Impact of hypertonic and hyperoncotic saline solutions on ischemia-reperfusion injury in free flaps

The purpose of this study was to evaluate the influence of hypertonic and hyperoncotic saline solutions on ischemia-reperfusion injury after free tissue transfer.

Twenty-eight Sprague-Dawley rats were used to design an inferior epigastric flap. After skin incision, microcirculation was investigated using orthogonal polarization spectral imaging. After free tissue transfer of the inferior epigastric flap to the right groin, a 7.5% hypertonic saline solution was administered to the flap at reperfusion in group A (n = 7). Groups B, C, and D (n = 7 each) received 6% dextran-70, hypertonic saline with dextran-70, and isotonic sodium chloride solution, respectively. Evaluation of microcirculation was again performed at reperfusion and 10, 20, and 40 minutes later. Flap survival was determined by measurement of viable flap area at day 2.

Group D demonstrated a decline in blood cell velocity, arterial vessel diameter, venous vessel diameter, and functional capillary density within 40 minutes after reperfusion. Groups A and B showed less of a decrease in these parameters. The administration of hypertonic saline and dextran-70 was able to maintain a sufficient microcirculation at all time points. At day 2, flap survival was decreased in group A by 12.7 percent, in group B by 32.8 percent, in group C by 3.9 percent, and in group D by 41 percent.

The authors conclude that local administration with hypertonic saline and dextran-70 improves microcirculatory disturbances on reperfusion and increases overall free flap survival. These data demonstrate that a positive influence on no-reflow mechanisms is possible by extensive fluid shifts on the level of the microcirculation.