Impact of groin flap ischemia-reperfusion on red blood cells' micro-rheological parameters in a follow-up study on rats

Red blood cell (RBC) micro-rheological parameters (deformability, aggregation) are known to affect the microcirculation. Their deterioration, such as decreased RBC deformability and enhanced aggregation reduce tissue perfusion. Since the viability of various flaps’ used in reconstructive surgery is strongly depends on the maintained microcirculation, we supposed that micro-rheological investigations might be informative in understanding better the pathophysiology of flaps’ ischemia-reperfusion that can be occurred during flap preparation and transposition procedures. We aimed to investigate this issue on groin adipocutaneous flaps in follow-up study in rats.
In the experiment (20/2011/UDCAR) 17 male CD outbred rats (399.5±70.7 g) were anesthetized (60 mg/kg sodium-thiopental, i.p.) and randomly divided into Control (n=10) and Ischemia-Reperfusion (I/R) group (n=7). On both sides groin adipocuteneous flap (area: 8.24 cm^2, using a standard template) were prepared bilaterally, pedicled on the superficial epigastric artery and vein. In Control group the flaps were re-sutured after one hour, while in I/R group microvascular clips were applied on the flap pedicles for 60 minutes, then the flaps were repositioned and sutured. Besides daily wound control, before the operation and on the 1st, 3rd, 5th, 7th and 14th postoperative (p.o.) days blood samples were collected from the lateral tail vein (about 0.5 ml each time, anticoagulant: K3-EDTA) for testing RBC deformability (LoRRca MaxSis Osmoscan ektacytometer) and RBC aggregation (Myrenne MA-1 erythrocyte aggregometer).
RBC deformability worsened by the 3rd (p<0.05 vs. base) and 5th p.o. day in I/R group. RBC aggregation enhanced significantly in both groups by the 1st day (p<0.001), and in I/R group it remained elevated on the 3rd day as well (p<0.001 vs. base and vs. Control). Leukocyte and platelet count rose higher in I/R group over the follow-up period.
In conclusion, the effect the operation and the wound healing of the flap (relatively long suture line in its total extension) affected micro-rheological parameters in the early postoperative period. I/R exacerbated the alterations mostly on 3rd-5th p.o. day.