IRCT20130311012782N37 IRCT 2019-11-13 Esfahan University of Medical Sciences Comparison of two methods of face or nasal mask in fat patients Comparison ventilation quality by anatomic or nasal mask after induction of general anesthesia in patients with body mass index more than 40 2019-09-22 anticipated 70 Complete https://irct.ir/trial/41907 interventional Randomization: Randomized, Blinding: Single blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Randomization description: Patients were randomly divided into two intervention 1 and intervention 2 groups by using Random Allocation Software, Blinding description: In this study, the face or nasal mask is embedded by the researcher and the data is collected by another person who is not aware of the process of the study. 1 Mechanical Ventilation. Intervention 1: Intervention group 1: In this group, routine ventilation with anatomical face mask and 100% oxygen is performed for three minutes. Ventilation is performed using anesthesia control mode at a volume of 8 cc / kg and speed of 12 min. The mean expiratory tidal volume, mean of SpO2, mean of EtCO2, mean of maximum air way pressure in three consecutive breaths in the second minute after the start of ventilation will be determined and recorded. Intervention 2: Intervention group2: In this group ventilation is done through the nasal mask. Ventilation is performed using anesthesia control mode at a volume of 8 cc / kg and speed of 12 min. The mean expiratory flow volume, SpO2 mean, EtCO2 mean, mean maximal airway pressure were measured and recorded in the second minute after the start of ventilation. No - There is not a plan to make this available Justification or reason for not sharing IPD is Because the project is owned by the university, it is not possible to publish its data.