title: Heat development at nasal endoscopes' tips: danger of tissue damage? A laboratory study.
abstract: OBJECTIVE
  The aim of this study was to measure the temperature generated by light sources in conjunction with angulated endoscopes and to analyze whether the heat generated at the endoscopes' tips harbors potential damage to mucosa or highly sensitive structures like the optic nerve or brain when in direct contact, considering a beginning necrosis of human protein starting at 40°C.
  
  
  METHODS
  Laboratory setting, prospective.
  
  
  METHODS
  Brand new 4-mm, 0° and 30° rigid nasal endoscopes were measured each with halogen, xenon, and light-emitting diode (LED) light sources, respectively, at different power levels for tip contact temperature.
  
  
  RESULTS
  The highest temperatures were reached with a xenon light source at a maximum of 44.3°C, 65.8°C, and 91.4°C at 33%, 66%, and 100% power levels, respectively, for 4-mm, 0° endoscopes. For 30° endoscopes, temperatures of 47.0°C, 75.1°C, and 95.5°C were measured at 33%, 66%, and 100% power levels (P < .001; 0° vs. 30°), respectively. At 5-mm distance from the tip, temperatures were below body temperature for all light sources (<36°C) at all power settings. Within 2 minutes after switching off light sources, temperatures dropped to room temperature (22°C).
  
  
  CONCLUSIONS
  Xenon light sources have the greatest illumination potential; however, at only 33% power level, potentially harmful temperatures can be reached at the tips of the endoscopes. Power LED and halogen have the highest safety; however, only LED has very good illumination. In narrow corridors, direct contact to tissues or vital structures should be avoided, or endoscopes should be cooled during surgical procedures.
authors.affiliation: Department of General Otorhinolaryngology, Head and Neck Surgery, Medical University Graz, Graz, Austria. peter.tomazic@medunigraz.at
authors.forename: Peter Valentin
authors.initials: PV
authors.lastname: Tomazic
authors.forename: Georg Philipp
authors.initials: GP
authors.lastname: Hammer
authors.forename: Claus
authors.initials: C
authors.lastname: Gerstenberger
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Koele
authors.forename: Heinz
authors.initials: H
authors.lastname: Stammberger
mesh_terms: D002056:Burns / Q000209:etiology*; D019723:Endoscopes / Q000009:adverse effects*; D004867:Equipment Design; D005336:Fiber Optic Technology; D006219:Halogens; D006358:Hot Temperature; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology*; D009297:Nasal Mucosa / Q000293:injuries*; D012225:Rhinoplasty / Q000009:adverse effects* / Q000295:instrumentation*; D013696:Temperature; D014978:Xenon
chemical_list: D006219:Halogens; D014978:Xenon