High-flow nasal oxygenation, not ventilation: time to stop holding our breath.

High-flow nasal oxygenation (HFNO) has gained popularity in tubeless upper airway surgery owing to its ability to maintain oxygenation during apnoea. We dissect current evidence on HFNO, discuss its limited ventilatory capability, and integrate established guidelines with emerging research to propose practical considerations in its use. Despite early claims of ventilatory benefit, accumulating evidence suggests that HFNO does not clear carbon dioxide. In both adults and children, consistent arterial carbon dioxide accumulation across a wide range of flow rates highlights the risk of hypercapnia. This has important clinical implications for haemodynamic and neurologic function, especially in high-risk populations. Anaesthetists and the scientific community should replace the term 'transnasal humidified rapid-insufflation ventilatory exchange (THRIVE)' with 'apnoeic high-flow nasal oxygenation (apnoeic HFNO)', with an emphasis on multimodal carbon dioxide monitoring the selective use of ventilatory adjuncts when required.