Intra- and postoperative microcirculatory and morphological investigation of groin flap ischemia-reperfusion in the rat

In reconstructive surgical procedures various pedicled flaps can be used for covering tissue defects. During their preparation, transposition and (auto)transplantion, the flaps may suffer from hypoperfusion and/or ischemia-reperfusion that can influence wound healing. We aimed to investigate and follow-up the effect of 1-hour ischemia on adipocutaneous flaps’ microcirculation.
Seventeen male CD outbred rats (399.5±70.7 g) were anesthetized (20/2011/UDCAR). In Control group (n=10) groin adipocutaneous flaps were formed bilaterally using a pre-prepared ellipsoid template (flap area: 8.24 cm^2). After one hour, the flaps were repositioned and sutured (4/0 Dexon, 32 single interrupted stitches). In Ischemia-Reperfusion (I/R) group (n=7) the flap pedicles, containing the superficial epigastric artery and vein, were clamped by microvascular clips for 60 minutes. After the ischemic periods the clips were removed, and the flaps were repositioned and sutured. Laser Doppler (LD) flowmetry and skin temperature (ST) probe of infrared thermometer were applied on the distal, central and proximal region of each flaps before the operation, after flap preparation, at the end of the ischemia, by the end of re-suturing, and on the 1st, 3rd, 5th, 7th and 14th postoperative (p.o.) days, besides daily wound control. At the end of the follow-up period in anesthesia the flaps were excised for histology and the animals were sacrificed.
Local skin temperature quickly recovered after resuturing the flaps. On 1st-7th p.o. days ST of I/R group flaps were higher compared to base and to Controls. In parallel, LD values were elevated on1st-3rd p.o. days. Histologically we could find the normal signs of the wound healing process with granulomas at the sutures. In some flaps of the I/R groups hypertrophized mammary gland parts were seen subcutaneously. Similar changes were not seen in control flaps.
In conclusion, the wound healing difference between Control and I/R group could be well followed-up by testing local skin temperature and microcirculatory pattern. The model can be suitable for further wound healing studies.