Supplementary Material for: Enhancing Visibility of the Hypopharyngeal-Esophageal Region by Introduction of a Physiological Eructation Maneuver

Background: In routine medical examination, the hypopharyngeal-esophageal area (HER) is difficult to assess due to its position and anatomical complexity. The purpose of this study was to evaluate the feasibility of a volitional eructation maneuver during transnasal flexible laryngoscopy and its influence on the visibility of the HER. Methods: Twenty healthy volunteers underwent flexible laryngoscopy. Once the larynx was freely visible during laryngoscopy, the subjects were asked to trigger a “burp.” The volitional belching during the study was assisted by drinking a carbonated cold drink. The triggered relaxation of the upper esophageal sphincter along with the widening of the hypopharynx region was recorded and subsequently analyzed frame by frame. Results: Out of 20 volunteers, 16 (80%) were able to volitionally induce an eructation. Significant widening of the hypopharynx region up to the relaxant upper esophageal sphincter could be recorded. The structures were clearly visible in the offline analysis. In 13 (81%) of the 16 subjects who could induce an eructation, the upper esophageal sphincter was partially visible or free for full inspection. Conclusion: The eructation method as a simple physiological function can be used as a complementary method during flexible transnasal endoscopy to enhance visibility of the entire hypopharynx region as well as the upper esophageal sphincter.