Pharmacological alterations in the clotting mechanism: use in microvascular surgery.

At the present time there is confusion as to what pharmacological adjuncts are helpful toward increasing patency rates of microvascular repairs. To select a drug rationally, an understanding of the clotting mechanism in small vessels is essential so that agents may be selected that alone or in combination will react with the elements of the blood and will allow for continued perfusion without risk of hemorrhage or toxicity. Drugs which are Federal Drug Aministration approved and currently available are drugs having nonspecific effects involving more than one aspect of the clotting mechanism; they often in undesirable as well as desirable effects. Further development will result in the use of more selective and sophisticated agents. Presently it would appear desirable to employ agents to (1) increase blood flow and decrease blood viscosity, such as dextran 70; (2) decrease platelet functions, such as aspirin-type drugs; (3) mitigate against the actions of thrombin on platelets and fibrinogen using low-dose heparin; (4) reduce anxiety and vasospasm using chlorpromazine or Thorazine.