title: Effect of acid on duodenal blood flow and mucus secretion measured by reflectance spectrophotometry: a prospective, randomized-controlled study.
abstract: BACKGROUND
  In animals, hydrochloric acid increases blood flow and mucus secretion in the duodenal mucosa. A significant correlation between index of haemoglobin oxygen saturation and mucosal blood flow, and between change in index of haemoglobin concentration and mucus thickness, respectively, has been demonstrated by reflectance spectrophotometry.
  
  
  OBJECTIVE
  To examine the effect of topical hydrochloric acid upon mucosal blood flow and mucus secretion in the human duodenum.
  
  
  METHODS
  This prospective study of 120 patients undergoing routine upper endoscopy, examined the effect of topical 0.1 n hydrochloric acid or 0.9% saline on the duodenal bulb in a randomized, double-blind fashion. Duodenal mucosal index of haemoglobin oxygen saturation and index of haemoglobin concentration were measured by endoscopic reflectance spectrophotometry before and after hydrochloric acid or saline.
  
  
  RESULTS
  Baseline index of haemoglobin oxygen saturation, calculated blood flow and index of haemoglobin concentration measurements were comparable between hydrochloric acid (n = 60) and saline (n = 60) treated groups. A history of current use of non-steroidal anti-inflammatory drug was associated with a significantly lower baseline index of haemoglobin oxygen saturation and calculated blood flow. Hydrochloric acid resulted in a significant increase in index of haemoglobin oxygen saturation and calculated blood flow, but a decrease in index of haemoglobin concentration, reflecting an increase in mucus thickness compared with saline.
  
  
  CONCLUSIONS
  Our observations in humans confirm data in animal studies that topical exposure to hydrochloric acid induces an increase in duodenal mucosal blood flow and mucus secretion. Post hoc analysis of the data also revealed that attenuation of basal duodenal mucosal blood flow is associated with a history of current non-steroidal anti-inflammatory drug use. Endoscopic reflectance spectrophotometry appears to be adequate to assess factors that influence duodenal defence mechanisms of blood flow and mucus secretion in humans.
authors.affiliation: Research and Medical Services, Carl T. Hayden VA Medical Center, Phoenix, AZ 85012, USA. francisco.ramirez2@med.va.gov
authors.forename: F C
authors.initials: FC
authors.lastname: Ramirez
authors.forename: J F
authors.initials: JF
authors.lastname: Holland
authors.forename: J
authors.initials: J
authors.lastname: Harker
authors.forename: F W
authors.initials: FW
authors.lastname: Leung
mesh_terms: D004386:Duodenum / Q000098:blood supply* / Q000378:metabolism; D006801:Humans; D006851:Hydrochloric Acid / Q000494:pharmacology*; D008875:Middle Aged; D009093:Mucus / Q000378:metabolism*; D011446:Prospective Studies; D013053:Spectrophotometry / Q000379:methods
chemical_list: D006851:Hydrochloric Acid