title: 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%.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata-shi, Yamagata 990-9585, Japan. Electronic address: tuito@med.id.yamagata-u.ac.jp.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Ito
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata-shi, Yamagata 990-9585, Japan.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Kubota
authors.affiliation: Division of Dentistry and Oral Surgery, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata-shi, Yamagata 990-9585, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Takagi
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata-shi, Yamagata 990-9585, Japan.
authors.forename: Tomoo
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata-shi, Yamagata 990-9585, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Futai
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata-shi, Yamagata 990-9585, Japan.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Furukawa
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata-shi, Yamagata 990-9585, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Kakehata
mesh_terms: D004432:Ear, Middle / Q000601:surgery*; D019723:Endoscopes; D006358:Hot Temperature; D006801:Humans; D008029:Lighting; D008953:Models, Anatomic; D013506:Otologic Surgical Procedures / Q000295:instrumentation*
keywords: Ear surgery; Endoscope; LED light source; Middle ear cavity; Temperature; Xenon light source