Faculty Bibliography

Selection of ideal laser parameters for tissue welding is inhibited by poor understanding of the mechanism. We investigated structural changes in collagen molecules extracted from rat tail tendon (> 90% type I collagen) after tissue welding using an 808 nm diode laser and indocyanine green dye applied to the weld site. Mobility patterns on SDS-PAGE were identical in the lasered and untreated tendon extracts with urea or acetic acid. Pepsin incubation after acetic acid extraction revealed a reduction of collagen alpha and beta bands in lasered compared with untreated specimens. Circular dichroism studies of rat tail tendon showed absence of helical structure in collagen from lasered tendon. No evidence for covalent bonding was present in laser-treated tissues. Collagen molecules are denatured by the laser wavelength and parameters used in this study. No significant amount of helical structure is regenerated on cooling. We conclude that non-covalent interactions between denatured collagen molecules may be responsible for the creation of tissue welding

The incidence of anastomotic leakage in colonic surgery is approximately 10%. We evaluated a technique of laser-fibrinogen reinforcement to strengthen experimental colonic anastomoses. The technique consisted of the topical application of indocyanine green dye-enhanced fibrinogen to the serosal surface of two-layer inverting anastomoses, followed by exposure with an 808-nm diode laser. In the 28 rabbits used for this study, mean bursting pressure at time 0 was 108 +/- 13 mm Hg in the group receiving anastomoses with sutures alone and 173 +/- 20 mm Hg in the group for which the sutured anastomosis was reinforced with laser-fibrinogen. The difference in bursting pressures between the two groups was statistically significant at time 0. However, at 1, 3, 5, and 7 days, the anastomosis became stronger in both groups and the difference in strength was reduced; the sutured group had more exceptionally weak (less than 110 mm Hg) bonds than the group treated by laser. Thus, laser-fibrinogen reinforcement significantly enhances the early strength of sutured colonic anastomoses. This technique may reduce the incidence of leakage during the first postoperative week and the associated complications in a clinical setting