Controlled temperature tissue fusion: Argon laser welding of canine intestine in vitro

Background and Objective: Thermal denaturation of proteins is recognized as a rate process governed by the local temperature-time response and is believed to be the principal mechanism for photothermal tissue welding. Since rate processes are exponential with temperature, feedback control of tissue surface temperature is hypothesized to create a quasi-constant rate of denaturation that will enhance the tissue welding process. Study Design, Materials and Methods: Controlled temperature tissue welding of severed edges of fresh canine jejunum was performed in vitro by remote sensing of tissue surface temperature with an infrared sensor. A hardware controlled temperature feedback system opened and closed a shutter located in the beam path of an argon ion laser to provide constant temperature welding. Results: Strong tissue fusion was not possible at or below a surface temperature of 70°C, but was accomplished at 80°, 90°, 95°, and 100°C. Fusion was achieved with thermal coagulation of the collagenous submucosa and mucosal tissues. The bursting strength of welds created at 90°C and 95°C were significantly stronger than those performed at 80°C. Conclusion: Laser- assisted intestinal anastomoses created in vitro are optimally strong at 90- 95°C feedback control temperatures.