Editing Dextran (section)

=== Microsurgery ===
These agents are used commonly by microsurgeons to decrease vascular [[thrombosis]]. The antithrombotic effect of dextran is mediated through its binding of [[erythrocytes]], [[platelets]], and vascular [[endothelium]], increasing their [[electronegativity]] and thus reducing [[erythrocyte]] aggregation and [[platelet]] adhesiveness. Dextrans also reduce factor VIII-Ag [[Von Willebrand factor]], thereby decreasing platelet function. Clots formed after administration of dextrans are more easily lysed due to an altered thrombus structure (more evenly distributed platelets with coarser [[fibrin]]{{Citation needed|reason=this fact should be cited somewhere, it is too interesting to leave without reference|date=May 2013}}). By inhibiting α-2 antiplasmin, dextran serves as a [[plasminogen]] activator, so possesses [[thrombolytic]] features.

Outside of these features, larger dextrans, which do not pass out of the vessels, are potent osmotic agents, thus have been used urgently to treat [[hypovolemia]] {{Citation needed|reason=missing reference|date=February 2022}}. The hemodilution caused by volume expansion with dextran use improves blood flow, thus further improving the patency of microanastomoses and reducing thrombosis. Still, no difference has been detected in antithrombotic effectiveness in comparison with intra-arterial and intravenous administration of dextran.

Dextrans are available in multiple molecular weights ranging from 3 kDa to 2 MDa.  The larger dextrans (>60,000 Da) are excreted poorly from the kidney, so remain in the blood for as long as weeks until they are metabolized. Consequently, they have prolonged antithrombotic and [[colloidal]] effects. In this family, dextran-40 (MW: 40,000 Da), has been the most popular member for [[Anticoagulant|anticoagulation]] therapy. Close to 70% of dextran-40 is excreted in urine within the first 24 hours after intravenous infusion, while the remaining 30% are retained for several more days.