Original contribution Aprotinin does not prolong the Sonoclot aprotinin- insensitive activated clotting time B Yue Dong MD (Research Associate) 1 , Gregory A. Nuttall MD (Professor), William C. Oliver Jr MD (Professor), Shvetank Agarwal MD (Research Fellow), Mark H. Ereth MD (Associate Professor) ⁎ Transfusion, Coagulation and Cardiopulmonary Bypass Research Group, Department of Anesthesiology, Mayo Clinic College of Medicine Rochester, MN 55905, USA Received 7 June 2006; revised 1 March 2007; accepted 9 March 2007 Keywords: Aprotinin; Activated clotting time; Cardiopulmonary bypass; Anticoagulation; Sonoclot analysis; Aprotinin-insensitive ACT Abstract Study Objective: To determine whether a new Sonoclot-based, aprotinin-insensitive activated clotting time (aiACT) assay yields stable results over a broad range of aprotinin concentrations. Design: Prospective trial conducted on in vitro blood samples. Setting: Tertiary-care teaching medical center. Participants: 19 healthy adult volunteers. Interventions: Whole blood samples were collected from volunteers. Heparin (2 U/mL) and escalating concentrations of aprotinin of 160 to 500 kallikrein inhibitory units (KIU)/mL were added in vitro. Measurements and Main Results: Celite ACT, kaolin ACT, and aiACT assays were completed. The aiACT showed stable activated clotting time (ACT) results on heparinized, noncitrated blood with added aprotinin (P = nonsignificant). In contrast, celite ACT and kaolin ACT were greatly prolonged when aprotinin was added to heparinized, noncitrated, and citrated blood (P b 0.05). The aiACT had consistent results at all aprotinin concentrations (P = nonsignificant). Conclusions: Aprotinin (160, 320, and 500 KIU/mL) significantly prolongs the ACT value with celite and kaolin activators but not with the aprotinin-insensitive activator. © 2007 Elsevier Inc. All rights reserved. 1. Introduction Adequate anticoagulation is critical to prevent thrombosis in patients undergoing cardiac surgery employing cardio- pulmonary bypass (CPB). Heparin has been the standard for anticoagulation therapy during CPB for decades, and is commonly administered by fixed-dose titration and bolus injection based on the activated clotting time (ACT). Aprotinin, a nonspecific serine protease inhibitor, was ☆ This study was supported by the Mayo Foundation for Medical Education and Research, Rochester, MN. Disposables were provided by Sienco, Inc, Arvada, CO. ⁎ Corresponding author. Tel.: +1 507 255 4235; fax: +1 507 255 6463. E-mail address: ereth.mark@mayo.edu (M.H. Ereth). 1 Current Address for Yue Dong MD, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, 200 First St., SW, Rochester, MN 55905. 0952-8180/$ – see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jclinane.2007.03.003 Journal of Clinical Anesthesia (2007) 19, 424–428