Clinically suspected heparin-induced thrombocytopenia during extracorporeal membrane oxygenation.

PURPOSE: Patients receiving extracorporeal membrane oxygenation (ECMO) are at risk for thrombocytopenia including heparin-induced thrombocytopenia (HIT). The purpose of this study was to determine the frequency of suspected HIT in patients receiving ECMO and unfractionated heparin (UFH). MATERIALS AND METHODS: We conducted a retrospective review in adult patients on ECMO. Patients were included if they received ECMO for at least 5 days and concomitant UFH. RESULTS: There were 119 patients who met inclusion criteria. Twenty-three patients (19%) had a heparin-platelet factor 4 immunoassay performed. Patients with suspected HIT had a significantly lower platelet count within the first 3 days of ECMO, 69×10(9)/L (22-126×10(9)/L) vs 87.5×10(9)/L (63-149×10(9)/L); P=.04. The lowest platelet count on the day of HIT testing was 43×10(9)/L (26-73), representing a 71% reduction from baseline. Twenty patients (87%) had an optical density score less than 0.4, and all patients had a score less than 1.0. A functional assay was performed in 7 patients (30%), with only 1 patient having laboratory-confirmed HIT. CONCLUSIONS: The evaluation of HIT occurred in a small percentage of patients, with HIT rarely being detected. Patients who had heparin-platelet factor 4 immunoassay testing exhibited lower platelet counts with a similar duration of ECMO and UFH exposure.

Incidence of amiodarone hypersensitivity in patients with previous allergy to iodine or iodinated contrast agents.

STUDY OBJECTIVE: To determine the incidence and nature of allergic reactions to amiodarone in hospitalized patients with a listed allergy to iodine or iodinated radiocontrast agents. DESIGN: Retrospective medical record review. SETTING: Two academic medical centers. PATIENTS: A total of 234 sequential hospitalized patients with a listed iodine and/or iodinated radiocontrast agent allergy who received oral or intravenous amiodarone between January 2006 and December 2010. MEASUREMENTS AND MAIN RESULTS: Demographic and clinical data, as well as documentation of an allergic reaction to amiodarone, were collected for each patient from electronic medical records. Mean ± SD age was 69 ± 12 years, and 51% were male. Of the 234 patients, 167 (71%) had a listed previous allergy to iodinated contrast agents, 55 (24%) to iodine, and 12 (5%) to both. Patients received an average inpatient total dose of 2.9 ± 3.2 g of either oral (106 patients [45%]), intravenous (39 patients [17%]), or both oral and intravenous (89 patients [38%]) amiodarone. Only 1 (0.4%) of the 234 patients was identified as having a probable allergic reaction to amiodarone (score of 6 on the Naranjo adverse drug reaction probability scale). One additional patient receiving intravenous amiodarone experienced a rash that was determined to be caused by an antibiotic. All other patients received amiodarone without any identifiable allergic reactions. CONCLUSION: The incidence of hypersensitivity reaction to amiodarone in hospitalized patients with a listed allergy to iodine or iodinated contrast agents was less than 1%, and all identified reactions were without long-term sequelae. Allergy to iodine and iodinated contrast agents may not be a valid absolute contraindication to amiodarone administration in the inpatient setting.