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The protein C system in patients undergoing cardiopulmonary bypass
Insights
Extracorporeal circulation during bypass grafting activates coagulation and significantly depletes protein C levels. This protein C system disturbance may explain increased bleeding risks in patients undergoing such cardiac surgeries.
Area of Science:
- Cardiovascular Surgery
- Hemostasis and Thrombosis
- Clinical Biochemistry
Background:
- Extracorporeal circulation (ECC) is used in cardiac surgery.
- Patients undergoing ECC often experience bleeding complications.
- The impact of ECC on coagulation factors needs further elucidation.
Purpose of the Study:
- To investigate plasma level alterations of key hemostatic proteins during ECC.
- To assess the effect of ECC on the protein C system.
- To correlate observed changes with bleeding tendencies.
Main Methods:
- Plasma levels of cross-linked fibrin degradation products, protein C, protein S, factor II, IgG, and albumin were measured.
- Ratios of protein C, S, and factor II to IgG were used for volume correction.
- Measurements were taken during ECC, after reperfusion, and postoperatively.
Main Results:
- Cross-linked fibrin degradation products increased, indicating coagulation activation.
- Protein C levels significantly decreased during late ECC and postoperatively.
- Protein S levels initially increased then decreased, while factor II remained largely unaffected.
Conclusions:
- ECC significantly disturbs the protein C system.
- This disturbance may contribute to the increased bleeding risk associated with ECC.
- Further research into managing hemostasis during ECC is warranted.
Abstract:
Fifteen men undergoing extracorporeal circulation for aorta-coronary bypass grafting were investigated for alterations of the plasma levels of cross-linked fibrin degradation products, protein C, free protein S, coagulation factor II, immunoglobulin G, and albumin. Although all patients were given heparin, a progressive increase of cross-linked fibrin degradation products was recorded during extracorporeal circulation, which indicates an activation of the plasmatic coagulation system. This increase was most pronounced in the late phase of extracorporeal circulation after reperfusion of the lung and in the early postoperative period. The levels of all other investigated plasma proteins decreased drastically after the patient was connected to the bypass circuit, which was primed with saline solution. These levels increased after termination of extracorporeal circulation and administration of fresh-frozen plasma. To study the consumption of protein C, protein S, and factor II during extracorporeal circulation, we formed ratios of the values of these parameters to the value of immunoglobulin G. After this volume correction, protein C was found to decrease significantly in the late phase of extracorporeal circulation, remaining low in the early postoperative period; protein S increased significantly soon after the onset of extracorporeal circulation and decreased after termination of extracorporeal circulation; factor II was unaffected by extracorporeal circulation, showing only a slight, insignificant increase in the postoperative phase. These results suggest a disturbance of the protein C system by extracorporeal circulation, which is possibly linked to the reported high bleeding tendency in patients undergoing operations with extracorporeal circulation.