Changes in the Relationship Between Plasma Fibrinogen Concentration and Functional Clot Strength After Cardiopulmonary Bypass: A Retrospective Observational Study.

OBJECTIVE

To evaluate whether the relationship between plasma fibrinogen concentration (Clauss method) and functional fibrinogen activity as measured by viscoelastic hemostatic assays (VHAs)- thromboelastography-derived citrated functional fibrinogen (CFF) and Quantra-derived fibrinogen contribution to clot stiffness (FCS)-changes before and after cardiopulmonary bypass (CPB).

DESIGN

A single-center retrospective observational study.

SETTING

Cardiovascular surgery center in Japan.

PARTICIPANTS

208 adult patients undergoing cardiovascular surgery with CPB.

INTERVENTIONS: No intervention.

MEASUREMENTS AND MAIN

RESULTS

Fibrinogen function was assessed at 3 time points: before CPB (T1), immediately after protamine administration (T2), and 1 hour later (T3). CFF (n = 170) and FCS (n = 79) values, along with plasma fibrinogen concentrations, were collected. For CFF, the regression slope against Clauss fibrinogen increased from 6.12 at T1 to 8.69 at T2 (p < 0.05), then returned to 6.58 at T3. The intercept decreased significantly at T2 (from 0.29 to -8.39), indicating enhanced clot strength per unit of fibrinogen. For FCS, the slope decreased from 1.66 at T1 to 0.61 at T2 and 0.72 at T3, and the intercept increased from -3.55 to -0.32, suggesting persistently reduced fibrinogen contribution post-CPB. Conventional tests showed prolonged prothrombin time/activated partial thromboplastin time, decreased hemoglobin and platelet counts, and elevated thrombin antithrombin complex, fibrin/fibrinogen degradation products, and D-dimer levels, indicating coagulation factor consumption and thrombin generation.

CONCLUSIONS

The association between fibrinogen concentration and functional clot strength changes significantly after CPB, with contrasting trends in TEG and Quantra. These findings highlight qualitative fibrinogen alterations post-CPB, suggesting that concentration alone might not reflect true coagulative function.