Intubations this month:          34

Airway Registry learning points reflect the challenges described and wisdom shared by Sydney HEMS personnel and guests at the Clinical Governance Airway Registry presentation for April 2018. Cases are discussed non-contemporaneously, anonymised and amalgamated over a time period to draw together unifying take-home messages. Details of specific cases are removed and/or changed, such that any similarity to real-life patients or scenarios is coincidental.

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Focus on: Blunt Neck Trauma

Our main discussion focused around the management of patients with potential/known upper airway injury. The majority of our potential laryngotracheal injuries are in multiply injured patients where the other injuries dictate patient management, including intubation, and the airway injury becomes an interesting (sometimes unexpected) finding on the hospital CT scan.

Occasionally we attend patients with isolated neck/laryngeal injuries. Examples include:

• strangulation
• motorbike rider crossing wire fences
• direct front of neck blunt trauma.

Laryngotracheal injuries can be challenging anywhere and as a retrieval team we are often faced with early presentations in non-tertiary institutions with the added challenges of an unfamiliar team & environment, limited investigations, and the need for long distance transport to tertiary care.

Potential for further harm to the patient comes from worsening the injury (e.g. turning a partial tracheal tear into total tracheal disconnection), creation of false passages (by blind instrumentation of the airway), loss of effective spontaneous negative pressure ventilation, generation/worsening air leak from positive pressure ventilation with failure of ventilation.

Principles of management for these patients are therefore:-

• Assess need for intubation as urgency varies between patients, and they may be best transported without RSI.
• Cervical spine collars or other constrictions around the neck may be best avoided
• Maintain spontaneous ventilation where possible
• Avoid positive pressure ventilation above the injury (e.g. BVM, LMA)
• Avoid instrumenting the injury (e.g. bougie/ETT) as it may complete a partial tracheal transection, or create a false passage
• Small ETT e.g. 6.0mm I.D in adults is prudent
• Place cuff of ETT below injury (visualization of defect ideal)
• Perform any surgical airway below the level of injury (e.g. tracheostomy rather than cricothyroidotomy for neck injury). Placing an ETT through the defect has been performed but is not without risk of completing a transection.
• Visualised actions preferable to blind interventions

Our clinical practice standard for Prehospital Intubations recommends using a bougie for every intubation. Despite visualizing the larynx above the vocal cords with laryngoscopy, the bougie is not seen as it passes below the cords where further damage to tracheal injuries is possible. There is an argument for not using a bougie in easy intubations. It is advisable to place the ETT deep so placing the cuff below likely injury level (which carries an endobronchial injury).

In smaller hospitals, the options for intubation increase and decision making can be less clear. A prehospital approach to intubation is not contra-indicated and could be used in lower resource settings alongside preparation for a surgical airway approach. Intubation under a spontaneous breathing general anaesthetic technique (gas induction or total intravenous technique) is most familiar. Awake fibreoptic intubation is an option though care needs to be taken to ensure a cough/struggle-free experience; remember also that the subsequent railroading of the ETT will be blind so the same risks apply.

Articles have described a two-operator technique involving spontaneous breathing anaesthesia with videolaryngoscopy and flexible intubating scope to assess tracheal injury at time of intubation and avoid creating a false passage. This is likely to need prior practice and a strong team.

The best plan of action may be both resource-dependent and context-dependent and we strongly recommend discussion with local staff and/or Duty Retrieval Consultant at the time.

Video Focus: Epiglottis

This video shows how adjusting the position of the tip of the laryngoscope in the vallecula can improve your view at laryngoscopy.

This video shows how we can sometimes use our Mac blade as a Miller blade by picking up the epiglottis: you may not have intended to pick up the epiglottis but if you get a good view as the one shown here, you might decide to proceed with passing the bougie or ETT rather than trying to get into the vallecula (especially as the earlier part of the video shows this might have been challenging).

This video appears to show a mass below the epiglottis when the laryngoscope is in the vallecula. This is, in fact, a normal variant – an epiglottic tubercle (see this anatomy diagram from this site).

In this video, the epiglottis appears swollen (this may be a result of local trauma caused by the use of an oropharyngeal airway or related to drug use). You can also see an issue with control of the coude (curved) tip of the bougie. This occurs because of the way we transport the bougie in our airway packs: we cannot transport the bougie without bending it and this case reminds us to ensure that the bending occurs along the plane of the coude tip curve during our pack checks.

You can see all the AiR videos here on our Vimeo page or here on the blog.