Protecting the Airway

Physical barriers & reflexes protect the airway and the lungs from foreign bodies (e.g. particles of various sizes).

Nasal hairs act as a physical barrier to foreign body inhalation and the respiratory mucosa secrete mucus to trap foreign bodies.

Protective airway reflexes stop foreign bodies and secretions from passing into the larynx. They include the cough, reflex swallowing and forced expiration. Just think of how we responded to a gentle swabbing of our throat for Covid-19 testing! If you have ever inhaled a bread-crumb or a peanut, the reflex reaction can be associated with the foreign body being expelled from the airway like a missile!

On the other hand, sometimes patients recovering from anaesthesia may develop over-sensitive airway reflexes, particularly as they emerge from deep anaesthesia to the “twilight” of wakefulness. Here, the reflexes of the airway may be heightened (a particular issue in children), leading to the muscles controlling the vocal cords to go into a spasm, closing and causing an airway obstruction.

The once useful Guedel airway may for a brief period act as a major stimulus, which closes the glottic opening causing airway obstruction. This is called laryngospasm and is an anaesthetic emergency and looks dramatic. In the worst case scenario, there is no snoring at all.

Fibreoptic view of the open vocal cords (pink-lilac) in the centre of the screen. When they clamp shut due to muscle spasm (laryngospasm) the airway can become dangerously obstructed. (Photo credit: J.D Williamson)

Why might this be?

Well of course, the airway is completely closed (unlike the vocal cords in the above image which show an open airway), and there is NO air flowing – this is a fully obstructed airway! The patient may make no sound.

Let’s close this section out by completing a look at 2 other devices used to maintain the patency of the upper airway.

Laryngeal Mask Airway (LMA)

The LMA, arguably more than any other device in modern times, has transformed anaesthetic practice.

In the mid-1980’s a British anaesthetist-inventor called Dr Archie Brain developed a tool which when placed optimally in the mouth to the level of the glottis, provided near complete unobstructed gas flow to the vocal cords and lower airway.

Suddenly, deeply anaesthetised patients could breath effectively and efficiently with a greatly reduced risk of airway obstruction. Like all things in life, the placement of the LMA needed some skill, but overnight it reduced the invasive nature of anaesthesia associated with tracheal intubation.

While the LMA can be seen as an airway adjunct sitting somewhere between a Guedel airway and tracheal intubation and associated with an excellent safety profile, it is important to note that there is still a significant risk of displacement and airway trauma paradoxically leading to airway obstruction when it becomes blocked or moves position.

Also, the LMA is considered a good tool for use in the elective setting, where the patient is starved, as, importantly, the LMA does not protect the lower airway from gastric content reflux and as such has limited use in the emergency surgical setting.

However, for those eagle-eyed amongst you, you may have spotted the LMA appearing on many cardiac arrest trolleys. Successful Bag and Mask Ventilation (BMV) is often difficult. The immediacy of definitive intubation may not be an option (due to skills or kit availability) and, therefore, an effective LMA may be life-saving. The thinking here is:

1. Bag & Mask ventilation is often difficult
2. The immediacy of definitive intubation may not be an option (due to skills or kit availability)
3. An effective LMA may be life-saving

Take a moment to look at the picture below.

Laryngeal Mask Airway. (Photo credit: ICUnurses, via Wikimedia Commons, license)

Endotracheal Tube

Endotracheal tube. (Photo credit: ICUnurses, via Wikimedia Commons, license)

1. Intubation, wherever it occurs, is a team event.

Elective intubation in the operating theatres. (Photo credit: J.D Williamson)

Simulated intubation.

2. Planning is key.

At University College London Hospitals, the POCU staff use an airway alert board at each and every patient bed space. In the event of an emergency with the airway, staff know in principle how a lost airway will be rescued. It is specific for each individual patient and incorporates any prior knowledge the team have about intubating each individual patient.

Please take a moment to review the picture below. The detail on the board is beyond the scope of this training module, but the learning point is clear. If airway boards are in operation in your unit, be sure your patient has a clearly documented plan which is reviewed daily as part of the routine bedspace checks you undertake. You will see also that the board mandates the team to address a turning plan – does an anaesthetist need to be present for planned turns for nursing care?

POCU airway notice board at UCLH. (Photo credit: Prof David Walker)

3. Leadership and role allocation

In an airway emergency, roles and responsibilities are allocated appropriately and the adoption of a checklist to aid the safe and effective episode is adopted in full. It’s like an ALS/BLS scenario.

Click on the checklist below and spend a few moments only reviewing the pre-intubation checklist below used on POCU at University College London Hospitals (you may have noticed one above on the picture at the bed space with the airway notice board too) – you probably have your own, which is likely to be similar.

Pre-intubation checklist used on POCU at UCLH, reproduced with departmental permission. (You can download it here for a bigger size.)