MONITORING THE EFFECTS OF HEPARIN - EVALUATION OF A NEW PORTABLE DEVICE

The aim of this study was to measure the effects of heparin therapy in patients undergoing Vascular surgery, and to monitor the effectivenes s of continuous intravenous heparin therapy in ward-based patients. In addition, we compared results from a new portable device with those f rom the standard laboratory assay. A prospective comparison of the two methods in patients undergoing peripheral vascular surgery, and in wa rd-based patients who were receiving intravenous heparin infusions was undertaken, Fifty patients who were undergoing vascular surgery and r eceiving a bolus dose of intravenous heparin, and 22 patients receivin g a continuous heparin infusion, were recruited. Blood samples were ta ken 10 and 40 min following bolus heparin administration or after > 12 h of a continuous heparin infusion. Plasma activated partial thrombopl astin times (APTTp) measured by the haematology laboratory were compar ed with whole blood (APTT(B)) ascertained with the CoaguChek Plus Devi ce (Boehringer Mannheim UK Diagnostics and Biochemicals Limited) at ea ch time point. The results from the two methods were compared using th e method of Bland and Altman (Lancet, 1986, 307-310). We found a good level of agreement between the two methods (at induction, mean bias wa s -0.050, limits of agreement -0.46-0.36: heparin infusions. mean bias was -0.283, limits of agreement -1.64-1.07). In addition we discovere d that many of our patients appeared to be excessively anticoagulated during surgery (10 min following heparin bolus 47/50 patients had an A PTT(B) > 150 s, 45/50 had an APTTp > 250 s; at 40 min 45/50 had an APT T(B) > 150 s, 39/50 had an APTTp > 250 s), In conclusion, whole blood APTT measurement allows rapid and accurate assessment of the effects o f heparin therapy when compared with laboratory APTT measurement and m ay prevent both excessive and suboptimal anticoagulation. (C) 1998 The International Society for Cardiovascular Surgery. Published by Elsevi er Science Ltd. All rights reserved.