Ultrastructural changes in rat adipomusculocutaneous flaps during warm ischaemic storage and reperfusion.

Electron microscopy (EM) was used to evaluate ultrastructural changes in adipomusculocutaneous rat flaps which had been stored for 0, 2, 4, 6 and 8 hours under normothermic conditions (37 degrees C). The effects of treatment with desferrioxamine (DFX) or hypertonic citrate flush (HCA), prior to 4 hours of storage, were compared to untreated flaps which had been stored for 4 hours. Ultrastructural changes caused by 30 minutes of reperfusion, were also studied. Most ultrastructural alterations occurred between 2 and 4 hours of warm storage and there were further changes in some cells after short periods of reperfusion. DFX decreased smooth muscle damage and HCA protected adipocytes but neither of these agents preserved endothelial cells. These studies indicated that free radical-dependent and independent mechanisms were both involved in events which led to flap necrosis after periods of warm storage and reperfusion.