High-flow Nasal Cannula Versus Conventional Oxygen During Awake Tracheal Intubation With Difficult Airways

Study Background Airway management is one of the most fundamental and critical technicalprocedures in anesthesiology, critical care, and emergency medicine. Difficult airwaymanagement remains a major challenge in these fields, particularly when a "cannotintubate, cannot ventilate" scenario occurs during the induction of general anesthesia.Such events can rapidly lead to hypoxemia, resulting in brain injury or even death, andhave become a significant source of anesthesia‐related severe complications and medicaldisputes.Awake tracheal intubation (ATI) is considered the gold standard for airway management inpatients with anticipated difficult airways, as it preserves spontaneous breathing andthereby reduces the risk of catastrophic airway failure during anesthesia induction.However, despite routine supplemental oxygen administration, hypoxemia remains one of themost common and potentially serious complications during ATI. When low‐flow oxygentherapy (<30 L/min) is used, the reported incidence of hypoxemia (SpO₂ ≤ 90%) ranges from12% to 29%. Once hypoxemia occurs during ATI, it may not only interrupt the procedure,increase the number of intubation attempts, and reduce the likelihood of successfulintubation, but also trigger serious cardiovascular events, thereby compromising patientsafety.High‐flow nasal cannula (HFNC) oxygen therapy can deliver heated and humidified gas atflow rates of up to 70 L/min and improve oxygenation and ventilation through mechanismssuch as anatomical dead space washout, reduction of work of breathing, and generation ofcontinuous positive airway pressure. HFNC has been shown to improve oxygenation in avariety of medical and procedural settings. However, evidence regarding the role of HFNCduring awake tracheal intubation remains controversial and of low quality. There is anurgent need for well‐designed multicenter randomized controlled trials specificallyfocused on the ATI setting, using hypoxemic events as the primary outcome and applyingstrictly standardized procedures, to provide high‐quality evidence on the effectivenessand safety of HFNC during ATI. Such evidence is essential to inform clinical practice andsupport future updates of airway management guidelines.Study Hypothesis This study hypothesizes that, in patients with anticipated difficultairways undergoing ATI, HFNC is more effective in preventing intubation‐related hypoxemicevents than conventional low‐flow nasal cannula oxygen therapy.Study ObjectivesPrimary Objective:To evaluate the effectiveness of high‐flow nasal cannula oxygen therapy compared withconventional low‐flow nasal cannula oxygen therapy in preventing hypoxemia during ATI inpatients with anticipated difficult airways.Secondary Objectives:To assess the effects of high‐flow nasal cannula oxygen therapy versus conventionallow‐flow nasal cannula oxygen therapy on procedural outcomes of awake trachealintubation, including the rate of interventions required after hypoxemia, first‐attemptintubation success rate, number of intubation attempts, overall ATI success rate,intubation time, and the incidence of adverse events.Study Methods This study is a multicenter, randomized controlled clinical trial. Adultpatients undergoing ATI will be recruited from six tertiary hospitals in China.Participants will be randomly assigned to receive either high‐flow nasal cannula oxygentherapy or conventional low‐flow nasal cannula oxygen therapy throughout the intubationprocedure. The study will compare the incidence of hypoxemia between the two groups andfurther evaluate intubation success rates, intubation time, the need for rescueinterventions following hypoxemia, and the incidence of adverse events.