The use of airway exchange catheters (AEC) in the extubation of patients with difficult airway – a report of two cases

Background
The significance of planned extubation in cases of difficult intubation and at-risk extubation has been highlighted by DAS extubation guidelines1 and NAP42. An AEC can be used to aid safe extubation if left in situ and used to railroad an endotracheal tube should re-intubation become necessary3. We report two cases where AEC was used to aid safe extubation.

Case Reports
1. A patient presented for biopsy of base of tongue tumour. Intubation was difficult because the tumour impeded the advancement of Macintosh and Aitraq© laryngoscopes. Fibreoptic intubation (FOI) was unsuccessful due to bleeding, which obscured the view. Intubation was achieved using Kingvision© laryngoscope. As the tumour itself was left in situ, reintubation in the immediate postoperative period was predicted to be difficult. So at the end of surgery, the patient was extubated over an oral 14Fr Cook© AEC. 
2. An obese patient presented for completion of thyroidectomy. Difficult intubation was anticipated (limited mouth opening, short neck, history of snoring and previous grade III laryngoscopy view). He had respiratory symptoms secondary to unilateral vocal cord palsy following previous hemi-thyroidectomy. An awake nasal FOI was carried out. The recurrent laryngeal nerve (RLN) on the operative side was not identified during surgery. There was a possibility of RLN damage and airway compromise after extubation. So at the end of surgery, the patient was extubated over a nasal 11Fr Cook© AEC.
Both patients tolerated the Cook© AEC and did not require reintubation. Cook© AEC’s were removed in the PACU 3 hours and 1 hour later, respectively.

Discussion 
An AEC is designed to aid oxygenation and bridge re-intubation in patients with difficult airway. Evidence of their use in clinical setting is limited and the largest series is by Mort3. AEC’s are bulky and rigid, and may cause discomfort in awake extubated patients. The Cook© Staged Extubation Set (SES) is designed to leave a wire in the trachea, which can be used for re-intubation, should it become necessary. Single centre experience with the SES was recently presented at WAMM4.

References
1. Popat M et al. Anaesthesia 2012; 67(3): 318–340
2. http://www.rcoa.ac.uk/system/files/CSQ-NAP4-Full.pdf 
3. Mort TC. Anesth Analg 2007; 105(5): 1357-62
4. Carmen L, Goddard H. World Airway Management Meeting. Dublin 2015.

Learning point
Various AEC’s can be used as aids to safe advanced extubation technique in selected patients with difficult airway.

The use of Cook© airway exchange catheters (AEC) in the extubation of patients with difficult airway - a report of two cases