Heparin elimination following continuous infusion during intra-aortic balloon counterpulsation

The decline of the activated partial thromboplastin time (APTT) following discontinuation of heparin infusion was measured in six intra-aortic balloon pump (IABP) patients. The heparin infusion requirement was determined for eight other IABP patients during stable therapeutic anticoagulation. Following discontinuation of infusion, APTT declined with a relatively constant half-life (t 1/2 of 2.4 +/- 0.08 hr, suggesting elimination by first-order kinetics. In comparison, the t 1/2 following single bolus doses has been shown to be markedly dose dependent, increasing from 30 min at low doses to 2 hr at very high doses. The heparin requirement for IABP patients was found to be 16 +/- 2.5 U/kg/hr, similar to that reported for other clinical situations. The t 1/2 of the APTT following discontinuation of heparin infusion can be used to time invasive procedures that would best be done with normal hemostasis.