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 due to aspiration. It can also commonly occur in children as a result of obstruction as a result of:
Upper airway obstruction can be heard as “stridor”, a harsh inspiratory noise (different from wheeze which is a high pitched expiratory sound as a result of lower airway obstruction).
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 as can aspiration of stomach contents. Conscious state can be assessed using the ‘AVPU’ score or Glasgow Coma Score (GCS), which is discussed later. In these patients it is important to protect the airway using airway manoeuvres or adjuncts until a definitive airway (endotracheal tube) can be established. 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 rash, stridor, wheeze and/or shock. Treatment includes antihistamines, steroids and adrenaline.
Soft tissue swelling: Swelling of the airway can occur due to infection (e.g. croup, 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. Steroids including dexamethasone and budesonide are often used.
Foreign body obstruction: This is common in children between the ages of 1 and 3. There is usually a history of sudden onset difficulty in breathing and often an associated choking episode. They usually have unilateral signs on examination and in toddlers it is important to always consider inhaled foreign body in a young child presenting with airway obstruction.