Complications of heparin therapy.

Currently, heparin therapy is rarely extended for periods required for the onset of chronic complications. Thus, alopecia and skeletal defects are infrequently encountered. However, during pregnancy, prolonged therapy with heparin may be used. Heparin does not cross the placental barrier, whereas the warfarin class of anticoagulants is freely transported across the barrier. Thus, if extended anticoagulation is required during pregnancy, heparin is preferred to provide maternal anticoagulation while protecting against fetal hemorrhage. Hemorrhage, the most frequent and most feared complication of heparin therapy, does not occur spontaneously in all patients receiving large doses of heparin. However, in certain populations, hemorrhage must be anticipated and appropriate modifications made in the heparin dosage. Elderly women, persons with thrombocytopenia or drug induced platelet dysfunction, or persons who have undergone recent surgical treatment or trauma are sensitive to standard heparin dosages and may bleed during heparin therapy. In these situations, the initial heparin dosage must be appropriately decreased and subsequent dosages carefully determined by frequently monitored coagulation studies. a well maintained, functional coagulation laboratory is imperative in these situations. By careful monitoring of coagulation parameters and by the selection of the smallest effective heparin dosage, complications can be minimized. The clinical cognizance of heparin induced thrombocytopenia is increasing. This disorder must be considered when hemorrhage and low platelet numbers appear during heparin therapy. Discontinuance of heparin therapy causes a rapid increase in platelet counts and diminution of bleeding. The indiscriminate use of protamine sulfate to neutralize heparin must be discouraged. One must resist the temptation to administer multiple extra doses of protamine to assure achievement of hemostasis. The precise dosage of protamine sulfate calculated to neutralize a given heparin dosage must be used. Additional doses of protamine must be determined by coagulation studies, such as whole blood clotting time, protamine titration test, or thrombin time with toluidine blue correction. If proper attention is directed to the dosage of protamine, relative to heparin, the complications of neutralization rarely will occur. Heparin is a basic drug in the armamentarium of the contemporary surgeon. Successful clinical use of heparin requires fundamental knowledge of coagulation mechanisms, the manner in which heparin alters these mechanisms, and the factors which predispose to complications. The complications of heparin therapy can be minimized by strictest attention to selection of initial dosage and by careful subsequent determination of the precise coagulation status of the patient.