High-flow nasal oxygen therapy via a single-prong cannula interface during bronchoscopy in patients with acute respiratory failure: a two-center, open-label, randomized controlled trial

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Background Flexible bronchoscopy (FB) is commonly performed in patients with acute respiratory failure (ARF), but the procedure can exacerbate hypoxemia and increase the need for respiratory support. The impact of high-flow nasal oxygen (HFNO) therapy during nasal FB in patients with ARF remains uncertain, as prior studies have focused primarily on oxygenation rather than clinical outcomes. We aimed to evaluate whether HFNO therapy via a single-prong cannula interface (HFNO-SPC) could reduce the need for respiratory support escalation within 24 h after FB compared to standard oxygen therapy (SOT). Methods We conducted a two-center, open-label, randomized controlled trial comparing HFNO-SPC to SOT in patients undergoing FB. The primary outcome was escalation of respiratory support within 24 h after FB, defined as the requirement for invasive mechanical ventilation (IMV), noninvasive ventilation (NIV), or HFNO, or as increases in support parameters without changing the mode of respiratory support. The secondary outcome was a hierarchical composite of these escalation events. Electrical impedance tomography (EIT) monitoring was performed during FB to assess tidal volume and end-expiratory lung volume changes. Results A total of 160 patients were randomized to either the HFNO-SPC group (n = 80) or the SOT group (n = 80), and all were included in the intention-to-treat analysis. HFNO-SPC significantly reduced the incidence of respiratory support escalation compared to SOT (15.0% vs. 33.8%, P = 0.006). Hierarchical analysis of the composite secondary outcome supported the primary findings (31.6% vs 12.1%, P = 0.004). Additionally, HFNO-SPC resulted in a lower intubation rate within 24 h (7.5% vs. 20.0%, P = 0.022). EIT measurements showed smaller reductions in tidal impedance variation (TIV) during FB and less pronounced changes in end-expiratory lung impedance (ΔEELI) during and after FB in the HFNO-SPC group. Conclusions In patients with ARF, HFNO-SPC significantly reduced the proportion of patients requiring respiratory support escalation within 24 h after FB compared with SOT. This finding was consistent across a hierarchical analysis of clinically ranked outcomes. Trial Registration ClinicalTrials.Gov: NCT 05759832. Registered 27 February 2023.