Upper airway signs: inspiratory stridor, suprasternal retractions, drooling e.g., laryngospasm, angioedema, anaphylaxis, tumors, croup, epiglottitis, diphtheria, drowning, OSA Above the level of the vocal cords: nasal cavity, nasopharynx, oropharynx, hypopharynx, larynx. They are mostly soft tissues, easily to collapse with negative pressure. Lower airway signs: expiratory wheezing, rhonchi, prolonged exhalation e.g., AECOPD, acute asthma exacerbation, bronchiolitis, aspiration, bronchiectasis, cystic fibrosis Below the vocal cords (subglottic): trachea, bronchi, bronchioles, alveoli Stridor E → I (inhalation closes upper airways = sound) Inspiratory stridor → glottis or supraglottis Expiratory stridor → obstruction at the level of alveoli
