Evaluation of a new point of care heparin test for cardiopulmonary bypass: the TAS heparin management test

Abstract

Patients undergoing cardiopulmonary bypass (CPB) require anticoagulation with heparin to avoid thrombosis within the bypass circuit. The common method used to monitor the degree of anticoagulation is the activated clotting time (ACT). We evaluated a novel point of care device, the TAS (Pharmanetics, Raleigh, NC, USA) heparin management test (HMT), for its suitability in monitoring anticoagulation during CPB. In vitro analysis showed a dose-response (r ²=0.988) of the HMT from 0.078-10.0 U/ml heparin, covering the range of heparin used during cardiac surgery (2-5 U/ml). Fifty randomly selected patients undergoing CPB were studied. Preheparin clotting times for these patients were 143±32 s for the HMT and 146±18 s for the ACT; 435±60 s HMT and 438±39 s ACT during CPB; 145±50 s HMT and 128±14 s ACT post-protamine (r ²=0.797). ε-Aminocaproic acid treatment for inhibition of fibrinolysis did not affect the HMT. We conclude that the HMT correlates well with the ACT and may be useful for monitoring heparin during CPB. Advantages of the HMT are small sample volume and good sensitivity to heparin.