Tracheal Intubation: The Proof is in the Bevel. 
Efficient airway management is paramount in emergency medicine.  Our experience teaching tracheal intubation has consistently identified gaps in the understanding of important issues.  Here we discuss the importance of the endotracheal tube (ETT) bevel in airway management.  The ETT bevel orientation is the main determinant of which mainstem bronchus the ETT enters when advanced too distally, despite a common belief that attributes a higher incidence of right mainstem bronchial intubation to the straighter angle sustained by the right mainstem bronchus.  Likewise, a bougie- or fiberscope-assisted tracheal intubation can be impeded by the ETT tip hooking onto laryngeal structures; a 90-degree counterclockwise turn of the ETT (such that the bevel is facing posteriorly) prior to advancing it toward the larynx produces a first-pass success rate of 100%.  Similarly, a posterior-facing bevel is believed to improve the ease of passage through the back of the nasal cavity when performing nasotracheal intubation.  If resistance is met after the ETT tip has reached the laryngeal vicinity, further counterclockwise rotation may change the plane and incident angle of the ETT tip, facilitating passage through the vocal cords.  Clockwise twisting of the ETT reduces the incident angle in the sagittal plane, thereby facilitating videolaryngoscopy-assisted tracheal intubation.  Finally, a posterior-facing ETT bevel is the least likely to intubate a tracheoesophageal fistula.  Understanding the implications of the ETT bevel direction may significantly change the efficiency of deliberate endobronchial, nasal, and bougie/fiberscope-, and videolaryngoscope-assisted intubations, and while managing the patient with a tracheoesophageal fistula.