title: Are cold light sources really cold?
abstract: BACKGROUND
  A fiber optic light source is the central part of endoscopic surgery. However, the light generation process causes heat transmission from a source to tip of a scope. In this study, we measured the amount of heating and pathologic effects of direct contact with the tip of scopes on the small bowel in an experimental set-up.
  
  
  METHODS
  Temperature measurements were performed at the tip of 4 different scopes (Aesculap, Olympus, Karl Storz, and Richard Wolf), which were connected to either of 3 different xenon light sources (Olympus, Richard Wolf, Karl Storz). Temperatures at the outlet of light sources and the tip of fiber optic cables were measured as well. Tissue samples from the small bowel of a pig were obtained after exposing them to direct contact with the tip of the scopes or the fiber optic cable.
  
  
  RESULTS
  The temperature measurements at the tip of the scopes varied between 60 degrees C and 100 degrees C (Celsius). The temperatures showed a wide variation according to the type of light source and fiber optic cable the scopes were connected to. The average temperature at the outlet of the light sources and the tip of fiber optic cables was 750 degrees C and 250 degrees C, respectively. The microscopic scores of the small bowel injury induced by exposition to the heat at the tip of the scopes were significantly high after 5 seconds of contact. Direct contact of the tip of the fiber optic cable caused total carbonization in the wall of the small bowel.
  
  
  CONCLUSIONS
  Direct contact of the tip of the scope with small bowel may cause functional and cytologic injury even after short durations of exposure. Therefore, we do not recommend direct contact of scopes with the intra-abdominal organs to avoid heat injuries. In addition, this study also emphasizes the variation in heat generation at the tip of the scopes when used with a mismatching light source and fiber optic cable.
authors.affiliation: National Center for Advanced Laparoscopic Surgery, Department of Surgery, St Olav's Hospital, Trondheim, Norway. nsalk@online.no
authors.forename: Yunus
authors.initials: Y
authors.lastname: Yavuz
authors.forename: Jan Gunnar
authors.initials: JG
authors.lastname: Skogås
authors.forename: Mine Güngör
authors.initials: MG
authors.lastname: Güllüoğlu
authors.forename: Thomas
authors.initials: T
authors.lastname: Langø
authors.forename: Ronald
authors.initials: R
authors.lastname: Mårvik
mesh_terms: D000818:Animals; D003080:Cold Temperature; D005336:Fiber Optic Technology; D006358:Hot Temperature; D020706:Laparoscopes; D008027:Light; D008297:Male; D055100:Optical Fibers; D013552:Swine; D013696:Temperature