Airway obstruction may occur anywhere from the front of the nose through to the lungs and the most recent concepts of airway obstruction and infection define the unified or single airway rather than thinking of the nose and throat as being distinctly separate from the lungs. We now know that diseases of the upper respiratory tract can impinge significantly on the lungs and in particular allergic rhinitis and chronic sinus infections can lead to aggravation of asthma and other lung conditions.

The main causes of airway obstruction are allergic rhinitis (see section on allergic rhinitis), adenoid obstruction, tonsillar hypertrophy or enlargement (see section), laryngeal conditions (see section) and obstruction in the trachea and bronchi in the lower airway which is relatively uncommon in children. Children with nasal obstruction may either sniffle which usually indicates a nasal or adenoid problem particularly in allergic rhinitis and the child who chronically sniffs and has difficulty blowing their nose. Adenoid and tonsillar enlargement can cause snoring and obstructive apnoea. In the larynx and trachea the obstruction is often heard as a stridor which may be either on inspiration, expiration or both. One of the more common conditions in the baby and toddler, is a condition known as laryngomalacia or floppy larynx or voice box, whereon in drawing a breath the various parts of the larynx above the vocal cords collapse inwards causing the crowing sound. Usually this is an inspiratory stridor which represents the upper part of the larynx or voice box. If there is obstruction at the vocal cord region there may be an inspiratory and expiratory stridor as seen for example with papilomas or warts on the vocal cords and children with obstruction below the vocal cords may have an expiratory obstruction. The expiratory wheeze is also characteristic of asthma. Stridor is seen in laryngomalacia, the rare narrowing of the vocal cord area, benign haemangiomas of the area under the vocal cord (or subglottic haemangiomas in infancy) whilst in age 1 – 6 inflammatory croup and epiglottitis can be causes of stridor. In the older age group from 8 – 12 bacterial tracheitis is more common. It is important to mention to the doctor whether the stridor has been present intermittently or chronically and whether it is increasing in severity. Often a flexible fibreoptic scope is used to examine the larynx and sometimes special Xrays – CT or MRI are required. If a child has a very weak voice and cry then we examine them for bilateral vocal cord paralysis and rule out any other systemic cause. Many children with vocal cord paralysis on one side have stridor, hoarseness and less commonly respiratory distress.