Laryngoscopy may identify but cannot exclude oesophageal intubation

Abstract

We appreciate Drs Wright and Sudan's interest [1] in the consensus guidelines for preventing unrecognised oesophageal intubation [2] and agree with the principle of ‘precision intubation’, a process that should be deliberate, careful and appropriately paced. As such, we support their view that tracheal tube cuff inflation should be performed under vision, and removal of the videolaryngoscope blade, following passage of the tracheal tube, should not be rushed. However, we feel that the guidelines' existing recommendation that “following intubation, the ability to see the tube between the cords and anterior to the arytenoids should be assessed prior to withdrawal of the laryngoscope blade” [2] achieves the proposed benefits of their “total videoscopic tracheal intubation” technique without the potential for unintended adverse consequences.

The suggestion by Wright and Sudan of total videoscopic tracheal intubation entails leaving the laryngoscope blade in position until sustained exhaled carbon dioxide is confirmed. As this requires at least seven breaths, the prolonged laryngoscopy may result in an extended stress response and an increased risk of airway trauma. Given most tracheal tubes are correctly located, the threat of these complications may outweigh any benefit. It also has the potential to make ergonomics awkward and impedes the airway operator managing other aspects of the induction process during this period. Conversely, once initial carbon dioxide return is observed, the guideline process would allow securing of the tracheal tube, confirmation of anaesthetic delivery, etc. while the first seven breaths are delivered, followed by a two-person check for sustained exhaled carbon dioxide. This process has been shown to be practical in a clinical setting [3].

Of greater concern is their suggestion that this technique could reduce the need to remove the tracheal tube. No matter how reassuring the view at laryngoscopy, the absence of sustained exhaled carbon dioxide mandates removal of the tracheal tube, unless it is considered dangerous to do so [2]. Laryngoscopy in isolation cannot be used to exclude oesophageal intubation. Even in the rare circumstance where default removal of the tracheal tube is considered dangerous, repeat laryngoscopy is recommended only to more rapidly identify oesophageal intubation, while valid alternative techniques of flexible bronchoscopy, ultrasound or use of an oesophageal detector device are required to exclude it [2]. Thus, repeat (or in this case sustained) laryngoscopy can only lower the threshold for removing the tracheal tube, not raise it. Leaving the tracheal tube in despite the absence of sustained exhaled carbon dioxide, based on continuous visualisation of the larynx, represents a potential fixation error that could increase the risk of unrecognised oesophageal intubation [4].

Optimal airway management should be safe and effective, while being as ergonomically straightforward, simple and elegant as possible. We feel that that the existing guideline recommendations achieve this.