Nasal Oxygen Delivery Devices

Nasal cannula can be used to deliver supplemental O2. Conventional nasal cannula are commonly used deliver low flow rates & moderate FiO2.

High flow nasal cannula (HFNC) delivers higher flow rates achieving a higher FiO2 with greater patient comfort.

In hypoxemic respiratory failure use of HFNC is associated with a lower rate of requiring intubation & lower ICU mortality compared to CNC or NIPPV. HFNC can prevent reintubation after thoracic and cardiac surgeries. Extubation to HFNC is also associated with lower rates of re-intubation.

Physiology of Heated High Flow Nasal Cannula

 • Higher flow washes out CO2 from anatomical dead space in the nasopharynx

 • Higher flow overcomes resistance against expiratory flow and creates a small positive nasopharyngeal pressure (approximatelv 0.7 cm H2O of PEEP for every 10 lpm of flow)

 • Patients in respiratory distress generate high flows and will entrain ambient air with conventional nasal cannula. HFNC can match demand so FiO2 remains relatively constant

 • Warm humidified gas preserves mucociliary function & is more comfortable for patients



- Nick Mark MD @nickmmark



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