Venous microanastomosis with the Unilink system, sleeve, and suture techniques: a comparative study in the rat.

Multiple microvascular anastomotic techniques have been described with varying rates of success. This experimental study presents the results of a comparison of three types of venous microanastomotic techniques: the Unilink system, the sleeve technique, and the suture technique. Twenty male Sprague-Dawley rats, 40 femoral veins, were used for this study. In vivo observation and microvasculography demonstrated that patency rates between the Unilink system and suture techniques were comparable (p > 0.05) and were significantly superior to the sleeve anastomosis (p < 0.05). The anastomotic time for the sleeve technique was significantly shorter than for the suture technique (p < 0.001). Compared with suture and sleeve anastomoses, the anastomotic time employing the Unilink system was significantly the shortest (p < 0.001). The Unilink system proved to be the fastest method with the highest patency rate. These results suggest that the use of the Unilink system is superior with regard to anastomotic time and patency rate, when compared to suture and sleeve techniques for venous microanastomosis.

Thrombocytosis after major lower extremity trauma: mechanism and possible role in free flap failure.

Microvascular thrombosis and free flap failure are complications of free tissue transfer for coverage of lower extremity soft-tissue and bony defects despite appropriate vessel selection and adherence to meticulous technique. Increased rates of flap failure have been associated with reconstruction performed between 3 days and 6 weeks after injury, as well as in patients with thrombocytosis. We have found that serum platelet levels rise significantly after lower extremity injury. It is our theory that a circulating mediator or cytokine is released in response to injury, inducing the thrombocytosis. Twenty-one patients with Gustilo grade IIIb and IIIc injuries were studied prospectively. Serum was collected throughout the postinjury period. Platelet count, leukocyte count, hemoglobin concentration, and hematocrit were determined. Samples were also subjected to a platelet aggregation study as well as enzyme-linked immunosorbent assay for interleukin-3, interleukin-6, interleukin-11, and granulocyte macrophage-colony-stimulating factor. Megakaryocyte growth and development factor enzyme-linked immunosorbent assay and a myleoproliferative leukemia virus-transfected cell line assay for thrombopoietin were performed. Bone marrow was studied with flow cytometric analysis. Mean initial platelet count was 196,000 per cubic millimeter. There was an initial 26% decline to 140,000 per cubic millimeter, followed by an increase to 361% of baseline on day 16. No significant variations in serum leukocyte count or hemoglobin concentration were seen. Spontaneous and induced platelet aggregation responses were normal. Interleukin-6 was detected at elevated levels. However, interleukin-3, interleukin-11, granulocyte macrophage-colony-stimulating factor, and thrombopoietin were not measurable. Marked megakaryocytosis was seen on bone marrow analysis. Interleukin-6 may, therefore, play a role in the mechanism of thrombocytosis. We suggest that because patients with complex bony injuries of the leg experience platelet elevations that peak approximately 2 weeks after injury, microvascular free flap reconstructions should be considered high risk during this time period.