RESUMO
An 80-year-old diabetic man undergoing emergent off-pump coronary artery bypass grafting for acute myocardial infarction developed anaphylactic shock immediately following administering a small dose of protamine sulfate. Preoperative examination revealed atrial fibrillation, severe three-vessel coronary artery disease and impaired left ventricular function with ejection fraction of 40% and severe septal as well as apical hypokinesis and akinesis. After successful completion of coronary bypass grafting, a total of 40 mg of protamine sulfate was given through the central venous line. Three minutes after protamine administration, profound hypotension occurred. Pulmonary artery pressure was low and the left ventricle was almost empty by transesophageal echocardiography. Hypotension was refractory to rapid administration of 2 l of crystalloid and albumin, and repeated administrations of phenylephrine. Blood pressure finally returned towards baseline after infusion of norepinephrine 0.2 microg x kg(-1) x min(-1) and epinephrine 0.1 microg x kg(-1) x min(-1). Hemoconcentration and impaired oxygenation were also noted. The situation suggested anaphylactic shock due to protamine. He had diabetes mellitus for 20 years and been treated by protamine containing insulin. Postoperative interview revealed that the patient had experienced urticaria over the abdominal area with neutral protamine hagedorn (NPH) insulin administration. This history suggested that the patient had been sensitized by protamine before surgery. Although it is rare to experience anaphylactic shock due to protamine, it is important to elicit the detailed allergic history to insulin in diabetic patients. Because anaphylactic shock still carries high mortality even in a patient without cardiac disease, we were lucky to save this elderly patient with acute myocardial infarction and compromised left ventricular function.
