A four-year experience with patient individualized heparin and protamine dosing using the Hemochron RxDx system

Cardiac surgical case histories, collected over 4 years at Huntsville Hospital in Alabama, were reviewed for 2,293 patients. Patients were separated into two dosing groups for both heparin and protamine, hospital empirically dosed and Hemochron RxDx dosed. Review of the heparin dosing information found that incomplete data were collected for 47 patients, leaving 2,246 patients eligible to be evaluated for heparin dose comparison. Both RxDx recommended and empirically calculated doses were recorded, as well as the actual dose given. Of the 2,246 patients, 1671 were administered heparin according to the RxDx calculated dose, and the remaining 575 patients were dosed according to the hospital's empirical protocol. The average RxDx calculated heparin dose was 17% greater then the empirically calculated heparin dose (350 U/kg) (p < .001). Anticoagulation to target ACT (480 sec) was achieved in 92% of the patients dosed according to the RxDx recommended dose; whereas, in the empirically dosed patient group only 80% of the patients reached the target ACT after initial heparin bolus dose. Incomplete protamine dosing data was recorded for 336 patients, leaving a total of 1,957 patients available for protamine dose evaluation. All patients had an RxDx protamine calculation, empirical protamine calculation, and actual amount of protamine dosed recorded. Of the 1,953 patients, 1,764 were dosed according to the RxDx recommended dose, with the remaining 189 patients dosed empirically (1 mg protamine/100 U of heparin). In both the RxDx and the empirical groups, 96% of the patients returned to baseline following initial protamine infusion. The overall RxDx dose (293 mg) was 16% lower than the average empirical dose (348 mg). The RxDx system has been shown to be an effective method for determining patient-specific dosing for both heparin and protamine. This long-term clinical experience demonstrates the consistency and reliability of patient maintenance using this individualized dosing system, which has been shown, in other independent evaluations, to lead to improved patient outcomes.