title: Dynamic article: steady pressure CO2 colonoscopy; its feasibility and underlying mechanism.
abstract: BACKGROUND
  Steady pressure automatically controlled endoscopy is a new insufflation concept, achieving a laparoscopy-like steady environment in the upper GI tract, recently reported in the esophagus.
  
  
  OBJECTIVE
  The purpose of this work was to validate the feasibility and safety of steady pressure automatically controlled endoscopy in the lower GI tract and to identify major factors that enable it.
  
  
  METHODS
  This was a nonsurvival animal study using canine models.
  
  
  METHODS
  The study was conducted in an academic center.
  
  
  METHODS
  Canine models were used in this study.
  
  
  METHODS
  In experiment 1, steady pressure automatically controlled endoscopy was attempted in the cecum with insufflation pressures of 4, 8, and 12 mm Hg. We assessed performance by video review and continuous intracecal pressure monitoring. Next, steady pressure automatically controlled endoscopy was performed for 20 minutes under optimal pressure, 8 mm Hg (n = 10). In experiment 2, steady pressure automatically controlled endoscopy was attempted in the rectum with or without artificial colonic flexure and with either low (8 mm Hg) or high (16 mm Hg) insufflation pressure to assess the effects of anatomic flexure and insufflation pressure on the establishment of steady pressure automatically controlled endoscopy (n = 6).
  
  
  METHODS
  We measured multipoint intraluminal pressure monitoring in the upstream bowel, as well as cardiopulmonary parameters.
  
  
  RESULTS
  For experiment 1, steady pressure automatically controlled endoscopy in cecum was successful at all of the tested insufflation pressures; 8 mm Hg provided the optimal result. Steady pressure automatically controlled endoscopy was safely performed for 20 minutes at 8 mm Hg without any cardiopulmonary parameter changes or intraluminal pressure elevation in the upstream bowel. For experiment 2, confinement of the steady pressure environment to the rectum was achieved only with the assistance of colonic flexure and at 8 mm Hg insufflation pressure. In other conditions, the insufflated gas extended throughout the entire colon.
  
  
  CONCLUSIONS
  This study was limited by being an animal study.
  
  
  CONCLUSIONS
  Steady pressure automatically controlled endoscopy is feasible and safe in the lower GI tract under the optimized insufflation pressure and in the presence of anatomical flexure (see Video, Supplemental Digital Content 1, http://links.lww.com/DCR/A150).
authors.affiliation: 1Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, Osaka, Japan 2Division of Collaborative Research for Next Generation Endoscopic Intervention, Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Hirota
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Takahashi
authors.forename: Makoto
authors.initials: M
authors.lastname: Yamasaki
authors.forename: Shuji
authors.initials: S
authors.lastname: Takiguchi
authors.forename: Masaki
authors.initials: M
authors.lastname: Mori
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Doki
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Nakajima
mesh_terms: D000818:Animals; D002245:Carbon Dioxide; D003113:Colonoscopy / Q000379:methods*; D004285:Dogs; D004869:Equipment Safety; D005240:Feasibility Studies; D007327:Insufflation / Q000379:methods*; D008297:Male; D023421:Models, Animal; D011312:Pressure
chemical_list: D002245:Carbon Dioxide