Aetiology
Infection of the supraglottis: classically with Haemophilus influenzae, but also from other potential pathogens, including Streptococcus pneumoniae, Staphylococcus aureus, and MRSA.[12][13] Other rare bacterial pathogens such as Pasteurella multocida have been reported.[14]
Less commonly, viral pathogens such as parainfluenza have been implicated as aetiological agents.[15]
Another rare aetiology of epiglottitis is fungal infection. Several reports of candidial epiglottitis have been reported.[16]
Traumatic: a mechanical insult to the epiglottis can occur, most commonly from caustic ingestion or thermal injury, which may result in marked oedema and inflammation of the epiglottis.
Pathophysiology
Inflammatory pathways lead to localised oedema of the airway, exponentially increasing airway resistance while narrowing the effective supraglottic aperture. The glottis is usually not inflamed or affected as the process affects the supraglottic structures. Further compromise can occur from secretions potentially resulting in complete airway obstruction.
Classification
Katori and Tsukuda, 2005[2]
Proposed to classify patients based on their flexible nasopharyngoscopic examination.
Class I is described as slight swelling, with the entire vocal cord visualised.
Class II is moderate swelling of the epiglottis, with >50% of the posterior vocal cord visualised.
Class III describes severe swelling with <50% of the posterior vocal cord visualised.
Modifiers in the schema include a lack of extension to the arytenoids and aryepiglottic folds (group A) or having extension (group B).
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