Laser skin welding: In vivo tensile strength and wound healing results

Background and Objective: Laser skin welding was investigated as a general model for laser tissue closure. Scanned delivery of near-infrared laser rad iation in combination with a dye can produce strong welds with limited ther mal damage. Study Design/Materials and Methods: Two-centimeter-long, full-thickness inc isions were made on the backs of guinea pigs. Wounds were closed either by laser welding or sutures and then biopsied at 0, 3, 6, 10, 14, 21, and 28 d ays postoperatively. Welding was achieved by using continuous-wave, 1.06-mu m, Nd:YAG laser radiation scanned over the incisions to produce a dwell ti me of similar to 80 msec. The cooling time between scans was fixed at 8 sec onds. A 4-mm-diameter laser spot was maintained during the experiments, and the power was kept constant at 10 W. The operation time was fixed at 10 mi nutes per incision. India ink was used as an absorber of the laser radiatio n at the weld site, and clamps were used temporarily to appose the incision edges. Results: Acute weld strengths of 2.1 +/- 0.7 kg/cm(2) were significantly hi gher than suture apposition strengths of 0.4 +/- 0.1 kg/cm(2) (P < 0.01), a nd weld strengths continued to increase over time. Lateral thermal damage i n the laser welds was limited to 200 +/- 40 mu m near the epidermal surface with less thermal damage deeper within the dermis. Conclusion: Our welding technique produced higher weld strengths and less t hermal damage than reported in previous skin welding studies and may repres ent an alternative to sutures. (C) 2000 Wiley-Liss, Inc.