CONTROLLED TEMPERATURE TISSUE FUSION - HO-YAG LASER-WELDING OF RAT INTESTINE IN-VIVO .2.

Background and Objective: Temperature feedback control (TFC) during la ser-assisted tissue welding was implemented to eliminate exponential i ncreases in the rate of denaturation associated with rapidly increasin g temperatures. This study was undertaken to investigate. and compare the weld strengths and healing responses of laser welded enterotomies with and without TFC using a cw Ho:YAG laser and to examine the effect s of wavelength on weld strength and histology. The Ho:YAG experimenta l results were compared with a similar study using cw argon ion laser irradiation. Study Design/Materials and Methods: An automated system w as developed for temperature feedback controlled laser irradiation. An experimental device incorporating co-aligned laser delivery and tempe rature detection was used to perform ow I-To:YAG laser-welded enteroto mies (with and without TFC). The weld strength and histology of laser welded and control sutured enterotomies were compared in an in vivo ra t model (Bo:YAG, n = 42; argon, n = 41). Animals were sacrificed at 1, 3, 7, and 21 days postoperatively and the anastomotic site was remove d for bursting/leaking pressure measurements and histological examinat ion. Results: Argon and Ho:YAG laser-welds with and without TFC and th e control sutured anastomoses healed comparably, although wound absces ses were more prevalent in the Ho:YAG group leading to delay in mucosa l healing. Laser-welded anastomoses without TFC were associated with m ore spontaneous ruptures and leaks (argon: 4/6 raptures; Ho:YAG: 1/4 l eak, 214 ruptures, & 1/3 stenosis) during the survival period than tho se with TFC (argon: 1/3 leak; Ho:YAG: 1/5 rupture). Bursting pressures of the Ho:YAG welds were weaker at 1 week than the argon welds, but b y 3 weeks, laser welds and suture anastomoses were equally strong. Con clusion: From the spontaneous failure rates encountered, it is believe d that TFC improves the quality and stability of laser-assisted entero tomy closures in surviving animals. However, TFC does not provide a sa tisfactory method to identify completion of a weld. (C) 1997 Wiley-Lis s, Inc.