Patients with full stomachs face a high risk of regurgitation and aspiration under general anesthesia. To minimize the time between the loss of airway protective reflexes and successful tracheal intubation, rapid sequence induction intubation is commonly used. However, these patients are particularly vulnerable to hypoxemia during anesthesia induction, especially in emergency cases. Pre-oxygenation before induction is crucial for ensuring patient safety during apnea.
High-flow nasal oxygen (HFNO) therapy, which consists of an air/oxygen blender, an active humidifier, and a single heated circuit, has recently gained widespread use in intensive care units (ICUs) for managing hypoxemic respiratory failure. HFNC can deliver a constant fraction of inspired oxygen (FiO₂) from 0.21 to 1.0 at high flow rates (up to 60 L/min or higher). Its advantages include generating continuous positive airway pressure, reducing anatomical dead space, improving ventilation-perfusion matching, enhancing mucociliary clearance, and decreasing the work of breathing.
Given these benefits, HFNO has the potential to improve pre-oxygenation before and during anesthesia induction in emergency surgery patients with full stomachs.
Emergency surgical patients at risk of gastric fullness requiring endotracheal intubation.
Patients aged 18 years or older.
Health status classified as ASA I or II.
Mallampati classification I or II.
Patients with a predicted difficult airway, facial deformities, or an inability to achieve a proper mask seal.
Patients with respiratory diseases.
Pregnant patients.
Patients allergic to anesthesia or resuscitation drugs.
Parallel
High-flow nasal cannula therapy application
DevicePatients will undergo HFNC preoxygenation for 3 minutes with a flow rate of 60 L/min of heated and humidified pure oxygen (100% FiO₂, 37°C - Optiflow; Fisher \& Paykel Healthcare, Auckland, New Zealand). To minimize air contamination, large or medium nasal cannulae will be selected based on the patient's nostril size
Traditional facemask
DevicePatients will undergo preoxygenation for 3 minutes using a face mask (sized appropriately to fit the patient and ensure an airtight seal) connected to an Aisys CS2 ventilation system (General Electric, GE Healthcare, Oy, Finland). In this group, the ventilation system will be set with a fresh gas flow of 10 L/min, FiO₂ = 100%, without inspiratory support or expiratory positive pressure. The face mask (Economy, Intersurgical, Fontenay-sous-Bois, France) will be removed after induction to enable intubation.
PaO2
PaO2 was checked via arterial blood gas at different time points
Changes SpO2 during 3 minutes of preoxygenation
SpO2 was recorded at baseline (before preoxygenation) and every 30 seconds during 3 minutes of preoxygenation
Incidence of desaturation during rapid sequence induction anesthesia
Desaturation is defined as SpO2 \< 94% during apnea and intubation period of induction anesthesia
Number of episode of facemask ventilation during apnea period
during apnea period, if SpO2 \< 94% facemask ventilation will be applied
Changes TcCO2
Continuous transcutaneous CO2 partial pressure monitoring (TcCO2). TcCO2 was monitored with a sensor (V-Sign™ 2 sensor; SenTec, Switzerland) attached to the skin of the forearm or anterior chest, connected to the SenTec digital display after calibration. TcCO2 was recorded every 30 seconds during preoxygenation, apnea and intubation period
Gastric volume
Gastric volume assessment was accessed using ultrasound
Incidence of regurgitation and aspiration
regurgitation and aspiration were checked during laryngoscopy
Nasal congestion
Evaluate after extubation
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Nguyen Dang Thu
Lead sponsor
Vietnam Military Medical University
Sponsor institution
Hanoi Medical University
Collaborator
Phu Tho General Hospital
Collaborator
