High-flow nasal cannula oxygenation in sedated endoscopy for high-risk obstructive sleep apnea patients: study protocol for a multicentre randomised controlled trial.

Abstract

BACKGROUND: Hypoxemia is the most common adverse event during sedated gastrointestinal endoscopy. Patients with high obstructive sleep apnea (OSA) risk (STOP-Bang &#x2265;5) are susceptible due to sedation-induced loss of upper airway tone exacerbating airway collapsibility. Although high-flow nasal cannula (HFNC) benefits general at-risk populations, its efficacy in this specific cohort remains uncertain, as its mild positive pressure falls far below therapeutic continuous positive airway pressure levels for moderate-to-severe OSA, questioning its ability to stent the collapsible airway. Our prior proof-of-concept study in this cohort observed a 5% incidence of hypoxemia with HFNC, confirming feasibility and safety and justifying this confirmatory trial. METHODS: This prospective, multicenter, randomized controlled single-blind trial will enroll 600 adults (STOP-Bang score &#x2265;5) undergoing elective sedated gastroenteroscopy across three centers. Participants will be 1:1 randomized (stratified by center) to HFNC (30&#x2009;L/min pre-oxygenation, 60&#x2009;L/min post-induction) or conventional nasal cannula (6&#x2009;L/min). Both groups receive standardized propofol-alfentanil sedation. The primary outcome is the proportion of patients with at least one episode of hypoxemia (SpO2 75%-90% <60&#x2009;s). Secondary outcomes include the proportion of patients with at least one episode of severe hypoxemia (SpO2 <75% or 75%&#x2264;SpO2<90% &#x2265;60&#x2009;s), the proportion with subclinical respiratory depression (90%&#x2264;SpO2<95%), and the frequency of other adverse events. DISCUSSION: This trial will provide definitive evidence on HFNC's efficacy in high-risk OSA patients, addressing whether it can overcome pressure limitations to prevent hypoxemia. Results are expected to inform sedation management guidelines, establish a new standard of care for this subgroup, and enhance procedural safety. TRIAL REGISTRATION: The trial was registered at the ClinicalTrials.gov on 14 December 2025 (NCT07307560).