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

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.