Theoretical and experimental investigation of the thermal effects within body cavities during transendoscopical CO₂ laser-based surgery

Background and Objectives: The recent development of flexible hollow waveguides for MID-IR lasers may be utilized transendoscopically to ablate selectively neoplastic, superficial tissues within body cavities. Study goals are to investigate theoretically and experimentally heat distribution and thermal response of cavity lining, during CO₂ laser minimally invasive surgery (MIS), and to thermally optimize the procedure under practical conditions. Study Design/Materials and Methods: Mathematical model was developed to predict temperature distribution along cavity lining. Experimental setup was built, including all the necessary components for a fully feedback-controlled MIS, i.e., laser generator, gas insufflating system, surgical suction, and infrared imaging feedback mechanism, all controlled by central PC-based program. Thermal images of cavity lining were recorded and analyzed throughout varying conditions. Results: Thermal gradients along the cavity lining, during and after the laser irradiation, were obtained mathematically and experimentally. Diverse modes of heat dispersions were observed, as well as the relative contributions of user-controlled parameters to the maximal heat of cavity lining. The software-controlled setup has demonstrated the capacity to instantly manage varying conditions, by which it automatically protects cavity lining from getting overheated. Conclusions: Analytical predictions and experimental measurements were highly correlated. The software-controlled system may serve a powerful tool to control thermal side effects during MIS within body cavities.