placement’. Securing a definitive airway in any setting as in operation theatre, intensive care unit (ICU), emergency department is always a necessary.

Various methodologies like visualization of vocal cords during laryngoscopy followed by endotracheal tube placement, chest wall expansion following ventilation, visualization of tracheal rings and carina by bronchoscopy, chest auscultation, capnometry or capnography are available for confirmation of endotracheal tube placement. But there is no perfect modality for confirmation and very few methods are reliable.  Constant non-availability of these modalities is a major drawback.

The Advanced Cardiac Life Support (ACLS) 2015 guidelines recommend the usage of capnographic waveform along with clinical assessment for confirmation of endotracheal tube placement. Capnography is said to be the gold standard for confirmation which works on the principle of carbon dioxide detection, but has its own limitations like the availability in emergency departments and its dependency on adequacy of pulmonary blood flow makes it non reliable in conditions like pulmonary embolism, low cardiac output states, cardiac arrest (where cardiopulmonary resuscitation is not initiated/arrest for a prolonged period) and airway obstruction. False results have been noted when epinephrine was used.

Ultrasonography is now emerging as a promising tool for rapid assessment of endotracheal tube placement. Ultrasound machine is portable, widely available, non-invasive, cost effective, easy reproducibility of images and has good safety record. Moreover, its available in all settings like emergency department, ICU and operation theatre. Confirmation of endotracheal tube in the trachea is confirmed by absence of “ Snow storm sign†(disturbance of tracheal air-mucosa interface with comet tail artefacts) visualized in ultrasound. Learning curve of transtracheal ultrasound has also been observed to be not difficult. Hence it can be used as a potential alternative to capnography during non-availability or when there is compromise in carbon dioxide detection by capnography.