[Complications caused by protamine. 2. Therapy and prevention]

Abstract

Treatment of reactions. The treatment of reactions to protamine is still symptomatic. Hypotension resulting from systemic vasodilation (anaphylactoid reaction) is treated by volume infusion, and alpha-stimulating catecholamines may be necessary. The combination of increased right ventricular afterload and systemic hypotension (anaphylactic/anaphylactoid reaction) requires primarily the improvement of coronary perfusion pressure and, thus, of O2 delivery to the right ventricular myocardium. To this end, catecholamines with alpha-stimulating action should be administered. Nitroglycerin is indicated when pulmonary hypertension persists in the presence of essentially normal systemic pressure. In the acute situation, steroids and antihistamines have no beneficial effect. Prevention of protamine reactions. For prevention of systemic hypotension by vasodilatation, protamine should be infused very slowly and not during hypovolemia. General prophylaxis using H1/H2 antagonists is not justified. Reliable preoperative identification of patients who would suffer an anaphylactic/anaphylactoid reaction to protamine, for example by skin tests or by measuring specific anti-protamine IgE or IgG antibodies, is not possible. This prevents individual prophylaxis in risk patients. In view of the low incidence of severe protamine reactions and the lack of better alternatives to the heparin/protamine regimen, general prevention is not indicated. For patients who are potentially at risk (insulin-dependent diabetics, prior protamine exposure), the side-effects of preventive measures must be weighed against their benefits. Only known sensitivity to protamine justifies certain preventive actions. In vascular surgery prostacyclin can be used instead of heparin/protamine or can be withheld (fading out of heparin action). Administration of steroids and/or antihistamines should be avoided. In cardiac surgery the use of hexadimethrine (if available) or total avoidance of protamine is paramount. Corticosteroids may be considered. Aortic administration of protamine and anticoagulation with ancrod are not recommended. The most promising compounds for rpharmacologic prevention of anaphylactic/anaphylactoid reactions in the future are thromboxane receptor antagonists.