Temperature controlled CO₂ laser welding of soft tissues: Urinary bladder welding in different animal models (rats, rabbits, and cats)

Background and Objective: Laser welding of tissues is a method of closure of surgical incisions that, in principle, may have advantages over conventional closure methods. It is a noncontact technique that introduces no foreign body, the closure is continuous and watertight, and the procedure is faster and requires less skill to master. However, in practice, there have been difficulties in obtaining strong and reliable welding. We assumed that the quality of the weld depends on the ability to monitor and control the surface temperature of the welded zone during the procedure. Our objective was to develop a 'smart' fiberoptic laser system for controlled temperature welding. Study Design/Materials and Methods: We have developed a welding system based on a CO₂ laser and on infrared transmitting AgClBr fibers. This fiberoptic system plays a double role: transmitting laser power for tissue heating and noncontact (radiometric) temperature monitoring and control. The 'true' temperature of the heated tissue was determined by using an improved calibration method. We carried out long-studies of CO₂ laser welding of urinary bladders in various animal models. Cystotomies were performed on the animals, and complete closure of the bladder was obtained with a surface temperature of 55 ± 5°C at the welding site. Results: In early experiments on 31 rats, the success rate was 73%. In later experiments with 10 rabbits and 3 cats, there was an 80% and a 100% success rate, respectively. Conclusion: The success rate in these preliminary experiments and the quality of the weld, as determined histologically, demonstrate that temperature controlled CO₂ laser welding can produce effective welding of tissues. The fiberoptic system can be adapted for endoscopic laser welding.