Heparin concentration-based anticoagulation for cardiac surgery fails to reliably predict heparin bolus dose requirements.
BACKGROUND
Hemostasis management has evolved to include sophisticated point-of-care systems that provide individualized dosing through heparin concentration-based anticoagulation. The Hepcon HMS Plus system (Medtronic, Minneapolis, MN) estimates heparin dose, activated clotting time (ACT), and heparin dose response (HDR). However, the accuracy of this test has not been systematically evaluated in large cohorts.


METHODS
We examined institutional databases for all patients who underwent cardiac surgery with cardiopulmonary bypass (CPB) at our institution from February 2005 to July 2008. During this period, the Hepcon HMS Plus was used exclusively for assessment of heparin dosing and coagulation monitoring. Detailed demographic, surgical, laboratory, and heparin dosing data were recorded. ACT, calculated and measured HDR, and heparin concentrations were recorded. Performance of the Hepcon HMS Plus was assessed by comparison of actual and target ACT values and calculated and measured HDR.


RESULTS
In 3880 patients undergoing cardiac surgery, heparin bolus dosing to a target ACT resulted in wide variation in the postheparin ACT (r(2) = 0.03). The postheparin ACT did not reach the target ACT threshold in 7.4%(i.e., when target ACT was 300 s) and 16.9% (i.e., when target ACT was 350 s) of patients. Similarly, the target heparin level calculated from the HDR did not correlate with the postbolus heparin level, with 18.5% of samples differing by more than 2 levels of the assay. Calculated and measured HDR were not linearly related at any heparin level.


CONCLUSIONS
The Hepcon HMS Plus system poorly estimates heparin bolus requirements in the pre-CPB period. Further prospective studies are needed to elucidate what constitutes adequate anticoagulation for CPB and how clinicians can reliably and practically assess anticoagulation in the operating room.
Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215, USA.
Sean
S
Garvin
Daniel C
DC
FitzGerald
George
G
Despotis
Prem
P
Shekar
Simon C
SC
Body
D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage*; D006348:Cardiac Surgical Procedures / Q000592:standards*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006489:Hemostatic Techniques / Q000295:instrumentation / Q000592:standards*; D006493:Heparin / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D017211:Treatment Failure; D014914:Whole Blood Coagulation Time / Q000592:standards
D000925:Anticoagulants; D006493:Heparin