Summer Clinical Practice Test

High-flow nasal cannula delivers heated, humidified oxygen at high flow, providing a high and variable fraction of inspired oxygen, plus a little positive airway pressure and dead-space washout. These effects improve oxygenation and reduce the work of breathing, so HFNC can be used in several situations where hypoxemia or breathing effort are the main problems. Acute hypoxemic respiratory failure clearly benefits because the patient often needs more oxygen delivery than standard oxygen can provide. Cardiogenic pulmonary edema often presents with significant hypoxemia, and the added flow and mild PEEP-like effect help recruit flooded alveoli and improve gas exchange. In COPD or asthma, oxygenation support is sometimes needed, and HFNC is well tolerated with humidified gas, can reduce work of breathing, and may be preferred when a mask is uncomfortable or NIV isn’t available. Taken together, HFNC is indicated in all of these scenarios, so the best choice is all of the above.