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.

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.

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