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Evidence for complement activation by protamine-heparin interaction after cardiopulmonary bypass
Surgery
|September 1, 1985
Summary
Protamine administration after cardiopulmonary bypass activates the complement system via the classic pathway, evidenced by increased C4a levels. This finding suggests a link between complement activation and protamine
Area of Science:
- Immunology
- Cardiovascular Science
- Anesthesiology
Background:
- The alternate complement pathway is implicated in cardiopulmonary bypass (CPB) pathophysiology.
- Laboratory studies suggest protamine-heparin complexes activate the complement cascade.
- Clinical evidence is lacking regarding protamine's effect on complement activation in patients.
Purpose of the Study:
- To investigate whether protamine administration to patients receiving heparin activates complement.
- To assess complement activation via the classic pathway (C4a) following protamine administration post-CPB.
Main Methods:
- Studied 100 patients undergoing CPB, measuring C3a and C4a levels.
- Group I (90 patients): Protamine administered 5 minutes post-CPB.
- Group II (10 patients): Protamine withheld until 45 minutes post-CPB (skin closure).
Main Results:
- C4a levels remained stable during CPB in both groups.
- Protamine administration in Group I significantly increased C4a levels (459 to 1047 ng/dl; p < 0.001).
- Delayed protamine administration in Group II also led to a significant C4a increase (484 to 1090 ng/dl; p < 0.001).
- C3a analysis corroborated complement cascade activation.
Conclusions:
- Provides the first clinical evidence that protamine-heparin complexes activate complement via the classic (C4a) pathway.
- Suggests that hemodynamic effects of protamine post-CPB may be linked to complement activation.