Browsing by Subject "Partial Thromboplastin Time"
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Item Open Access Chronic in vivo testing of the Penn State infant ventricular assist device.(ASAIO journal (American Society for Artificial Internal Organs : 1992), 2012-01) Weiss, William J; Carney, Elizabeth L; Clark, J Brian; Peterson, Rebecca; Cooper, Timothy K; Nifong, Thomas P; Siedlecki, Christopher A; Hicks, Dennis; Doxtater, Bradley; Lukic, Branka; Yeager, Eric; Reibson, John; Cysyk, Joshua; Rosenberg, Gerson; Pierce, William SThe Penn State Infant Ventricular Assist Device (VAD) is a 12-14 ml stroke volume pneumatically actuated pump, with custom Björk-Shiley monostrut valves, developed under the National Heart, Lung, and Blood Institute Pediatric Circulatory Support program. In this report, we describe the seven most recent chronic animal studies of the Infant VAD in the juvenile ovine model, with a mean body weight of 23.5 ± 4.1 kg. The goal of 4-6 weeks survival was achieved in five of seven studies, with support duration ranging from 5 to 41 days; mean 26.1 days. Anticoagulation was accomplished using unfractionated heparin, and study animals were divided into two protocol groups: the first based on a target activated partial thromboplastin time of 1.5-2 times normal, and a second group using a target thromboelastography R-time of two times normal. The second group required significantly less heparin, which was verified by barely detectable heparin activity (anti-Xa). In both groups, there was no evidence of thromboembolism except in one animal with a chronic infection and fever. Device thrombi were minimal and were further reduced by introduction of the custom valve. These results are consistent with results of adult VAD testing in animals and are encouraging given the extremely low levels of anticoagulation in the second group.Item Open Access Defining heparin resistance: communication from the ISTH SSC Subcommittee of Perioperative and Critical Care Thrombosis and Hemostasis.(Journal of thrombosis and haemostasis : JTH, 2023-12) Levy, Jerrold H; Sniecinski, Roman M; Rocca, Bianca; Ghadimi, Kamrouz; Douketis, James; Frere, Corinne; Helms, Julie; Iba, Toshiaki; Koster, Andreas; Lech, Tara K; Maier, Cheryl L; Neal, Mathew D; Scarlestscu, Ecatarina; Spyropoulos, Alex; Steiner, Marie E; Tafur, Alfonso J; Tanaka, Kenichi A; Connors, Jean MThe term heparin resistance (HR) is used by clinicians without specific criteria. We performed a literature search and surveyed our SSC membership to better define the term when applied to medical and intensive care unit patients. The most common heparin dosing strategy reported in the literature (53%) and by survey respondents (80.4%) was the use of weight-based dosing. Heparin monitoring results were similar based on the proportion of publications and respondents that reported the use of anti-Xa and activated partial thromboplastin time. The most common literature definition of HR was >35 000 U/d, but no consensus was reported among survey respondents regarding weight-based and the total dose of heparin when determining resistance. Respondent consensus on treating HR included antithrombin supplementation, direct thrombin inhibitors, or administering more heparin as the strategies available for treating HR. A range of definitions for HR exist. Given the common use of heparin weight-based dosing, future publications employing the term HR should include weight-based definitions, monitoring assay, and target level used. Further work is needed to develop a consensus for defining HR.Item Open Access Effects of therapeutic plasma exchange on anticoagulants in patients receiving therapeutic anticoagulation: a systematic review.(Transfusion, 2019-05) Hodulik, Kimberly L; Root, Adam G; Ledbetter, Leila S; Onwuemene, Oluwatoyosi ATherapeutic plasma exchange (TPE) removes coagulation proteins, but its impact on therapeutic anticoagulation is unknown. We performed a systematic review of the literature to determine the coagulation effects of TPE in patients receiving systemic anticoagulation. We searched MEDLINE, CINAHL, EMBASE, and Web of Science until June 2018 for studies combining controlled vocabulary and keywords related to therapeutic plasma exchange, plasmapheresis, anticoagulants, and therapy. The primary outcome was the effect of TPE on anti-Xa activity, activated partial thromboplastin time (aPTT), or international normalized ratio (INR). The secondary outcome was reports of post-TPE bleeding or thrombosis. A total of 1830 references were screened and eight studies identified. Our selected studies (five case reports and three case series) involved 23 patients and evaluated the effects of seven anticoagulants. Six studies of unfractionated heparin, low-molecular-weight heparins, and direct oral anticoagulants demonstrated an anti-Xa level decline. Two studies of unfractionated heparin and low-molecular-weight heparins showed an aPTT increase. One study of warfarin showed a post-TPE INR increase. Reports of post-TPE bleeding occurred in two patients and thrombosis in one. In patients receiving therapeutic anticoagulation, TPE is associated with anti-Xa activity decline and aPTT and INR increase. These coagulation changes do not appear to significantly increase bleeding or thrombotic risk. Our data suggest the need for prospective studies to investigate the true clinical impact of TPE on therapeutic anticoagulation.