• Upper airway signs: inspiratory stridor, suprasternal retractions, drooling
  • e.g., laryngospasm, angioedema, anaphylaxis, tumors, croup, epiglottitis, diphtheria, drowning, OSA
• Lower airway signs: expiratory wheezing, rhonchi, prolonged exhalation
  • e.g., AECOPD, acute asthma exacerbation, bronchiolitis, aspiration, bronchiectasis, cystic fibrosis

Stridor

• E → I (inhalation closes upper airways = sound)
• Inspiratory stridor → glottis or supraglottis
• Expiratory stridor → obstruction at the level of alveoli