An obstructed airway prevents the passage of oxygen to the lungs leading rapidly to hypoxia and potentially cardiac arrest.

Functional airway obstruction may be partial or complete and occur at any point from the level of the mouth/nose down to the end of the trachea (at the level of the carina). Airway obstruction commonly occurs in patients with a reduced conscious level.  Less common causes include foreign bodies, secretions (e.g. vomit), and swelling (e.g. anaphylaxis, angio-oedema).

Reduced conscious level: Patients who have a depressed level of consciousness may find it difficult to maintain their own airway. Soft tissues (tongue, soft palate and epiglottis) may occlude the upper airway. Conscious state can be assessed using the ‘ACVPU’ score or Glasgow Coma Score (GCS), which is discussed later. Seizure activity is often associated with airway occlusion.

Secretions in the airway: In a patient with reduced consciousness and a ‘compromised’ airway, secretions or vomit may precipitate airway obstruction. In such cases, placing the patient in the recovery position and gentle suction is helpful.

Anaphylaxis: A severe, life-threatening allergic reaction during which oedema of the larynx and upper and lower airways may cause obstruction, making breathing extremely difficult. There may be stridor, rash, wheeze and/or shock.

Soft tissue swelling: Swelling of the airway can occur due to infection (e.g. epiglottitis, supraglottitis) or trauma such as burns and inhalational injury.  The management of these can be difficult and early involvement of an anaesthetist is crucial.

Foreign body obstruction: This is rare in adults and most foreign body aspirations occur in children aged 1-3 years.