What are the temperature variations of nasal endoscopes, and do older scopes reach higher temperatures?
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February 2011Background: Although advances in endoscopic technology have improved illumination and light transmission, there may be greater heat production that places patients at risk for thermal injury, especially when endoscopic equipment comes into direct contact with the tissue of otolaryngology patients. Additionally, older scopes may reach higher temperatures as a result of less efficient light transmission.
Study design: Observational study.
Setting: Department of Otolaryngology, SUNY Upstate Medical University; Syracuse VA Medical Center, Syracuse, New York.
Synopsis: Temperature measurements were taken along different parts of a rigid nasal endoscope, with the highest temperatures found at the tip. Measurements were taken at various times between zero and 30 minutes. The light source was then turned off, and another reading was taken 10 minutes after turn-off. Temperature measurements were also taken from the tip of the light cord without an endoscope attached. Additional temperature time trials were performed in multiple sets to assess new endoscopes, light cords and light boxes compared with used and old equipment. The authors found that endoscope temperatures with 175W and 300W light sources demonstrated temperature maximums less than 40 degrees C, but a significant and potentially dangerous maximum of up to 62.5 degrees C was seen with the 550W light source. The light cord without the scope attached recorded a temperature higher than 130 degrees C; with the 550W light source, the temperature was nearly 200 degrees C. None of the new, used or old nasal endoscopes reached temperatures likely to cause significant thermal injury. Only the light box age statistically affected the final temperature. A limitation of the study was that it was performed in vitro and not in vivo.
Bottom line: Nasal endoscopes have the potential to reach temperatures high enough to cause thermal injury, especially with a 550W light source. The differences between the temperatures of old and new equipment are not clinically significant.
Citation: Nelson JJ, Goyal P. Temperature variations of nasal endoscopes. Laryngoscope. 2011;121(2):273-278.
—Reviewed by Sue Pondrom