Are cold light sources really cold?

Abstract

Background: A fiber optic light source is the central part of endoscopic surgery. However, the light generation process causes heat transmission from a source to tip of a scope. In this study, we measured the amount of heating and pathologic effects of direct contact with the tip of scopes on the small bowel in an experimental set-up.

Materials and methods: Temperature measurements were performed at the tip of 4 different scopes (Aesculap, Olympus, Karl Storz, and Richard Wolf), which were connected to either of 3 different xenon light sources (Olympus, Richard Wolf, Karl Storz). Temperatures at the outlet of light sources and the tip of fiber optic cables were measured as well. Tissue samples from the small bowel of a pig were obtained after exposing them to direct contact with the tip of the scopes or the fiber optic cable.

Results: The temperature measurements at the tip of the scopes varied between 60 degrees C and 100 degrees C (Celsius). The temperatures showed a wide variation according to the type of light source and fiber optic cable the scopes were connected to. The average temperature at the outlet of the light sources and the tip of fiber optic cables was 750 degrees C and 250 degrees C, respectively. The microscopic scores of the small bowel injury induced by exposition to the heat at the tip of the scopes were significantly high after 5 seconds of contact. Direct contact of the tip of the fiber optic cable caused total carbonization in the wall of the small bowel.

Conclusion: Direct contact of the tip of the scope with small bowel may cause functional and cytologic injury even after short durations of exposure. Therefore, we do not recommend direct contact of scopes with the intra-abdominal organs to avoid heat injuries. In addition, this study also emphasizes the variation in heat generation at the tip of the scopes when used with a mismatching light source and fiber optic cable.