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Low-dose protamine based on heparin-protamine titration method reduces platelet dysfunction after cardiopulmonary
O Shigeta1, H Kojima, Y Hiramatsu
1Division of Cardiovascular Surgery, Insitute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.
The Journal of Thoracic and Cardiovascular Surgery
|July 29, 1999
Summary
Reduced protamine doses in cardiac surgery preserve platelet function and reduce bleeding. This heparin-protamine titration method improves platelet aggregation and alpha-granule secretion after cardiopulmonary bypass.
Area of Science:
- Cardiovascular Surgery
- Hemostasis Management
- Platelet Physiology
Background:
- The heparin-protamine titration method using the Hepcon system has shown reduced blood loss in cardiac surgery.
- The precise mechanism by which this method reduces blood loss, particularly concerning platelet function, remains incompletely understood.
Purpose of the Study:
- To investigate the hypothesis that reduced protamine administration, guided by heparin-protamine titration, preserves platelet function during human cardiac surgery.
- To elucidate the impact of optimized protamine dosing on platelet alpha-granule secretion and aggregation responses.
Main Methods:
- Evaluation of platelet count, alpha-granule secretion (CD62P expression), and aggregation to thrombin before and after cardiopulmonary bypass.
- Comparison between a control group receiving a fixed protamine dose (3 mg/kg) and a titration group where protamine dose was determined by Hepcon system measurements.
- Protamine infusion rate standardized at 0.3 mg.kg(-1).min(-1) for both groups.
Main Results:
- The titration group required significantly lower protamine doses compared to the control group.
- Platelets in the control group showed significantly higher activation (CD62P expression) during protamine infusion compared to the titration group.
- Platelet aggregation to thrombin recovered to near preoperative levels in the titration group post-administration, but remained significantly lower in the control group.
Conclusions:
- Low-dose protamine administration, guided by heparin-protamine titration, effectively restores platelet function and coagulation after heparin neutralization.
- This method attenuates excessive platelet alpha-granule secretion, unlike higher protamine doses which can activate platelets.
- Optimizing protamine dosage is crucial to prevent platelet activation and reduce the risk of excessive bleeding post-cardiac surgery.