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

Wenxian Li

Status: Not yet enrolling

Conditions: Awake Tracheal Intubation; Difficult Airway

Treatments: Device: Ligh-Flow Nasal Cannula; Device: High-Flow Nasal Cannula

Study type: Interventional

Funder types: Other

Identifiers

NCT07384494

EENTFudan 2025155-1

Details and patient eligibility

About

Study Background Airway management is one of the most fundamental and critical technical procedures in anesthesiology, critical care, and emergency medicine. Difficult airway management remains a major challenge in these fields, particularly when a "cannot intubate, cannot ventilate" scenario occurs during the induction of general anesthesia. Such events can rapidly lead to hypoxemia, resulting in brain injury or even death, and have become a significant source of anesthesia-related severe complications and medical disputes.

Awake tracheal intubation (ATI) is considered the gold standard for airway management in patients with anticipated difficult airways, as it preserves spontaneous breathing and thereby reduces the risk of catastrophic airway failure during anesthesia induction. However, despite routine supplemental oxygen administration, hypoxemia remains one of the most common and potentially serious complications during ATI. When low-flow oxygen therapy (<30 L/min) is used, the reported incidence of hypoxemia (SpO₂ ≤ 90%) ranges from 12% 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 successful intubation, but also trigger serious cardiovascular events, thereby compromising patient safety.

High-flow nasal cannula (HFNC) oxygen therapy can deliver heated and humidified gas at flow rates of up to 70 L/min and improve oxygenation and ventilation through mechanisms such as anatomical dead space washout, reduction of work of breathing, and generation of continuous positive airway pressure. HFNC has been shown to improve oxygenation in a variety of medical and procedural settings. However, evidence regarding the role of HFNC during awake tracheal intubation remains controversial and of low quality. There is an urgent need for well-designed multicenter randomized controlled trials specifically focused on the ATI setting, using hypoxemic events as the primary outcome and applying strictly standardized procedures, to provide high-quality evidence on the effectiveness and safety of HFNC during ATI. Such evidence is essential to inform clinical practice and support future updates of airway management guidelines.

Study Hypothesis This study hypothesizes that, in patients with anticipated difficult airways undergoing ATI, HFNC is more effective in preventing intubation-related hypoxemic events than conventional low-flow nasal cannula oxygen therapy.

Study Objectives

Primary Objective:

To evaluate the effectiveness of high-flow nasal cannula oxygen therapy compared with conventional low-flow nasal cannula oxygen therapy in preventing hypoxemia during ATI in patients with anticipated difficult airways.

Secondary Objectives:

To assess the effects of high-flow nasal cannula oxygen therapy versus conventional low-flow nasal cannula oxygen therapy on procedural outcomes of awake tracheal intubation, including the rate of interventions required after hypoxemia, first-attempt intubation 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. Adult patients undergoing ATI will be recruited from six tertiary hospitals in China. Participants will be randomly assigned to receive either high-flow nasal cannula oxygen therapy or conventional low-flow nasal cannula oxygen therapy throughout the intubation procedure. The study will compare the incidence of hypoxemia between the two groups and further evaluate intubation success rates, intubation time, the need for rescue interventions following hypoxemia, and the incidence of adverse events.

Enrollment: 336 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Presence of an anticipated difficult airway;
• Planned awake tracheal intubation;
• Age ≥ 18 years;
• Willingness to participate in the study and provision of written informed consent.

Exclusion criteria

• Contraindications to HFNC use, such as severe nasal obstruction or deformity, recent (within 3 months) nasal or skull base surgery, skull base fracture, or active epistaxis;
• Hemodynamic instability, defined as a mean arterial pressure (MAP) < 65 mmHg or the need for vasoactive medications to maintain blood pressure;
• Pregnancy;
• Current participation in another interventional clinical trial.

Trial design

Primary purpose: Supportive Care

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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336 participants in 2 patient groups

HFNC group

Experimental group

Description:

During awake tracheal intubation, participants receive heated and humidified high-flow nasal cannula oxygen therapy at a flow rate of 40 L/min, FiO₂ of 100%, and a temperature of 37 °C, starting before the procedure and continuing until successful intubation is confirmed by the presence of end-tidal carbon dioxide.

Treatment:

Device: High-Flow Nasal Cannula

LFNC group

Active Comparator group

Description:

During awake tracheal intubation, participants receive oxygen via a disposable nasal cannula at a flow rate of 4 L/min, starting before the procedure and continuing until successful intubation is confirmed by the presence of end-tidal carbon dioxide.

Treatment:

Device: Ligh-Flow Nasal Cannula