Safety of heat generated by endoscope light sources in simulated transcanal endoscopic ear surgery

Abstract Objective To determine whether heat generated by endoscope light sources during ear surgery is safe. Methods Transcanal endoscopic ear surgery (TEES) was simulated using 2.7-mm or 4-mm endoscopes coupled to xenon or LED light sources and a 3D model of human temporal bone. The endoscope tip was fixed at the center of tympanic annulus. Light sources were tested at clinical (30% for xenon and 40% for LED) and 100% settings. Temperatures were measured using thermocouples attached to the endoscope tip and three points within the middle ear cavity: promontory, horizontal portion of the facial nerve and lateral semicircular canal. Results Maximum temperatures measured within the middle ear cavity were below 31 °C at clinical settings, while the temperatures rose to 44.1 °C using a 4-mm endoscope with a xenon light source set at 100%. Temperatures measured at the tip were all safe at clinical settings, but rose dramatically to 110.1 °C for the 4-mm endoscope with xenon at 100%. Conclusion Endoscopes can be safely used within the middle ear at clinical settings. However, operators should not exceed clinical settings, particularly with 4-mm endoscopes with a xenon light source, to ensure temperatures generated within the middle ear cavity are safe.