In vitro reversal of heparin effect with heparinase: Evaluation with whole blood prothrombin time and activated partial thromboplastin time in cardiac surgical patients

G. J. Despotis, A. L. Summerfield, J. H. Joist, L. T. Goodnough, S. A. Santoro, J. J. Zimmermann, D. G. Lappas

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Abstract

This study was designed to evaluate the potential in vitro use of heparinase to eliminate functionally active heparin prior to performing whole blood (WB) prothrombin time (PT) and activated partial thromboplastin time (APTT) assays. A total of 250 U/kg of heparin for cardiopulmonary bypass (CPB) was administered to 30 cardiac surgical patients in three consecutive, divided doses (20, 80, and 150 U/kg) at 15-min intervals. Blood specimens were obtained prior to heparin administration (baseline) and 10 min after each heparin dose. After collection, blood specimens were fractionated into three aliquots of which the first was used for determination of heparin concentration. After gentle mixing, WB PT and APTT measurements were performed for heparinase (Aliquot 2)- and nonheparinase (Aliquot 3)-treated blood. With consecutive heparin doses of 20 and 80 U/kg, WB PT increased from a baseline of 12.3 ± 0.1 s to 13.3 ± 0.2 and 18.5 ± 1.3 s, while WB APTT increased from a baseline of 28.3 ± 1.1 s to 89.5 ± 5.4 after the initial heparin dose (20 U/kg). When compared to baseline (no heparin) results, small, progressive increases in heparinase-treated WB PT (0.7 ± 0.1, 1.5 ± 0.1, 2.1 ± 0.1 s) and APTT (2.3 ± 0.3, 5.7 ± 0.4, 9.5 ± 0.5 s) were seen with increasing heparin concentration (0.23, 1.58, and 3.95 U/mL, respectively). Heparinase was highly effective in eliminating the anticoagulant effects of even large amounts of heparin in plasma from cardiac surgical patients. Our data indicate that heparinase can be used reliably to assess whether and to what extent WB PT and/or APTT prolongations are secondary to the effects of heparin.

Original languageEnglish
Pages (from-to)670-674
Number of pages5
JournalAnesthesia and analgesia
Volume79
Issue number4
StatePublished - Jan 1 1994

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