Dehydration: a model for (low-temperature) argon laser tissue bonding.

Despite considerable investigation, the mechanism of laser assisted vascular anastomosis remains unknown. Indications suggest that bonding is the result of thermal action, particularly the thermal denaturation of tissue proteins. However, our own work has led us to conclude that dehydration is an important factor. Hence, we have proposed that laser anastomosis is the result of dehydration at the apposed tissue faces, induced by laser irradiation. This was investigated by comparing the properties of bonds created by dehydration with those created by laser. The bonds were created using parameters consistent with laser anastomoses created in vivo. Results revealed that anastomoses created by dehydration were equivalent to those created by laser, with little difference in strength, histology or response to rehydration. The only significant difference (p < 0.02) was mean bond strength created at temperatures above the denaturation temperature of the tissue (548 g cm(-2) by laser, 994 g cm(-2) by dehydration). Given the similarity of bonds created by the two methods, we conclude that the same mechanism (i.e. dehydration) is likely to be responsible for bonding in both cases and therefore that argon laser bonding is mediated by dehydration.