Effects of diode laser therapy on blood flow in axial pattern flaps in the rat model

Axial pattern skin flaps are a very important reparative tool for the plastic and reconstructive surgeon in the reconstruction of tissue defects. From whatever unfortunate reason, part or all of such flaps occasionally suffers from irreversible ischaemia with loss of the flap. Infrared diode laser therapy has been shown to improve local and systemic circulation. The present study was designed to assess the effect of an 830 nm diode laser (power density, 18.5 W/cm(2), energy density 185 J/cm(2)) on the blood flow of axial pattern flaps in the rat model and their survival, compared with unirradiated controls. The flaps were raised in all animals (n=40), and blood flow assessed with laser speckle flowmetry (LSF). In the experimental groups (3 groups, n=10 per group), the flaps were irradiated either directly over the dominant feeder vessel (iliolumbar artery), at the proximal end or at the distal end of the flap itself and blood flow assessed during irradiation. Flowmetry was performed again in all animals at 5 and 10 min postirradiation, and the flaps sutured back in position. The unirradiated controls were handled in exactly the same way, but the laser was not activated. The survival rate of the flaps was assessed on the fifth postoperative day. LSF demonstrated significant increased blood flow in the flaps at 5 and 10 min postirradiation in all experimental groups compared with the control animals. At five days postirradiation, there was significantly better survival of the flaps in all the experimental groups compared with the controls (p<0.01), but no significant difference was seen between any of the experimental groups. We conclude that laser therapy increases the blood flow and perfusion of transferred flaps, and that this has significant effects on the survival of the flaps. One possible mechanism of modulation of the autonomic nervous system is discussed.