Mechanisms and benefits of oxygen delivered via high flow nasal cannula

Mechanism	Physiologic and clinical benefit
Small, pliable nasal prongs	Enhanced patient comfort
Heat and humidification	Facilitates removal of airway secretions Avoids airway desiccation and epithelial injury Decreased work of breathing Enhances patient comfort
Washout of nasopharyngeal deadspace	Improved ventilation and oxygen delivery
Positive end-expiratory (PEEP) effect	Unload auto-PEEP (if present) Decrease work of breathing Enhance oxygenation
High nasal flow rate	Reliable delivery of fraction of inspired oxygen (FiO₂) Improved breathing pattern (eg, increased tidal volume, decreased respiratory rate)

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