CO2 and argon laser vascular welding: Acute histologic and thermodynamic comparison

CO2 and argon lasers have been used successfully for vascular welding in both experimental and clinical settings. This study compared the thermodynamics during CO2 and argon laser welding of 1‐cm longitudinal arteriotomies in a canine model. Continuous recordings using an AGA 782 digital thermographic system with spatial and thermal resolution of ±0.2 mm and ±0.2°C, respectively, were analyzed. A HGM argon laser using a 300‐μm optic fiber held at 1 cm from the vessel edges (spot diameter = 2.8 mm) with concomitant room temperature saline irrigation (1 drop/sec) was used for argon welds. Total exposure time was 150 sec/cm. CO2 welds were performed with a Sharplan CO2 laser (spot diameter = 0.22 mm) with no irrigation for total exposure time of 10 sec/cm. Thermodynamic results and laser parameters are summarized as follows: Argon–n = 20; power = 500 mW; energy fluence = 1,400 J/cm2; Tmax = 48.8°C; T mean ± S.D. = 45.1 ± 2.7°C; CO2–n = 20; power = 150 mW; energy fluence = 3,000 J/cm2; Tmax 84.0°C; T mean ± S.D. = 60.7 ± 9.8°C. There was a significant difference (P < .05) in thermal measurements between successful CO2 and argon vascular welds. Temperature rise during the argon welds was limited by saline irrigation. In contrast, during CO2 laser welding, the temperature rose quickly to its maximum and was maintained at a relatively high level as the laser progressed (0.1 cm/sec) along the anastomosis. Histologic examination revealed charring at the CO2 weld site but absence of thermal damage at the argon laser weld. These thermodynamic differences may account for the different welding mechanisms currently described.