A Comparison of Five Devices for the Bedside Monitoring of Heparin Therapy

Abstract

Five instruments were testedfor their capacity to monitor heparin therapy on whole blood at the bedside. The instruments were 512 Coagulation Monitor (Ciba-Corning), Thrombotrack (Nycomed), Automated Coagulation Timer (Hemotec), Hemochron-ACT and Hemochron-APTT (International Technidyne Corporation). Fifty subjects with various levels of heparinisation were tested on each instrument and were also assayed for antithrombin Ill, fibrinogen, haematocrit, platelet count and plasma heparin level. The results were compared with a reference APTT performed on the Automated Coagulation Laboratory 300R (Instrumentation Laboratories). The Hemochron-ACT correlated least well. The Hemotec and Thrombotrack were unsuitable in a clinical setting because of pipetting requirements, although the Thrombotrack did correlate well with the reference parameters. The 512 Coagulation Monitor was the simplest to use, but its maximum response corresponded to the midpoint of the reference APTT therapeutic range. The Hemochron-APTT was simple to use, had an adequate response range and correlated well with reference parameters.

The use of the activated clotting time for monitoring heparin therapy in critically ill patients

“…The use of laboratory aPTT results in significant turnaround times before dose adjustments can be made. Irrespective of this, the aPTT has a lack of correlation with high heparin plasma concentrations, making it unusable in situations such as cardio pulmonary bypass [7]. We cannot extrapolate our data using the Hemochron 401 to ACT measurements performed on other devices, as different mechanisms for clot detection are used.…”

“…However, it can also be used in patients who require lower levels of anticoagulation. Few comparative studies exist on the use of the ACT outside the coronary care units [7]. The purpose of this study was to determine the relationship between bedside ACT and laboratory aPTT values in a population of ICU patients receiving intravenous heparin therapy.…”

Extracorporeal Membrane Oxygenation in the Adult

“…[106][107][108] In contrast to the 400 to 480 second target for CPB, an ACT range of 180 to 220 seconds has been suggested for ECMO. [110][111][112][113][114] Therefore, ACT monitoring alone may not achieve consistent and appropriate anticoagulation monitoring for patients requiring ECMO. [110][111][112][113][114] Therefore, ACT monitoring alone may not achieve consistent and appropriate anticoagulation monitoring for patients requiring ECMO.…”

Two Instruments to Determine Activated Partial Thromboplastin Time: Implications for Heparin Monitoring

“…Such important differences were not obvious in most previous studies. [10][11][12][13][14][15][21][22][23][24][25] Since instrumentspecific APTT reference ranges for the TAS were not reported at our institution, values determined by the TAS were interpreted using the therapeutic range reported in the computer system. Assuming dosage adjustments would occur with APTTs outside the reported therapeutic range (61-93 sec), 9 (36%) of our patients could have received inappropriate dosage changes due to misinterpretation of anticoagulation intensity with whole blood analysis.…”

“…Although studies comparing portable heparin coagulometers and standard analytical equipment reported correlation coefficients of 0.57-0.96, it was determined that this comparison is not an adequate method to evaluate new methods of testing. [10][11][12][13][14][15][16][17] The correlation coefficient describes whether two methods produce related results. Instead, one should describe how closely the result by one method approximates that obtained by the other method.…”