Comparison of High-Flow Nasal Cannula and Tight Face Mask for Maintaining Oxygenation During Rapid Sequence Induction

Rapid sequence induction (RSI) is the preferred technique for securing the airway in patients at risk of aspiration. Despite standardized airway management protocols, hypoxemia during the apneic period remains one of the most frequent and clinically important complications of RSI. Oxygen desaturation may lead to serious adverse events including cardiac arrhythmias, hemodynamic instability, cardiac arrest, neurological injury, and increased mortality. Effective preoxygenation before induction is therefore essential to maximize oxygen reserves and prolong safe apnea time.

Conventional preoxygenation is commonly performed using a tight face mask delivering 100% oxygen. Although this method is widely accepted, oxygen delivery is interrupted when the face mask is removed for laryngoscopy, potentially reducing oxygen reserves during prolonged intubation attempts. High-Flow Nasal Cannula (HFNC) delivers heated and humidified oxygen at high flow rates with a high inspired oxygen fraction while allowing continuous oxygen administration throughout laryngoscopy and apnea. HFNC also generates low-level positive airway pressure and facilitates clearance of upper airway dead space, which may improve oxygenation during rapid sequence induction.

Previous randomized trials and systematic reviews have produced inconsistent findings regarding the comparative effectiveness of HFNC and conventional face mask preoxygenation. Some studies have demonstrated prolonged safe apnea time and improved oxygenation with HFNC, whereas others have shown similar oxygen saturation between both techniques. Additional randomized controlled trials are required to determine whether HFNC provides clinically meaningful advantages in adult patients undergoing rapid sequence induction.

This single-center, prospective, parallel-group, randomized controlled trial will be conducted at the Department of Anesthesiology, Khyber Teaching Hospital, Peshawar. Eligible adult patients requiring rapid sequence induction for endotracheal intubation in the operating room, emergency department, or intensive care unit will be enrolled after providing informed consent. Participants will be randomly assigned in a 1:1 ratio to receive either High-Flow Nasal Cannula or Tight Face Mask preoxygenation using a computer-generated randomization sequence with allocation concealment through sequentially numbered, opaque, sealed envelopes.

Patients allocated to the intervention group will receive heated, humidified oxygen via High-Flow Nasal Cannula at the protocol-defined flow rate and fraction of inspired oxygen before induction and throughout laryngoscopy until successful endotracheal intubation. Participants allocated to the control group will receive conventional preoxygenation using a tightly fitting face mask delivering 100% oxygen according to standard institutional practice until induction of anesthesia.

The primary outcome will be the lowest peripheral oxygen saturation (SpO₂) recorded from induction until successful tracheal intubation. Secondary outcome measures will include the incidence of oxygen desaturation below 90%, duration of apnea, duration of laryngoscopy, time required for successful intubation, first-pass intubation success, number of intubation attempts, and peri-intubation adverse events including hypotension, arrhythmias, aspiration, and cardiac arrest.

Data will be collected prospectively using standardized case report forms by trained investigators. Statistical analyses will follow the intention-to-treat principle. Continuous variables will be compared using the independent-samples t-test or Mann-Whitney U test as appropriate, whereas categorical variables will be compared using the Chi-square test or Fisher's exact test. A two-sided p-value of less than 0.05 will be considered statistically significant.

The results of this trial are expected to provide high-quality evidence regarding the optimal preoxygenation strategy during rapid sequence induction and may contribute to improved airway management protocols and reduction of peri-intubation hypoxemia in adult patients.

Inclusion criteria

• Adults aged 18 years or older.
• Patients requiring rapid sequence induction (RSI) for endotracheal intubation in the operating room, emergency department, or intensive care unit.
• Patients in whom both high-flow nasal cannula (HFNC) and tight face mask preoxygenation are technically feasible.
• Patients (or their legally authorized representatives, when applicable) able to provide written informed consent.

Exclusion criteria

• Patients requiring immediate crash intubation without sufficient time for preoxygenation.
• Patients with facial deformities, upper airway obstruction, or other conditions preventing the use of either HFNC or a tight face mask.
• Known contraindications or hypersensitivity to medications used for rapid sequence induction.
• Pregnant women.
• Patients younger than 18 years of age.
• Patients with do-not-intubate (DNI) orders.
• Patients already intubated or mechanically ventilated before enrollment.
• Patients who underwent endotracheal intubation within the previous 24 hours.