SAQs on this topic are relatively recent. Question 7.2 from the first paper of 2010 offers a photograph of a teenager who clearly has some sort of neck injury, and gives his history as "ran his motorbike into a single strand of fencing wire". The young man looks like he has been garotted, and presents with stridor. The candidates were asked to manage the stridor, and (as a separate question) to secure the airway. Question 24 from the first paper of 2013 is more about the pros and cons of different approaches to the patient with traumatic airway distortion due to facial injuries.
As far as published literature goes, the UpToDate article ("Emergency airway management in the adult with direct airway trauma") is an excellent resource for the paying customer. If one has institutional access, one may be able to acquire one excellent article from Anesthesiology by Jain et al (2016). Both of these sources were boiled drained and compressed into the summary below.
Timing of airway intervention in airway trauma
Rationale for delayed airway control
- If the patient is still breathing, then the airway is still patent (noisy breathing is better than no breathing).
- It is still patent because the patient still has muscle tone and reflexes.
- Once you give them some mind-altering intubation drugs, the airway will no longer be patent because you take away the tone and reflexes.
- It is therefore possible to argue for a delayed airway control procedure, with optimal equipment and staff (i.e. in the operating theatre, with an ENT surgeon ready to assist).
- Airway injuries may not be externally obvious, and a cack-handed intubation could convert a partial lower airway injury into a complete tracheal transection, or something similarly disastrous. It is therefore possible to argue for a CT scan before attempts at airway control.
Rationale for early (emergency) airway control
- They will have progressive swelling, which will make subsequent airway management more difficult. The earlier the airway can be controlled, the better.
- They will get mind-altering drugs anyway, to control their pain.
- The pre-intubation CT scan will not be possible anyway, because they will either be unable to lie flat, or will be uncooperative and combative, or some combination of the two.
- The airway injury may not be isolated, and the airway may need to be controlled more urgently for other reasons, eg. because of a closed head injury.
Evidence regarding timing of intubation in airway trauma
Obviously. this is not something that can be protocolised, as eah specific scenario will be different. The main thing to remember is that delay is an option. A review by Kummer et al (2007) found that approximately 30% of the patients had their definitive airway established in the operating theatre, demonstrating that it is occasionally safe to wait. Nothing particularly fancy was done in OT - of those patients about half were intubated conventionally, though the mouth with direct laryngoscopy.
Considerations specific to sites of injury
Severe facial injuries
This is a group of patients for whom conventional oral or nasal intubation may not be an option. Question 24 from the first paper of 2013 presents such a patient. They have a mobile mid-face, noisy breathing, facial swelling, and they insist on sitting up to a 90° angle. Possible injuries in this group are listed below, along with the way in which they complicate management:
- Bag-mask ventilation becomes more difficult (more leak)
- Teeth in the airway! Intubation may push them into the bronchi. Nasty pneumonia ensues.
- Jagged tooth fragments tear the ETT cuff.
- Use of oropharyngeal airway may be counterproductive if the tongue is lacerated (i.e. more bleeding and worse obstruction may result).
- Limited mouth opening by trismus (or... less limited, when the patient is anaesthetised and one is able to move the fragments. Neuromuscular blockade tends to resolve the trismus)
- Drooling and difficulty swallowing: even the conscious patient will have problems with blood and secretions
- Oedema from such fractures tends to encircle the airway
- Le Forte fractures (I and II) tend to result in significant bleeding into the airway. The patient tends to resist being put supine because blood goes back into their airway (sitting forward is more omfortable).
- Nasal intubation is out of the question
General issues to consider:
- Pre-oxygenation should be by atmospheric pressure oxygen rather than by any sort of positive pressure mask: the positive pressure will dissect through broken tissue planes and cause subcutaneous emphysema, making the airway impossible.
- Facial fractures frequently co-exist with base of skull fractures.
- Avoid positive pressure mask ventilation (this also goes for high flow nasal prongs) - subcutaneous emphysema or air emboli may develop, not to mention pneumoencephalus.
Severe laryngeal trauma
- This tends to present with hoarseness, cough and stridor.
- Vascular injury (eg. carotid) is present in 25% of such patients (Bhojani et al, 2005).
- Airway obstruction develops gradually over hours
- Sudden deceleration (flexion/extension) injuries can cause a disruption of the trachea from the larynx
- Laryngeal injuries may be exacerbated by cricoid pressure
- The presence of subcutaneous emphysema suggests that there may be disruption of the airway. In this situation, intubation is better performed in the operating theatre, or at least with bronchoscopy. The larynx may be attached to the trachea only tenuously, and an attempt to intubate the patient may severe that connection completely.
Severe tracheal trauma
Thankfully, this is rare (the trachea is well defended by the thoracic inlet and ribcage). Things to consider:
- Sudden deceleration injuries can also cause a disruption of the carina, because it is tethered structure.
- A disrupted trachea will retract into the thorax, and will need to be surgically retrieved.
- When there is mediastinal free gas or subcutaneous emphysema, it is impossible to say whether they are coming from the trachea or the oesophagus. Oesophageal perforation almost inevitably requires intubation, especially if there is a communication between the oesophagus and the airway.
Penetrating airway trauma
Penetrating neck injury is discussed in greater detail elsewhere. A case series by Shearer et al (1993) reported that direct laryngoscopy with RSI or a primary surgical airway were the most frequently successful techniques in the management of penetrating neck trauma. Things to consider:
- A supine or Trendelenber position minimises the risk of an air embolism if the greater vessels are breached
- Avoidance of positive pressure ventilation also minimises air embolism, as well as preventing subcutaneous emphysema.
- About 10% of these patients will have an oesophageal injury (Bhojani et al, 2005).
General principles of managing the traumatised airway
- Rapid sequence induction is a reasonable choice. Kummer et al (2007) report that 70% of airway trauma patients end up being intubated in this way.
- RSI may need to be modified slightly:
- No cricoid pressure
- Passive pre-oxygenation (no manual bagging)
- No positive pressure until the cuff is up
- Awake fiberoptic bronchoscopy may not be an option, because:
- Airway swelling decreases access
- The patient may be obtunded and uncooperative
- Copious blood and mucus in the airway will frustrate the view
- There may not be time to set up the appropriate equipment
- A "double set-up" is probably the most sensible approach to the airway trauma patient who is rapidly losing their oxygenation
- This approach resembles the Respiratory Death Airway Algorthm from EMCrit, via the failed intubation chapter.
- Essentially, one person gets the laryngoscopy ready while the other sets up for a cricothyroidotomy.
- If a couple of quick-succession attempts to intubate the patient are ineffective, a cricothyroidotomy can be quickly performed before the patient requires CPR.