HFNO

High-flow nasal oxygen (HFNO) is a respiratory support modality that delivers heated, humidified oxygen at high flow rates through specialized nasal cannulas. In adults, typical flow settings range from 30 to 60 liters per minute, with FiO2 adjustable from 0.21 to 1.0. The therapy includes a heated humidifier and temperature control to keep airways moist.

Physiologic effects include meeting or exceeding inspiratory flow demands, washing out nasopharyngeal dead space, and generating a modest positive airway pressure that can aid alveolar recruitment. These factors reduce the work of breathing, improve oxygenation, and may stabilize ventilation in patients with hypoxemic respiratory failure.

Indications include acute hypoxemic respiratory failure, post-extubation support, and pre-oxygenation for airway management. HFNO is widely used in children for bronchiolitis and other respiratory illnesses. It is typically considered when patients require higher oxygen delivery than standard masks but can tolerate nasal access.

Clinical evidence suggests HFNO can reduce the need for intubation in certain populations and improve oxygenation and comfort, but results on mortality are inconsistent. Guidelines emphasize appropriate patient selection, monitoring, and readiness to escalate care if there is deterioration.

Common risks include nasal dryness, mucosal injury or epistaxis, and, rarely, gastric distension or barotrauma. Potential drawbacks include delayed intubation or inappropriate use in hypercapnic failure. Contraindications include facial trauma, significant nasal obstruction, or inability to maintain airway protection.