High-Flow Nasal Cannula (HFNC) Explained: Physiology, Settings & Clinical Applications High-Flow Nasal Cannula (HFNC) has become one of the most important respiratory support modalities in emergency medicine, critical care medicine, respiratory therapy, and hospital medicine. By delivering heated, humidified oxygen at high flow rates, HFNC can improve oxygenation, reduce work of breathing, wash out anatomic dead space, and provide a small amount of positive airway pressure. HFNC has emerged as a key tool for managing acute hypoxemic respiratory failure and is increasingly used across emergency departments, ICUs, and inpatient settings. In this episode, we review the physiology behind HFNC, discuss how it differs from conventional oxygen therapy, and explore practical applications in acute hypoxemic respiratory failure, pneumonia, ARDS, preoxygenation, post-extubation support, and other critical care scenarios. We also discuss flow rates, FiO₂ adjustments, troubleshooting, and common pitfalls when caring for patients requiring advanced oxygen therapy. Topics Covered: • What is HFNC? • How HFNC works • Physiology of high-flow oxygen therapy • Flow rates and FiO₂ settings • Heated and humidified oxygen • Dead space washout • Positive airway pressure effects • Work of breathing reduction • Acute hypoxemic respiratory failure • Pneumonia and ARDS • Preoxygenation before intubation • Post-extubation respiratory support • HFNC vs conventional oxygen therapy • HFNC vs BPAP • Troubleshooting HFNC • Clinical pearls and pitfalls 📺 Watch the full video: https://www.youtube.com/watch?v=kSM2AI1cfYQ 📚 Download the full study guide + access our complete emergency critical care curriculum: https://www.patreon.com/c/WhiteBoardMedicine Our Patreon includes: • 📄 Study guides for every video • 📋 One Pagers • 🎓 Mini-courses (ventilation, shock, RRT & more) • ❓ Practice questions • 🚫 Ad-free videos • 🧠 A structured ICU curriculum 🌐 WhiteBoard Medicine Website: https://whiteboardmedicine.com Disclaimer: This content is intended for educational purposes only and should not be considered medical advice. Clinical decisions should always be based on individual patient circumstances, local protocols, and consultation with appropriate healthcare professionals.

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