"Plasmatic imbibition" in the rabbit flow-through venous flap, using horseradish peroxidase and fluorescein

In the present study, the phenomenon of "plasmatic imbibition" was investigated histologically in a rabbit flow-through venous flap model, using horseradish peroxidase and fluorescein. Horseradish peroxidase introduced between the flap and the recipient bed, produced brown staining of the entire contact surface 10 min postoperatively. At 30 min, erythrocytes in the flow-through vein stained red. The flap and the erythrocytes became more intensely stained over time. When horseradish peroxidase was introduced from a central artery after a Silastic sheet had been inserted between the flap and recipient bed, the flap color became a soft brown and the erythrocytes of the flow-through vein stained red 10 min postoperatively. In the experimental groups subjected to fluorescein, introduced between the graft (or flap) and the recipient bed, fluorescence was seen 10 min postoperatively, except in the flow-through vein. At 30 and 120 min, the whole graft (or flap) showed fluorescence. Fluorescein was introduced into the femoral vein after flap elevation, or a Silastic sheet was inserted between the flap and the recipient bed. At 10 min, these groups showed a weak fluorescence only in the flow-through vein; subsequently, at 120 min, the flow-through vein and its surrounding tissue showed fluorescence, but the flap showed none. Plasmatic imbibition was proved to be acting in the flow-through vein, and it is considered as important a phenomenon in flap survival as venous flow itself.