Effects of temperature on tissue thermal injury and wound strength after photothermal wound closure

Background and Objectives: Our goal was to determine the effect of temperat ure on the induction of tissue damage after laser-welded wound closure with and without albumin solder. Study Design/Materials and Methods: Multiple full-thickness skin incisions were made in a porcine model. Incisions were repaired by using a 1.32-mu m laser at temperatures of 65 degrees C, 75 degrees C, 85 degrees C, or 95 de grees C with and without a 50% human albumin solder. The rate of apoptosis (programmed cell death) was quantified by counting the proportion of cells that stained positively for nuclear DNA fragmentation (nick end labeling). The distance that necrosis extended from the wound edge was also measured. The strength of the weld was measured with a tensiometer. Results: For laser-welded repairs with solder, the amount of apoptosis at 6 5 degrees C and 75 degrees C was comparable to that of controls but became significantly elevated at 85 degrees C and 95 degrees C. The extent of necr osis was similar to that of controls at low temperature but also increased at 95 degrees C. Incisions repaired without solder showed increased necrosi s compared with those repaired with solder at temperatures of 65 degrees C, 75 degrees C, and 95 degrees C at 0-0.5 mm from the incision. Wounds repai red at 85 degrees C and 95 degrees C showed more apoptosis in the absence o f solder. The increased cell death at higher temperatures correlated with s ignificantly decreased wound strengths at 3 days after repair in the solder group. A lower rate of cell death was observed in the solder group, which correlated with superior wound strength when compared with repairs without solder at days 0 (65-95 degrees C) and 3 (95 degrees C). Conclusion: Both apoptotic and necrotic cell death were used as quantitativ e measures of tissue injury and were accurate predictors of short-term woun d strength. The addition of albumin solder decreased overall tissue injury. These results suggest that temperatures of 65-75 degrees C with solder pro vide the optimal conditions for maximizing acute wound strength and minimiz ing tissue injury. (C) 1999 Wiley-Liss, Inc.