Optimal Insertion Depth of FOB for Oral FOB Intubation

For oral fiberoptic intubation, the preliminary insertion depth of the fiberoptic bronchoscope should be important because the excessive insertion depth or too shallow depth might be the reason why the clinicians cannot perform oral fiberoptic intubation completely. The purpose of the study is to find out the optimal preliminary insertion depth of the fiberoptic bronchoscope for visualization of glottic opening in oral fiberoptic intubation.