2024 FSA Podium and Poster Abstracts

P046: ANAPHYLAXIS TO PROTAMINE DURING A CAROTID ENDARTERECTOMY
Mariana Rubini Silva Ceschim, MD; Gisele Wakim, MD; University of Miami/Jackson Health System

Introduction: Protamine is used to reverse the anticoagulation of unfractionated heparin (UFH) and is routinely used after cardiac or vascular procedures. During a carotid endarterectomy (CEA) a bolus of heparin is given before clamping the carotid artery and reversal with protamine is left to the discretion of the surgeon depending on bleeding risk. When given, it binds to UFH and has a half-life of approximately five minutes. Despite protamine’s beneficial attributes and applications, it also has a notable side-effect profile. We report a case of an anaphylactic reaction to protamine during a CEA.

Case Report: A 77-year-old male with hypertension, diabetes, cerebrovascular disease, and no allergies presented with dizziness and difficulty walking. Work-up demonstrated severe stenosis of the left internal carotid artery. Patient was planned to undergo left CEA by Neurosurgery.

Patient received general anesthesia with continuous blood pressure (BP), cerebral oximetry, sensory, and motor evoked potentials monitoring. Induction was performed with lidocaine, propofol, etomidate, and rocuronium. Total intravenous anesthesia was initiated with propofol and remifentanil. Antibiotics were given and the procedure started at 12:20 PM. A low-dose phenylephrine infusion was used to maintain higher mean arterial pressures. At 13:15 PM, 5,000 units of heparin were given at surgeon’s request.

At 13:44 PM protamine 50 mg was requested, diluted in NaCl 0.9% 50 mL, and infused over 10 minutes through a peripheral intravenous (IV) access. At 13:55 PM patient developed tachycardia and severe refractory hypotension. Fluid resuscitation was started and increasing doses of IV epinephrine boluses were given (20-20-60-100mcg; 200mcg total), as well as vasopressin. At 14:00 PM help was called. A mild transient increase in both plateau and peak inspiratory pressures were noted. An arterial blood gas was obtained and a tryptase level was sent. At this point in time, the tubing used for protamine administration was removed completely. Sodium Bicarbonate 50mEq and hydrocortisone 100mg were given. The patient’s BP was labile until approximately 14:20 PM, when he became hemodynamically stable. Surgery finished at 14:24 PM. Hives were noted on patient’s torso when the drapes were removed (Figure 1). At 14:39 PM the patient was extubated.

Discussion: The incidence of protamine reactions in cardiac surgery is approximately 0.06%. Patients with a history of protamine exposure, vasectomy, fish allergies, and insulin-controlled diabetes are at increased risk. Vasodilation is common and may cause transient hypotension. Life-threatening anaphylactic reactions are non-dose dependent immediate hypersensitivity reactions. They may occur within 5 to 20 minutes of administration and are usually IgE or IgG-mediated. Signs range from cutaneous, pulmonary to cardiovascular responses. Treatment includes stopping protamine and administration of epinephrine (Figure 2). Other therapies are described in Figure 3. Blood should be collected for tryptase determination. In this case, the patient’s tryptase was 20.6 mcg/L (levels of 11.5 ng/mL or higher may indicate anaphylaxis), and 24 hours later 6.0 mcg/L. IgE levels were also significantly increased (464.42 IU/mL). Measures to prevent/mitigate reactions include using a test dose and a slow infusion rate. After discharge patients should be referred to an allergist.

Figure 1

Figure 2

Figure 3