This was a prospective, randomized cross-over manikin study in which participants first completed a standardized two-hour theoretical and hands-on training session on airway anatomy, laryngoscopy techniques, and the use of stylet and bougie. Each participant subsequently performed four intubation techniques -direct and video laryngoscopy, each combined with either a stylet or a bougie- according to a randomized sequence on the same airway manikin using a 7.5-mm endotracheal tube. The primary outcome was first-pass success, defined as successful tracheal tube placement on the first attempt. The secondary outcome was intubation time, measured from initial contact of the laryngoscope blade with the manikin to successful advancement and release of the tube; attempts exceeding five minutes were classified as failed first-pass attempts.

Airway management is a fundamental emergency medicine skill, and first-pass success in endotracheal intubation (ETI) is strongly operator-dependent. Novice intubators have lower success rates and a higher risk of complications, making the identification of simple and effective adjuncts essential in training environments. Although devices such as the bougie, stylet, and video laryngoscope are widely used, the most suitable combination for beginners remains uncertain. To address this, a controlled simulation study was conducted under standardized conditions.

This was a single-center, prospective, randomized cross-over manikin study conducted between April and July 2025 following ethics approval and written informed consent. Sixth-year medical students without prior real-world intubation experience were enrolled. Before the study procedures, all participants completed a standardized two-hour training session consisting of theoretical instruction and hands-on practice delivered in small groups by an emergency medicine specialist. Training focused on airway anatomy, laryngoscopy technique, and the correct use of both stylet and bougie, using the same airway manikin model employed in the study.

Participants were randomly assigned in a 1:1:1:1 ratio to one of four sequence groups using a computer-based online randomization tool. Each group followed a predefined order of four techniques-direct laryngoscopy with bougie (DL+B), direct laryngoscopy with stylet (DL+S), video laryngoscopy with bougie (VL+B), and video laryngoscopy with stylet (VL+S)-so that every participant performed all techniques once while minimizing order and learning effects associated with repeated attempts. Group allocation was determined before the session, and all intubations were performed according to the assigned sequence.

Intubation attempts were performed on a human airway manikin using a Macintosh size 3 blade for direct laryngoscopy and an i-view disposable video laryngoscope for video laryngoscopy. A 7.5-mm endotracheal tube was used in all attempts, and either a stylet or a bougie was applied according to the allocated technique. A 10-minute rest period was provided between attempts to reduce fatigue-related bias.

The primary outcome was first-pass success, defined as successful placement of the endotracheal tube into the trachea on the first attempt. The secondary outcome was intubation time, measured from the moment the laryngoscope blade first contacted the manikin to the moment the endotracheal tube was successfully advanced into the trachea and released, as confirmed by study observers. Attempts lasting longer than five minutes were classified as failed first-pass attempts.

Inclusion Criteria:

• Sixth-year medical students
• Not on clinical duty at the time of participation
• No scheduled clinical duty on the following day
• Free of any acute illness at the time of the study
• Exclusion Criteria:
• Any prior real-world experience in endotracheal intubation