390 Protamine Allergy

BACKGROUND: An anaphylactic reaction to protamine sulfate during cardiac surgery is a rare but known entity. Preoperative prediction and outcome of such a reaction is still unclear. A 68-year-old man presented for elective coronary artery bypass grafts. His medical history included hypertension and he was non-diabetic. Review of his angiogram indicated 2-vessel coronary artery disease. According to the patient's notes, he had a known allergy to shellfish and avoids fish due to personal discomfort, although the exact nature of his reaction to fish was not well described. The information prompted the thoracic surgery team to alert the allergologist to perform an allergological checkup before thoracic surgery. METHODS: Skin prick tests were performed with standard solutions for shrimp, fish-mix, mackerel and salmon (Bencard, Munich, Germany). Protamine sulfate (CP Pharmaceuticals Ltd, Wrexham, UK) was pricked undiluted and was tested intradermally diluted 1:10. Physiological saline and 0.01% histamine solution served as controls. A wheal with a diameter >3 mm in comparison with the negative control was scored as positive. Furthermore, in vitro allergy testing using the Phadia CAP system for specific IgE against shrimp, fish-mix, rainbow trout, rCyp p 1 and protamine sulfate was performed. RESULTS: Skin prick tests were positive to shrimp, fish-mix, mackerel, salmon and protamine sulfate. Intradermal testing with protamine showed a wheal diameter of 7 mm. Analysis of a blood sample showed elevated total IgE (2600 kU/L) and specific IgE to shrimp (2.94 kU/L), fish-mix (0.53 kU/L), rainbow trout (0.39 kU/L), rCyp p1 (0.53 kU/L) and protamine sulfate (0.77 kU/L). CONCLUSIONS: Protamine sulfate is a polycationic peptide used to reverse the anticoagulant effects of heparin during cardiac surgery. It is commercially produced from the sperm of salmon and it is considered that persons who have an allergy to fish could be at risk of protamine reactions. The exact mechanisms by which it causes anaphylaxis are not fully understood. Due to a clear sensitization to fish proteins and protamine sulfate and a known allergy to shellfish we disapproved the standard anticoagulation protocol with heparin/protamine. Bivalirudin was used as an anticoagulant and the surgery proceeded without any untoward events.