This study is a prospective, cross-over manikin study which is based on an ambulance simulation. Written inform consent was obtained from all doctors who agreed to participate to the study. Inexperienced doctors who attended in Kocaeli between February 2018 and March 2018 will be included to the survey. Novice doctors participated to this research. The research will be carried out in the department of emergency medicine of Derince training and research hospital. In order to prevent bias, the eight-hour training module for the participants , theoretical and practical airway training will be provided by an emergency medical specialist who has no knowledge about the research.

The participants will be informed about the study after the training. Doctors who participate to the study will be included after the written inform consent is obtained. The participants will be informed about the research, but they will be blind to the specific purposes of the study. The participants will practice for 5 minutes on the manikin by themselves and with the emergency medicine specialist if they ask for. Life / form® Deluxe Crisis ™ Manikin Torso with Advanced Airway Management will be used as the research manikin. The participants will perform airway interventions in the sitting position and the height of the stretcher will be set at the same height with the ambulance stretcher. Practitioner's seat will be set on the same height with the ambulance seat. 8.0 (mm ID) endotracheal tube will be used for the procedure. Endotracheal tube and manikin airway will be lubricated with pump spray lubricant provided with the simulator. Airway manikin will be in supine position. Lund University Cardiac Arrest System-version 2 (LUCAS 2TM) automatic chest compression device will be used to provide 5 cm compression depth and 100 chest compressions per minute in order to provide standardization in chest compression and prevent bias created by practitioners. The airway devices will be next to the model's head.

The study was planned as a randomized, crossover clinical trial to reduce the influence of the learning. Equal numbers 1 and 2 will be written on the same sized papers to provide randomization. All papers will be folded in the same way and placed inside brown and invisible envelopes. All of the envelopes will be placed in the same box. After the training, every doctor will be asked to choose one of the envelopes. After separating the participants into two groups, doctors that drawed envelop number 1 will be asked to intubate by using only No. 3 Macintosh blade. The doctors that drawed envelop number 2 will be asked to intubate with the adult size endotracheal tube introducer with using No. 3 Macintosh laryngoscopy.

After the groups completed their interventions, those who drawed envelope number 1 will be asked to intubate with Macintosh laryngoscopy using endotracheal tube introducer and those who drawed envelope number 2 will be asked to intubate with Macintosh laryngoscopy. Each doctor will be given 1 minute for each successful intervention. Each practitioner will make maximum 2 trial attempts for each method. The initiation time is considered to be taking the laryngoscopy on hand. After ventilation, the manikin's chest wall movement is considered as a successful intervention. All transactions will be recorded with a camera that is placed in the room and the participants will have the information about the presence of the camera. The first intervention success , intubation time, the number of interventions of the participants will be recorded. After the interventions are over, the participants will be asked to rate the difficulty of the ventilation methods according to the Likert scale as 1-very easy, 2-easy, 3-medium, 4-difficult 5- very difficult. In addition, they will be asked whether they have any experiences with Macintosh laryngoscopy or endotracheal tube introducer and their responses will be recorded.