A Pilot Study to Assess the Clinical Onset of IV Heparin in Interventional Cardiology and Cardiac Surgery.

OBJECTIVES: To determine the onset of heparin anticoagulation, using 2 different measures of activated clotting times (ACT), thromboelastography (TEG; R-time), and anti-Xa levels, after administering low- (100 U/kg) and high- (300 U/kg) dose intravenous (IV) heparin to patients undergoing transcatheter aortic valve replacement (TAVR) and cardiac surgery, respectively. DESIGN: Prospective study. SETTING: Single academic institution. PARTICIPANTS: Patients with normal baseline coagulation presenting for TAVR or cardiac valve surgery. INTERVENTIONS: Coagulation studies were performed at baseline, 30 seconds, 90 seconds, and 180 seconds after IV heparin administration. The tests included iSTAT (iACT) and Hemochron ACT (hACT), TEG R-Time, and anti-Xa levels. At the authors' institution, anti-Xa is the preferred measure of heparin anticoagulation when time permits. ACT, a rapid point- of-care test, is used to assess intraprocedural anticoagulation. MEASUREMENTS AND MAIN RESULTS: After both low- and high-dose heparin, there are peak increases in ACT and anti-Xa at 30 seconds, followed by a decline at 90 seconds and plateau at 180 seconds. The TEG R-time remained elevated (>80 minutes) throughout. For TAVR cases, all anti-Xa was >1.5 IU/mL, and was associated with an iACT >180 seconds and an hACT >200 seconds. For cardiac valve surgery cases, all anti-Xa was >2.4 and associated with an iACT >420 seconds and and hACT >340 seconds. Compared with hACT, iACTs were significantly lower at all time points after low-dose heparin, but not after high-dose heparin. CONCLUSIONS: In this pilot study, heparin anticoagulation was detected as early as 30 seconds after IV administration, based on ACT, anti-Xa levels, and TEG R-time.

Remote Dispensing of Emergency Release Red Blood Cells.

OBJECTIVES: Patients with acute bleeding are frequently transfused with emergency release (ER) group O RBCs. This practice has been reported to be safe with a low rate of acute hemolytic transfusion reactions (AHRs). METHODS: Records of patients who received ER RBCs over a 30-month period were examined at our hospitals. During this period, satellite refrigerators were on site in the emergency department (ED), which were electronically connected to the blood bank (electronically connected satellite refrigerator [ECSR]). Nurses accessing the refrigerator were required to give patient identification information, when known, prior to removal of the ER RBCs, allowing technologists the opportunity to check for previous serologic records and communicate directly with the ED if a serologic incompatibility was potentially present. RESULTS: In total, 935 patients were transfused with 1,847 units of ER RBCs. Thirty of these patients had a current (22/30) or historic (8/30) antibody. In 15 cases, incompatible RBCs were interdicted. In six cases, the transfusion was considered urgent, and an AHR occurred in four of these six (overall 0.4%), including one fatal AHR due to anti-KEL1. CONCLUSIONS: Use of KEL1-negative RBCs and ECSR merits consideration as approaches to mitigate the occurrence of ER RBC-associated AHRs.