Heat development at nasal endoscopes' tips: Danger of tissue damage? A laboratory study

Objectives/Hypothesis: 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 degrees C. Study Design: Laboratory setting, prospective. Methods: Brand new 4-mm, 0 degrees and 30 degrees 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 degrees C, 65.8 degrees C, and 91.4 degrees C at 33%, 66%, and 100% power levels, respectively, for 4-mm, 0 degrees endoscopes. For 30 degrees endoscopes, temperatures of 47.0 degrees C, 75.1 degrees C, and 95.5 degrees C were measured at 33%, 66%, and 100% power levels (P < .001; 0 degrees vs. 30 degrees) respectively. At 5-mm distance from the tip, temperatures were below body temperature for all light sources (<36 degrees C) at all power settings. Within 2 minutes after switching off light sources, temperatures dropped to room temperature (22 degrees 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.