# High-flow nasal cannula oxygenation reduces desaturation risk during diagnostic flexible bronchoscopy under deep sedation: a randomized controlled trial

## TL;DR

Using high-flow nasal cannula oxygen during bronchoscopy with deep sedation reduces the risk of low blood oxygen levels compared to standard oxygen.

## Contribution

This study is the first to demonstrate that high-flow nasal cannula reduces desaturation during deep sedation for bronchoscopy.

## Key findings

- HFNC groups had significantly lower desaturation rates compared to conventional nasal cannula.
- HFNC maintained higher minimum oxygen saturation and reduced CO₂ retention.
- Over 97% of patients were willing to undergo repeat bronchoscopy with HFNC.

## Abstract

Deep sedation for flexible bronchoscopy (FB) improves procedural conditions but exacerbates desaturation risks. High-flow nasal cannula (HFNC) may mitigate this situation, yet efficacy under deep sedation remains unproven.

In this randomized trial (ChiCTR2400083597), 340 ASA I-II patients undergoing FB under deep sedation (MOAA/S ≤ 1) received conventional nasal cannula (5 L/min; NC) or HFNC (25/45/65 L/min). The primary outcomes were the incidence of intraoperative desaturation (SpO₂ < 90% > 10s) and intraoperative nadir SpO₂ value. The intraoperative VAS scores for cough that reflect the stimulation inhibition as a result of deep sedation were used as secondary outcome. Other evaluated outcomes included the EtCO₂ values before induction and after awakening, incidence of intraoperative hypertension/hypotension, postoperative adverse events, as well as the willingness to undergo re-examination.

All procedures were completed in approximately 5 min, without requiring the application of laryngeal mask airway or endotracheal intubation. HFNC groups showed significantly lower desaturation incidence (HF25:16.87%, HF45:12.05%, HF65:5.00%) versus NC (57.14%, p < 0.000), with weak flow-dependence. All HFNC cohorts maintained higher nadir SpO₂ (p < 0.000) and reduced CO₂ retention versus NC (p < 0.05). Cough scores were uniformly low (median VAS:1–1.5), with >97% willingness for repeat FB.

The application of HFNC can markedly lower the risks of desaturation during FB under deep sedation in a weak flow-dependent manner, while partially mitigating carbon dioxide accumulation, enabling safer deep sedation without intubation.