This content has been generated for SALG by the anaesthetist involved in the case, with editorial assistance from Dr Sandeep Sudan on behalf of the Difficult Airway Society

A patient of BMI 40+ underwent surgical tracheostomy to facilitate weaning from mechanical ventilation. On the third day after tracheostomy, the patient suffered a cardiac arrest due to suspected obstruction of the tracheostomy tube. The tracheostomy tube was removed, and the trachea reintubated via the oral route using a video laryngoscope and bougie. A sustained, square-wave end tidal carbon dioxide trace was obtained, followed by return of spontaneous circulation. As there was a large leak of air from the tracheostoma, the endotracheal tube tip was presumed to be lying above this section of the trachea, so was advanced further in line with NTSP guidance.^]

Shortly after advancing the endotracheal tube, subcutaneous emphysema of the chest and neck developed and the patient sustained a further cardiac arrest. An attenuated, intermittent, CO2 trace was present during this time, which was interpreted as indicating an appropriate position of the endotracheal tube in the context of an ongoing cardiac arrest. Tension pneumothorax was postulated as a cause for the second arrest and bilateral needle decompressions were undertaken, without improvement in the patient’s condition.

Subsequent flexible endoscopic examination via the endotracheal tube failed to reveal tracheobronchial anatomy. The tracheostoma was explored at the bedside by an ENT surgeon who found that the oral endotracheal tube had exited the trachea, via the tracheostoma, into the adjacent soft tissues of the neck – a finding that was not evident on external examination due to the raised BMI. The endotracheal tube was removed from the mouth and an Igel placed, with reoxygenation, sustained ETCO2 and return of circulation occurring shortly afterwards.

Commentary

During oral reintubation of a patient with a recently removed tracheostomy, an oral tube will normally follow the lumen of the trachea and pass safety into the distal trachea, beyond the tracheostoma. In this case though, the tube tip passed through the anterior deficit in the tracheal wall, which resulted in it coming to lie outside of the trachea. While infrequent, this sequence has been observed in other patients. ^2,3 It also re-occurred in this same patient during later, elective, intubation attempts.  The occurrence of subcutaneous emphysema after oral intubation in a patient with a tracheostoma should raise suspicion of extra tracheal passage, particularly in a patient with a raised BMI where the tracheostoma is deep and an aberrant (oral) tube position may not be visible in the neck.

As the extra-tracheal plane created by the endotracheal tube tip was in communication with the airway, intermittent CO2 was obtained, despite the tip lying outside of the trachea.

This case highlights potential issues that can occur when performing airway management in a patient with disrupted or abnormal tracheal anatomy. Where feasible, intubation with the assistance of a fibreoptic scope should be considered to improve the likelihood of safe passage beyond any area of anatomical abnormality. Alternatively, an early endoscopic check of tube placement may be prudent to allow prompt recognition of inadvertent extra-tracheal tip placement. ⁴

References:

1. National Tracheostomy Safety Project. Comprehensive Tracheostomy Care. NTSP Manual, 2013
2. Safe Anaesthesia Liaison Group. Patient Safety Update (April 2021 – June 2021):2
3. Personal Communication, Prof B McGrath
4. Baumgartner FJ, Ayres B, Theuer C. Danger of False Intubation After Traumatic Tracheal Transection. Ann Thorac Surg 1997; 63:227-8.