Evidence of angioedema: suggestive of an anaphylactic reaction.Position of the patient: patients may often sit in a ‘tripod’ position (sat forward, neck extended with their arms by their side to aid in breathing) 5.Signs of cyanosis: indicative of significant airway compromise.Examination should focus on identifying features of airway compromise and potential underlying causes of stridor. 4 Airwayīy definition, the presence of stridor indicates a degree of airway compromise. Stridor warrants a rapid A-E assessment, primarily focusing on assessment of the airway. *Stridor is not to be confused with ‘ stertor/snoring’ – a low pitched sound, generally produced from obstruction of the nares or nasopharynx. Any history of foreign body ingestion (often seen in children – history from parents).Other important areas to cover in the history include: Drooling or inability to swallow saliva.Allergic/immune- anaphylaxis, hereditary angioedema.Deep neck space infections – parapharyngeal, retropharyngeal, submandibular (Ludwig’s angina).Laryngomalacia (most common) – a congenital abnormality of the laryngeal cartilage that predisposes to the airway collapsing in during the inspiratory phase of respiration 3.

The most common causes of stridor can be differentiated by age group (Table 1). 1,2 It is a life-threatening emergency as there is potential for airway compromise and respiratory arrest.

Stridor is an externally audible, high-pitched sound caused by turbulent airflow due to obstruction of the upper respiratory tract (pharynx, larynx or trachea).

Stridor lung sounds